Electronic effects in Emission of core/shell CdSe/ZnS Quantum dots conjugated to anti-Interleukin 10 antibodies

The paper presents the study of photoluminescence (PL) and Raman scattering spectra of nonconjugated and bioconjugated CdSe/ZnS core-shell quantum dots (QDs). Commercial CdSe/ZnS QDs used are characterized by color emission with the maxima at 605 nm (2.05eV) and 655 nm (1.89 eV). The QD conjugation has been performed with biomolecules – anti Interleukin-10 antibodies (anti IL10 mAb). PL spectra of nonconjugated QDs are characterized by only one symmetric PL band related to the exciton emission in the CdSe core. PL spectra of bioconjugated QDs have changed: PL band shifts into the high energy side and becomes asymmetric. To explain these effects the model has been proposed which assumes that the PL spectrum transformation in bioconjugated QDs, apparently, is connected with the quantum confinement and/or the Stark effects. To confirm the existence of electric charges (or dipoles) in the anti-Interleukin 10 antibodies, which can provoke the Stark effect, the Raman scattering spectra have been investigated as well. The enhancement of Raman scattering is observed in bioconjugated CdSe/ZnS QDs. The last effect testifies that the IL10 antibodies are characterized, actually, by the electric charges (or dipoles) that permit them to interact with an electric field of excitation light and to provoke the surface enhanced Raman scattering (SERS) and the Stark effects in QDs.