Browsing by Author "Shivani Shukla"

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An Array-based Photolithographically Patterned Electrochemical Sensing Platform for Highly Sensitive Determination of Uric Acid, Dopamine, l-Tryptophan, and Pyridoxine in Biological Samples
(Springer Nature, 2024) Ankit Kumar Singh; Shreanshi Agrahari; Shivani Shukla; Ida Tiwari; Muhammad Ahmad; S. Ravi P. Silva
Biomolecules play important roles in physiological functions and pharmacological characteristics of human body. Uric acid (UA) is the end product of purine. Dopamine (DA) is a neurotransmitter of catecholamine group. l-tryptophan is an essential amino acid that can be metabolized to neuroactive substances. Pyridoxine is a water-soluble vitamin playing an important role in nervous system. The abnormalities in their concentration levels led to a wide range of significant mental and physical illnesses. Thus, electrochemical analysis of these analytes on an array system would be beneficial from clinical or scientific points of view. This work was aimed at the development of practical sensor array for determination of multiple analytes on a single sensing platform using individually addressable microelectrodes. The occurrence of adsorption–desorption phenomenon on the surface of palladium microelectrode array (Pd MEA) printed on the silicon wafer through photolithography was exploited for electro-oxidation of UA, DA, l-tryptophan and pyridoxine. The sensing of electroactive UA was done using carbon nanotubes(CNTs) grown Pd MEA as a working electrode, while selectivity for other analytes was achieved by the modification of CNTs/Pd MEA through electrodeposition of poly(l-lysine) (poly(l-lysine)/CNTs/Pd MEA) for DA sensing, poly(l-arginine) (poly(l-arginine)/CNTs/Pd MEA) for l-tryptophan sensing and reduced graphene oxide (rGO/CNTs/Pd MEA) for pyridoxine sensing. The electrochemical differential pulse voltammetry (DPV) analyses reveal excellent linearity in the concentration ranges of 50–6000 µmol/L, 2–8000 µmol/L, 20–15,000 µmol/L, and 10–5000 µmol/L with detection limits of 15.0, 0.5, 10.0, and 1.0 µmol/L for UA, DA, l-tryptophan, and pyridoxine, respectively. The proposed multiple analytes sensor has shown very high sensitivities of 140, 9580, 2280, and 940 µA·(µmol·L−1)−1·cm−2 for UA, DA, l-tryptophan, and pyridoxine sensing, respectively. Further, accuracy and reliability of the fabricated sensor were also tested in real samples. © The Nonferrous Metals Society of China 2024.
ZnO-MoS2 supported on boron nitride nano-sheets for the adsorptive removal and degradation of ciprofloxacin from aqueous solution
(Taylor and Francis Ltd., 2025) Shivani Shukla; Ravindra Kumar Gautam; I. C. Tiwari
MoS2/ZnO supported on boron nitride nanocomposite (BN/MoS2/ZnO) was synthesised via simple co-precipitation and mechanical stirring method. The removal of ciprofloxacin (CIP) from wastewater was examined by utilising synthesised BN/MoS2/ZnO nanomaterial. The synthesised nanomaterial was successfully characterised by sophisticated techniques such as FT-IR, XRD, HR-TEM, HR-SEM and EDX analysis. BN/MoS2/ZnO was further utilised to examine the impact of different optimising factors, including contact time and solution pH. The result shows that pH 4 was the optimum parameter for CIP removal within 90 min of contact time, on which 81% and 67.72% of CIP were removed. The adsorption follows the pseudo-second-order kinetics (R2 = 0.99) and isotherm modelling was best explained by the Langmuir model (qm = 83.333 mg g−1). Thermodynamic study shows the spontaneous and endothermic nature for the adsorption of CIP. For the catalytic degradation, the ultrasonication method gives the best result, where 98.25% of CIP was degraded within 60 min of ultrasonic wave exposure. Recycling of the nanocomposite was achieved by using a 0.1 M NaOH solution, and it can be used for up to five cycles. © 2024 Informa UK Limited, trading as Taylor & Francis Group.
ZnO-MoS2 supported on boron nitride nano-sheets for the adsorptive removal and degradation of ciprofloxacin from aqueous solution
(Taylor and Francis Ltd., 2024) Shivani Shukla; Ravindra Kumar Gautam; Ida Tiwari
MoS2/ZnO supported on boron nitride nanocomposite (BN/MoS2/ZnO) was synthesised via simple co-precipitation and mechanical stirring method. The removal of ciprofloxacin (CIP) from wastewater was examined by utilising synthesised BN/MoS2/ZnO nanomaterial. The synthesised nanomaterial was successfully characterised by sophisticated techniques such as FT-IR, XRD, HR-TEM, HR-SEM and EDX analysis. BN/MoS2/ZnO was further utilised to examine the impact of different optimising factors, including contact time and solution pH. The result shows that pH 4 was the optimum parameter for CIP removal within 90 min of contact time, on which 81% and 67.72% of CIP were removed. The adsorption follows the pseudo-second-order kinetics (R2 = 0.99) and isotherm modelling was best explained by the Langmuir model (qm = 83.333 mg g−1). Thermodynamic study shows the spontaneous and endothermic nature for the adsorption of CIP. For the catalytic degradation, the ultrasonication method gives the best result, where 98.25% of CIP was degraded within 60 min of ultrasonic wave exposure. Recycling of the nanocomposite was achieved by using a 0.1 M NaOH solution, and it can be used for up to five cycles. © 2024 Informa UK Limited, trading as Taylor & Francis Group.