The mechanism of the photoluminescence changes in bio-conjugated CdSe/ZnS quantum dots

► The changes in luminescence and Raman spectra in CdSe/ZnS quantum dots (QDs) during storage have been studied. ► The QD luminescence band blue shifts, broadens and decreases in intensity. ► The CdSe (LO) peak shifts to the low frequency region and broadens. ► The changes are ascribed to QD oxidation, which decreases the QD size. ► Bio-conjugation is supposed to promote QD oxidation.