Optimization of the eco-friendly synthesis of graphene oxide from graphite using Plackett–Burman and Box–Behnken models for industrial production orientation

Phuc Nguyen Thien,Giang Nguyen Thi Huong,An Vu Nguyen Thien Truong,Nam Nguyen Thanh Hoai,Anh Ly Duc,Nguyen Huynh Cam,An Hoang,Phong Mai Thanh,Hieu Nguyen Huu 한국탄소학회 2023 Carbon Letters Vol.33 No.2

In this study, graphene oxide (GO) was synthesized by the improved Hummers’ method. The degree of oxidation from graphite (Gi) to GO was determined through interlayer spacing calculated from X–ray diffraction. Besides, the effect of KMnO4:Gi ratios (X1), H2SO4 volume (X2), oxidation temperature (X3), oxidation time of stage 1 (X4), and oxidation time of stage 2 (X5) was screened by the Plackett–Burman model. The simultaneous impact of three factors that influenced the degree of oxidation (X1, X2, and X3) was studied by the Box–Behnken experimental model of response surface methodology to achieve suitable conditions for the GO synthesis process. The characterization of GO product was investigated via the modern analytical methods: X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, UV–Vis spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, and atomic force microscopy. In addition, the study was also carried out on a pilot scale for orientation in industrial application with the yield of 14 g/batch.

A two-step design of experiments approach to investigate the simultaneous effects of ion-pairing and chemical enhancers to improve the permeability of lornoxicam in a topical hydrogel patch

Nguyen Huu-Manh,Duong The-Khang,Nguyen Van-Khuyen,Nguyen Thi-Khanh-Ly,Dong Thi-Hoang-Yen,Nguyen Canh-Hung,Tung Nguyen-Thach 한국약제학회 2024 Journal of Pharmaceutical Investigation Vol.54 No.2

Purpose A two-step experimental design was used to develop a lornoxicam (LOR)-loaded topical hydrogel patch. We specifically focused on the simultaneous effect of the ion pair formation agent (triethanolamine [TEA]) and the chemical enhancer (cremophor RH40 [RH40]) on flux and conducted physicochemical studies and skin physiology assessments to obtain further information. Methods Drug-in-adhesive patches were fabricated using a micrometer-adjustable film applicator. The applied Design of Experiments (DoE) approach consisted of the Fractional Factorial Resolution V + design and the Central Composite Face design established by the MODDE® 12.0 software. Molecular-level drug-excipient interactions were investigated using infrared (IR) and proton nuclear magnetic resonance (1H NMR) spectroscopy. The effects on skin physiological function was assessed using DermaLab Combo. Results DoE results revealed that TEA enhanced flux by 3.14-fold, whereas RH40 reduced it by 4.62-fold. The addition of RH40 resulted in the disappearance of the proton peak within the region of 12–13 ppm, suggesting competition for hydrogen bonding with LOR between TEA and RH40. The optimized formulation (4% TEA, 0% RH40, and 0.2% Al(OH)3) increased skin hydration by 6.20-fold. Opposing effects of TEA and RH40 on skin elasticity were observed. Conclusion Expected flux and adhesion strength for the optimized formulation were 7.18 μg·cm–2·h–1 and 11.79 mJ, respectively. Our understanding of the conflicting effects of TEA and RH40 has been advanced. The integrated use of the two-step DoE, physicochemical studies, and skin physiology assessments was proven to be effective in elucidating the simultaneous effects of different permeation-modifying strategies on patches, thus having substantial value for the successful execution of future research endeavors.

Raman Spectroscopy of Di-(2-picolyl)amine on Gold Nanoparticles for Hg(II) Detection

Nguyen Hoang Ly,주상우 대한화학회 2015 Bulletin of the Korean Chemical Society Vol.36 No.1

In an effort to develop a spectroscopic mercury ion sensor, the Raman spectral features of di-(2-picolyl)amine (DPA) on gold nanoparticles (AuNPs) were examined in the presence of various ions. The two bands at 1020 and 1060 cm−1 showed different intensities in the presence of Hg2+, whereas the other ions, Pb2+, Ni2+, NH4 +, Na+,Mn2+,Mg2+,K+, Zn2+, Fe2+, Cd2+,Cu2+,Cr3+,Co2+, Fe3+, and Ca2+ at the same concentrations of 100 μM did not produce such spectral changes. The band at 1060 cm−1 became stronger than that at 1020 cm−1, only for Hg2+. These two bands may correspond to the ring-breathing and trigonal ring-breathing vibration of the two pyridine rings of DPA. The Hg(II) concentration-dependent surface-enhanced Raman scattering (SERS) spectra indicated that the relative intensities of the two bands reversed above 10 μM. In addition to this noteworthy feature, the bands at 270 cm−1, which may be ascribed to the Au Nstretching, show much higher intensities in the presence of Hg2+. Our Raman spectral analysis of DPA may be useful to discriminate the Hg2+ ion above 10 μM using AuNPs on the basis of molecular vibrational spectroscopy.

Hg(II) Raman Sensor of Poly-L-Lysine Conformation Change on Gold Nanoparticles

Nguyen Hoang Ly,주상우 한국바이오칩학회 2014 BioChip Journal Vol.8 No.4

In order to develop optical Hg(II) sensors,the adsorption characteristics of poly-L-lysine (PLL)after the conjugation of various ions on gold nanopar-ticles (AuNPs) were examined by means of Ramanspectroscopy, UV-Vis absorption, and quasi-elastic lightscattering (QELS). The intensities of the two bands at458 and 1115 cm-1 appeared to decrease, in compari-son with that at 1150 cm-1 in the presence of 100 μMof Hg(II). The other ions of Cr3++, Pb2++, Mn2++, Zn2++,Co2++, Ni2++, Cd2++, Fe2++, Na++, K++, Ca2++, Mg2++, Cu2++,NH4++, and Fe3++ did not show such spectral changes. The prominent band at 1150 cm-1, which may be asc-ribed to the C-N or γ (NH3++) band, suggests that a con-formational change of poly-L-lysine (PLL) occurs afterits interaction with Hg(II) ions. The Hg(II) concentra-tion-dependent SERS spectra indicated that the rela-tive intensities of the two bands at 458 and 1115 cm-1decreased and that at 1150 cm-1 increased above 1 μM. These vibrational fingerprints may be useful to discri-minate the Hg(II) ion above 1 μM using AuNPs andRaman spectroscopy. On the basis of the presentedspectroscopic study, we plan to develop an efficientmethod of detecting the Hg(II) ion at lower concen-trations by introducing a variety of SERS platforms.

The Moderating Role of CSR Associations on the Link between Brand Awareness and Purchase Intention

HOANG, Xuan Lam,NGUYEN, Thi Kim Chi,LY, Hoang Mai,LUONG, Thu Thuy,NGUYEN, Thi Thanh Quy Korea Distribution Science Association 2020 The Journal of Asian Finance, Economics and Busine Vol.7 No.6

This study uses the moderating model to explore the relationships between Corporate Social Responsibility (CSR) associations, brand awareness and consumer purchase intention. Besides investigating the direct effects of CSR associations on brand awareness and consumer purchase intention, this study also focuses on discovering the moderating role of CSR associations on the relationship between brand awareness and consumer purchase intention among Vietnamese students. Adapting scales from previous research, the authors distribute questionnaires to consumers across the country. Then, the validity and reliability are tested via Cronbach's alpha, Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA). Moreover, by employing a meta-analytical path analysis with a sample of 686 consumers, the authors show that CSR associations play an important role in shaping purchase intention among Vietnamese consumers regarding the consumption of organic milk products. Also, CSR associations have a strong effect on brand awareness. However, our study shows that purchase intention is not directly affected by brand awareness. In other words, brand awareness does not mediate the relationship between CSR associations and purchase intention. Interestingly, authors show that CSR associations moderate the link between brand awareness and consumer purchase intention. Based on the research, some recommendations are made to companies that produce organic milk products.

Gold Nanoparticle-based Surface-enhanced Raman Scattering Fe(III) Ion Sensor

Nguyen Hoang Ly,조광휘,주상우 대한화학회 2015 Bulletin of the Korean Chemical Society Vol.36 No.1

We performed density functional theory (DFT) calculations of 4-aminobenzo-15-crown-5 (4AB15C5) in conjugation with 4-mercaptobenzoic acid (4MCB) with the polarizable continuum model (PCM) while considering the aqueous media. After specific binding of the ferric ion onto the 4MCB–4AB15C5 compound, the Raman frequencies and intensities were estimated by DFT calculations with the PCM. It was predicted that the Raman intensities became significantly increased upon binding of the ferric ion. 4MCB–4AB15C5 could be assembled on gold nanoparticles (AuNPs) via the cleavage of the thiol bond. Colorimetric and UV–Vis absorption spectroscopy indicated that AuNPs became significantly aggregated in the presence of 1–10 mM of the ferric ion. Surface-enhanced Raman scattering (SERS) of 4MCB–4AB15C5 was used to identify the dissimilar spectral behaviors that yield a difference in intensity in the presence of the ferric ion. These changes were not observed in the other biological ions Zn2+, Mn2+, Fe2+, Na+, K+, Ca2+, Mg2+, NH4 +, and Co2+. This study indicated that 4AB15C5 could be used to detect ferric ions in aqueous AuNP solutions by a combined method of colorimetric, UV–Vis absorption, and Raman spectroscopy. AuNPs–[4MCB– 4AB15C5] can thus be utilized as a selective turn-on sensor to Fe3+ in aqueous solutions above 1 mM.

Spectroscopic measurements of interactions between hydrophobic 1-pyrenebutyric acid and silver colloidal nanoparticles

Ly, Nguyen Hoang,Nguyen, Thanh Danh,Bui, Thanh Lam,Lee, Sangyeop,Choo, Jaebum,Joo, Sang-Woo Elsevier 2017 Colloids and surfaces. A, Physicochemical and engi Vol.518 No.-

<P><B>Abstract</B></P> <P>We compared the adsorption and desorption of 1-pyrenecarboxylic acid (PyC), 1-pyreneacetic acid (PyA), and 1-pyrenebutyric acid (PyB) on silver nanoparticles (AgNPs) via interfacial spectroscopic tools to study the role of the aliphatic units between pyrene and carboxylic group. The negative surface charges of AgNPs at ca. −51mV shifted up to −11mV, after adsorbing hydrophobic pyrene compounds. The three pyrene acid compounds appeared to adsorb onto AgNPs via their carboxylate units by referring to the observation of the broad <I>ν</I>(COO<SUP>−</SUP>) bands at 1380–1410cm<SUP>−1</SUP> in the Raman spectra. X-ray photoelectron spectroscopy (XPS) also supported the CO species in the C<SUB>1s</SUB> region. AgNPs were found to efficiently quench the fluorescence of the three pyrene acid adsorbates. The highest Stern–Volmer constant of PyA may be due to the largest overlap integral with the surface Plasmon absorption band of AgNPs. The butyric unit was expected to lead a stronger binding on Ag, as suggested by density functional theory (DFT) calculations. The adsorbed pyrene acid compounds appeared to be released from AgNPs by thiol-containing glutathione (GSH). PyB with the butyric group exhibited larger quenched fluorescence intensities and smaller released amounts than PyC and PyA in aqueous solutions and A549 cancer cells. Our study will be helpful in designing pyrene-based fluorescence sensors in cellular imaging.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Hydrophobic pyrene acids were chemically interacted with Ag nanoparticles. </LI> <LI> 1-Pyrene acids were found to adsorb on silver via the COO<SUP>−</SUP> bonds. </LI> <LI> Fluorescence quenching behaviors of pyrene acids were compared on Ag. </LI> <LI> Glutathione-triggered desorption of pyrene acids were observed in cancer cells. </LI> <LI> 1-Pyrenebutyrate showed stronger binding than 1-pyrenecarboxlyate on Ag. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

On-site detection of sub-mg/kg melamine mixed in powdered infant formula and chocolate using sharp-edged gold nanostar substrates

Nguyen, Thi Ha,Nguyen, Thanh Danh,Ly, Nguyen Hoang,Kwak, Cheol Hwan,Huh, Yun Suk,Joo, Sang-Woo Informa UK (TaylorFrancis) 2018 Food additives & contaminants. Part A. Chemistry, Vol.35 No.6

Factors Affecting Green Entrepreneurship Intentions During the COVID-19 Pandemic: An Empirical Study in Vietnam

Trong Luan NGUYEN,Nguyen Anh Ngu PHAM,Thi Kim Nhung NGUYEN,Ngoc Khai Vy NGUYEN,Hoang Thang NGO,Tran Thien Ly PHAM 한국유통과학회 2022 The Journal of Asian Finance, Economics and Busine Vol.9 No.2

At present, environmental problems are gradually becoming quite serious because of the expansion of the business scale of companies, factories, and enterprises, and that is also the reason for the global pollution of the world. Green entrepreneurship is playing an increasingly crucial role in influencing people’s intentions, behaviors, and attitudes toward environmental protection through sustainable development. The purpose of this research was to examine the factors affecting university students’ green entrepreneurship levels in Vietnam. To do this, we performed a scientific research survey with 773 students from reputable universities in Vietnam, 337 of whom are male and 436 of whom are female. To assess the reliability and correlation between observed and total variables, this study employs scale testing methods such as Cronbach alpha, EFA, CFA, and SEM. After evaluating the influencing elements, the findings reveal that the Subjective norm factor and the Risk-aversion component are two distinct aspects that influence university students’ green entrepreneurship intentions in Vietnam and of which, the greatest influence is Risk Aversion. Furthermore, the findings revealed that the level of interest in green entrepreneurship is mostly seen by students with university education between the ages of 18–25.

In situ Raman spectroscopic monitoring of organic dyes and ferric ions in Fenton reactions on sharp-edged gold nanostar surfaces

Le, Thi Thao Nguyen,Ly, Nguyen Hoang,Nguyen, Thanh Danh,Nguyen, Thi Ha,Kim, Moon-Kyung,Zoh, Kyung-Duk,Joo, Sang-Woo Elsevier 2018 Colloids and surfaces. A, Physicochemical and engi Vol.551 No.-

<P><B>Abstract</B></P> <P>For this report, we compared interfacial spectroscopic tools to monitor in situ Fenton reactions of organic dyes on ascorbic acid-reduced gold nanostars (AuNSs). Ultraviolet-visible (UV–vis) absorption and Raman spectroscopic tools were introduced to check the hydroxyl radical destruction of ethyl violet (EV), which contains a triarylmethane group. AuNSs with sharp edges, tips, and corners were used as efficient surface-enhanced resonance Raman scattering (SERRS) substrates for in situ Fenton reaction monitoring. The SERRS intensity of the EV showed a first-order decay curve with a reaction rate constant value of 0.0263 min<SUP>−1</SUP>, while the decolorization yielded second-order kinetic behavior with a constant value of 0.00430 L/mol min. In addition to the destruction of the organic dyes, the increased number of ferric (III) ions, as a result of the Fenton reactions, was detected via 4-aminobenzo-15-crown-5 (4AB15C5) conjugated with 4-mercaptobenzoic acid (4MBA). We found that the SERRS bands at ∼1500 cm<SUP>−1</SUP> of 4AB15C5 on AuNSs increased after treatment with H<SUB>2</SUB>O<SUB>2</SUB> and FeSO<SUB>4</SUB>. Real industrial textile wastewater samples were then tested to determine whether this Raman method could be applied to detect increases in ferric ions. Our spectroscopic data used SERRS peaks via Fenton reaction results to calculate an estimated ∼65% destruction of the organic dyes.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>