The antifungal activity of polyvinylpyrrolidone (PVP)-stabilized quantum-sized silver nanoparticles (SNPs) against the growth of Candida albicans has been demonstrated in the present study. C. albicans is a known opportunistic human pathogen causing superficial and systemic infections. Research data carried out on C. albicans so far have shown unequivocally that it develops resistance against conventional antifungal drugs and that the infections it causes are difficult to cure with conventional antifungal agents. Hence, it is urgent to find newer materials for the treatment of infections caused by C. albicans that must be safe for the host. PVP-capped SNPs were synthesized, and its surface plasmon band was observed at 410 nm. The growth of C. albicans was markedly inhibited when the cells were incubated with SNP. The minimum inhibitory concentration (MIC) of SNP was determined as 70 ng/ml, and this value is relatively lower when compared with the conventionally used antifungal drugs such as amphotericin B (0.5 μg/ml), fluconazole (0.5 μg/ml), and ketoconazole (8 μg/ml). The viability of SNP-treated cells was checked by measuring the metabolic activity using XTT assay. Field emission scanning electron microscopic (FE-SEM) and transmission electron microscopic (TEM) analyses of the cells treated with SNP have lost the structural integrity to a greater extent.

Silver nanoparticles (AgNPs), due to their interesting properties and many potential applications have attracted enormous interests in recent years. An attempt has been made in this present study to synthesize AgNPs through biological reduction of silver nitrate, with leaf extract of Hyptis suaveolens (L) Poit serving as a reducing agent. AgNPs formed were characterized with spectral (UV-Vis, XRD, FTIR) and electron microscopic investigations. Dispersed spherical nanosilver particles in the range of 2 nm-85 nm were observed through microscopic analysis and the crystalline nature was evidenced through XRD analyses. Anticandidal activity of biosynthesised AgNPs was evaluated against two Candida albicans strains. The minimum inhibitory concentration (MIC) values for AgNPs against the two clinical strains were 0.27 � 0.03 μg/ml and 0.97 � 0.13 μg/ml. AgNPs were found to be more effective than the amphotericin-B used as control against the strains of the test pathogens. Scanning electron microscopic (SEM) analyses of the Candida cells treated with AgNPs shows change in the surface morphology, suggesting cell wall disruption to be a potential mode of anticandidal activity. Based on our observations, AgNPs synthesized with leaf extract of Hyptis suaveolens could be potentially used in combating candidal infections.