Emission of double core infrared (CdSeTe)/ZnS quantum dots conjugated to antibodies

Commercially available double core CdSeTe/ZnS quantum dots (QDs) with emission at 800 nm (1.60 eV) have been studied by photoluminescence (PL) and Raman scattering methods in non-conjugated states and after the conjugation to the anti-Interleukin 10 (IL-10) antibodies. The PL energy shift, stimulated by the electric charge of antibodies, has been detected in PL spectra of bioconjugated QDs. All optical measurements are performed on the dried droplets of the original solution of non-conjugated and bio-conjugated QDs located on the Si substrate. Raman scattering spectra are studied with the aim to reveal the CdSeTe core compositions, as well as to design the QD energy diagrams in non-conjugated and bio-conjugated states, and to detect the elastic strains at the QD bioconjugation. The optical band gap of CdSeTe core in nonconjugated QDs has been calculated numerically versus core radii, using the effective mass approximation model. Then the energy diagrams for the non-conjugated and bio-conjugated QDs have been designed. The QD energy diagrams permit the analysis of the PL spectra and their transformations at the bioconjugation of QDs. It is revealed that the interface in double core QDs has the type II quantum well character that permits one to explain the IR optical transition (800 nm) in CdSeTe QD core materials with the relatively wide band gaps. The variation of the energy gap profile in QDs conjugated to charged antibodies is discussed as well. It is shown that the PL energy shift is useful for the study of QD bioconjugation with specific antibodies and can be a powerful technique in biology and early medical diagnostics.