A. Gopalan

Kyungpook National University, Daikyū, Daegu, South Korea

Are you A. Gopalan?

Claim your profile

Publications (212)531.59 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: In this investigation, a facile one step synthesis was utilized to prepare gold nanoparticles (Au NPs) dispersed poly(2-aminophenyl boronic acid) (PAPBA) nanocomposite (PAPBA/Au-NC). PAPBA/Au-NC was characterized by field effect scanning electron microscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis. The synergistic properties of the boronic groups, conducting polyaniline matrix and Au NPs in the new PAPBA/Au-NC were effectively utilized for the fabrication of a high sensitive non-enzymatic glucose sensor electrode. The sensor electrode was characterized by cyclic voltammetry and electrochemical impedance spectroscopy. We demonstrated that the new non-enzymatic sensor electrode exhibited good electrocatalytic activity for the oxidation of glucose. The Au NPs, PANI and boronic groups synergistically influence electrochemical detection of glucose. PAPBA/Au-NC exhibited excellent selectivity for glucose, good electron transduction to the electrode and high electrochemical sensitivity. The greater progress achieved in this investigation will pave the way for the potential development of a practical non-enzymatic glucose sensor.
    Science of Advanced Materials 07/2014; 6(7). DOI:10.1166/sam.2014.1836 · 2.91 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: 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.
    Journal of Nanoscience and Nanotechnology 03/2014; 14(3):2451-8. DOI:10.1166/jnn.2014.8507 · 1.34 Impact Factor
  • Source
    Sai-Anand Gopalan, Anantha Iyengar Gopalan, Shin-Won Kang, Kwang-Pill Lee
    [Show abstract] [Hide abstract]
    ABSTRACT: 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.
    IEEE Electron Device Letters 08/2013; 34(8):1065-1067. DOI:10.1109/LED.2013.2266669 · 3.02 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The course of the reaction between copper sulfate (CuSO4) and 4-aminodiphenylamine (4ADPA) was monitored by UV-visible spectroscopy in p-toluene sulfonic acid (p-TSA). Formation of poly(4-aminodiphenylamine)/copper nanoparticle composite (P4ADPA/CuNC) was witnessed through the steady increase in absorbance at 410, 580 and >700nm. The absorbance at 410nm as well as >700nm are correlated to the amount of P4ADPA/CuNC formation and was subsequently used to determine the rate of formation of P4ADPA/CuNC (RP4ADPA/CuNC) at any time during the course of the reaction. RP4ADPA/CuNC shows a first-order dependence on [4ADPA] and a half-order dependence on [CuSO4]. A kinetic rate expression was established between RP4ADPA/CuNC and experimental parameters such as [4ADPA] and [CuSO4]. The rate constant for the formation of P4ADPA/CuNC was 8.98×10(-3)mol(-0.5)l(0.5)s(-1). Field emission scanning electron and transmission electron micrographs revealed that the morphology of the P4ADPA/CuNC was influenced by the reaction conditions.
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 07/2013; 116C:321-330. DOI:10.1016/j.saa.2013.06.064 · 2.13 Impact Factor
  • Byung Hun Chang, Se Hee Lee, Anantha Iyengar Gopalan, Kwang Pill Lee
    [Show abstract] [Hide abstract]
    ABSTRACT: In this report, the chains of poly (aminophenylbornoic acid) (PAPBA) were grafted onto the surface of silica nanoparticles to obtain Si-g-PAPBA. Si-g-PAPBA was characterized through field emission scanning electron microscopy (FESEM), fourier transform infrared (FTIR) spectroscopy, UV-Vis spectroscopy and thermogravimetric analysis (TGA). Grafting of PAPBA chains onto silica surface was confirmed by TGA and FTIR spectroscopy.
    07/2013; 717:90-94. DOI:10.4028/www.scientific.net/AMR.717.90
  • Source
    Gopalan Sai Anand, Anantha Iyengar Gopalan, Shin-Won Kang, Kwang-Pill Lee
    [Show abstract] [Hide abstract]
    ABSTRACT: In this investigation, we established a new sensitive, selective and label free optical method for the detection of mercury ions (Hg2+) 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 Hg2+ 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 Hg2+ 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 Hg2+ ions, reduction to Hg0 atoms by ascorbic acid (AA), and monitoring the SPR of GNRs. The porous network in GNR@silica-CN allows efficient migration of Hg0 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 Hg2+ ions. The very low detection limit of 1 ppb with GNR@silica-CN for Hg2+ 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 Hg2+ ion detection in practical samples. We demonstrated the effectiveness of the present method by detecting Hg2+ 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.
    Journal of Analytical Atomic Spectrometry 03/2013; 28(4):488-498. DOI:10.1039/C3JA30300D · 3.40 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We report a simple and one-pot procedure for the simultaneous immobilization of poly(N-[3-(trimethoxy silyl)propyl]aniline (PTMSPA) and horseradish peroxidase (HRP) on gold nanorods (GNRs) to yield HRP/PTMSPA@GNRs. HRP/PTMSPA@GNR was well characterized by field emission scanning electron microscopy and UV–visible spectroscopy. High resolution image of HRP/PTMSPA@GNR attributes GNRs are welded/connected to one another through the surface coated PTMSPA. Direct electron transfer was achieved at HRP/PTMSPA@GNR with an electron transfer rate constant (ks) of 3.2 ± 0.1 s−1. Cyclic voltammograms of H2O2 at HRP/PTMSPA@GNR modified electrode exhibited a stable reduction peak at approximately −0.25 V. Amperometric response of HRP/PTMSPA@GNR modified electrode showed quick response (<5 s) for the reduction of H2O2. HRP/PTMSPA@GNR showed wide linear range from 1 × 10−5 to 1 × 10−3 M with detection limit (0.06 μM) (S/N = 3). HRP/PTMSPA@GNR modified electrode exhibited high selectivity with sensitivity (0.021 μA/μM) toward H2O2.
    Electrochimica Acta 03/2013; 92(1):71-78. DOI:10.1016/j.electacta.2013.01.032 · 4.09 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A "modular approach" has been demonstrated for the preparation of nanodiamond (ND) based sponges (NS) with entrapped enzyme (horseradish peroxidase, HRP) (ND-NS(HRP)) and utilization as an electrochemical probe for detection of hydrogen peroxide (H2O2). ND-NS comprises ND, porous poly(aniline)-poly(2-acrylamido 2-methyl propane sulfonic acid) (PANI-PAMPSA) network and entrapped HRP. Field emission scanning electron microscope image of ND-NS(HRP) reveals sponge like suprastructure comprising interconnected nanospheres with numerous openings/pinholes/cavities. The entrapped HRP in ND-NS exhibits effective direct electron transfer with an electron transfer rate constant of 1.85s(-1). ND-NS(HRP) exhibited excellent bioelectrocatalytic reduction of hydrogen peroxide (H2O2) with a wide linear concentration range (1-45mM), quick response (5s), high sensitivity (129.6μAM(-1)) and low detection limit 59μM (S/N=3).
    Biosensors & Bioelectronics 03/2013; 46C:136-141. DOI:10.1016/j.bios.2013.02.036 · 6.45 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We have demonstrated a new, simple and effective technique for the synthesis of Pt, Sn or Pt-Sn nanoparticles supported on thiol-functionalized, multiwalled carbon nanotube (MWNT(SH)) catalysts using γ-irradiation. The use of γ-irradiation minimizes the preparation time and produces a clean catalyst, as no additional reducing agents are involved in the preparation. The morphology of the MWNT(SH)/Pt, MWNT(SH)/Sn and MWNT(SH)/Pt-Sn catalysts was examined by field emission transmission electron microscopy (FE-TEM). The Pt-Sn catalyst particles exhibited a core–shell morphology with Pt as the core (15 nm) and Sn as the shell (10 nm). The catalysts showed electroactive behavior towards methanol oxidation, due to the synergistic contribution of MWNT(SH) and the metal or alloy particles.
    Journal of Nanoelectronics and Optoelectronics 10/2012; 7(5):444-448. DOI:10.1166/jno.2012.1391 · 0.37 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The authors describe the preparation of a novel electrocatalyst, composed of palladium particles dispersed in poly(diphenylamino-3-aminobenzomine) (P(DPA-co-3ABN)/PdNP). P(DPA-co-3ABN)/Pd was characterized by field emission scanning electron microscopy, and by energy dispersive X-ray and X-ray diffraction analysis. The electrocatalytic activity of P(DPA-co-3ABN)/PdNP with respect to oxygen reduction reaction (ORR) was investigated by cyclic voltammetry and linear sweep voltammetry. The cyano groups in P(DPA-co-3ABN)/PdNP were found to enhance ORR electrocatalysis. The authors believe that the new catalyst could be used to explore platinum free catalysts for fuel cell applications.
    Journal of Nanoelectronics and Optoelectronics 10/2012; 7(5):449-453. DOI:10.1166/jno.2012.1394 · 0.37 Impact Factor
  • M Francklin Philips, Anantha Iyengar Gopalan, Kwang-Pill Lee
    [Show abstract] [Hide abstract]
    ABSTRACT: Poly(diphenylamine-co-2-aminobenzonitrile) (P(DPA-co-2ABN)), a cyano group containing conducting polyaniline derivative, has been electrodeposited developed as the new material and utilized for the simultaneous electrochemical determination of trace levels of cadmium (Cd(2+)) and lead (Pb(2+)). P(DPA-co-2ABN) film preconcentrates effectively through cyano chelation and electrochemically strips the heavy metal ions with well separated potentials, which are beneficially utilized for ppb level simultaneous detection of Cd(2+) and Pb(2+). Differential pulse voltammetry studies revealed that Cd(2+) and Pb(2+) ions were simultaneously stripped with well-defined, separated and sharp peaks for Cd(2+) and Pb(2+). The influence of various operational parameters such as pulse amplitude, pulse time, scan rate, initial potential, end potential, accumulation potential and accumulation time on the electrochemical stripping of heavy metals were investigated in details. Under the optimal conditions, good linear correlations were obtained from 1.26 to 907.8ppm for Cd(2+) and 0.26 to 58.73ppm for Pb(2+), respectively. Low detection limits for Cd(2+) and Pb(2+), 0.255ppm and 0.165ppm, respectively, were observed. The practical utility of the new procedure was demonstrated in real samples.
    Journal of hazardous materials 08/2012; 237-238:46-54. DOI:10.1016/j.jhazmat.2012.07.069 · 4.33 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In this work, we have demonstrated that 4-carboxy phenyl groups based modification could be performed on different electrodes, such as indium tin oxide (ITO), gold (Au), and glassy carbon electrode (GCE). The electrode modification has been performed through cyclic voltammetry by sweeping the potential between +1.0 V and −1.0 V for ‘n’ number of potential cycles. The 4-carboxyphenyl modification at different electrode surfaces was confirmed by cyclic voltammetry, contact angle measurements, atomic force microscopy, and X-ray photoelectron spectroscopy analysis. Subsequently, the electrochemical DNA sensor (E-DNA sensor) based on the 4-carboxy phenyl modified GCE was fabricated by the immobilization of probe DNA. The fabricated E-DNA sensor can detect the influenza virus (type A). The current density of the E-DNA sensor was also evaluated by cyclicvoltammetry when the probe DNA and target DNA were hybridized.
    Electrochimica Acta 08/2012; 76:394–403. DOI:10.1016/j.electacta.2012.05.044 · 4.09 Impact Factor
  • Thangavelu Kavitha, Anantha Iyengar Gopalan, Kwang-Pill Lee, Soo-Young Park
    [Show abstract] [Hide abstract]
    ABSTRACT: A simple and efficient approach was developed to uniformly decorate graphene nanosheets with zinc oxide (ZnO) nanoparticles. A single source precursor, zinc benzoate dihydrazinate complex, has been used for the in situ generation of ZnO nanoparticles onto graphene at a relatively low temperature, 200 °C. Physico chemical analyses such as X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy revealed that ZnO nanoparticles were finely dispersed on the surface of graphene. ZnO–graphene hybrids were further characterized by Raman spectroscopy and ultraviolet visible spectroscopy and room-temperature photoluminescence. The materials exhibited excellent photocatalytic activity as evident from the degradation of methylene blue in ethanol under UV irradiation. An electrochemical glucose biosensor was fabricated by immobilization of glucose oxidase on the ZnO–graphene hybrids. This biosensor showed improved sensitivity towards glucose as compared to graphene. Also, the hybrids showed significant antibacterial activity against E. coli, gram negative bacteria. This simple and economical preparation strategy may be extended for the preparation of other graphene-based hybrids.
    Carbon 07/2012; 50(8):2994–3000. DOI:10.1016/j.carbon.2012.02.082 · 6.16 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Poly(4-aminodiphenylamine)-silver nanocomposites were synthesized by an easy one-step aqueous chemical oxidative polymerization of 4-aminodiphenylamine (4ADPA) using silver nitrate (AgNO3) as the oxidant. Two different structure directing surfactants, p-toluene sulfonic acid (p-TSA) and cetyl trimethyl ammonium bromide/hydrochloric acid (CTAB/HCl), were independently used for the nanocomposite (NC) preparation. The NCs prepared in p-TSA and CTAB/HCl medium were designated as P4ADPA/AgNC(p−TSA) and P4ADPA/AgNC(CTAB/HCl), respectively. We investigated the morphological variations in the NCs based on the medium. P4ADPA/AgNC(p−TSA) and P4ADPA/AgNC(CTAB/HCl) were characterized by field emission scanning electron microscopy, X-ray diffraction analysis, Fourier transform infrared spectroscopy, thermogravimetric analysis and UV-visible spectroscopy. Copyright © 2011 Society of Chemical Industry
    Polymer International 04/2012; 61(4). DOI:10.1002/pi.3200 · 2.13 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Herein, we report the facile synthesis of a new nanocomposite, poly(4-aminodiphenylamine) (P4ADPA) supported silver nanoparticles (AgNPs) nanocomposite (NC) (P4ADPA/AgNC) in p-toluene sulfonic acid (p-TSA) medium. Field emission transmission electron microscopy reveals the existence of uniformly distributed AgNPs in the rod shaped P4ADPA matrix. P4ADPA/AgNC has been employed as the catalyst for the reduction of 4-nitrophenol (4NP) and the rate of reduction of 4NP was monitored by UV–Visible spectroscopy.
    Journal of Materials Science Materials in Electronics 03/2012; 23(3). DOI:10.1007/s10854-011-0496-5 · 1.97 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Hollow spherical PANI nanocapsules (HSPNs) were prepared via γ-irradiation and were subsequently loaded with gold (Au) nanoparticles to obtain an HSPN/Au catalyst. The morphology of the HSPN/Au catalyst was examined via field emission scanning electron microscopy while the electronic property was investigated via ultraviolet-visible spectroscopy. The electroactivity of the HSPN/Au catalyst modified electrode towards the oxidation of methanol was evaluated to ascertain the utility of the catalyst in direct methanol fuel cell application.
    Journal of Nanoelectronics and Optoelectronics 08/2011; 6(3):325-329. DOI:10.1166/jno.2011.1178 · 0.37 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Gold nanoparticles (AuNPs) were anchored onto thiol-functionalized multiwalled carbon nanotubes (MWNT(-SH)) as the stabilizing linker (SL), and a MWNT(-SH)-SL-AuNP catalyst support was successfully prepared via the γ-irradiation of a solution consisting of MWNT(-SH) and gold chloride in 2-propanol. Scanning electron microscopy, transmission electron microscopy, and X-ray diffraction analysis were used to characterize the catalysts. The electrocatalytic activity of the catalyst towards methanol oxidation was evaluated via cyclic voltammetry. A membrane electrode assembly (MEA) was fabricated using Nafion 117 as the membrane and MWNT(-SH)-SL-AuNP as the cathode catalyst. The simplicity of preparation and excellent performance of the MWNT(-SH)-SL-AuNP catalyst suggest its potential application in direct methanol fuel cells (DMFC).
    Journal of Nanoelectronics and Optoelectronics 08/2011; 6(3):353-356. DOI:10.1166/jno.2011.1184 · 0.37 Impact Factor
  • M. Francklin Philips, Anantha Iyengar Gopalan, Kwang-Pill Lee
    [Show abstract] [Hide abstract]
    ABSTRACT: A new palladium (Pd) based catalyst was developed using poly(diphenylamine-co-3-aminobenzonitrile) (P(DPA-co-3ABN)) as the new catalyst support. The sizes, distribution and stability of Pd nanoparticles (Pd NPs) are strongly influenced by the cyano group (–CN) present in P(DPA-co-3ABN). Field emission scanning electron microscopy image and energy dispersive x-ray analysis revealed good dispersion of Pd NP onto P(DPA-co-3ABN) matrix. The electrocatalytic activity of P(DPA-co-3ABN)/Pd catalyst electrode (CE) was investigated in terms of formic acid (FA) electro oxidation. The onset potential and catalytic current for the electro oxidation of FA are higher at P(DPA-co-3ABN)/Pd-CE as compared to PdNPs loaded pristine PDPA catalyst electrode (PDPA/Pd-CE). P(DPA-co-3ABN)/Pd-CE exhibited 18 time higher electrocatalytic current than PDPA/Pd-CE for oxidation of FA.
    Catalysis Communications 07/2011; 12(12):1084-1087. DOI:10.1016/j.catcom.2011.03.027 · 3.32 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Kinetics of chemical oxidative polymerization of 4-aminodiphenylamine (4ADPA) was followed in aqueous 1 M p-toluene sulfonic acid (p-TSA) using silver nitrate (AgNO3) as an oxidant by UV-vis spectroscopy. The medium was found to be clear and homogeneous during the course of polymerization. The absorbances corresponding to the intermediate and the polymer were followed for different concentrations of 4ADPA and AgNO3 and at different reaction time. The appearance of a band around 450 nm during the initial stages of polymerization corresponds to the plasmon resonance formed by the reduction of Ag+ ions. Rate of poly(4-aminodiphenylamine)/Ag nanocomposite (RP4ADPA/AgNC) was determined for various reaction conditions. R(P4ADP/AgNC) showed second order power dependence on 4ADPA and first order dependence on AgNO3. The observed order dependences of 4ADPA and AgNO3 on the formation of P4ADPA/AgNC were used to deduce a rate equation for the reaction. Rate constant for the reaction was determined through different approaches. The good agreement between the rate constants obtained through different approaches justifies the selection of rate equation.
    Spectrochimica Acta Part A Molecular and Biomolecular Spectroscopy 05/2011; 79(5):1256-66. DOI:10.1016/j.saa.2011.04.052 · 2.13 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In the present communication, a novel composite nanofibrous electrode is developed for the detection of superoxide anion (O(2)˙(-)) in phosphate buffered saline (PBS). The composite fiber electrode is fabricated by dispersing gold nanoparticles onto poly(methyl methacrylate) (PMMA)-polyaniline (PANI) core-shell electrospun nanofibers. The constructed architecture is proven to be a favorable environment for the immobilization of the enzyme, superoxide dismutase (SOD). Direct electron transfer is achieved between SOD and the electrode with an electron transfer rate constant of 8.93 s(-1). At an applied potential of +300 mV, PMMA/PANI-Au(nano)/SOD-ESCFM shows highly sensitive detection of O(2)˙(-). In addition to this, quantification of different activities of SOD is realized at PMMA/PANI-Au(nano)/SOD-ESCFM. These analytical features offer great potential for construction of the third-generation O(2)˙(-) biosensor.
    The Analyst 02/2011; 136(8):1557-61. DOI:10.1039/c0an00616e · 3.91 Impact Factor

Publication Stats

3k Citations
531.59 Total Impact Points


  • 2005–2013
    • Kyungpook National University
      • • Department of Chemistry Educaion
      • • Department of Chemistry
      • • Department of Wood Science and Technology
      Daikyū, Daegu, South Korea
  • 1995–2008
    • Alagappa University
      • Department of Industrial Chemistry
      Karaikudi, Tamil Nādu, India
  • 2006
    • Indira Gandhi Centre for Atomic Research
      • Materials Chemistry Division (MCD)
      Chennai, Tamil Nādu, India
  • 2004–2006
    • Hannam University
      • Department of Chemistry
      Daiden, Daejeon, South Korea
  • 2001–2005
    • National Cheng Kung University
      • Department of Chemical Engineering
      臺南市, Taiwan, Taiwan