Preparation of a reduced graphene oxide/poly-L-glutathione nanocomposite for electrochemical detection of 4-aminophenol in orange juice samples

Vilian, A. T.,Veeramani, V.,Chen, S. M.,Madhu, R.,Huh, Y.,Han, Y. K. Royal Society of Chemistry 2015 Analytical methods Vol.7 No.13

Recent advances in molybdenum disulfide-based electrode materials for electroanalytical applications

Vilian, A. T. Ezhil,Dinesh, Bose,Kang, Sung-Min,Krishnan, Uma Maheswari,Huh, Yun Suk,Han, Young-Kyu Springer-Verlag 2019 Mikrochimica acta Vol.186 No.3

Pd nanospheres decorated reduced graphene oxide with multi-functions: Highly efficient catalytic reduction and ultrasensitive sensing of hazardous 4-nitrophenol pollutant

Vilian, A.T. Ezhil,Choe, Sang Rak,Giribabu, Krishnan,Jang, Sung-Chan,Roh, Changhyun,Huh, Yun Suk,Han, Young-Kyu Elsevier 2017 Journal of hazardous materials Vol.333 No.-

<P><B>Abstract</B></P> <P>We illustrate a facile approach for in situ synthesis of Pd-gum arabic/reduced graphene oxide (Pd-GA/RGO) using GA as the reducing agent, which favors the instantaneous reduction of both Pd ions and GO into Pd nanoparticles (NPs) and RGO. From the morphological analysis of Pd-GA/RGO, we observed highly dispersed spherical 5nm Pd NPs decorated over RGO. The as-synthesized Pd-GA/RGO composite was employed for the catalytic reduction and the electrochemical detection of 4-nitrophenol (4-NP), respectively. The catalytic reduction of 4-NP was highly pronounced for Pd-GA/RGO (5min) when compared to Pd NPs (140min) and Pd/RGO (36min). This enhanced catalytic activity was attributed to the synergistic effect of Pd NPs and the presence of various functional groups of GA. Significantly, the fabricated sensor offered a low detection limit (9fM) with a wider linear range (2–80 pM) and long-term stability. The simple construction technique, high sensitivity, and long-term stability with acceptable accuracy in wastewater samples were the main advantages of the developed sensor. The results indicated that the as-prepared Pd-GA/RGO exhibited better sensing ability than the other graphene-based modified electrodes. Therefore, the proposed sensor can be employed as a more convenient sensing platform for environmental and industrial pollutants.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Pd-GA/RGO catalysts were successfully synthesized by a simple chemical reduction method. </LI> <LI> Pd-GA/RGO catalysts show excellent fast catalytic activity (5min) towards the reduction of 4-NP to 4-AP. </LI> <LI> The developed sensor showed a wide linear range of 2–80pM with a low detection limit of 9fM. </LI> </UL> </P> <P><B>Graphical Abstract</B></P> <P>[DISPLAY OMISSION]</P>

Palladium Supported on an Amphiphilic Triazine-Urea-Functionalized Porous Organic Polymer as a Highly Efficient Electrocatalyst for Electrochemical Sensing of Rutin in Human Plasma

Vilian, A. T. Ezhil,Sivakumar, Rajamanickam,Huh, Yun Suk,Youk, Ji Ho,Han, Young-Kyu American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.23

<P>Metal nanoparticle-containing porous organic polymers have gained great interest in chemical and pharmaceutical applications owing to their high reactivity and good recyclability. In the present work, a palladium nanoparticle-decorated triazine-urea-based porous organic polymer (Pd@TU-POP) was designed and synthesized using 1,3-bis(4-aminophenyl)urea with cyanuric chloride and palladium acetate. The porous structure and physicochemical properties of the electrode material Pd@TU-POP were observed using a range of standard techniques. The Pd@TU-POP material on the electrode surface showed superior sensing ability for rutin (RT) because the Pd dispersion facilitated the electrocatalytic performance of TU-POP by reducing the overpotential of RT oxidation dramatically and improving the stability significantly. Furthermore, TU-POP provides excellent structural features for loading Pd nanoparticles, and the resulting Pd@TU-POP exhibited enhanced electron transfer and outstanding sensing capability in a linear range between 2 and 200 pM having a low detection value of 5.92 × 10<SUP>-12</SUP> M (S/N = 3). The abundant porous structure of Pd@TU-POP not only provides electron transport channels for RT diffusion but also offers a facile route for quantification sensing of RT with satisfactory recoveries in aqueous electrolyte containing human plasma and red wine. These data reveal that the synthetic Pd@TU-POP is an excellent potential platform for the detection of RT in biological samples.</P> [FIG OMISSION]</BR>

Immobilization of hemoglobin on functionalized multi-walled carbon nanotubes-poly-l-histidine-zinc oxide nanocomposites toward the detection of bromate and H₂O₂

Vilian, A.,Chen, S.M.,Kwak, C.H.,Hwang, S.K.,Huh, Y.S.,Han, Y.K. Elsevier Sequoia 2016 Sensors and actuators. B Chemical Vol.224 No.-

A novel biocompatible sensing strategy has been developed based on functionalized multi-walled carbon nanotube (f-MWCNT), poly-l-histine (P-l-His), and ZnO nanocomposite film for the immobilization of hemoglobin (Hb). The direct electron transfer properties and bioelectrocatalytic activity of the Hb in f-MWCNT-P-l-His-ZnO composite film is further investigated. The apparent heterogeneous electron transfer rate constant (k<SUB>s</SUB>) of Hb confined to f-MWCNT-P-l-His-ZnO nanocomposite is found to be 5.16s<SUP>-1</SUP> using Laviron's equation. Moreover, the surface coverage concentration (Γ) of the electroactive Hb in the f-MWCNT-P-l-His-ZnO film is estimated to be 1.88x10<SUP>-9</SUP>molcm<SUP>-2</SUP>. The fabricated electrochemical biosensor based on the immobilized Hb revealed a fast response time (<3s) with a wide linear range (4-18,000μM and 2-15,000μM) and detection limit (as low as 0.01μM and 0.30μM) for the electrocatalytic determination of a mediator-free H<SUB>2</SUB>O<SUB>2</SUB> and bromate under optimal experimental conditions. The ca. apparent Michaelis-Menten constant is 0.14mM, which indicates that the Hb has a high affinity to H<SUB>2</SUB>O<SUB>2</SUB>. The high sensitivity, good reproducibility, and long-term stability of the proposed nanocomposite film indicates that it can serve as an electrode for the development of an amperometric H<SUB>2</SUB>O<SUB>2</SUB> and bromate-based biosensor. The proposed third-generation biosensor was successfully applied to milk and urine samples for the detection of H<SUB>2</SUB>O<SUB>2</SUB> and bromate.

Electrochemical determination of quercetin based on porous aromatic frameworks supported Au nanoparticles

Vilian, A.T.E.,Puthiaraj, P.,Kwak, C.H.,Choe, S.R.,Huh, Y.S.,Ahn, W.S.,Han, Y.K. Pergamon Press 2016 ELECTROCHIMICA ACTA Vol.216 No.-

Gold nanoparticles (Au NPs) were decorated on porous aromatic framework (Au-PAF-6) using a simple reduction method. The prepared Au-PAF-6 material was characterized by X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and transmission electron microscopy (TEM), which clearly illustrated that Au NPs were dispersed with an average particle size of 15.1nm on the PAF-6 surface. The obtained Au-PAF-6 offered a remarkable analytical performance in the electrocatalytic oxidation of quercetin (QC) at reduced potential. The modified Au-PAF-6 electrode exhibited a good differential pulse voltammetric response in the QC concentration of 1x10<SUP>-12</SUP>-6x10<SUP>-10</SUP>M with the detection limit of 2x10<SUP>-13</SUP>M. The designed sensor platform was also implemented directly to determine the QC in apple juice and green tea samples. Reliable recovery (98.2-99.4%) showed that Au-PAF-6 was highly stable and reproducible, and had good anti-interference properties.

Fabrication of Palladium Nanoparticles on Porous Aromatic Frameworks as a Sensing Platform to Detect Vanillin

Vilian, A. T. Ezhil,Puthiaraj, Pillaiyar,Kwak, Cheol Hwan,Hwang, Seung-Kyu,Huh, Yun Suk,Ahn, Wha-Seung,Han, Young-Kyu American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.20

<P>Here, we report the fabrication of palladium nanoparticles on porous aromatic frameworks (Pd/PAF-6) using a facile chemical approach, which was characterized by various spectro- and electrochemical techniques. The differential pulse voltammetry (DPV) response of Pd/PAF-6 toward the vanillin (VA) sensor shows a linear relationship over concentrations (10-820 pM) and a low detection limit (2 pM). Pd/PAF-6 also exhibited good anti -interference performance toward 2 -fold excess of ascorbic acid, nitrophenol, glutathione, glucose, uric acid, dopamine, ascorbic acid, 4-nitrophenol, glutathione, glucose, uric acid, dopamine, and 100 -fold excess of Na4, Mg2+, and r during the detection of VA. The developed electrochemical sensor based on Pd/PAF-6 had good reproducibility, as well as high selectivity and stability. The established sensor revealed that Pd/PAF-6 could be used to detect VA in biscuit and ice cream samples with satisfactory results.</P>

Efficient electron-mediated electrochemical biosensor of gold wire for the rapid detection of C-reactive protein: A predictive strategy for heart failure

Vilian, A.T. Ezhil,Kim, Wonyoung,Park, Bumjun,Oh, Seo Yeong,Kim, TaeYoung,Huh, Yun Suk,Hwangbo, Chang Kwon,Han, Young-Kyu Elsevier 2019 Biosensors & bioelectronics Vol.142 No.-

<P><B>Abstract</B></P> <P>C-reactive protein (CRP) is considered a promising biomarker for the rapid and high-throughput real-time monitoring of cardiovascular disease and inflammation in unprocessed clinical samples. Implementation of this monitoring would enable various transformative biomedical applications. We have fabricated a highly specific sensor chip to detect CRP with a detection limit of 2.25 fg/mL. The protein was immobilized on top of a gold (Au) wire/polycarbonate (PC) substrate using 1-ethyl-3-(3-dimethylamino-propyl) carbodiimide hydrochloride/N-hydroxy succinimide-activated 3-mercaptoproponic acid (MPA) as a self-assembled monolayer agent and bovine serum albumin (BSA) as a blocking agent. In contrast to the bare PC substrate, the CRP/BSA/anti-CRP/MPA/Au substrate exhibited a considerably high electrochemical signal toward CRP. The influence of the experimental parameters on CRP detection was assessed via various analysis methods, and these parameters were then optimized. The linear dynamic range of the CRP was 5–220 fg/mL for voltammetric and impedance analysis. Morever, the strategy exhibited high selectivity against various potential interfering species and was capable of directly probing trace amounts of the target CRP in human serum with excellent selectivity. The analytical assay based on the CRP/BSA/anti-CRP/MPA/Au substrate could be exploited as a potentially useful tool for detecting CRP in clinical samples.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The sensor utilizes Au wires to attaching antibodies for specific binding of CRP for heart failure diagnostics. </LI> <LI> A low detection limit of 2.25 fg/mL with linear concentrations of 5–220 fg/mL for CRP was measured. </LI> <LI> The advanced sensor has excellent stability, reproducibility and selective sensing for CRP. </LI> <LI> The offered sensor is used to detect CRP in human serum and saliva with a good recovery. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Fabrication of 3D honeycomb-like porous polyurethane-functionalized reduced graphene oxide for detection of dopamine

Vilian, A.T. Ezhil,An, Suyeong,Choe, Sang Rak,Kwak, Cheol Hwan,Huh, Yun Suk,Lee, Jonghwi,Han, Young-Kyu Elsevier 2016 Biosensors & bioelectronics Vol.86 No.-

<P><B>Abstract</B></P> <P>A three dimensional reduced graphene oxide/polyurethane (RGO-PU) porous material with connected pores was prepared by physical adsorption of RGO onto the surface of porous PU. The porous PU was prepared by directional melt crystallization of a solvent, which produced high pores with controlled orientation. The prepared RGO-PU was characterized by scanning electron microscopy, spectroscopy and electro-chemical methods. The RGO-PU porous material revealed better electrochemical performance, which might be attributed to the robust structure, superior conductivity, large surface area, and good flexibility. Differential pulse voltammetry (DPV) analysis of DA using the RGO-PU exhibited a linear response range over a wide DA concentration of 100–1150pM, with the detection limit of 1pM. This sensor exhibited outstanding anti-interference ability towards co-existing molecules with good stability, sensitivity, and reproducibility. Furthermore, the fabricated sensor was successfully applied for the quantitative analysis of DA in human serum and urine samples with acceptable recovery, which indicates its feasibility for practical application.</P> <P><B>Highlights</B></P> <P> <UL> <LI> RGO-PU sensor was constructed for DA detection. </LI> <LI> The developed method exhibited wide linear range and low detection limit. </LI> <LI> The fabricated RGO-PU sensor exhibits good selectivity, reproducibility and excellent anti-interference property. </LI> <LI> The prepared sensor was applied to detect DA in real sample with satisfactory results. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

A spick-and-span approach to the immobilization of horseradish peroxidase on Au nanospheres incorporated with a methionine/graphene biomatrix for the determination of endocrine disruptor bisphenol A

Vilian, A.T. Ezhil,Giribabu, Krishnan,Choe, Sang Rak,Muruganantham, Rethinasabapathy,Lee, Hoomin,Roh, Changhyun,Huh, Yun Suk,Han, Young-Kyu Elsevier Sequoia 2017 Sensors and actuators. B Chemical Vol.251 No.-

<P><B>Abstract</B></P> <P>In the present study, we employ a straightforward, benign strategy to prepare thiol-functionalized reduced graphene oxide (S-RGO) using methionine as the sulphur source and reducing agent. The immobilization of horseradish peroxidase (HRP) over the AuNPs/S-RGO was developed by incorporating AuNPs on the S-RGO surface. The fabricated HRP/AuNPs/S-RGO electrode exhibits a remarkable decrease in the overpotential and a significantly increased oxidation peak current of bisphenol A (BPA) compared with the bare glassy carbon electrode (GCE) and AuNPs/S-RGO electrode. The biosensor shows an excellent amperometric analytical performance with a low detection limit of 2.6×10<SUP>−12</SUP> M and a linear range from 2.0×10<SUP>−11</SUP> to 1.18×10<SUP>−9</SUP> M, with the response time <2s for BPA. From the results, the apparent Michaelis-Menten constant was calculated as 8.14nM. The HRP/AuNPs/S-RGO biosensor exhibited faster response, adequate storage stability, inexpensive, simple fabrication with disposability, satisfactory reproducibility and repeatability, and outstanding selectivity. Finally, the constructed biosensor was utilized successfully for detecting BPA in tomato juice and milk samples with acceptable results.</P> <P><B>Highlights</B></P> <P> <UL> <LI> HRP/AuNPs/S-RGO biocomposite has been prepared to determine bisphenol A. </LI> <LI> The AuNPs/S-RGO is a promising platform for HRP immobilization. </LI> <LI> The biosensor exhibits excellent stability, reproducibility and high selectivity. </LI> <LI> It exhibits LOD of 2.6×10<SUP>−12</SUP> in a wide linear range from 2.0×10<SUP>−11</SUP> to 1.18×10<SUP>−9</SUP> M. </LI> <LI> It detects bisphenol A in real samples such as tomato juice and milk. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>