Synthesis of Nanoparticles of ZnS:Ag-L-cysteine-protoporphyrin IX Conjugates and Investigation its Potential of Reactive Oxygen Species Production

In this paper, L-cysteine capped Ag doped ZnS nanoparticles (NPs) were synthesized and its usage in photodynamic therapy was examined. Also, the details of the conjugation method for prepared NPs with sensitizer of protoporphyrin IX (PpIX) were reported. FT-IR studies indicate the formation of ZnS:Ag nanoparticles capped with L-cysteine and an amide-bond formation between PpIX and L-cysteine-capped ZnS:Ag NPs. The formation of ZnS:Ag NPs conjugated to protoporphyrin IX was confirmed through the use of SEM, TEM, UV-Visible, FT-IR and DLS analysis. The efficient energy transfer from ZnS:Ag to PpIX sensitizer was estimated at about 90%. The production of reactive oxygen species, including singlet oxygen and free radicals, from ZnS:Ag NPs conjugated to protoporphyrin IX, was observed using a chemical method. The production of reactive oxygen species of this conjugate indicates its potential application in photodynamic therapy.