Abstract

• Phytochemical cocktail stabilized AgNP decorated on biopolymer polydopamine by single pot approach. • AgNP@PDA has shown peroxidase mimicking activity as a synergetic role of AgNP and PDA for TMB oxidation and •OH radical generation. • The enhanced degradation efficiency of AgNP@PDA for p -NPP via peroxidase mimicking activity than AgNP. • PDA enhanced antibacterial activity and economy of AgNP@PDA. • The improved cytocompatibility of AgNP by biocompatible PDA. Organophosphates are the nerve agent simulant structure and are classified as widely used insecticides. Their exposure turns lethal due to instant blockage of neural communication by inhibiting acetylcholinesterase enzyme. In the present study, a single pot technique was employed to produce silver nanoparticles (AgNP) using a phytochemical cocktail of gallic acid and quercetin as reducing and stabilizing agents, decorated on the biopolymer polydopamine (PDA). The AgNP@PDA exhibits peroxidase mimicking activity mediated degradation of p -nitrophenyl phosphate ( p -NPP) an organophosphate representative at pH 7. Peroxidase mimicking activity study revealed oxidation of TMB by reducing Ag + ion generated from AgNP upon H 2 O 2 exposure. However, the H 2 O 2 upon interaction with surface AgNP produces hydroxyl anion and subsequently •OH radicals where PDA serves as an ultimate electron sink. Compared to individual components, AgNP@PDA has shown maximum p -NPP degradation efficiency ( k (AgNP@PDA) = 3.91 × 10 -2 min. −1 , k (AgNP) = 0.24 × 10 -2 min. −1 , k (H 2 O 2 ) = 0.17 × 10 -2 min. −1 ). The kinetics of AgNP@PDA for p -NPP degradation has shown well-fitted Michaelis Menten behavior with K m = 0.016 mM and V max = 2.80 × 10 -5 which is ten-fold higher than AgNP. The degradation mechanism was proposed based on electrospray ionization mass spectroscopy which suggests the breaking of the phospho-ester bond. The extent of mineralization of organic skeleton was assessed by a significant decrease in total organic carbon (TOC). The presence of PDA has improved the antibacterial activity with AgNP and cytocompatibility of AgNP@PDA than AgNP.

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