Modification of optical properties at bioconjugation of core-shell CdSe/ZnS quantum dots

This paper presents the results of photoluminescence study of core-shell CdSe/ZnS quantum dots (QDs) with radiative interface states in nonconjugated and bioconjugated conditions. PL spectra of nonconjugated QDs are characterized by a superposition of PL bands related to exciton emission in CdSe cores (2.36 eV) and to electron-hole emission via interface states (2.00, 2.75 and 3.04 eV) at the CdSe/ZnS or ZnS/polymer interfaces. The CdSe/ZnS QDs with emission at 525 nm have been conjugated with bio-molecules - mouse ovarian cancer (OC 125) antibodies. It is revealed that PL spectrum of bioconjugated QDs has changed dramatically with essential decreasing of the hot electron-hole recombination flow via interface states. This effect is explained on the base of the model deals with re-charging of QD interface states at the bioconjugation with OC125 antibodies. The nature of interface states and their changes at the QD aging process have been discussed as well.