Interface states and bio-conjugation of CdSe/ZnS core-shell quantum dots.
The paper presents the results of photoluminescence (PL) and Raman scattering studies of non-conjugated and bio-conjugated CdSe/ZnS core-shell quantum dots (QDs). The commercial CdSe/ZnS QDs used are characterized by color emission with maxima at 605-610 nm (2.03-2.05 eV). PL spectra of non-conjugated QDs are the superposition of PL bands related to exciton emission in the CdSe core (2.03-2.05 eV) and to hot electron-hole emission via defect states at the CdSe/ZnS interface (2.37 and 2.68 eV). QD conjugation was performed with biomolecules -- the antihuman interleukin 10 antibody (antihuman IL10). The PL spectra of bio-conjugated QDs have been changed dramatically: only one PL band related to exciton emission in the CdSe core was detected in bio-conjugated QDs. To explain this effect a model has been proposed which assumes that the QD bio-conjugation process is accompanied by the recharging of acceptor-like interface states at the CdSe/ZnS interface. A comparative analysis of normalized PL spectra of non-conjugated CdSe/ZnS QDs with different intensities of interface state PL has confirmed the proposed electron-hole recombination model in QDs.
ESFM, Instituto Politécnico Nacional, México DF, Mexico. ttorch@esfm.ipn.mx
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Torchynska
D000818:Animals; D019187:Cadmium Compounds / Q000737:chemistry*; D003198:Computer Simulation; D006801:Humans; D008027:Light; D008954:Models, Biological; D045663:Quantum Dots; D012542:Scattering, Radiation; D018036:Selenium Compounds / Q000737:chemistry*; D013050:Spectrometry, Fluorescence / Q000379:methods*; D017967:Zinc Compounds / Q000737:chemistry*
D019187:Cadmium Compounds; D018036:Selenium Compounds; D017967:Zinc Compounds; C058667:cadmium selenide; C044696:zinc selenide