Effects of Bio-conjugation and annealing on the photoluminescence and Raman Spectra of CdSe/ZnS quantum dots

The effect of thermal annealing at ambient conditions on the photoluminescence (PL) and Raman scattering spectra of non-conjugated and conjugated with S6K2 antibody CdSe/ZnS core-shell quantum dots (QDs) has been studied. In the PL spectra, the annealing is found to produce the blue shift of the PL band spectral position and degradation of the PL intensity. These changes are found to be much more intense in conjugated QDs and are accompanied by the increase of a PL band half-width. In the Raman scattering spectra, the spectral shift and a decrease of the intensity of CdSe LO phonon peak as well as a increase of the intensity and narrowing of the peak ascribed to a mixed interface layer are found. The effect of annealing is supposed to be the result of partial core-shell intermixing that is accompanied by the QD oxidation in bio-conjugated QDs.