Publications

(166) Acta Materialia, 215, 117068 (Q1, IF = 8.203)

Revealing DeNOx and DeVOC Reactions via the Study of the Surface and Bandstructure of ZnSn(OH)6 Photocatalysts   Minh-Thuan Pham, Hong-Huy Tran, Truc-Mai T. Nguyen, Dai-Phat Bui, Yu Huang, Junji Cao, Sheng-Jie You, Pham Van Viet, Vu Hoang Nam, Ya-Fen Wang                                                                                                                 Abstract: Photocatalytic materials present a robust approach in tackling pollutants in the air. However, the involving reactions and their associated toxicity, those are important for practical implications, have not been sufficiently reported. Here, we synthesize ZnSn(OH)6 and control its morphology by changing NaOH's dosage in a one-step hydrothermal growth. Combining results from density functional theory and experimentation, we initiatively show the roles of exposed facets, oxygen defects, metal terminated surface, and bandstructure of ZnSn(OH)6. By carefully characterizing reactions during DeNOx and DeVOC processes, this work enables a comprehensive understanding of photocatalytic activity against pollution of nitric oxide and VOCs. Also, a new systematic calculation of the apparent DeNOx index is introduced for evaluating the total toxicity. The trapping experiments reveal a balance in the involvement of e–, h+, •OH radicals in the photocatalytic DeNOx and DeVOC. Thus, our findings would enable an important understanding of addressing air pollution using high-performance photocatalysts and proper evaluation of total toxicity.    Read more...Require Full Article

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(165) Photonics and Nanostructures-Fundamentals and Application, Accepted (Q2, IF = 3.008)

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(164) Ceramics International, 48, 2, 2605-2613 (Q1, IF = 4.527)

Relaxation of residual stress-controlled thermopower factor in transparent-flexible Ti-doped ZnO thin films Dai Cao Truong, Somporn Thaowonkaew, Pennapa Muthitamongkol, Mati Horprathum, Manish Kumar, Thu Bao Nguyen Le, Anh Tuan Thanh Pham, Tosawat Seetawan, Athorn Vora-ud and Thang Bach Phan                                                                                                                 Abstract: Transparent-flexible thermoelectric materials are attractive for future small-sized consumer electronics, the internet of things, and wearable devices. The microstructural evolution and subsequent thermoelectric properties of Ti 1%.at-doped ZnO thin films, grown on polyimide flexible substrates, are presented. The thin films were grown using radio frequency a magnetron sputtering method followed by annealing for 60 min at temperatures of 200–400 °C under vacuum atmosphere. Post-annealed films demonstrate a hexagonal Wurtize structure. It is found that the annealing helped to relax residual stresses in the thin films, subsequently leading to enhanced charge concentration, carrier mobility, mean free path, and density-of-states effective mass. The thin film, annealed at 300 °C, illustrates the highest power factor of the films measured at room temperature at 19.10 μW m−1 K−2. Further increases in the annealing temperature suggest Ti2+ diffuses into the ZnO lattice and in turn disturbs the crystalline structure; this results in a reduction of the power factor to 9.32 μW m−1 K−2 at an annealing temperature of 350 °C.   Read more...Require Full Article

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(163) Journal of Physics: Conference Series (JPCS), 2013, 012008 (Scopus)

Dependence of mechanical and electrical properties on crystal orientation of CuCr0.95Mg0.05O2 ceramics   Dung Van Hoang, Anh Tuan Thanh Pham, Truong Huu Nguyen, Dai Cao Truong, Ngoc Kim Pham, Hanh Kieu Thi Ta, Vinh Cao Tran, Thang Bach Phan                                                                                                                 Abstract: Mg-doped CuCrO2 material has emerged as a p-type semiconductor, especially, in the field of thermoelectric materials because of its lowest resistivity in delafossite material family. In this work, CuCr0.95Mg0.05O2 bulk materials were prepared in a series of sintering temperatures including 1000, 1200, and 1400°C using solid-state reaction method. From XRD results, all samples exhibit the significant existence of delafossite phase CuCrO2, and a small portion belongs to the spinel phase MgCr2O4. An interesting finding in this study is that the Vickers hardness is mainly governed by the crystallite size of (110) plane. Besides, the change in the crystallite size of (110) plane also indirectly affects the carrier concentration of the compounds with increasing sintering temperature. The highest power factor (PF) was reached for the sample prepared at the sintering temperature 1400°C with the value of 193 μW/mK2 along with the Seebeck coefficient value of 600 μV/K measured at 400°C.   Read more...Require Full Article

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(162) Microporous and Mesoporous Materials, 327, 111445 (Q1, IF = 5.455)  

Zeolitic Imidazolate Frameworks as an Efficiently Platform for Potential Curcumin-Based On/Off Fluorescent Chemosensor Duyen Thi Nguyen, Linh Dang Tran Nguyen, Tri Minh Le, Tan Le Hoang Doan, Linh Ho Thuy Nguyen                                                                                                                   Abstract: ZIF-8 and ZIF-11 nanomaterials were synthesized by using surfactant and cold centrifugation with size below 100 nm and analyzed for structure, morphology and properties by methods such as: PXRD, TGA, N2, FT-IR, and SEM. The curcumin adsorption process on ZIF-8 and ZIF-11 materials showed the influence of the surface area and polarity of organic linker on the adsorption activity. The strong interaction between the ZIF system and curcumin demonstrated in the curcumin release experiment is the basis for the curcumin sensor system on the carrier to capture fluoride ions.   Read more... Require Full Article

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(161) Polymer, 13(18), 3116  (Q1, IF = 4.329)

The efficacy of silver-based electrospun antimicrobial dressing in accelerating the regeneration of partial-thickness burn wounds  using a porcine model Do Thien Nguyen, Tien Ho Minh, Do Thai Nguyen, Nghi Vo Dai, Hua Ha, Phan Thang, Tran Phong, Nguyen Hoai, Vo Van Toi, Nguyen, Thi-Hiep                                                                                                                      Abstract: (1) Background: Wounds with damages to the subcutaneous are difficult to regenerate because of the tissue damages and complications such as bacterial infection. (2) Methods: In this study, we created burn wounds on pigs and investigated the efficacy of three biomaterials: polycaprolactone-gelatin-silver membrane (PCLGelAg) and two commercial burn dressings, Aquacel® Ag and UrgoTulTM silver sulfadiazine. In vitro long-term antibacterial property and in vivo wound healing performance were investigated. Agar diffusion assays were employed to evaluate bacterial inhibition at different time intervals. Minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and time-kill assays were used to compare antibacterial strength among samples. Second-degree burn wounds in the pig model were designed to evaluate the efficiency of all dressings in supporting the wound healing process. (3) Results: The results showed that PCLGelAg membrane was the most effective in killing both Gram-positive and Gram-negative bacteria bacteria with the lowest MBC value. All three dressings (PCLGelAg, Aquacel, and UrgoTul) exhibited bactericidal effect during the first 24 h, supported wound healing as well as prevented infection and inflammation. (4) Conclusions: The results suggest that the PCLGelAg membrane is a practical solution for the treatment of severe burn injury and other infection-related skin complications.   Read more... Require Full Article

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(160) Chem. Commun., 49, 3706-3708 (Q1, IF = 4.914)

Microwave-assisted solvothermal synthesis of defective zirconium-organic framework as a recyclable nano-adsorbent with superior adsorption capacity for efficient removal of toxic organic dyes Linh Ho Thuy Nguyen, Hue Thi Thu Nguyen, Bao Quang Gia Le, Minh-Huy Dinh Dang, Trang Thi Thu Nguyen, Ngoc Xuan Dat Mai, Tan Le Hoang Doanm                                                                                                                   Abstract: Herein, the Zr-based metal–organic framework nanomaterial was successfully and rapidly synthesized by microwave method to serve as a new recyclable adsorbent. According to the material characterization, Zr-NDC with a particle size of 100 nm was a highly defective framework due to the missing linkers during the synthesis. The MOF showed excellent efficiency with low cost for adsorption of organic dyes, methylene blue and methyl orange, because of its superior maximum capacity (746 and 726 mg g−1, respectively) and reusability over several cycles of the adsorption. From results of adsorption studies, the high adsorption activity of Zr-NDC can be attributed to the defect sites in the framework and its physisorption character towards the dyes.   Read more... Require Full Article

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(159) Sensors and Actuators B: Chemical, 349, 130741  (Q1, IF = 7.46)

Facile synthesis of metal-organic framework-derived ZnO/CuO nanocomposites for highly sensitive and selective H2S gas sensing Tan Le Hoang Doan, Jin-Young Kim, Jae-Hyoung Lee, Linh Ho Thuy Nguyen, Hue Thi Thu Nguyen, Anh Tuan Thanh Pham, Thu Bao Nguyen Le, Ali Mirzaei, Thang Bach Phan and Sang Sub Kim                                                                                                              Abstract: ZnO/CuO nanocomposites were derived from a metal-organic framework (MOF) using a simple precipitation method. The mesoporous nature, crystallinity, and fine particle size of the synthesized ZnO/CuO nanocomposites varied with CuO amounts, affecting the gas sensing ability of different gases (H2S, CO, C6H6, and C7H8 gases). It was found that the ZnO/CuO (40 mol%) gas sensor showed the highest sensing capacity in terms of response, selectivity, and repeatability on low concentrations of H2S gas (10 ppm). The strong sensing performance, short response time (58 s) and recovery time (273 s) were explained in terms of the texture coefficients (phase percentage, crystal size, and crystallinity) of the ZnO and CuO phase compositions, resulting in the formation of a high number of p-n junctions and quantum confinement effects in the nanocomposite, as well as the lower binding energy of H2S. The fast sensing ability of a low H2S concentration highlights the practical importance of these MOF-derived ZnO/CuO nanocomposites.   Read more... Require Full Article

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(158) Sensors and Actuators B: Chemical, 348, 130684  (Q1, IF = 7.46)

Preparation of n-ZnO/p-Co3O4 heterojunctions from zeolitic imidazolate frameworks (ZIF-8/ZIF-67) for sensing low ethanol concentrations Tan Le Hoang Doan, Jin-Young Kim, Jae-Hyoung Lee, Linh Ho Thuy Nguyen, Y Thi Dang, Kim-Binh Thi Bui, Anh Tuan Thanh Pham, Ali Mirzaei, Thang Bach Phan, Sang Sub Kim                                                                                                            Abstract: Nano-heterojunctions of n-ZnO/p-Co3O4 with varying molar ratios of Co3O4 derived from a zeolitic imidazolate framework (ZIF-8/ZIF-67) were efficiently synthesized and well-characterized. The heterojunction-based gas sensors were then used for sensing various gases, including ethanol. Owing in part to the ZIF-8/ZIF-67 structure, the calcined n-ZnO/p-Co3O4 with 30 mol% Co3O4 was the best sensor, in-terms of high response, outstanding selectivity, and good repeatability for low concentrations of ethanol at 300 °C. According to detailed analysis, the high ethanol-sensing performance of the n-ZnO/p-Co3O4 nanocomposite could be attributed to the high porosity of sensing materials, formation of p-n heterojunction at interfaces, the catalytic ability of Co3O4, and the high crystallinity of the ZnO phase in the nano-heterojunctions.   Read more...Require Full Article

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(157) ACS Applied Energy Materials, 9, 8910  (Q1, IF = 6,024)

Spatially Controlled Photogenerated Charge Carriers Induced by SrTiO3-Architectured Heterojunction Nanocubes for a Photocatalytic Hydrogen Evolution Reaction Trang Ton Nu Quynh, Tran Van Man, Phan Bach Thang, Thu Vu Thi Hanh                                                                                                            Abstract: Effective charge separation and transfer of photoinduced electron (e–)–hole (h+) pairs in a perovskite photocatalyst, namely, SrTiO3 (STO), are crucial factors for a highly effective and durable photocatalytic hydrogen evolution reaction (HER). Herein, we develop a highly efficient pathway based on a semiconductor–metal heterostructured photocatalyst, in which Ir-doped (STO) nanocubes loaded with Ag nanoparticles are prepared by two facile approaches for water splitting driven by visible-light irradiation. This strategy was easily accessible to highly enhanced photocatalytic HER activities by (i) Ir3+ doping in the forbidden gap of STO nanocubes for broadening the light absorption wavelengths up to 730 nm and (ii) incorporating Ag nanoparticles for controlling the electron-hole transportation at the interface and developing active reaction sites. Remarkably, the as-synthesized Ag/Ir/STO showed apparent quantum efficiencies of up to 0.17% and 0.06% under UV light and 420 nm illumination, respectively, which are 7.4-, 2-, and 1.6-fold higher than those of bare STO, binary Ag/STO, and Ir/STO, respectively. It also possessed outstanding stability in the photocatalytic process after four cycling tests. This work provides a rational design of a metal cocatalyst–semiconductor channel for enhancing the photocatalytic HER under visible light..   Read more... Require Full Article

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(156) J. Industrial and Engineering Chemistry, 103, 340-347 (Q1, IF =6,064)

Using sulfate-functionalized Hf-based metal-organic frameworks as a heterogeneous catalyst for solven-free synthesis of pyrimido[1,2-a]benzimidazoles via one-pot three-component reaction Minh-Huy Dinh Dang, Linh Ho Thuy Nguyen, Trang Thi Thu Nguyen, Ngoc Xuan Dat Mai, Phuong Hoang Tran, Tan Le Hoang Doan                                                                                                            Abstract: Functionalized metal-organic frameworks have recently received significant attention in heterogeneous catalysis applications due to their high catalytic activity. In this work, a sulfate-functionalized Hf-cluster-based metal-organic framework was prepared via sulfation of a Hf-MOF, named Hf-BTC, constructed by Hf6 clusters and 1,3,5-tricarboxylate linkers. The Hf-BTC-SO4 material was consequently demonstrated to be an efficiently reusable superacid catalyst for a one-pot three-component reaction of pyrimido[1,2-a]benzimidazoles synthesis. The reaction catalyzed by the sulfated Hf-BTC could be carried out under mild and solvent-free conditions and give superior performance in a wide range of substrates. According to detailed investigation, the good catalytic performance of the sulfated-functionalized MOF likely originates from the high-porosity framework and the high active sites of the functionalized clusters. Importantly, the catalyst could be easy to recover and reuse the functionalized framework several times with minor changes in catalytic efficiency.   Read more... Require Full Article

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(155) Scientific Reports, 11, 14192  (Q1, IF = 4,379)

Iodine containing porous organosilica nanoparticles trigger tumor spheroids destruction upon monochromatic X-ray irradiation: DNA breaks and K-edge energy X-ray Yuya Higashi, Kotaro Matsumoto, Hiroyuki Saitoh, Ayumi Shiro, Yue Ma, Mathilde Laird, Shanmugavel Chinnathambi, Albane Birault, Tan Le Hoang Doan, Ryo Yasuda, Toshiki Tajima, Tetsuya Kawachi, Fuyuhiko Tamanoi                                                                                                            Abstract: X-ray irradiation of high Z elements causes photoelectric effects that include the release of Auger electrons that can induce localized DNA breaks. We have previously established a tumor spheroid-based assay that used gadolinium containing mesoporous silica nanoparticles and synchrotron-generated monochromatic X-rays. In this work, we focused on iodine and synthesized iodine-containing porous organosilica (IPO) nanoparticles. IPO was loaded onto tumor spheroids and the spheroids were irradiated with 33.2 keV monochromatic X-ray. After incubation in CO2 incubator, destruction of tumor spheroids was observed which was accompanied by apoptosis induction, as determined by the TUNEL assay. By employing the γH2AX assay, we detected double-strand DNA cleavages immediately after the irradiation. These results suggest that IPO first generates double-strand DNA breaks upon X-ray irradiation followed by apoptosis induction of cancer cells. Use of three different monochromatic X-rays having energy levels of 33.0, 33.2, and 33.4 keV, as well as X-rays with 0.1 keV energy intervals, showed that the optimum effect of all three events (spheroid destruction, apoptosis induction, and generation of double-strand DNA breaks) occurred with a 33.2 keV monochromatic X-ray. These results uncover the preferential effect of K-edge energy X-ray for tumor spheroid destruction mediated by iodine-containing nanoparticles.   Read more... Require Full Article

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(154) RSC Advances, 11, 22450-22460  (Q1, IF = 3,361)

Ultrasensitive biosensors based on waveguide-coupled long-range surface plasmon resonance (WC-LRSPR) for enhanced fluorescence spectroscopy Nhu Hoa Thi Tran, Viet-Duc Phung, Hanh Kieu Thi Ta, Vu Dinh Lam, Do Hung Manh, Ngoc Kim Pham, Jae Young Kim, Nae Yoon Lee, Bach Thang Phan                                                                                                            Abstract: We investigated the coupling phenomenon between plasmonic resonance and waveguide modes through theoretical and experimental parametric analyses on the bimetallic waveguide-coupled long-range surface plasmon resonance (Bi-WCLRSPR) structure. The calculation results indicated that the multi-plasmonic coupling gives rise to the enhanced depth-to-width ratio of the reflection dip compared to that of LRSPR excited using a single set of Ag and Teflon. The optimized thickness of Ag(40 nm)/Teflon(700 nm)/Ag(5 nm)/Au(5 nm) was obtained and generated the highest plasmon intensity enhancement, which was 2.38 folds in comparison to the conventional bimetallic surface plasmon resonance (SPR) configuration (Ag/Au). 17β-Estradiol was used in the fluorescence enhancement experiment by the reflection geometry-based system, wherein the excitation light source was on the side of a WC-LRSPR chip opposite to that of the light detection unit. The phenomenon of surface plasmon-couple emission (SPCE) depends on the number of 17β-estradiol molecule promoters from female sex steroid hormones, which demonstrated a limit of detection (LOD) of 2 pg mL−1 and 1.47-fold fluorescence improvement as compared to the non-coated material on the surface of pristine glass. This enhanced WC-LRSPR can readily find application in fluorescence escalation needed in cases where a weak fluorescence signal is predicted, such as the small volume of liquid containing fluorescent dyes in biological diagnosis.   Read more... Require Full Article

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(153) J. Science: Advanced Materials and Devices, In Press (Q1, IF = 5,496)

Effect of Hydrogen-Bonding Networks of Water on Temperature and Relative Humidity Dependence of Proton Conductivity in Metal-Organic Frameworks My V. Nguyen, Hieu C. Dong, Duc Nguyen-Manh, Nam H. Vu, Thuat T. Trinh and Thang B. Phan                                                                                                            Abstract: We study the proton conductivity properties of MOF-801. We find that MOF-801 possesses intrinsic proton carrier sites, μ3-OH groups, in clusters yielding the generation of hydrogen-bonding networks with guest water molecules at high relative humidity (RH), facilitating proton transport. Remarkably, this material has a high proton conductivity of 1.82 × 10−3 S cm−1 under 98% RH at 90 °C and maintains its performance over an extended time. Our investigations reveal that the increase in proton conductivity is correlated to numerous hydrogen bonds within the MOF structure. The activation energy of this process is low (Ea = 0.21 eV), showing that the protons hop through the membrane by the Grotthus mechanism. Interestingly, density functional theory (DFT) calculations combined with molecular dynamics (MD) simulations show that a water cluster mechanism dominates the proton conductivity in this material via the large number of hydrogen bonds formed at different temperatures and relative humilities.   Read more... Require Full Article

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(152) Materials Science and Engineering C, 127, 112232 (Q1, IF = 7,328)

Tailoring chemical composition of biodegradable mesoporous organosilica nanoparticles for controlled slow release of chemotherapeutic drug Ngoc Xuan Dat Mai, Thu-Ha Thi Nguyen, Long Binh Vong, Minh-Huy Dinh Dang, Trang Thi Thu Nguyen, Linh Ho Thuy Nguyen, Hanh Kieu Thi Ta, Thi-Hiep Nguyen, Thang Bach Phan and Tan Le Hoang Doan                                                                                                            Abstract: Biodegradable periodic mesoporous organosilica nanoparticles (B-PMO) are an outstanding nanocarrier due to their biodegradability and high drug load capacities. The present study describes a synthesis of a phenylene-containing tetrasulfide based B-PMO, named P4S. The incorporation of aromatic phenylene groups into the framework creates a strong interaction between nanoparticles (NPs) with aromatic rings in the cordycepin molecules. This results in the low release profile under various conditions. In addition, the replacement of this linker slowed the degradation of nanoparticles. The physicochemical properties of the nanoparticles are evaluated and compared with a biodegradable ethane-containing tetrasulfide based PMO and a non-degradable MCM-41. The biodegradability of P4S is also demonstrated in a reducing environment and the 100 nm spherical nanoparticles completely decomposed within 14 days. The porous structure of P4S has a high loading of hydrophilic cordycepin (approximately 731.52 mg g−1) with a slow releasing speed. The release rates of P4S NPs are significantly lower than other materials, such as liposomes, gelatin nanoparticles, and photo-crosslinked hyaluronic acid methacrylate hydrogels, in the same solution. This specific release behavior could guarantee drug therapeutic effects with minimum side-effects and optimized drug dosages. Most importantly, according to the in vitro cytotoxicity study, cordycepin-loaded P4S NPs could retain the toxicity against liver cancer cell (HepG2) while suppressed the cytotoxicity against normal cells (BAEC).   Read more... Require Full Article

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(151) J. Biomedical Materials Research: Part A, 2021, 1-11 (Q1, IF = 4,396)

Investigating the effect of multi-coated hydrogel layer on characteristics of electrospun PCL membrane coated with gelatin/silver nanoparticles for wound dressing application Tien Nguyen, Thien Do, Minh Ho, Nam Tran, Nhi Dang, Thai Do, Hoai Nguyen, Thang Phan, Quyen Tran, Toi Vo, Hiep Nguyen                                                                                                            Abstract: In this study, the effect of coated hydrogel layer on characteristics of the whole gelatin/silver nanoparticles multi-coated polycaprolactone membrane (PCLGelAg) was investigated through systematic and typical wound dressing characterizations to select the optimal number of layers for practical applications. Scanning electron microscopy, free swell absorptive capacity and tensile test in both wet and dry conditions were conducted to characterize all fabricated membranes of six coating times. In vitro cytotoxicity and agar diffusion evaluation were also carried out to assess the biocompatibility and antibacterial activity of the membranes. The findings illustrated that as the coated layers increase, the absorptive capacity, and degradation rate were higher, the membranes were stiffer in dry state while the tensile strength in wet state, elongation, and cell viability were significantly decreased. PCLGelAg3 was chosen to be the best fit for wound healing since it maintained quite sufficient maximum buffer uptake, elasticity, cell viability along with inducing abnormalities in bacterial morphology and preventing biofilm formation.                                                                                          Read more... Require Full Article

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(150) Nanotechnology, 32, 335505 (Q1, IF = 3,874)

Development of a highly sensitive sensor chip using optical diagnostic based on functionalized plasmonically active AuNPs Huong Vu Thi, Ta Hanh Kieu Thi, Mai Ngoc Xuan Dat, Tran Thi Thanh Van, Xuan Khuyen Bui, Trinh Kieu The Loan, Lee Nae Yoon, Phan Bach Thang, Nhu Hoa Thi Tran                                                                                                            Abstract: Measuring solution concentration plays an important role in chemical, biochemical, clinical diagnosis, environmental monitoring, and biological analyses. In this work, we develop a transmission-mode localized surface plasmon resonance sensor chip system and convenient method which is highly efficient, highly sensitive for detection sensing using multimode fiber. The plasmonically active sensor's surface AuNPs with high-density NPs were decorated onto 1 cm sensing length of various clad-free fiber in the form of homogeneous monolayer utilizing a self-assembly process for immobilization of the target molecule. The carboxyl bond is formed through a functional reaction on the sensor head. Using the significance in the refractive index difference and numerical aperture, which is caused by a variation in the concentration of measuring bovine serum albumin (BSA) protein which can be accurately measured by the output signal. The refractive index variation of the medium analyte layer can be converted to signal output power change at the He-Ne wavelength of 632.8 nm. The sensor detection limit was estimated to be 0.075 ng ml-1for BSA protein which shows high sensitivity compared to other types of label-free optical biosensors. This also leads to a possibility of finding the improvement in the sensitivity label-free biosensors. The conventional method should allow multimode fiber biosensors to become a possible replacement for conventional biosensing techniques based on fluorescence.                                                                                                                              Read more... Require Full Article

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(149) J. Science: Advanced Materials and Devices, 3, 446-452 (Q1, IF = 5,496)

High-mobility sputtered F-doped ZnO films as good-performance transparent-electrode layers Nhut Minh Ngo, Oanh Kieu Truong Le, Truong Huu Nguyen, Dung Van Hoang, Thang Bach Phan, Vinh Cao Tran, Anh Tuan Thanh Pham                                                                                                            Abstract:  Point-defect engineering is an effective way to control the mobility and transparent-conducting performance of sputtered fluorine-doped ZnO (FZO) thin films. In this study, doping with fluorine (F) is accomplished through a simple one-step deposition process and is demonstrated to enhance the crystal quality, eliminate the point defects, and boost the mobility as well as the performance of the films. Furthermore, the films’ characteristics are observed to be strongly dependent on F content. At the optimum F content of 1%, the FZO films exhibited the best crystal quality and the lowest concentration of Zn interstitial and O vacancy defects due to F passivation. Moreover, a mobility as high as 45.3 cm2/V and the greatest figure-of-merit performance are achieved for cutting-edge transparent electrode applications. However, a further increase of F content brought about an increased concentration of defects relating to Zn vacancies, especially F interstitials, which yielded the low mobility and poor performance due to the degraded structure.    Read more... Require Full Article

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(148) Materials Letters, 297, 129995 (Q1, IF = 3,423)

Simple fabrication of a chitin wound healing membrane from Soft-Shell crab carapace Chau Ngoc-Hai Vo, Duyen Hong-My Do,Thang Bach Phan, Quyen Ngoc Tran, Toi Van Vo, Hiep Thi Nguyen                                                                                                            Abstract: A chitin wound healing membrane was extracted and minimally processed from soft-shell crab carapace, a fabrication method simpler than the conventional process of chemically modifying chitin into more soluble and bioactive derivatives. We observed an interesting difference between the topography of the membrane’s internal and external surface, which correlated with their different abilities to promote cell adhesion and proliferation. The internal surface was dotted with prickles where cells could adhere and elongate, while the smooth external surface demonstrated poor cell adhesion and proliferation. Applying the internal surface of the membrane onto the wound improved the epidermis surface homogeneity and accelerated epidermis-dermis re-attachment. This membrane also showed an excellent tensile strength of 105.7 ± 29.9 MPa and ultimate strain of 6.5 ± 4.2%, higher than those of common wound healing membranes from cellulose, and collagen. These results showed the ability of chitin membranes from soft-shell crab carapaces to support cell attachment, proliferation, and migration and its potential for further wound healing applications.                                                                                                                                         Read more... Require Full Article

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(147) Journal of Materiomics, In Press (Q1, IF = 6,425)

Hydrogen roles approaching ideal electrical and optical properties for undoped and Al doped ZnO thin films Dung Van Hoang, Nam Hoang Vu, Nga Do, Anh Tuan Thanh Pham, Truong Huu Nguyen, Jer-Lai Kuo, Thang Bach Phan and Vinh Cao Tran                                                                                                            Abstract: This paper distinguished hydrogen roles to improve electron mobility and carrier concentration in ZnO and Al doped ZnO sputtered films. By combining experimental evidences and theoretical results, we find out that hydrogen located at oxygen vacancy sites (HO) is the main factor gives rise to increase simultaneously mobility and carrier concentration which has not been mentioned before. Introducing appropriate hydrogen content during sputtering not only results in crystalline relaxation but also supports doping Al into ZnO, increasing carrier concentration and electron mobility in the film. First principles calculations confirmed hydrogen substitutional stability for oxygen vacancy, significantly reducing electron conductivity effective mass and hence increasing electron mobility. In particular, 0.8% hydrogen partial pressure ratio achieved 61 cm2V−1s−1 maximum electron mobility, optical transmittance above 82% in visible and near-infrared regions, and 2 × 1020 cm−3 carrier concentrations for Hsingle bondAl co-doped ZnO film. These values approach ideal electrical and optical properties for transparent conducting oxide films. The presence of one maximum electron mobility was attributed to competition between increasing mobility due to restoring effective electron mass and hydrogen passivation of native defects, and decreased electron mobility due to electron-phonon scattering.   Read more... Require Full Article

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(146) Dalton Transactions, 50, 6962-6974 (Q1, IF = 4,39)

Metal-enhanced sensing platform for the highly sensitive detection of C-reactive protein antibody and rhodamine B with applications in cardiovascular diseases and food safety Nguyen Thanh Thao, Thi Xoan Hoang, Thang Bach Phan, Jae Young Kim, Hanh Kieu Thi Ta, Kieu The Loan Trinh, and Nhu Hoa Thi Tran                                                                                                            Abstract: The potential applications of metal-enhanced fluorescence (MEF) devices include biosensors for the detection of trace amounts in biosciences, biotechnology, and pathogens that are relevant to medical diagnostics and food control. In the present study, the silver (Ag) film thickness (56 nm) of an MEF system was calibrated to maximize the depth-to-width ratio (Γ) of the surface plasmon resonance (SPR) active metal from reflectance dip curves. Upon plasmon coupling with thermally evaporated Ag, we demonstrated a 2.21-fold enhancement compared to the pristine flat substrate with the coefficient of variation (CV) ≈0.22% and the limit of detection (LOD) 0.001 mg L−1 of the concentration of an Alexa Fluor 488-labeled anti-C-reactive protein antibody (CRP@Alexa fluor 488). The structure was developed to simplify the in situ generation of biosensors for the surface-enhanced Raman spectroscopy (SERS) to determine Rhodamine B (RhB) with a highly robust performance. The procedure presented a simple and rapid sample pretreatment for the determination of RhB with a limit of quantification of 10−10 M and a satisfactory linear response (0.98). The results showed the excellent performance of the surface plasmon coupled emission (SPCE), which opens up possibilities for the accurate detection of small-volume and low-concentration target analytes due to the improved sensitivity and signal-to-noise ratio (SNR).   Read more... Require Full Article

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(145) Journal of Nanomaterials, 2021, 1-6 (Q2, IF = 2,986)

Gold Nanoparticles Modified a Multimode Clad-Free Fiber for Ultrasensitive Detection of Bovine Serum Albumin Vu Thi Huong, Nguyen Tran Truc Phuong, Nguyen Tien Tai, Nguyen Thuy An, Vu Dinh Lam, Do Hung Manh, Tran Thi Kim Chi, Ngoc Xuan Dat Mai, Viet-Duc Phung, Nhu Hoa Thi Tran.                                                                                                            Abstract:  Gold nanoparticles (Au NPs) were almost chosen as the first option for biological and biosensor applications due to their enhancement and their outstanding properties. The combining of optical fiber with localized surface plasmon resonance (LSPR) for forming a biosensor is widely used in diagnosis. In this work, we report a fiber optical biosensor based on LSPR of Au NPs for the detection of bovine serum albumin (BSA) protein. BSA was functionalized on Au NPs immobilized fiber optic sensing head (length of 1 cm) via methanesulfonic acid (MSA) by carboxylic binding. It is the binding between the analytes with the surface-modified Au NPs that caused refractive index changes in the sensing medium led to changes in optical power at the output of the sensor. The detection limit of the LSPR fiber biosensor was found to be 0.18 ng/mL for the BSA detection with the low coefficient of variation (CV) at under 1%. We have demonstrated the effectiveness of combining multimode fiber with Au NPs to generate the biosensor as the label-free sensor that can be a feasible tool for highly sensitive, rapid response time, stable, and miniaturized point-of-care analytical systems.                                                                                                                                                      Read more... Require Full Article

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(144) RSC Advances, 11, 12460( Q1, IF = 3,361)

Effect of axial molecules and linker length on CO2 adsorption and selectivity of CAU-8: a combined DFT and GCMC simulation study Diem Thi-Xuan Dang, Hieu Trung Hoang, Tan Le Hoang Doan, Nam Thoai, Yoshiyuki Kawazoe and Duc Nguyen-Manh                                                                                                            Abstract: Density Functional Theory (DFT) and Grand Canonical Monte Carlo (GCMC) calculations are performed to study the structures and carbon dioxide (CO2) adsorption properties of the newly designed metal–organic framework based on the CAU-8 (CAU stands for Christian-Albrechts Universität) prototype. In the new MOFs, the 4,4′-benzophenonedicarboxylic acid (H2BPDC) linker of CAU-8 is substituted by 4,4′-oxalylbis(azanediyl)dibenzoic acid (H2ODA) and 4,4′-teraphthaloylbis(azanediyl)dibenzoic acid (H2TDA) containing amide groups (–CO–NH- motif). Furthermore, MgO6 octahedral chains where dimethyl sulfoxide (DMSO) decorating the axial position bridged two Mg2+ ions are considered. The formation energies indicate that modified CAU-8 is thermodynamically stable. The reaction mechanisms between the metal clusters and the linkers to form the materials are also proposed. GCMC calculations show that CO2 adsorptions and selectivities of Al-based MOFs are better than those of Mg-based MOFs, which is due to DMSO. Amide groups made CO2 molecules more intensively distributed besides organic linkers. CO2 uptakes and selectivities of MOFs containing H2TDA linkers are better in comparison with those of MOFs containing H2BPDC linkers or H2ODA linkers.                                                                                                                                                  Read more... Require Full Article

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(143) Organic Electronics, 93, 106136 (Q1, IF = 3,721)

C-AFM study on multi-resistive switching modes observed in metal–organic frameworks thin films Nhu Tram Tran Hoang, Hoang Tam Le, Kieu Hanh Thi Ta, Y Dang Thi, Linh Ho Thuy Nguyen, Tan Le Hoang Doan,Chung-Kai Fang, Ing-Shouh Hwang, Bach Thang Phan, Ngoc Kim Pham,                                                                                                            Abstract: Metal-organic framework (MOF) materials have recently attracted much attention for use in resistive random-access memory due to the advantages of having high insulative properties, well-defined structures, a large specific surface area, and an adjustable pore size. In this study, the memory device based on zirconium (IV)-carboxylate MOF (UiO-66) nanoparticles exhibits the low operation voltage (V < 0.5 V), high ON/OFF ratio (~104), excellent endurance (5 × 102 cycles), and longtime retention (104 s). To clarify the resistive switching mechanism of the Ag/PVA-MOF/FTO device, conductive atomic force microscopy (C-AFM) was used. The results indicate that all of the electrode, Zr6 clusters of UiO-66, PVA, and UiO-66 conjugation have simultaneous contributions to the resistance switching behavior. The resistive switching can be controlled either by the electron hopping process between Ag+ ions and Zr6 nodes in threshold mode or the formation/rupture of the metal filaments in the bipolar switching mode. Interestingly, inherent characteristics of MOF materials, such as high porosity and large size cages (octahedral, tetrahedral), strongly influence the transport properties and switching mechanism of the device which is also discussed in detail. These resistive switching characteristics and mechanisms of UiO-66 could provide a thorough understanding for future research and application not just for UiO-66 but also for the general MOFs materials.                                          Read more... Require Full Article

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(142) International Journal of Molecular Sciences, vol (Q1, IF = 5,923)

Construction of Boronophenylalanine-Loaded Biodegradable Periodic Mesoporous Organosilica Nanoparticles for BNCT Cancer Therapy Fuyuhiko Tamanoi, Shanmugavel Chinnathambi , Mathilde Laird, Aoi Komatsu, Albane Birault, Takushi Takata, Tan Le-Hoang Doan, Ngoc Xuan Dat Mai, Arthur Raitano, Kendall Morrison, Minoru Suzuki and Kotaro Matsumoto                                                                                                   Abstract: Biodegradable periodic mesoporous organosilica (BPMO) has recently emerged as a promising type of mesoporous silica-based nanoparticle for biomedical applications. Like mesoporous silica nanoparticles (MSN), BPMO possesses a large surface area where various compounds can be attached. In this work, we attached boronophenylalanine (10 BPA) to the surface and explored the potential of this nanomaterial for delivering boron-10 for use in boron neutron capture therapy (BNCT). This cancer therapy is based on the principle that the exposure of boron-10 to thermal neutron results in the release of a-particles that kill cancer cells. To attach 10 BPA, the surface of BPMO was modified with diol groups which facilitated the efficient binding of 10 BPA, yielding 10 BPA-loaded BPMO (10 BPA-BPMO). Surface modification with phosphonate was also carried out to increase the dispersibility of the nanoparticles. To investigate this nanomaterial’s potential for BNCT, we first used human cancer cells and found that 10 BPA-BPMO nanoparticles were efficiently taken up into the cancer cells and were localized in perinuclear regions. We then used a chicken egg tumor model, a versatile and convenient tumor model used to characterize nanomaterials. After observing significant tumor accumulation, 10 BPA-BPMO injected chicken eggs were evaluated by irradiating with neutron beams. Dramatic inhibition of the tumor growth was observed. These results suggest the potential of 10 BPA-BPMO as a novel boron agent for BNCT.                                                                                                                           Read more... Require Full Article

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(141) Journal of Nanomaterials, 2021, 5530606 (Q2, IF = 2,986)

Comparing Thermal Durability and Effects of Annealing Temperature on Characteristics of Hydrogen-Doped ZnO, AZO, and GZO Thin Films Dung Van Hoang, Anh Tuan Thanh Pham, Truong Huu Nguyen, Thang Bach Phan, Vinh Cao Tran                                                                                                            Abstract: In this work, undoped, aluminum-, and gallium-doped ZnO thin films (ZnO-H, AZO-H, and GZO-H, respectively) deposited on soda-lime glass substrates by magnetron sputtering method in a gas mixture of hydrogen and argon are annealed at various temperatures in the range of 200–500°C in air to evaluate the durability of those films under annealing temperature. From photoluminescence spectra, formation of point defects, especially oxygen vacancies, when hydrogen diffuses out of the films at high annealing temperature is exhibited via a significant increase of visible emissions. We find out that carrier concentration and Hall mobility of AZO-H and ZnO-H films dramatically decrease, while those of GZO-H film are still stable as the annealing temperature increased from 200°C to 300°C. We proposed a model for interpreting the thermal durability of GZO-H film that, at an annealing temperature of 300°C, Ga3+ ions located at adjacent Zn sites can push hydrogen atoms, which are broken out of the antibonding sites which are perpendicular to the -axis (AB┴), into bond center sites paralleled to the -axis (BC//). The movement of hydrogen from AB┴ to BC// site also gives rise to the durability of electrical properties of GZO-H films at the high annealing temperature.   Read more... Require Full Article

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(140) Current Applied Physics, 25, 62-69 (Q2, IF = 2.46 )

Mechanism of proton transport in water cluster and the effect of electric fields, Nam H. Vu, Hieu Cao Dong, My Van Nguyen, Thang B-Phan and Thuat T. Trinh,                                                                                                            Abstract: Proton transport inside metal organics frameworks (MOFs) plays an important role to understand and develop a new type of material for a high conductivity application. One of the possible pathways of this process is via water cluster which is confined inside the MOFs structure. In this work, the mechanism of proton transport is investigated within the Density Functional Theory (DFT) calculations. Different water clusters from dimer to pentamer and octamer, which are equivalent to water structures inside the tetrahedral and cubic cavities of MOF-801, respectively, were systematically considered. The results show that proton transfer inside the pentamer cluster has the lowest barrier around 16 kJ/mol. Moreover, the presence of electric fields has a strong effect on the mechanism and energy profile of the proton transfer in both pentamer and octamer cluster. Our DFT prediction of proton migration energies is supported by experimental data of high conducting MOFs such as MOF-801.                                                                                                           Read more... Require Full Article

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(139) Semiconductor Science and Technology, 36, 045009 (Q1, IF = 2.352)

Enhancing the performance of photodetectors based on ZnO nanorods decorated with Ag nanoparticles Tan Muon Dinh, Hung Quang Huynh, Thi My Nhung Mai, Hong Sang Truong, Hoai Nhan Luong, Ngoc Phuong Nguyen, Cong Khanh Tran, Bach Thang Phan, Vinh Quang Dang                                                                                                            Abstract: Zinc oxide nanorods (ZnO NRs) were modified by decorating with silver (Ag) nanoparticles to enhance visible absorption. The morphology, structure and optical properties of the modified ZnO NRs were investigated by scanning electron microscopy, x-ray diffraction and UV–vis absorption spectroscopy. Photodetectors (PDs) based on the modified ZnO NRs successfully detected visible radiation. The result showed high performance of the visible sensor (λ = 400 nm) with a maximum responsivity of 46 mA W−1. The photoconductive gain of Ag/ZnO NR-based PDs was 5.8 times higher than that of pure ZnO NR ones. With their enhanced visible absorption, the multi-modified ZnO NRs are suitable for practical applications, especially in optoelectronic devices operating in the visible region.                                                                                                                                                     Read more... Require Full Article

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(138) Journal of Alloys and Compounds, 867, 158995 (Q1, IF = 5,316)

The roles of interstitial oxygen and phase compositions on the thermoelectric properties CuCr0.85Mg0.15O2 delafossite material, Dung Van Hoang, Tu Anh Kieu Le, Anh Tuan Thanh Pham, Hanh Kieu Thi Ta, Ngoc Kim Pham, Truong Huu Nguyen, Hoa Thi Lai, Dai Cao Truong, Ngoc Van Le, Cong Thanh Huynh, Sunglae Cho, Hongjun Park, Sehwan Song, Sunkyun Park, Takao Mori, Thang Bach Phan, Vinh Cao Tran                                                                                                            Abstract: In this work, role of phase composition and interstitial oxygen on the thermoelectric properties of CuCr0.85Mg0.15O2 materials prepared at different sintering temperatures (1273–1673 K) for short time (3 h) are reported. Interestingly, the samples sintered at 1273 K and 1673 K had the same Seebeck coefficient, despite the 1273 K sample having significantly lower conductivity, which are discussed via phase composition and interstitial oxygen induced during the CuCrO2 phase formation and its related defect (VCu, VCr, …). Besides, high conductivity of the 1673 K sample originated from the low percentage of CuO phase and the appearance of Cu2O phase. Since the 1273 K and 1673 K sintered samples have almost the same percentage of delafossite and spinel phases so the 1673 K sample still remain its high Seebeck coefficient. We suggest some reaction chemical equations for elucidating the roles of interstitial oxygen on the phase composition and thermoelectric properties CuCr0.85Mg0.15O2 delafossite material.                                                                     Read more... Require Full Article

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(137) Microporous and Mesoporous Materials, 315, 110913 (Q1, IF = 5,455)

Facile Synthesis of Biodegradable Mesoporous Functionalized-Organosilica Nanoparticles for Enhancing the Anti-Cancer Efficiency of Cordycepin, Ngoc Xuan Dat Mai, Uyen-Chi Nguyen Le, Linh Ho Thuy Nguyen, Hanh Thi Kieu Ta, Ha Van Nguyen, Tri Minh Le, Thang Bach Phan, Lien-Thuong Thi Nguyen,Fuyuhiko Tamanoi,                                                                                                            Abstract: Cordycepin, a major compound of Cordyceps sp., has been shown to have anticancer potential. However, its low solubility in water is a hurdle in drug delivery in the human body and for cellular uptake. This study focuses on the ability to load cordycepin onto a biodegradable silica nanoparticle as an effective nanocarrier. Biodegradable tetrasulfide-based organosilica nanomaterial with homogeneously spherical particles, average particle size of approximately 50 nm, and pore size of 3.56 nm were successfully synthesized. The nanomaterial could efficiently load cordycepin with a loading capacity up to 755.02 mg g−1. The release profile of cordycepin-loaded nanoparticles at pH 5.5 showed a burst release within the first 1 h and a gradually slow rate thereafter. Moreover, the results of in vitro toxicity of the drug-loaded material against two malignant cancer cell lines including gastric (AGS) and lung (A549) indicated the potential of the nanosystem for drug delivery in cancer therapy.                                                                                                     Read more... Require Full Article

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(136) Journal of the European Ceramic Society, 6, 3493-3500 (Q1, IF = 5,302)

Controlling thickness to tune performance of high-mobility transparent conducting films deposited from Ga-doped ZnO ceramic target Anh Tuan Thanh Pham, Oanh Kieu Truong Le, Dung Van Hoang, Truong Huu Nguyen, Trang Huyen Cao Pham, Phuong Thanh Ngoc Vo, Thang Bach Phan, Vinh Cao Tran                                                                                                            Abstract: Structure modification has been found to tune significantly the transparent-conducting performance, especially mobility and conductivity of hydrogenated Ga-doped ZnO (HGZO) films. The strong correlation between film thickness and mobility of the films is revealed. The mobility increases quickly with increasing the thickness from 350 to 900 nm, and then tends to be saturated at further thicknesses. A higher mobility than 50 cm2/Vs can be achieved, which is an extra-high value for polycrystalline ZnO films deposited by using the sputtering technique. The thickness-dependent mobility originates from scatterings on grain boundaries and dislocation-induced defects controlled by thin-film growth. Based on the Volmer-Weber model, an expansion model is built up to describe the thickness-dependent crystal growth of the HGZO films, especially at the thick films. As a result, the 800 nm-thick HGZO film obtains the highest performance with high mobility of 51.5 cm2/Vs, low resistivity of 5.3 × 10−4 Ωcm, and good transmittance of 83.3 %.                   Read more... Require Full Article

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(135) Advanced Electronic Materials, 4 2000874 (Q1, IF = 6,295)

Correlation between Symmetry and Phase Transition Temperature of VO2 Films Deposited on Al2O3 Substrates with Various Orientations Yesul Choi, Dooyong Lee, Sehwan Song, Jiwoong Kim, Tae‐Seong Ju, Hyegyeong Kim, Jayeong Kim, Seokhyun Yoon, Yunseok Kim, Thang Bach Phan, Jong‐Seong Bae, Sungkyun Park                                                                                                            Abstract: The structural aspects of the insulator–metal transition (IMT) characteristics of VO2 are sensitive to the octahedral symmetry variation of VO6. By varying substrate orientation (c-, a-, and m-plane Al2O3), the correlation between IMT temperature and local symmetry is investigated. For a VO2 film deposited on m-plane Al2O3, which has high symmetry due to fewer domain boundaries induced by m-plane Al2O3, the IMT temperature is low (326.47 K). In contrast, for a film deposited on c-plane Al2O3 (having lower symmetry), the IMT temperature is the highest (336.74 K) among the films used in this work. Furthermore, temperature-dependent Raman spectra reveals that the structural phase transition temperature decreases in the order of the VO2 film deposited on c-, a-, and m-plane Al2O3, suggesting that the symmetrical structure reduces the activation energy for IMT by decreasing thermodynamic energy. These results demonstrate that structural symmetry plays a crucial role in lowering the transition temperature.                                                                 Read more... Require Full Article

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(134) Thin Solid Films, 721, 138537 (Q1, IF = 2,183)

Improved thermoelectric power factor achieved by energy filtering in ZnO:Mg/ZnO hetero-structures Anh Tuan Thanh Pham, Phuong Thanh Ngoc Vo, Hanh Kieu Thi Ta, Hoa Thi Lai, Vinh Cao Tran, Tan Le Hoang Doan, Anh Tuan Duong, Ching-Ting Lee, P.K Nair, Yohandys A Zulueta, Thang Bach Phan, Son D N Luu                                                                                                            Abstract: ZnO:Mg(5 at%)/glass and ZnO:Mg/ZnO/glass thin films with a total thickness of 1000 nm were prepared by direct current sputtering. Crystalline diameter in ZnO:Mg (200 nm)/ZnO (800 nm) improved to 26.5 nm compared with 21.9 nm in ZnO:Mg film. Mg-substitution of Zn-sites in ZnO:Mg shortened the c-axis with an increase in the optical bandgap of the bilayers to 3.35 eV (ZnO, 3.3 eV). Notably, the electrical conductivity of a ZnO:Mg (200 nm)/ZnO (800 nm) layer of 67.5 S cm−1 is superior to ZnO:Mg (1000 nm), 6.7 S.cm−1. The charge carrier mobility for this bilayer is 21 cm2V −1s −1, at least 2.5 times higher than the best value reported for ZnO or metal-doped ZnO single layers. This increase in the carrier mobility is ascribed to the energy filtering phenomena due to the potential barrier at the ZnO:Mg/ZnO interface. This leads to a superior Seebeck coefficient of the bilayer (-175.2 μV.K−1 at 300 °C), nearly double that of a ZnO:Mg film. The energy filtering process significantly increased its power factor to 253.5 μWm−1K−2 at 300 °C, for the hetero-structured bilayer, nearly five times compared with that of ZnO:Mg. Further, it is comparable with power factor values of 100 – 200 μWm−1K−2  at 200 – 300 °C reported for other materials with energy filtering processes. Thus, simple cost-effective semiconductor structures with significant improvement in the thermoelectric parameters were achieved in ZnO:Mg/ZnO heterostructures thin film layers.                                 Read more... Require Full Article

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(133) Journal of Alloys and Compounds, 860, 158518 (Q1, IF = 5,316)

Hydrogen enhancing Ga doping efficiency and electron mobility in high-performance transparent conducting Ga-doped ZnO films Anh Tuan Thanh Pham, Dung Van Hoang, Truong Huu Nguyen, Oanh Kieu Truong Le, Deniz P Wong, Jer-Lai Kuo, Kuei-Hsien Chen, Thang Bach Phan, Vinh Cao Tran                                                                                                            Abstract: In this work, we prepare H and Ga co-doped ZnO (HGZO) films by a sputtering method with over 80% transparency in 400–1100 nm wavelength range and a sheet resistance as low as 3.9 Ω/sq. Hydrogen is recognized as a key element to enhance transmittance and conductivity. Spectroscopic evidence has indicated that hydrogen assists in substituting Ga3+ for Zn2+ (GaZn) in ZnO lattice; it produces more effective GaZn donors and increases electron concentration. We propose for the first time based on interstitial and substitutional hydrogen configurations that the interactions of Zn atom with its neighboring hydrogen atoms can weaken Zn–O bonds in ZnO lattice, and thus facilitate the substitution of Ga3+ for Zn2+. Furthermore, hydrogen can improve the quality of crystalline grains by lowering point-defect density such as Ga, Zn interstitials, Zn, and O vacancies, which strongly enhance electron mobility in HGZO films. The highest mobility of 48.6 cm2/Vs was obtained in the best-performing film.                                                                                                                                                    Read more... Require Full Article

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(132) Journal of Materiomics,4, 742-755 (Q1, IF = 6,425)

Compensation of Zn substitution and secondary phase controls effective mass and weighted mobility in In and Ga co-doped ZnO material Oanh Kieu Truong Le, Anh Tuan Thanh Pham, Ngoc Kim Pham, Trang Huyen Cao Pham, Truong Huu Nguyen, Dung Van Hoang, Hanh Kieu Thi Ta, Dai Cao Truong, Hoa Thi Lai, Thuy Dieu Thi Ung, Vinh Cao Tran, Thang Bach Phan                                                                                                            Abstract: Conductivity σ and thermal conductivity κ are directly related to carrier concentration while Seebeck coefficient S is inversely proportional to carrier concentration. Therefore, improving thermoelectric (TE) performance is challenging. Here, the first-time analysis of secondary phase-controlled TE performance in terms of density-of-state effective mass, weighted mobility μw and quality factor B is discussed in ZnO system. The results show that the secondary spinel phase Ga2O3(ZnO)9 not only impacts κ but also on σ and S at high temperature, while the effect of carrier concentration seem to be dominant at low temperature. For the high-spinel-segregation sample, a compensation of dopant atoms from the spinel to substitutional sites in the ZnO matrix at high temperature leads to a low decreased rate of temperature-dependent. The compensation process also induces a band sharpening, a small μw reduction, and a large B enhancement. As a result, In and Ga co-doped ZnO bulk with the highest spinel segregation achieves the greatest PF improvement by 112.8%, owing to enhanced Seebeck coefficient by 110% as compared to the good Zn-substitution sample.                                                                                                                                  Read more... Require Full Article

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(131) Biosensor and Bioelectronics, 176, 112900 (Q1, IF = 10,818)

Coupling of silver nanoparticle-conjugated fluorescent dyes into optical fiber modes for enhanced signal-to-noise ratio Nhu Hoa Thi Tran, Thang Bach Phan, Than Thi Nguyen, Heongkyu Ju                                                                                                            Abstract: We present the optical coupling of the silver nanoparticles (AgNPs)-conjugated dye molecule into fiber optical modes for detecting fluorescence with the enhanced signal-to-noise (S/N) ratio. This near field coupling of the excited state of organic dye (FAM) molecules into the fiber multimodes occurs by immobilizing them on the exposed surface of fiber core, permitting the coupled light to be guided along the fiber for detection. This fiber based scheme is the first attempt to single out the fluorescence using fiber modes not for carrying excitation light but only for collecting emission light via the dye-fiber coupling. The emission-selective coupling into fiber modes turns out to be effective in reducing the unwanted background noise arising from both the false detection of excitation light and bulk autofluorescence.                                                                 Read more... Require Full Article

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(130) Applied Surface Science, 537, 148000 (Q1, IF = 6,707)

Improving memory performance of PVA:ZnO nanocomposite: The experimental and theoretical approaches Nhu Phuong Le Pham Quynh, Tu Uyen Doan Thi, Kim My Tran, Hoang Nam Vu, Hanh Kieu Thi Ta, Cao Vinh Tran, Thang Bach Phan, Ngoc Kim Pham                                                                                                            Abstract: The interactions between organic and inorganic components of nanocomposites plays a key role in their microstructure and optoelectrical properties. The comprehensive understanding of these interactions can promote various potential applications of materials, especially in the field of electronic memory devices. In this study, we investigate the interactions of polyvinyl alcohol (PVA) and oxygen vacancy-rich ZnO nanoparticles (NPs) and resistive switching effect of PVA:ZnO nanocomposite. The density functional theory calculation indicates that the PVA chemisorption and the oxygen vacancies of ZnO play a key role in strongly reducing the work function of ZnO NPs of which conduction band can act as a bottom of potential well for trapping electrons in the PVA:ZnO nanocomposite. The oxygen vacancies also increase the stability of the potential well by enhancing chemical bonding between PVA and ZnO. Moreover, we show that at a specific content of ZnO NPs in the PVA matrix, the Ag/PVA:ZnO/FTO memory device has the best resistive switching behavior (operating voltage < 1 V). This implies there exists an optimal average width of the energy barriers between the ZnO NPs in the PVA matrix. The electrical transport mechanisms and resistive switching behavior of this device are also investigated in details.                                                                                                                                                         Read more... Require Full Article

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(129) Molecular Catalysis, 499, 111291 (Q1, IF = 5,602)

Heterocyclic reaction inducted by Brønsted–Lewis dual acidic Hf-MOF under microwave irradiation Linh Ho Thuy Nguyen, Trang Thi Thu Nguyen, Minh-Huy Dang Dinh, Phuong Hoang Tran, Tan Le Hoang Doan                                                                                                            Abstract: Use of green chemistry and alternative strategies has been explored to prepare diverse organic derivatives. The combination between heterogeneous catalyst, environmentally benign reaction and high-yielding methods is gaining momentum. Herein, a defective 6-connected Hf-MOF, named Hf-BTC, was efficiently synthesized and characterized for the heterogeneous catalysis under microwave irradiation. The MOF features including structural defect, porosity, acidity, and stability was analyzed by powder X-ray diffraction, N2 sorption isotherms, acid-base titration, and thermal gravimetric analysis. In the catalytic studies, the Brønsted-Lewis dual acidic Hf-BTC was efficiently applied for the synthesis of the heterocyclic compounds via the microwave-assisted cycloaddition and condensation reactions. The reactions proceeded smoothly in the presence of the Hf-MOF with a broad scope of substrates provided the expected products in high to excellent yields (up to 99 %) for few minutes and the catalyst could be easily recycle over many consecutive reactions without loss of its reactivity and structure.                                                                        Read more... Require Full Article

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(128) Materials Today Communications, 26, 101771 (Q2, IF = 2,678)

Poloxamer additive as luminal surface modification to modulate wettability and bioactivities of small-diameter polyurethane/polycaprolactone electrospun hollow tube for vascular prosthesis applications An Nguyen-My Le, Nam Minh-Phuong Tran, Thang Bach Phan, Phong A Tran, Lam Dai Tran, Thi Hiep Nguyen                                                                                                            Abstract: In regard of engineering small-diameter vascular graft, a stable surface treatment targeting only the tube lumen toward rapid endothelialization and anti-thrombosis without weakening or deconstructing the prosthesis remains a technical challenge. In this study, a bilayer hollow tube with a hydrophilic inner layer polyurethane/polycaprolactone/Poloxamer (PU/PCL/Poloxamer) was fabricated. Poloxamer 407 was blended with PU/PCL as a one-step surface modification to enhance the hydrophilicity and bioactive properties of the electrospun tube’s luminal surface. Hydrophobic polypropylene glycol backbones anchored poloxamer onto based polymer while hydrophilic side chains migrated to the surface to modify the behaviors of electrospun inner surface. The poloxamer blended surface, interestingly, exhibited complicated attraction and repellent behaviors regulated by the dynamic of PEG chains. Moderate grafting density (2 %–8 %) exhibited high bioactive performance of PEG tails to simultaneously modulate cells' adhesion, elongation and proliferation while restricting platelet adhesion in comparison with PU/PCL and super-hydrophilic PU/PCL/Poloxamer surface. The elevation of poloxamer content in composition resulted in a corresponding increase in both hydrophilicity and tensile strength while maintained the homogenous fibrous structure of electrospun mat. Besides, a hydrophobic outer layer PU/PCL was fabricated to prevent the leakage and permeable transmembrane phenomenon toward the sustain application in vascular engineering.                          Read more... Require Full Article

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(127) Journal of Materials Science, 56, 3713–3722 (Q1, IF = 4,2290)

Reducing particle size of biodegradable nanomaterial for efficient curcumin loading Ngoc Xuan Dat Mai, Y Thi Dang, Hanh Kieu Thi Ta, Jong-Seong Bae, Sungkyun Park, Bach Thang Phan, Fuyuhiko Tamanoi, Tan Le Hoang Doan                                                                                                            Abstract: Periodic mesoporous organosilica (PMO) are well known as highly potential materials in biomedical applications. In this work, biodegradable PMO nanoparticles, named E4S, which was incorporated of redox-responsive tetrasulfide bonds, were successfully synthesized with particle size smaller than 50 nm. We study the effect of synthetic conditions, especially the amounts of an alkaline catalyst on particle size and porosity of the nanomaterial. X-ray photoelectron spectroscopy, scanning electron microscope, N2 isotherm sorption, Fourier transform infrared (FT-IR) and thermogravimetric analysis techniques were applied to define structural characteristics. Curcumin, a highly hydrophobic, bioactive natural product, was chosen for loading onto the porous structure of E4S. The material exhibited high efficiency for curcumin loading with the capacity up to 1984 mg g−1. According to the loading investigation of the nanoparticles with various sizes, it is noted that the smallest particle shows the highest curcumin loading capacity which may result from small particle sizes and high specific surface area. These results suggest that ethane-tetrasulfide BPMO could be used as an excellent nanomaterial for curcumin loading.                                                                                                      Read more... Require Full Article

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(126) Journal of Materials Research, 36, 508–517 (Q2, IF = 2,5)

The chitosan/ZnO bio-nanocomposites with selective antibacterial efficiency Kiet Tuan Nguyen, Dat Xuan Ngoc Mai, Uyen Tu Thi Doan, Thoai Trung Nguyen, Y Thi Dang, Hanh Kieu Thi Ta, Thang Bach Phan & Ngoc Kim Pham                                                                                                            Abstract: Chitosan/ZnO (CS/ZnO) nanocomposite materials have recently attracted intensive research interest because of their combined ZnO bactericidal activity and good biological compatibility of CS. In this study, ZnO NPs were synthesized via a green process using orange peel extract as a reducing agent. The CS/ZnO nanocomposites were chemically synthesized with different CS/ZnO weight ratios. The microstructure, morphology, and thermal stability of the nanocomposite materials greatly depended on the weight ratio of CS/ZnO. The nanocomposite materials exhibited strong antimicrobial activity towards both Gram-negative bacteria (Escherichia coli) and Gram-positive bacteria (Staphylococcus aureus) in the absence of UV light at all of the investigated CS/ZnO ratios. Due to the different characteristics of bacteria types, the activity inhibition towards E. coli was nearly constant in all samples, while that towards S. aureus slightly decreased with the increment of chitosan content. The results of this study suggest that nanocomposites have potential applications in controlling the spread of infection by various bacteria.                                                                  Read more... Require Full Article

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(125) Journal of Hazardous materials, 403, 124104 (Q1, IF = 10,588)

Functionalization of zirconium-based metal–organic frameworks for gas sensing applications Jae-Hyoung Lee, Trang Thi Thu Nguyen, Linh Ho Thuy Nguyen, Thang Bach Phan, Sang Sub Kim, Tan Le Hoang Doan                                                                                                            Abstract: The functionalization and incorporation of noble metals in metal–organic frameworks have been widely used as efficient methods to enhance their applicability. Herein, a sulfone-functionalized Zr-MOF framework labeled Zr–BPDC–SO2 (BPDC–SO2 = dibenzo[b,d]-thiophene-3,7-dicarboxylate 5,5-dioxide) and its Pd-embedded composite were efficiently synthesized by adjusting their functional groups. The obtained compounds were characterized to assess their potential for gas sensing applications. X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, specific surface area measurements, and thermogravimetric analysis were employed to characterize the new sensor materials. The gas sensing properties of the novel functionalized sensor materials were systematically investigated under various temperature, concentration, and gas type conditions. Owing to the strong hydrogen bonds of the sulfonyl groups and Zr6 clusters in the framework with the hydroxyl groups of ethanol, Zr–BPDC–SO2 emerged as an effective sensor for ethanol detection. In addition, Pd@Zr–BPDC–SO2 exhibited efficient hydrogen sensing performance, in terms of sensor dynamics and response. More importantly, the material showed a higher sensing response to hydrogen than to other gases, highlighting the important role of Pd in the Zr-MOF-based hydrogen sensor. The results of the sensing tests carried out in this study highlight the promising potential of the present materials for practical gas monitoring applications.                                                                                  Read more... Require Full Article

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(124) Green Sustainable Process for Chemical and Environmental Engineering and Science, book chapter, 511-534 (Book, NXB Elsevier)

Microwave-assisted for solvent-free organic synthesis Phuong Hoang Tran, Hai Truong Nguyen, Linh Ho Thuy Nguyen, Tan Hoang Le Doan                                                                                                            Abstract: Microwave irradiation has received much attention in organic synthesis because it can be used to activate several organic reactions efficiently. This technique provides a quick way to obtain the desired products in high yield with a few minutes. In this chapter, we summarize the advantages of microwave activation and their applications in organic synthesis.                                                                                            Read more... Require Full Article

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(123) J. Drug Delivery Science and Technology, 61, 102135 (Q2, IF = 3,981)

Mild and large-scale synthesis of nanoscale metal-organic framework used as a potential adenine-based drug nanocarrier Trang Thi Thu Nguyen, Linh Ho Thuy Nguyen, Ngoc Xuan Dat Mai, Hanh Kieu Thi Ta, Thi Lien Thuong Nguyen, Uyen-Chi Nguyen Le, Bach Thang Phan, Nhuan Ngoc Doan, Tan Le Hoang Doan                                                                                                            Abstract: Nanoscale metal organic frameworks (MOFs) have been a steady growing interest worldwide in biomedical applications, especially in drug carriers. Adenosine, an unstable nucleoside composed of adenine and D-ribose, plays many important biological roles and recently used in many treatments. In this study, Zn-based MOF nanoparticles were successfully synthesized in large-scale by using polyvinylpyrrolidone (PVP) as a modulator for controlling the particle size, and characterized for efficient incorporation and protection of adenosine. Nano MOF displayed homogeneously polyhedral crystals with particle size smaller than 50 nm. According to X-ray diffraction, N2 isotherm sorption, and thermogravimetric analysis characterizations, the nano material has high crystallinity, high porosity, and stable structure. Moreover, investigation of adenosine encapsulation onto nano MOF showed that the material was high potential for nano carrier with high loading capacity up to 833 mg g-1. The kinetics and mechanism studies reveal the adenosine adsorption of MOF fit well with the pseudo‐second‐order model and Langmuir model. The results of in vitro release of adenosine/nano MOF sample show the presence of adenosine in phosphate-buffered saline solution, exhibiting adenosine protection role of the nanocarrier.                                                                                                                                                       Read more... Require Full Article

https://www.sciencedirect.com/science/article/abs/pii/S1773224720314246