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Synthesis, characterization and electrochemical properties of functionalized graphene oxide
Veerapandian, Murugan,Lee, Min-Ho,Krishnamoorthy, Karthikeyan,Yun, Kyusik Elsevier 2012 Carbon Vol.50 No.11
<P><B>Abstract</B></P><P>Graphene oxide (GO) was functionalized by a simple reaction of its carboxylic acid groups with a silanized-metalloid polymer, which gave the resulting hybrid GO the property of efficient dispersion in a variety of solvents. Spectroscopic investigations show that the covalent attachment is effectively accomplished through an amidation process. The combination of a metalloid polymer and GO is unique and the composite material exhibits interesting features not seen in the individual structures. The electrochemical properties of this metalloid–polymer-GO were demonstrated by immobilizing the sample on a conventional gold-printed circuit board (Au-PCB) electrode. Functionalized GO showed a perfect scaling of steady-state currents with correlation coefficients of 0.9600 (<I>I</I><SUB>pc</SUB>) and 0.9552 (<I>I</I><SUB>pa</SUB>), indicating the promise of this new GO hybrid as a transducer material for many sensing applications.</P>
Functionalized graphene oxide for clinical glucose biosensing in urine and serum samples
Veerapandian, Murugan,Seo, Yeong-Tai,Shin, Hyunkyung,Yun, Kyusik,Lee, Min-Ho Dove Medical Press 2012 INTERNATIONAL JOURNAL OF NANOMEDICINE Vol.7 No.-
<P>A novel clinical glucose biosensor fabricated using functionalized metalloid-polymer (silver-silica coated with polyethylene glycol) hybrid nanoparticles on the surface of a graphene oxide nanosheet is reported. The cyclic voltammetric response of glucose oxidase modification on the surface of a functionalized graphene oxide electrode showed a surface-confined reaction and an effective redox potential near zero volts, with a wide linearity of 0.1–20 mM and a sensitivity of 7.66 μA mM<SUP>−1</SUP> cm<SUP>−2</SUP>. The functionalized graphene oxide electrode showed a better electrocatalytic response toward oxidation of H<SUB>2</SUB>O<SUB>2</SUB> and reduction of oxygen. The practical applicability of the functionalized graphene oxide electrode was demonstrated by measuring the peak current against multiple urine and serum samples from diabetic patients. This new hybrid nanoarchitecture combining a three-dimensional metalloid-polymer hybrid and two-dimensional graphene oxide provided a thin solid laminate on the electrode surface. The easy fabrication process and retention of bioactive immobilized enzymes on the functionalized graphene oxide electrode could potentially be extended to detection of other biomolecules, and have broad applications in electrochemical biosensing.</P>
Copper-Glucosamine Microcubes: Synthesis, Characterization, and C-Reactive Protein Detection
Veerapandian, Murugan,Subbiah, Ramesh,Lim, Guei-Sam,Park, Sung-Ha,Yun, KyuSik,Lee, Min-Ho American Chemical Society 2011 Langmuir Vol.27 No.14
<P>Cubelike microstructures of glucosamine-functionalized copper (GlcN-CuMC’s) have been fabricated by the integration of injection pump and ultrasonochemistry. Although bulk microstructures and the nanostructure of metallic copper exhibit distinct applications, the amino sugar surface-functionalized copper is almost biocompatible and exhibits advanced features such as more crystallinity, high thermal stability, and electrochemical feasibility toward biomolecule (C-reactive protein, CRP) detection. An electrochemical test of this GlcN-CuMC’s was demonstrated by immobilization on a conventional gold-PCB (Au-PCB) electrode. The combination of a biointerface membrane, from glucosamine functionalization, and electroactive sites of metallic copper provides a very efficient electrochemical response against various concentration of CRP. A perfect scaling of steady-state currents with <I>r</I><SUP>2</SUP> values of 0.9862 (<I>I</I><SUB>pa</SUB>) and 0.9972 (<I>I</I><SUB>pc</SUB>) indicate the promise of this kind of biofunctionalized microstructure electrode for many surface and interface applications.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/langd5/2011/langd5.2011.27.issue-14/la2009495/production/images/medium/la-2011-009495_0001.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/la2009495'>ACS Electronic Supporting Info</A></P>
Veerapandian, Murugan,Yun, Kyusik Wiley Subscription Services, Inc., A Wiley Company 2010 Polymer composites Vol.31 No.9
<P><B>Abstract</B></P><P>Poly(ethylene glycol)‐octafunctionalized polyhedral oligomeric silsesquioxane (POSS) (<I>M</I><SUB>n</SUB> = 5576.6 g/mol) alloying agent stabilized amphiphilic silica@silver metalloid nanocomposite blended with a triblock copolymer poly(<I>p</I>‐dioxanone‐<I>co</I>‐caprolactone)‐<I>block</I>‐poly(ethylene oxide)‐<I>block</I>‐poly(<I>p</I>‐dioxanone‐<I>co</I>‐caprolactone) (POSS‐SiO<SUB>2</SUB>@Ag/PPDO‐<I>co</I>‐PCL‐<I>b</I>‐PEG‐<I>b</I>‐PPDO‐<I>co</I>‐PCL) has been synthesized in both water and in organic medium utilizing ultrasonochemical reaction. The POSS stabilized pre‐made metalloid was successfully dispersed in amphiphilic PPDO‐<I>co</I>‐PCL‐<I>b</I>‐PEG‐<I>b</I>‐PPDO‐<I>co</I>‐PCL (ABA) triblock copolymer matrix of molecular weight 45.9 × 10<SUP>4</SUP> g/mol. The mechanism of synthesis of high concentration of SiO<SUB>2</SUB>@Ag nanocomposite from TEOS/AgNO<SUB>3</SUB> (in the presence of NH<SUB>4</SUB>OH as catalyst/NaBH<SUB>4</SUB> as reductant) nonmetal/metal precursors and the successful EISA of POSS‐SiO<SUB>2</SUB>@Ag/ABA nanocomposite into films has been discussed. The successful synthesis of metalloid nanocomposite was morphologically accessed by field emission‐scanning electron microscopy, transmission electron microscopy and atomic force microscopy. Surface plasmon resonance was ensured from UV–visible spectral analysis. Identity and the crystallinity of as prepared nanocomposite were studied by X‐ray diffractometer. Structural and luminescence properties of the nanocomposite were examined by Fourier transform infrared spectroscopy and photoluminescence. Thermogravimetric analysis was carried out to study the thermal stability of the resulting hybrid nanocomposite. The resultant inorganic–organic nanocomposite can be easily suspended in water and would be useful in variety of applications. POLYM. COMPOS., 31:1620–1627, 2010. © 2009 Society of Plastics Engineers</P>
Antibacterial Efficiency of Graphene Nanosheets against Pathogenic Bacteria via Lipid Peroxidation
Krishnamoorthy, Karthikeyan,Veerapandian, Murugan,Zhang, Ling-He,Yun, Kyusik,Kim, Sang Jae American Chemical Society 2012 The Journal of Physical Chemistry Part C Vol.116 No.32
<P>Graphene nanosheets are highly recognized for their utility toward the development of biomedical device applications. The present study investigated the antibacterial efficiency of graphene nanosheets against four types of pathogenic bacteria. Graphene nanosheets are synthesized by a hydrothermal approach (under alkaline conditions using hydrazine hydrate). UV–vis and X-ray diffraction show a maximum absorbance at 267 nm and appearance of new broad diffraction peak at 26°, which ensures the reduction of graphene oxide into graphene nanosheets. Stretching and bending vibrations of C–C bonds, chemical states, disorder, and defects associated with the graphene nanosheets are evaluated in comparison with graphene oxide. The minimum inhibitory concentration (MIC) of graphene nanosheets against pathogenic bacteria was evaluated by a microdilution method. MICs such as 1 μg/mL (against <I>Escherichia coli</I> and <I>Salmonella typhimurium</I>), 8 μg/mL (against <I>Enterococcus faecalis</I>), and 4 μg/mL (against <I>Bacillus subtilis</I>) suggest that graphene nanosheets have predominant antibacterial activity compared to the standard antibiotic, kanamycin. Measurement of free radical modulation activity of graphene nanosheets suggested the involvement of reactive oxygen species in antibacterial properties.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2012/jpccck.2012.116.issue-32/jp3047054/production/images/medium/jp-2012-047054_0008.gif'></P>
KRISHNAMOORTHYKARTHIKEYAN,Murugan Veerapandian,Ling-He Zhang,윤규식,김상재 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.5
The present study investigated the bacterial toxicity of cerium oxide (CeO2) nanocubes. The X-ray diffraction and Raman spectral studies revealed the formation of nanoceria with cubic fluorite structure. The minimum inhibitory concentration (MIC) of CeO2 nanocubes against pathogenic bacteria was evaluated by a microdilution method. MICs such as 16 mg/mL (against Escherichia coli) and 8 mg/mL (against Salmonella typhimurium and Enterococcus faecalis), and 4 mg/mL (against Bacillus subtilis) suggest that CeO2 nanocubes have predominant anti-bacterial activity. The evaluation of bacterial enzymatic (b-D-galactosidase) activity in the hydrolysis of o-nitrophenol-b-D-galactopyranoside suggested the disruption of bacterial cell wall mechanism, responsible for bacterial toxicity.
Linghe Zhang,윤규식,Murugan Veerapandian 한국바이오칩학회 2014 BioChip Journal Vol.8 No.2
We report the fabrication and fluorescent properties of hybrid material composed of fluorescent silica nanoparticles (FSNs) functionalized multi-walled carbon nanotubes(MWCNTs). Stöber method derived FSNs were successfully conjugated with MWCNTSchemically activated concentrated acids, poly(acrylic acid) (PAA) and 3-aminopropyl-trimethoxysilane (APTES) to obtain the nanocomposite FSNs/MWCNTs. Electron microscopic investigations revealed the spherical shape and smooth surface of FSNs with the diameter ~150±50 nm. Activated functional groups of MWCNTs provided the necessary support for functionalization of FSNs. FT-IR spectral analysis shows the structural integrity of FSNs, MWCNTs, and the hybrid FSNs/MWCNTs. Fluorescent emission property of FSNs/MWCNTs are observed to be significant than pristine dye fluorescein isothiocyanate and FSNs. Enhanced fluorescent emission and photostability of FSNs/MWCNTs provides promising feasibility for further exploration in biomedical applications.