Transformation of photoluminescence spectra at the bioconjugation of core‐shell CdSe/ZnS quantum dots

Abstract

The photoluminescence (PL) of nonconjugated and bioconjugated core‐shell CdSe/ZnS quantum dots (QDs) has been discussed in this paper. Commercial CdSe/ZnS QDs with the size of 3.6‐4.0 nm covered by polymer with emission at 560‐565 nm (2.19‐2.22 eV) have been used. The QD bioconjugation is performed with the mouse anti PSA (Prostate‐Specific Antigen) antibody (mab). PL spectra of nonconjugated QDs are characterized by a superposition of PL bands related to exciton emission in the CdSe core (2.19‐2.22 eV) and to hot electron‐hole emission via surface states (2.37, 2.73 and 3.06 eV) at the CdSe/ZnS or ZnS/polymer interfaces. The 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 re‐charging of QD interface states at the bioconjugation. It is shown that the CdSe/ZnS QDs with interface states are very promising for the study of bioconjugation effects to antibodies (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Semiconductor II-VI Quantum Dots with Interface States and Their Biomedical Applications

“…We have shown early (Torchynska et al, 2009 a, b and c) that core/shell CdSe/ZnS QDs with radiative interface state are very promising for the spectroscopic confirmation of the bioconjugation process. These systems permit to detect both the variation of PL intensity at the bioconjugation, that ordinary has been monitored, and the transformation of emission spectra related to the change of a full width at half maximum (FWHM) (Torchynska b and c;Vega Macotela et al, 2010a) and PL peak positions, as well as the transformation of Raman scattering spectra (Torchynska et al, 2007;Torchynska et al, 2008;Vega Macotela, 2010b;. The nature of radiative interface states in the core /shell CdSe/ZnS QDs has to be investigated.…”

“…Other parts of CdSe/ZnS QDs (named 525N, 565N, 605N and 640N) have been left nonconjugated and serve as a reference object. Nonconjugated CdSe/ZnS QDs in the form of a 5 mm size spot were dried on a polished surface of crystalline Si substrates as described earlier in (Torchynska et al, 2009 a, b and c;Vega Macotela et al, 2010a). PL spectra were measured at 300 K and some of them at 10 K at the excitation by a He-Cd laser with a wavelength of 325 nm and a beam power of 20 mW using a PL setup described in (Torchynska et al, 2009 a, b and c;Vega Macotela et al, 2010a).…”

“…Nonconjugated CdSe/ZnS QDs in the form of a 5 mm size spot were dried on a polished surface of crystalline Si substrates as described earlier in (Torchynska et al, 2009 a, b and c;Vega Macotela et al, 2010a). PL spectra were measured at 300 K and some of them at 10 K at the excitation by a He-Cd laser with a wavelength of 325 nm and a beam power of 20 mW using a PL setup described in (Torchynska et al, 2009 a, b and c;Vega Macotela et al, 2010a). Normalized PL spectra of nonconjugated CdSe/ZnS QDs measured at 300 K demonstrate the broad PL band in the spectral range of 1.80-3.20 eV with a main maximum at 2.37 eV and with shoulders (or small peaks) (Fig.…”

Physical Reasons of Emission Varying in CdSe/ZnS and CdSeTe/ZnS Quantum Dots at Bioconjugation to Antibodies

“…These kits contain aminederivatized polymer-coated QDs and the amine-thiol cross-linker SMCC. The samples of QDs (bioconjugated and nonconjugated) in the form of a 5-mm spot were dried on a surface of crystalline Si substrates (Figure 1) as described earlier by Torchynska [22] and Vega Macotela et al [24].…”

“…A set of publications, related to the study of QD bioconjugation using PL spectroscopy, revealed that the emission intensity of QDs decreased [12,24,25] or increased [22,26] owing to the energy exchange between the QDs and the biomolecules. Thus, the QD luminescence intensity depends on the concentration of attached biomolecules, promising the QD application as a protein sensor as well [6].…”