Role of plant (tulasi, neem and turmeric) extracts in defining the morphological, toxicity and catalytic properties of silver nanoparticles

Abstract

Silver nanoparticles (SNPs) synthesized using tulasi, neem and turmeric aqueous extracts; both individually and in combination were characterized using various analytical techniques. None of the SNPs have shown bactericidal activity against the Coagulase-negative staphylococci (CoNS), Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. SNPs-2 (Neem) have shown highest toxic effect against HeLa (59.19 ± 2.60 µg/mL) and K-562 (60.26 ± 2.23 µg/mL) cancer cell lines, whereas SNPs-7 (Tulasi:Neem:Turmeric) has shown least toxicity (>100 µg/mL). SNPs-2 has also shown highest mortality against Artemia nauplii with LC50 value of 16.98 µg/mL after 48 h exposure, whereas SNPs-7 has shown lowest mortality (>100 µg/mL). Contrastingly, SNPs-2 has shown highest catalytic activity in the reduction of rhodamine-B (rh-B) and methyl orange (MO) dyes in the presence of sodium borohydride (SBH) as reducing agent. SNPs-2 has degraded 98.45 ± 1.35% rh-B dye under 45 min with 0.0954 min−1 (pseudo-first order rate constant), whereas 94.27 ± 1.74% reduction was observed for MO dye under 35 min with 0.0857 min−1. SNPs-7 has shown 68.93 ± 2.18% (0.0288 min−1 under 45 min) and 90.81 ± 1.87% (0.0730 min−1 under 35 min) reduction for rh-B and MO dyes, respectively.