Probing the cytotoxicity of CdS–MPA and CdSe–MUA QDs on the bacterial pathogen Staphylococcus aureus using MALDI-MS

Abstract

Two quantum dots, CdS QDs capped with “mercaptopropionic acid” (MPA) and CdSe capped with “mercaptoundecanoic acid” (MUA), were synthesized and their toxicity against the well known bacterial pathogen, Staphylococcus aureus, was compared using matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS), epifluorescence microscopy and spectrophotometric analysis (O.D. 600 nm). CdS–MPA QDs were observed to be more compatible compared to CdSe–MUA QDs. The CdSe–MUA QDs were toxic at all concentrations and at incubation time <3 h too. It was also observed that the CdS–MPA QDs were not entirely biocompatible, but exhibited toxicity at concentrations >0.5 mg mL⁻¹ after prolonged incubation (>12 h). The epifluorescence technique confirmed the results which have been observed in the MALDI-MS studies.