Abstract
The emergence of highly drug-resistant fungal strains is the major concern in health care sector. There is an urgent need to develop novel and potent antifungal drugs with minimal side effects to encounter invasive fungal infections. In this study, we have green-synthesized silver nanoparticles (AgNPs) by using leaf extract of Selaginella bryopteris and checked their antifungal activity against different Candida spp. The optimization of parameters involved in the synthesis of AgNPs includes pH, temperature, concentration of silver nitrate, reaction time. The synthesis of NPs was investigated by the UV-Vis spectrophotometric analysis. The physicochemical properties of AgNPs were further analysed by FESEM, TEM, DLS, zeta potential, FTIR and XRD studies. AgNPs were found to be spherical in shape with an average size of 35 nm and were monodispersed in nature without any agglomeration. The results of antifungal susceptibility testing (AFST) and growth curve kinetics revealed that AgNPs displayed significant anticandidal activity with MIC and MFC values of 0.003 and 0.006 ng/mL respectively. Treatment of Candida spp. with AgNPs leads to damage in fungal cell wall, cell membrane along with disruption of mitochondrial enzyme activity and release of nuclear content. The green-synthesized AgNPs not only caused damage and destruction to the morphology of Candida but also affected the ergosterol biosynthetic pathway. The green-synthesized AgNPs were also found to exhibit antibiofilm activity against Candida spp. which was assessed by crystal violet assay and SEM analysis confirming biofilm reduction by 80-82% as compared to control.