Spectroscopic behavior of bioconjugated quantum dots

We report on a short-wavelength, 'blue' spectral shift of the photoluminescence (PL) spectrum in CdSeTe/ZnS core/shell quantum dots (QDs) caused by bioconjugation with several monoclonal cancer-related antibodies (ABs). Scanning PL spectroscopy was performed on samples dried on solid substrates at various temperatures. The influence of the AB chemical origin on the PL spectral shift was observed. The QD-AB conjugation reaction was confirmed using the agarose gel electrophoresis technique. The spectral shift was strongly increased and the process facilitated when the samples were dried above room temperature. The PL spectroscopic mapping revealed a profile of the PL spectral shift across the dried QD-AB spot. A mechanism of the blue shift is attributed to changes in the QD electronic energy levels caused by a local stress applied to the bioconjugated QD.