Synthesis of N‐Acetylcysteine Conjugated Cholic Acid Stabilized Gold and Silver Nanoparticles: Evaluation of Their Catalytic Activity and Toxicity Assessment

Abstract

AbstractHere we report an efficient and simple protocol for the preparation of N‐acetylcysteine conjugated cholic acid (ACyCA) by adopting thiol‐yne click chemistry approach. The synthesized ACyCA amphiphiles showed primary and secondary critical micellar concentration (CMC) at 3.6 and 11.05 mM. The prepared ACyCA was used as a soft template for the preparation of gold (Au) and silver (Ag) nanoparticles (NPs) under sun light exposure. The optical and morphological properties of NPs were studied by UV‐visible, DLS, zeta potential and HR‐TEM techniques. The synthesized NPs having monodispersed spherical shaped and anisotropic nature with an average size of ∼10.5 nm and ∼45.8 nm for Au and Ag NPs, respectively. The catalytic activity of the prepared NPs was evaluated for the reduction of 4‐nitrophenol (4‐NP) to 4‐aminophenol (4‐AP) as a model reaction and the apparent rate constant (kapp) was found to be 3.27×10−4 s−1 and 15.6×10−4 s−1 for Au and Ag NPs respectively. Also, Ag and Au NPs were screened for antimicrobial activity against five human pathogens. Among these, AgNPs showed maximum zone of inhibition (ZOI) 23 mm for Staphylococcus aureus when compared to AuNPs, and the minimum inhibitory concentration of AgNPs was found to be 64 μg/mL for S. aureus. From the haemocompatibility studies, the AgNPs showed more compatibility for the human blood cells as compared to AuNPs. Multiphoton confocal fluorescent microscopic observation of bacterial cells treated with AgNPs showed 45 to 50 % of dead cells.