Cytotoxic effect of ZnS nanoparticles on primary mouse retinal pigment epithelial cells

The multiple properties of zinc sulphide nanoparticles (ZnS-NPs) are attracting great attention in the field of chemical and biological research. ZnS-NPs also find their application in biosensor and photocatalysis. Zinc is an important metal ion in retina and its deficiency leads to age-related macular degeneration. As of now, not much research is available on bio-interaction of ZnS as nanoform with retinal pigment epithelial (RPE) cells. RPE cells in the retina help in maintaining normal photoreceptor function and vision. To begin with, ZnS-NPs were synthesized and characterized using UV-visible spectra, X-ray diffraction, Fourier transform infrared spectrum, transmission electron microscopy and dynamic light scattering. Followed by the confirmation of nanoparticles, our study extended to investigate the impact of ZnS-NPs in primary mouse RPE (MRPE) cells at different concentrations. ZnS-NPs showed dose-dependent cytotoxicity in MRPE cells and no changes were observed in cells' tight intactness at minimal concentration. In addition, exposure to ZnS-NPs increased cellular permeability in dose- and time-dependent manner in MRPE cells. The findings from DCFH-DA analysis revealed that ZnS-NPs-treated cells had elevated level of reactive oxygen species and partial activation of cell apoptosis was identified after exposure to ZnS-NPs at higher concentration. Furthermore, pre-treatment of the primary MRPE cells with ZnS-NPs led to phosphorylation of Akt (Ser 473), which indicates the crucial role of ZnS-NPs in regulating cell survival at minimal concentration. Altogether, this study enumerates requisite dose of using ZnS-NPs to maintain healthy RPE cells and contributes to future studies in development of therapeutic drug and drug carrier for ocular-related disorders.