Development of a surface plasmon assisted label-free calorimetric method for sensitive detection of mercury based on functionalized gold nanorods

Anand, Gopalan Sai,Gopalan, Anantha Iyengar,Kang, Shin-Won,Lee, Kwang-Pill The Royal Society of Chemistry 2013 Journal of analytical atomic spectrometry Vol.28 No.4

<P>In this investigation, we established a new sensitive, selective and label free optical method for the detection of mercury ions (Hg<SUP>2+</SUP>) by utilizing cyano (–CN) ligand functionalized gold nanorods (GNRs) based on the surface plasmon resonance (SPR) of the GNRs. The functionalization of the GNRs was specifically done with a –CN group containing polymer, poly(2-aminobenzonitrile) (P2ABN), to preconcentrate the Hg<SUP>2+</SUP> ions on the surface of the GNRs prior to detection. The functionalization of the GNRs was carried out by two approaches. In the first approach, the GNR surface was modified with a porous silica network containing P2ABN (designated as GNR@silica-CN). In the second approach, GNR was modified with P2ABN (designated as GNR@P2ABN). The Hg<SUP>2+</SUP> ion detection strategy involves the preconcentration of Hg ions on the surface of GNR@silica-CN or GNR@P2ABN through the interaction of the –CN groups in P2ABN with Hg<SUP>2+</SUP> ions, reduction to Hg<SUP>0</SUP> atoms by ascorbic acid (AA), and monitoring the SPR of GNRs. The porous network in GNR@silica-CN allows efficient migration of Hg<SUP>0</SUP> to reach the GNR surface and causes effective amalgamation compared to GNR@P2ABN. As a result, GNR@silica-CN exhibits a significant change in the SPR of GNRs over a wide dynamic concentration range (from 50 nM to 5 μM) for Hg<SUP>2+</SUP> ions. The very low detection limit of 1 ppb with GNR@silica-CN for Hg<SUP>2+</SUP> ions suggests its excellent potential for the monitoring and detection of ultra low levels of Hg. In addition, the GNR@silica-CN shows no sensitivity for other environmentally relevant metal ions which confirms the high specificity for Hg<SUP>2+</SUP> ion detection in practical samples. We demonstrated the effectiveness of the present method by detecting Hg<SUP>2+</SUP> ions in spiked water (pond and water) samples. We envisage that this simple, fast and sensitive method will be suitable for environmental monitoring in the future.</P> <P>Graphic Abstract</P><P>A new highly selective sensing strategy for detection of mercury ions has been developed utilizing polymer containing cyano group functionalized gold nanorods. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c3ja30300d'> </P>

Fabrication of Gold Nanoflower Anchored Conducting Polymer Hybrid Film Electrode by Pulse Potentiostatic Deposition

Sai-Anand, Gopalan,Gopalan, Anantha Iyengar,Shin-Won Kang,Kwang-Pill Lee IEEE 2013 IEEE electron device letters Vol.34 No.8

<P>In this letter, we report a simple and rapid (~60 s) method to fabricate a new organic-inorganic hybrid film based on poly (di phenyl amine-co-4 amino thiophenol) (designated as PDPAAT) and gold nanoflowers (Au NFs). The fabrication involves a fast facile and pulse potentiostatic approach for the electrodeposition of Au NFs onto PDPAAT. The electrochemical, interfacial, and optical properties of the PDPAAT/Au NF hybrid film electrode are investigated. The superior electroactivity, electrochemical, and interfacial characteristics of the PDPAAT/Au NF electrode suggests its suitability for sensor, electrocatalysis, and diode applications.</P>

Depinning of the ferroelectric domain wall in congruent LiNbO₃

Gopalan, Venkatraman,Phillpot, Simon R. American Institute of Physics 2016 Applied Physics Letters Vol.109 No.8

Nanostructuring of poly(diphenylamine) inside the galleries of montmorillonite organo clay through self-assembly approach.

Gopalan, Anantha Iyengar,Lee, Kwang-Pill,Hong, Mung-Hwa,Santhosh, Padmanabhan,Manesh, Kalayil Manian,Kim, Sang-Ho American Scientific Publishers 2006 Journal of nanoscience and nanotechnology Vol.6 No.6

<P>Hollow spheres of poly(diphenylamine) (PDPA) was prepared by confining PDPA in the galleries of montmorillonite organo clay modified with organoammonium cations (MMT). At first instant, diphenylamine (DPA) was loaded into the galleries of MMT and subjected to subsequent oxidative polymerization to form PDPA. beta-naphthalene sulfonic acid (NSA) was used as medium to influence self-assembly of DPA inside the galleries of MMT. Polymerization of self assembled structure resulted hollow spheres of PDPA inside galleries of MMT. X-ray diffraction analysis (XRD), field emission transmission electron microscopy (FETEM), Fourier transform infra-red spectroscopy (FT-IR) and thermogravimetric analysis (TGA) were used to characterize the composites. Transmission emission microscopy of the composite shows the hollow spherical morphology of PDPA. FT-IR, UV-Visible spectroscopy, conductivity measurement and X-ray photoelectron spectroscopy were used to characterize the PDPA extracted from MMT galleries. PDPA extracted from MMT galleries was found to have difference in electronic property than PDPA formed by the conventional method, due to the confinement effect.</P>

Synthesis of Novel Poly(amidoxime) Grafted Multiwall Carbon Nanotube Gel and Uranium Adsorption

Gopalan, A.,Philips, M.F.,Jeong, J.-H.,Lee, K.-P. American Scientific Publishers 2014 Journal of nanoscience and nanotechnology Vol.14 No.3

This is the first report on the synthesis of a new functional nanocomposite gel containing amidoxime functionalized multiwall carbon nanotube (AO-MWNT-FNC GEL). The surface morphology of AO-MWNT-FNC GEL was investigated by field emission scanning electron microscopy. The modification of gel with amidoxine groups was confirmed by Fourier transform infra red spectroscopy. The AO-MWNT-FNC GEL provides effective binding with uranium ions as was ascertained by X-ray photoelectron spectroscopy. The AO-MWNT-FNC GEL was utilized as the new adsorbent for the recovery of uranium ions from aqueous solution. UV-visible spectroscopy was used to monitor the adsorption capacity of the AO-MWNT-FNC GEL toward uranium ions. The influence of initial uranium ion concentration and solution pH on the adsorption capacity of the AO-MWNT-FNC GEL were studied in batch experiments. The new FNC-GEL designed in this study is distinguished by higher adsorption capacity for uranium ions due to the synergistic contributions from high surface area of MWNT and the functional AO groups in FNC-GEL and exhibits potential for efficient recovery of uranium ions.

The Effect of a Speed Reading Course on the Reading Comprehension of Impulsive vs. Reflective Learners

Gopalan Aroo,Vahid Nimehchisalem 아시아테플 2023 The Journal of Asia TEFL Vol.20 No.3

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A novel bismuth oxychloride-graphene hybrid nanosheets based non-enzymatic photoelectrochemical glucose sensing platform for high performances

Gopalan, AI.,Muthuchamy, N.,Lee, KP. Elsevier 2017 Biosensors & bioelectronics Vol.89 No.1

<P><B>Abstract</B></P> <P>A novel non-enzymatic photoelectrochemical (PEC) glucose sensor was first constructed based on the unique two-dimensional (2D) bismuth oxychloride-graphene nanohybrid sheets (BiOCl-G NHS). We have utilized a facile hydrothermal approach for the preparation of BiOCl-G NHS. Results from cyclic voltammetric and differential pulse voltammetric measurements revealed that the BiOCl-G NHS electrode is capable of generating photocurrent for glucose when its surface is irradiated with a light source (wavelength=365nm). The photocurrents produced for the presence of glucose at the bias potential of +0.50V showed a linear dependence on glucose concentration in the range between 0.5 and 10mM and had a detection limit of 0.22mM. The PEC detection of glucose at BiOCl-G NHS was not influenced by the presence of other common interfering species. The glucose levels, as determined by the BiOCl-G NHS sensor, agreed well with those obtained by the commercial glucometers. This novel non-enzymatic PEC glucose sensor exhibited good performances, such as a wider concentration range (500µM-10mM), high sensitivity (1.878µMmM<SUP>−1</SUP> cm<SUP>−2</SUP> (500µM–2mM) and 127.2µMmM<SUP>−1</SUP> cm<SUP>−2</SUP> (2mM–10mM)), good selectivity, reproducibility (RSD=2.4%) and applicability to real sample (human serum).</P> <P><B>Highlights</B></P> <P> <UL> <LI> Bismuth oxychloride-graphene nanohybrid sheets based glucose sensor was constructed. </LI> <LI> A wide linear-detecting range is reported with photoelectrochemical non-enzymatic sensing mode. </LI> <LI> Reports an innovative strategy for non-enzymatic biomolecule detection. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Mild wetting poor solvent induced hydrogen bonding interactions for improved performance in bulk heterojunction solar cells

Gopalan, S. A.,Seo, M. H.,Anantha-Iyengar, G.,Han, B.,Lee, S. W.,Kwon, D. H.,Lee, S. H.,Kang, S. W. Royal Society of Chemistry 2014 Journal of Materials Chemistry A Vol.2 No.7

In this paper, we demonstrate a facile, mild wetting (short residence time) poor solvent [isopropyl alcohol (IPA)] treatment, carried out on the top surface of a spin-cast poly (3-hexylthiopene) (P3HT) and [6,6]-phenyl-C71-butyric acid methyl ester (PCBM) blend film, in order to fabricate high-performance polymer solar cells (PSCs). This method utilizes the hydrophilic and polar/hydrogen bonding interactions of IPA with the blend components (P3HT and PCBM). The photovoltaic (PV) performance of the fabricated PSCs was optimized by utilizing a preheated IPA wetting treatment and devices fabricated with the configuration: ITO/PEDOT: PSS/P3HT:PCBM/M-IPA-T degrees/Al (T degrees: 25 degrees C/45 degrees C/65 degrees C/85 degrees C) (where 'M' stands for modified IPA and 'T' signifies the temperature used for the IPA wetting). Our investigation encompasses electrical, optical, crystalline, and morphological studies on the P3HT: PCBM blend films, modified by preheated IPA, to elucidate the associated enhancements in the PV characteristics and performance. The device fabricated with IPA-85 degrees C (ITO/PEDOT: PSS/P3HT: PCBM/M-IPA-85 degrees C/Al) exhibited the best power conversion efficiency (PCE) of 3.51%, with an open circuit voltage of 0.65 V, a fill factor of 0.52, and a short-circuit current density of 10.20 mA cm(-2). In contrast, the non-modified blend film device showed a PCE of only similar to 3.04%. Ultraviolet-visible absorption studies and X-ray diffraction results suggest that the use of the pre-heated mild-wetting IPA treatment improves the crystallinity and self-organization of the blend layer. We rationalize our findings based on the interactions between IPA and the blend components, due to its high polar and hydrogen bonding Hansen solubility parameters to impart supramolecular assembly of P3HT chains during the blend film formation. This is the first report demonstrating that the poor solvent (IPA) can induce an optimal phase separation in a P3HT: PCBM blend through our proposed mild wetting preheated treatment, toward achieving high-performance PSCs.

Pedicle screws; Pullout strength; Bone density; Osteoporosis; Rigid polyurethane foam

Balachandar Gopalan,Janardhan Srinivas Yerramshetty 대한척추외과학회 2018 Asian Spine Journal Vol.12 No.3

Study Design: Case control study. Purpose: The association of lumbosacral transitional vertebra (LSTV) with low back pain (LBP) is controversial, as is the role of occupational physical activity and radiological spinal abnormalities suggestive of other spinal disorders (OSDs) such as spinal degeneration and instability. This study aimed to determine if any association of LSTV with LBP exists. If so, the association of the level of physical activity and presence of OSD with LSTV-related LBP was determined. Overview of Literature: The cause of LBP has been linked to proximal level disc degeneration, arthritic pseudoarticulation between LSTV and the sacral ala, facet joint degeneration, and nerve root compression due to a broadened transverse process. LSTV associated with LBP is present among individuals who are involved in high-level physical activity, including military recruits and athletes. Methods: This was an unmatched study comprising 372 cases and 224 controls consecutively recruited with clinical and radiographic documentation. The relationship between LSTV and LBP was analyzed, and the effects of LSTV and OSD on this relationship were also assessed and statistically controlled. Results: The presence of LSTV (p =0.039) was significantly associated with LBP, and the presence of OSD was associated with LTSVrelated LBP, after statistically controlling for the level of physical activity (p =0.024). The level of physical activity was not associated with LBP. Demographic analysis revealed female predominance with an advanced age (>45 years) among those with LSTV-related LBP who have OSD. Conclusions: The presence of LSTV was associated with an increased prevalence of LBP. This association was probably due to the confounding effect of OSD. The level of occupational physical activity was not associated with LSTV-related LBP. We speculate that advanced age and female sex caused the spurious association of LSTV with LBP in our study, rendering LSTV-related LBP controversial in published literature.

Insight into metal-impregnated biomass based activated carbon for enhanced carbon dioxide adsorption: A review

Jayaprina Gopalan,Archina Buthiyappan,Abdul Aziz Abdul Raman 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.113 No.-

Recently, biomass has been understood and investigated to develop adsorbents for carbon dioxide (CO2)adsorption due to their non-hazardous nature, availability, low disposal cost, and thermal stability. In thisperspective, the sustainable approach of converting biomass into activated carbon (BAC) for the adsorptionof CO2 is promising for solid waste management while reducing anthropogenic greenhouse gas emissions. Among other biomass adsorbents, metal oxide impregnated activated carbon (MBAC) hasdemonstrated excellent adsorption affinity for CO2 adsorption. Therefore, in this review, an evaluationand detailed study of various MBACs for CO2 adsorption is presented for the first time. BAC synthesizemethod, including various carbonization techniques, surface activation and functionality approacheshave been discussed. This study also provides detailed overview of MBAC in the context of various preparationmethods, critical factors and operating parameters for a high CO2 adsorption capacity. Besides, thesolid–gas reactor configuration, cyclic regeneration techniques, CO2 adsorption process mechanism, andCO2 adsorption kinetics also have been discussed. Finally, concluding remarks and future perspectives forbiomass-derived MBAC for CO2 adsorption capture were addressed. This review will also assist in thesearch for alternatives to CO2 adsorption technology, which is both cost-effective and environmentallyfriendly.