Fabrication and stabilization of nanosilver using Houttugniae for antibacterial and catalytic application

Silver nanoparticles (AgNPs) were synthesised utilising a one-pot green synthesis process using phytonutrients obtained from Houttugniae herba (HH) as a reductant and stabiliser. The proposed technique was fast, simple, eco-friendly, and cost-effective, and it does not require any additional processing or toxic ingredients to reduce and stabilise the AgNPs. All parameters (concentration of HH, reaction duration, temperature, and pH) involved in the reduction/stabilisation reaction were evaluated using a one-factor-at-a-time (OFAT) technique in a set of the experimental array to establish an optimal reaction state. Intense yellow colour and a prominent peak at 411 nm in the UV-vis absorption spectra indicated the growth of AgNPs in the reaction system. The produced AgNPs deploying optimum parameters were nearly spherical, with nanometre size (16.28 +/- 4.48 nm), highly crystalline (d-spacing = 0.234 and 0.258 nm), and well stabilised (zeta potential = -26.4 mV). The measurement and analysis also yielded that the AgNPs were formed by an oxidation-reduction reaction between plant-derived phytonutrients and metal precursors and subsequently stabilised by the encapsulation of phytonutrients. The biogenic AgNPs exhibited remarkable antibacterial effectiveness against gram-positive and gram-negative bacteria. In addition, the AgNPs demonstrated significant catalytic degradation and mineralisation of industrially essential di-azo dyes with a degradation efficiency of nearly 100% within 20 min. The present investigation shows a simple and environmentally friendly way to synthesise AgNPs, which might be feasible to meet the current need for bacterial reduction and textile wastewater treatment.