Raman spectrum modification of CdSe/ZnS quantum dots at the bio-conjugation to IgG antibodies

The paper presents the analysis of Raman scattering spectra of non-conjugated and bio-conjugated CdSe/ZnS core-shell quantum dots in the range of Raman shifts of 80-2000 cm ^-1. Commercial CdSe/ZnS QDs covered by polymer and characterized by color emission with the maxima at 605 and 655 nm (1.89 and 2.04 eV) were used. Raman scattering spectra were measured at 300K and the excitation by the line 785.0 nm of a solid state LED. The analysis of Raman spectra has shown that the QD bio-conjugation to the immunoglobulin G (IgG) antibodies of the Pseudorabies virus is accompanied by the changes of the intensity of Raman lines related to the CdSe/ZnS core/shell QDs, PEG polymer covered QDs, the Si substrate and/or some organic groups of antibody molecules. The comparison of Raman spectra of CdSe/ZnS QDs with different sizes in non-conjugated and bio-conjugated states gives the opportunity to detect the bio-conjugation without mistake.