Cell Viability Study of ZnCuInS/ZnS–TPPS₄ Conjugates against Different Cell Lines as a Promising Fluorescent Probe

In the present work, we report a simple synthetic strategy for fabricating ZnCuInS/ZnS–TPPS₄ conjugates and study its cytotoxicity as a promising material for imaging and phototherapy applications. The quaternary QDs were synthesized using eco-friendly materials such as glutathione and water as a solvent, while the anionic 10,15,20-(4-sulphonatophenyl) porphyrin (TPPS₄) was synthesized via the acidification of a meso-tetraphenylporphyrin precursor. Interest in TPPS₄ results from its high-water dispersity, stability, and ability to generate singlet oxygen. Conjugation of ZnCuInS/ZnS QDs with TPPS₄ was performed by titrating porphyrin with different amounts of ZnCuInS/ZnS QDs while keeping all other experimental parameters constant. Comparative analysis of the conjugate to the bare QDs and porphyrin revealed enhanced spectral and photophysical properties. Comparative cytotoxicity assays were performed for TPPS₄ and ZnCuInS/ZnS–TPPS₄ conjugates in BHK21, Hela, A549, Hek 293 and B16-F10 Nex 2 cell lines using the MTT cell viability assay. The results showed negligible in vitro cytotoxicity indicating the conjugate is an excellent and biocompatible candidate for imaging and phototherapy applications.