Peculiarities of Raman scattering in bioconjugated CdSe/ZnS quantum dots

The article presents the results of analysis of Raman scattering spectra of non-conjugated and bioconjugated CdSe/ZnS core-shell quantum dots (QDs). Commercial CdSe/ZnS QDs used covered by polymer are characterized by color emission with the maxima at 605-610nm (2.03-2.05eV). The bioconjugation process is performed to biomolecules - the antihuman Interleukin 10 (IL10) antibodies (mab). Raman scattering spectra measured at room temperature with excitation by a He-Ne laser line (632.8nm) demonstrate two groups of peaks: (1) related to the Si substrate at 230-460, 522, 610, 670, 940-1040 cm^-1 and (2) to the PEG polymer on the QD surface in the range of 837-3320 cm^-1. It is revealed that the CdSe/ZnS QD bioconjugation to the antihuman Interleukin 10 antibodies is accompanied with the dramatic changes in the intensity of the Raman lines of both types: the intensity of the Si related line increases six-or ten-fold, but the intensity of the polymer related line decreases ten-fold. The models explaining the mentioned effects in Raman scattering spectra have been discussed.