Applications of L-arginine functionalised green synthesised nickel nanoparticles as gene transfer vector and catalyst

Abstract

ABSTRACTGreen synthesised nickel nanoparticles (NiGs) using Ocimum sanctum leaf extract have been stabilised with L-arginine (Arg–NiGs) and used as gene transfer vector for bacterial transformation and as catalyst for hydrolytic dehydrogenation. Effective binding of L-arginine with NiGs was confirmed by characterisation of Arg–NiGs. L-arginine coating on NiGs prevented the agglomeration of NiGs and reduced the size of the nanoparticles. Synthesised Arg–NiGs was conjugated with green fluorescent protein (GFP) inserted pUC 18 (pDNA–Arg–NiGs) and employed for transforming non-competent Escherichia coli DH5 α. Transformation efficiency of pDNA–Arg–NiGs was found to be higher (3.8 × 106 µg–1 DNA) than the CaCl2-mediated method (2.9 × 105 µg–1 DNA). Fluorescence micrograph of transformants showed enhanced uptake and transformation of pDNA–Arg–NiGs by bacterial cells. Electrophoretic analysis of expressed GFP confirmed that pDNA could retain its functional activity even after binding with Arg–NiGs. This biocompatible, efficient and economical method could be exploited for transforming non-competent bacterial cells. Arg–NiGs catalysed hydrolytic dehydrogenation of ammonia borane (AB) generated 198 mL of hydrogen in 8 min with 128 mg AB and 10 mL of catalyst at 35 °C. The hydrogen generation rate of Arg–NiGs catalysed AB dehydrogenation was determined to be 24.8 mol H2 min–1 with activation energy (Ea) of 34.05 kJ mol–1 and turnover frequency (TOF) of 12.30 mol H2 (mol Ni) –1 min–1. Arg–NiGs retained 89% of its initial catalytic activity even after 10 recycles, indicating its high durability in catalytic reactions. Kinetic studies of AB dehydrogenation by Arg–NiGs show the first-order kinetics with respect to catalyst concentration and zero-order kinetics with respect to AB concentration. This efficient and durable catalyst could be applied in hydrolytic dehydrogenation of AB for effective hydrogen storage.