Synthesis and characterisation of functional manganese doped ZnS quantum dots for bio-imaging application

Fluorescent quantum dots (QDs) are potential candidates for bio-imaging but major problems in using them for bio-imaging applications are either bandgap lying in UV region or the cytotoxicity of the visible light-excited cadmium-based QDs. Keeping these things in mind, glutathione (GLT) functionalised Mn-doped ZnS QDs has been studied to make a desired fluorescent system for bioimaging application. XRD measurements show that grain size decreases at higher concentration of GLT capping on Mn-doped quantum dots. UV–visible studies show that the band gap shows a blue shift at higher GLT concentration. FTIR studies confirm GLT functionalisation on the surface of ZnS QDs. Both UV excited and IR excited photoluminescence spectrum of samples exhibited a tunable orange emission intensity with increase in GLT concentration however multiphoton infrared excited spectra was used to show the feasibility of GLT functionalised ZnS:Mn quantum dots for a real application in a biological window of 650–950 nm.