Selective and sensitive determination of one of the purine nucleotides, inosine (INO) using a low... more Selective and sensitive determination of one of the purine nucleotides, inosine (INO) using a low cost carbon dot (CD) modified glassy carbon (GC) electrode in 0.2 M phosphate buffer solution (pH 7.2) was demonstrated in this paper.
Disulfide bond formation is the decisive event in the protein folding to determine the conformati... more Disulfide bond formation is the decisive event in the protein folding to determine the conformation and stability of protein. To achieve this disulfide bond formation in vitro, we took 2,5-dimercapto-1,3,4-thiadiazole (DMcT) as a model compound. We found that disulfide bond formation takes place between two sulfhydryl groups of DMcT molecules in methanol. UV-Vis, FT-IR and mass spectroscopic as well as cyclic voltammetry were used to monitor the course of reaction. We proposed a mechanism for the solvent induced disulfide bond formation on the basis of the results we obtained.
Short time preparation of stable graphene layers was fabricated on electrode surface using simult... more Short time preparation of stable graphene layers was fabricated on electrode surface using simultaneous electroreduction of diazonium salts and graphene oxide.
Gold@silver core–shell nanoparticles were synthesized by galvanic displacement reaction and modif... more Gold@silver core–shell nanoparticles were synthesized by galvanic displacement reaction and modified on glassy carbon electrode for the reduction of hydrogen peroxide and nitrobenzene.
This paper describes the fabrication of cubic, spherical, dendritic and prickly copper nanostruct... more This paper describes the fabrication of cubic, spherical, dendritic and prickly copper nanostructures (CuNS) on indium-tin-oxide (ITO) substrates by electrodeposition and their electrocatalytic activity towards the oxidation of glucose and hydrazine. CuNS with different shapes were fabricated on ITO substrates by using different applied potentials of +0.10, −0.10, −0.30 and −0.50 V for 400 s in the presence of 10 mM CuSO4 and 0.1 M H2SO4. The formed CuNS were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), X-ray photoelectron spectroscopy (XPS) and electrical impedance spectroscopy (EIS). SEM images showed that cubic, spherical, dendritic and prickly CuNS were formed at applied potentials of +0.10, −0.10, −0.30 and −0.50 V, respectively. XPS showed characteristic peaks at 935 and 955 eV corresponding to Cu(0). The dendritic CuNS modified electrode exhibits a higher heterogeneous electron transfer rate constant of 3.70 × 10−7 cm s−1 and an electroactive area of 51.32 cm2 when compared to other CuNS modified electrodes. Further, the electrocatalytic activity of the different shaped CuNS modified ITO electrodes was examined towards the oxidation of glucose and hydrazine. Interestingly, the dendritic CuNS modified ITO substrate dramatically enhanced the oxidation currents of both glucose and hydrazine and also shifted their oxidation potential towards less positive potential when compared to bare ITO and other CuNS modified ITO substrates. The formation of dendritic CuNS was optimized with respect to deposition time, anion and pH and was monitored by SEM. Based on the results, a plausible mechanism for dendritic CuNS formation was proposed.
A non-enzymatic hydrogen peroxide sensor was developed using gold@platinum nanoparticles (Au@PtNP... more A non-enzymatic hydrogen peroxide sensor was developed using gold@platinum nanoparticles (Au@PtNPs) with core@shell structure fabricated on glassy carbon electrode (GCE) by electroless deposition method. Initially, gold nanoparticles (AuNPs) were deposited on GCE by reducing HAuCl 4 in the presence of NH 2 OH and the deposited AuNPs on GCE act as the nucleation centre for the deposition of platinum nanoparticles (PtNPs) in the presence of H 2 PtCl 6 and NH 2 OH. SEM and AFM studies demonstrated that the electroless deposition of Pt on Au was isotropic and uniform. Further, Au@PtNP-modified substrates were characterized by X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray analysis (EDAX) and cyclic voltammetry (CV). XPS showed characteristic binding energies at 71.2 and 74.4 eV for PtNPs and, 83.6 and 87.3 eV for AuNPs indicating the zero-valent nature in both of them. The electrocatalytic activity of Au@PtNP-modified electrode was investigated towards hydrogen peroxide (HP) reduction. The modified electrode exhibited higher electrocatalytic activity towards HP by not only shifting its reduction potential by 370 mV towards less positive potential but also by enhancing the reduction current when compared to bare and AuNP-modified GCE. The present method shows better sensitivity compared to the reported methods in literature and the detection limit was found to be 60 nM.
Colorimetric and fluorimetric determination of tannic acid using blue luminescent graphene quantu... more Colorimetric and fluorimetric determination of tannic acid using blue luminescent graphene quantum dots (GQDs).
Gold@platinum core–shell nanoparticles were modified on a glassy carbon electrode by an electrole... more Gold@platinum core–shell nanoparticles were modified on a glassy carbon electrode by an electroless deposition method and then used for the electrocatalytic reduction of dioxygen and oxidation of hydrazine.
This article describes the selective and sensitive determination of mefenamic acid (MA) using a c... more This article describes the selective and sensitive determination of mefenamic acid (MA) using a carboxylated multiwalled carbon nanotube nanostructured conducting polymer composite modified glassy carbon electrode in 0.2 M phosphate buffer solution (pH 7.2).
Electrochemically reduced graphene oxide film catalyzed electroless deposition of gold nanopartic... more Electrochemically reduced graphene oxide film catalyzed electroless deposition of gold nanoparticles.
Petrophysical measurements are used to construct reservoir models at a scale that are different f... more Petrophysical measurements are used to construct reservoir models at a scale that are different from that at which they are measured. This disparity necessitates an adjustment or scale-up of the measured values before they are used. Scale-up is complicated by the properties being heterogeneously distributed in space and self- or autocorrelated. The autocorrelation means that the heterogeneity itself must be
This paper describes the fabrication of thin films of porphyrin and metallophthalocyanine derivat... more This paper describes the fabrication of thin films of porphyrin and metallophthalocyanine derivatives on different substrates for the optochemical detection of HCl gas and electrochemical determination of L-cysteine (CySH). Solid state gas sensor for HCl gas was fabricated by coating meso-substituted porphyrin derivatives on glass slide and examined optochemical sensing of HCl gas. The concentration of gaseous HCl was monitored from the changes in the absorbance of Soret band. Among the different porphyrin derivatives, meso-tetramesitylporphyrin (MTMP) coated film showed excellent sensitivity towards HCl and achieved a detection limit of 0.03 ppm HCl. Further, we have studied the self-assembly of 1,8,15,22tetraaminometallophthalocyanine (4α-MTAPc; M = Co and Ni) from DMF on GC electrode. The CVs for the self-assembled monolayers (SAMs) of 4α-Co II TAPc and 4α-Ni II TAPc show two pairs of well-defined redox couple corresponding to metal and ring. Using the 4α-Co II TAPc SAM modified electrode, sensitive and selective detection of L-cysteine was demonstrated. Further, the SAM modified electrode also successfully separates the oxidation potentials of AA and CySH with a peak separation of 320 mV.
Selective and sensitive determination of one of the purine nucleotides, inosine (INO) using a low... more Selective and sensitive determination of one of the purine nucleotides, inosine (INO) using a low cost carbon dot (CD) modified glassy carbon (GC) electrode in 0.2 M phosphate buffer solution (pH 7.2) was demonstrated in this paper.
Disulfide bond formation is the decisive event in the protein folding to determine the conformati... more Disulfide bond formation is the decisive event in the protein folding to determine the conformation and stability of protein. To achieve this disulfide bond formation in vitro, we took 2,5-dimercapto-1,3,4-thiadiazole (DMcT) as a model compound. We found that disulfide bond formation takes place between two sulfhydryl groups of DMcT molecules in methanol. UV-Vis, FT-IR and mass spectroscopic as well as cyclic voltammetry were used to monitor the course of reaction. We proposed a mechanism for the solvent induced disulfide bond formation on the basis of the results we obtained.
Short time preparation of stable graphene layers was fabricated on electrode surface using simult... more Short time preparation of stable graphene layers was fabricated on electrode surface using simultaneous electroreduction of diazonium salts and graphene oxide.
Gold@silver core–shell nanoparticles were synthesized by galvanic displacement reaction and modif... more Gold@silver core–shell nanoparticles were synthesized by galvanic displacement reaction and modified on glassy carbon electrode for the reduction of hydrogen peroxide and nitrobenzene.
This paper describes the fabrication of cubic, spherical, dendritic and prickly copper nanostruct... more This paper describes the fabrication of cubic, spherical, dendritic and prickly copper nanostructures (CuNS) on indium-tin-oxide (ITO) substrates by electrodeposition and their electrocatalytic activity towards the oxidation of glucose and hydrazine. CuNS with different shapes were fabricated on ITO substrates by using different applied potentials of +0.10, −0.10, −0.30 and −0.50 V for 400 s in the presence of 10 mM CuSO4 and 0.1 M H2SO4. The formed CuNS were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive X-ray analysis (EDAX), X-ray photoelectron spectroscopy (XPS) and electrical impedance spectroscopy (EIS). SEM images showed that cubic, spherical, dendritic and prickly CuNS were formed at applied potentials of +0.10, −0.10, −0.30 and −0.50 V, respectively. XPS showed characteristic peaks at 935 and 955 eV corresponding to Cu(0). The dendritic CuNS modified electrode exhibits a higher heterogeneous electron transfer rate constant of 3.70 × 10−7 cm s−1 and an electroactive area of 51.32 cm2 when compared to other CuNS modified electrodes. Further, the electrocatalytic activity of the different shaped CuNS modified ITO electrodes was examined towards the oxidation of glucose and hydrazine. Interestingly, the dendritic CuNS modified ITO substrate dramatically enhanced the oxidation currents of both glucose and hydrazine and also shifted their oxidation potential towards less positive potential when compared to bare ITO and other CuNS modified ITO substrates. The formation of dendritic CuNS was optimized with respect to deposition time, anion and pH and was monitored by SEM. Based on the results, a plausible mechanism for dendritic CuNS formation was proposed.
A non-enzymatic hydrogen peroxide sensor was developed using gold@platinum nanoparticles (Au@PtNP... more A non-enzymatic hydrogen peroxide sensor was developed using gold@platinum nanoparticles (Au@PtNPs) with core@shell structure fabricated on glassy carbon electrode (GCE) by electroless deposition method. Initially, gold nanoparticles (AuNPs) were deposited on GCE by reducing HAuCl 4 in the presence of NH 2 OH and the deposited AuNPs on GCE act as the nucleation centre for the deposition of platinum nanoparticles (PtNPs) in the presence of H 2 PtCl 6 and NH 2 OH. SEM and AFM studies demonstrated that the electroless deposition of Pt on Au was isotropic and uniform. Further, Au@PtNP-modified substrates were characterized by X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray analysis (EDAX) and cyclic voltammetry (CV). XPS showed characteristic binding energies at 71.2 and 74.4 eV for PtNPs and, 83.6 and 87.3 eV for AuNPs indicating the zero-valent nature in both of them. The electrocatalytic activity of Au@PtNP-modified electrode was investigated towards hydrogen peroxide (HP) reduction. The modified electrode exhibited higher electrocatalytic activity towards HP by not only shifting its reduction potential by 370 mV towards less positive potential but also by enhancing the reduction current when compared to bare and AuNP-modified GCE. The present method shows better sensitivity compared to the reported methods in literature and the detection limit was found to be 60 nM.
Colorimetric and fluorimetric determination of tannic acid using blue luminescent graphene quantu... more Colorimetric and fluorimetric determination of tannic acid using blue luminescent graphene quantum dots (GQDs).
Gold@platinum core–shell nanoparticles were modified on a glassy carbon electrode by an electrole... more Gold@platinum core–shell nanoparticles were modified on a glassy carbon electrode by an electroless deposition method and then used for the electrocatalytic reduction of dioxygen and oxidation of hydrazine.
This article describes the selective and sensitive determination of mefenamic acid (MA) using a c... more This article describes the selective and sensitive determination of mefenamic acid (MA) using a carboxylated multiwalled carbon nanotube nanostructured conducting polymer composite modified glassy carbon electrode in 0.2 M phosphate buffer solution (pH 7.2).
Electrochemically reduced graphene oxide film catalyzed electroless deposition of gold nanopartic... more Electrochemically reduced graphene oxide film catalyzed electroless deposition of gold nanoparticles.
Petrophysical measurements are used to construct reservoir models at a scale that are different f... more Petrophysical measurements are used to construct reservoir models at a scale that are different from that at which they are measured. This disparity necessitates an adjustment or scale-up of the measured values before they are used. Scale-up is complicated by the properties being heterogeneously distributed in space and self- or autocorrelated. The autocorrelation means that the heterogeneity itself must be
This paper describes the fabrication of thin films of porphyrin and metallophthalocyanine derivat... more This paper describes the fabrication of thin films of porphyrin and metallophthalocyanine derivatives on different substrates for the optochemical detection of HCl gas and electrochemical determination of L-cysteine (CySH). Solid state gas sensor for HCl gas was fabricated by coating meso-substituted porphyrin derivatives on glass slide and examined optochemical sensing of HCl gas. The concentration of gaseous HCl was monitored from the changes in the absorbance of Soret band. Among the different porphyrin derivatives, meso-tetramesitylporphyrin (MTMP) coated film showed excellent sensitivity towards HCl and achieved a detection limit of 0.03 ppm HCl. Further, we have studied the self-assembly of 1,8,15,22tetraaminometallophthalocyanine (4α-MTAPc; M = Co and Ni) from DMF on GC electrode. The CVs for the self-assembled monolayers (SAMs) of 4α-Co II TAPc and 4α-Ni II TAPc show two pairs of well-defined redox couple corresponding to metal and ring. Using the 4α-Co II TAPc SAM modified electrode, sensitive and selective detection of L-cysteine was demonstrated. Further, the SAM modified electrode also successfully separates the oxidation potentials of AA and CySH with a peak separation of 320 mV.
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