Browsing by Author "Purnendu Kumar Pathak"

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A novel electrocatalytic nanocomposite of reduced graphene oxide/silver nanocube hybrid decorated imprinted polymer for ultra-trace sensing of temozolomide
(Royal Society of Chemistry, 2018) Purnendu Kumar Pathak; Anil Kumar; Bhim Bali Prasad
A new nanocomposite of reduced graphene oxide/silver nanocube hybrid decorated molecularly imprinted polymer at the surface of a screen-printed carbon electrode was developed for the electroanalysis of an anticancerous drug, temozolomide, at the ultra-trace level. For this, a hybrid of reduced graphene oxide/silver nanocubes was successfully obtained through the simultaneous reduction of Ag+ and graphene oxide via simple one-pot green synthesis. Among the various shapes of nanomaterials used in imprinted polymer synthesis, silver nanocubes, as evident from SEM, TEM and, X-ray diffraction methods, have been found to render high surface to volume ratios and a higher electrocatalytic activity. Herein, the synergistic electrocatalytic effect of reduced graphene oxide and silver nanocubes was utilized for decreasing the analyte oxidation overpotential, without any interfacial barrier in between the imprinted film and the electrode surface, owing to the porous texture of the coating. Consequently, approximately 3-fold differential pulse anodic stripping current and ∼5-fold electron transfer rate kinetics were obtained on the reduced graphene oxide/silver nanocube hybrid compared with the simple graphene oxide decorated sensor. The covalent Ag-S links, in between the imprinted film and the silver nanocube decorated screen-printed carbon electrode, were crucial for imparting higher stability to the coating of the film. A perfect linearity in the current-concentration profile was observed, in the range 1.09-144.21 ng mL-1, with the detection limits of 0.16 (aqueous), 0.24 (blood plasma), 0.31 (pharmaceutics), and 0.42 (urine) ng mL-1 (S/N = 3). The proposed sensor was found to be useful in aqueous and real samples (human blood plasma, human urine, and pharmaceutics), without any matrix effect, cross-reactivity, or false-positives. © The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.
Development of surface imprinted nanospheres using the inverse suspension polymerization method for electrochemical ultra sensing of dacarbazine
(Elsevier B.V., 2017) Bhim Bali Prasad; Purnendu Kumar Pathak
A new ultra sensing molecularly imprinted polymer beads modified pencil graphite electrode was fabricated, with the help of the inverse suspension polymerization technique, for ascertaining the adequate supplementation of dacarbazine in the cancer treatment. The inverse suspension polymerization technique was beneficial in obtaining surface imprinted polymer-based electrocatalytic nanospheres with narrow size distribution. These nanospheres were found to be superior to the corresponding microspheres and planar films, in terms of electrode kinetics and sensitivity, with the differential pulse anodic stripping voltammetric transduction. Herein, multiwalled carbon nanotubes functionalized ester links were invoked in between the imprinted nanospheres and the pencil graphite electrode surface to secure a stable coating and better electrodics. The proposed electrochemical sensor showed the imprinting factor and the analyte adsorption coefficient as high as 24.3 and 1.06 × 109 L mol−1, respectively. Furthermore, 16-fold and 4-fold faster electron transfer kinetics were observed with the imprinted nanospheres than the corresponding imprinted planar film and the microspheres based electrodes, respectively. The limits of detection [0.02 (aqueous), 0.02 (plasma), 0.01 (urine), and 0.03 ng mL−1 (pharmaceutics), (3σ, RSD ≤ 0.23%)] of dacarbazine, realized with the imprinted polymer nanospheres, were free from any cross-reactivity and false-positive complications in aqueous, blood plasma, urine, and pharmaceutical samples. © 2017 Elsevier B.V.
Electrocatalytic Imprinted Polymer of N-Doped Hollow Carbon Nanosphere-Palladium Nanocomposite for Ultratrace Detection of Anticancer Drug 6-Mercaptopurine
(American Chemical Society, 2019) Anil Kumar; Purnendu Kumar Pathak; Bhim Bali Prasad
In this work, a nanohybrid-based imprinted polymer consisting of N-doped hollow carbon nanospheres and palladium is reported for the electroanalysis of ultratrace level of anticancer drug, 6-mercaptopurine, used in the treatment of leukemia. For this, N-doped carbon nanospheres decorated with palladium were first developed, and subsequently, a molecular imprinted polymer layer was grown onto their surfaces. The so-produced silica-embedded nanocomposite was made hollow by etching silica moieties with hydrofluoric acid. Finally, the whole system was doped on an ionic-liquid-modified pencil graphite electrode. The underlying synergistic effect of hollow carbon nanosphere-supported palladium nanoparticles inculcated electrocatalytic action. Notably, all rebinding sites in solid core-shells were confined within the shell, which hampers the effective diffusion of template. However, in this work, an effective diffusion of template across the hollow structure of inner and outer surfaces was observed. Consequently, this rendered approximately 2-fold heterogeneous rate constant as compared to the solid core-shell-based sensor. Differential pulse voltammetric transduction was used for ultratrace detection of 6-mercaptopurine through anodic stripping method. The hollow imprinted sensor revealed a linear dependence of current with concentration range 0.80-70.748 ng mL -1 . The limits of detection 0.11-0.22 ng mL -1 were realized in water, human blood plasma, urine, and pharmaceuticals. Thus, the proposed sensor demonstrated an attractive sensitivity reproducibility, as well as endurance requisite for the treatment of leukemia patients. © 2019 American Chemical Society.
Functionalized nitrogen doped graphene quantum dots and bimetallic Au/Ag core-shell decorated imprinted polymer for electrochemical sensing of anticancerous hydroxyurea
(Elsevier Ltd, 2019) Purnendu Kumar Pathak; Anil Kumar; Bhim Bali Prasad
A novel molecularly imprinted polymer-capped acrylated nitrogen doped graphene quantum dots and bimetallic Au/Ag core-shell was synthesized to serve as a sensing nano-hybrid film for the detection of an anticancerous drug, hydroxyurea. This exploited the use of a functionalized nitrogen doped graphene quantum dots iniferter. This initiated the polymerization, following “surface grafting-from” approach, over the surface of a screen-printed carbon electrode to obtain requisite stability and selectivity of the measurement. Herein, nitrogen doped graphene quantum dots were prepared utilizing the degree of dehydration/carbonization of citric acid (carbon skeleton) and urea (nitrogen dopant) as source materials. This provided an efficient sensor platform anchoring bimetallic Au/Ag core-shell on its surface. The nano-assembly of acrylated nitrogen doped graphene quantum dots and bimetallic Au/Ag core-shell@imprinted polymer actually amplified the electrode kinetics by improving the diffusion coefficient (~20-fold) and electron-transfer kinetics (~5-fold), in comparison to the simple bimetallic Au/Ag core-shell decorated imprinted sensor. Under optimized conditions of differential pulse anodic stripping voltammetric transduction, a linear relationship between the current and the concentration was obtained in the range of 0.62–102.33 ng mL −1 for hydroxyurea. The detection limit was observed to be 0.07 ng mL −1 in blood plasma, without having any matrix effect, cross-reactivity, and false-positives. The proposed sensor assures its clinical applicability for the treatment of cancer. © 2018 Elsevier B.V.