Synthesis, characterization and antimicrobial activity of novel silver nanoparticles functionalized with nitrogenous ligands

As-synthesized nanoparticles AgNPs(AA) prepared using ascorbic acid (AA) were post-functionalized with ligands, viz., 4-hydroxybenzhydrazide (BH) and with 4-hydroxybenzaldehyde thiosemicarbazone (BTSC) to produce new silver nanoparticles, AgNPs(AA-BH) and AgNPs(AA-BTSC). The nanoparticles were characterized by using UV-visible spectroscopy, FT-IR spectroscopy, P-XRD, SEM with EDX, and TEM techniques. The PXRD patterns of AgNPs(AA), AgNPs(AA-BH), and AgNPs(AA-BTSC) revealed diffraction peaks which correspond to (1 1 1), (2 0 0), (2 2 0), and (3 1 1) planes of face-cantered cubic (FCC) crystalline structure. The TEM images revealed spherical and agglomerated rod-like morphologies of as-synthesized and post-functionalized, respectively. The average particle sizes of AgNPs(AA) AgNPs@BH, and AgNPs@BTSC are found to be 28.4, 46.6, and 135.6 nm, respectively. The nanoparticles exhibited significant activity against bacteria, viz., Staphylococcus aureus, Escherichia coli and fungal species, viz., Candida albicans. The post-functionalized silver nanoparticles (AgNPs(AA-BH) and AgNPsAA(-BTSC)) showed higher antimicrobial activity than as-synthesized AgNPs(AA) metal nanoparticles.