Raman spectra of CdSe/ZnS quantum dots bioconjugated to ovarian cancer antibodies
- PDF / 831,468 Bytes
- 5 Pages / 612 x 792 pts (letter) Page_size
- 108 Downloads / 191 Views
Raman spectra of CdSe/ZnS quantum dots bioconjugated to ovarian cancer antibodies A.L.Quintos Vazquez1, T. V. Torchynska2 and L. Shcherbyna3 1
ESIME – Instituto Politécnico Nacional, av.IPN, México D. F. 07738, México. ESFM – Instituto Politécnico Nacional, av.IPN, México D. F. 07738, México. 3 V. Lashkarev Institute of Semiconductor Physics at NASU, av. Nauky 45, Kiev, 03028, Ukraine. 2
ABSTRACT This paper presents the analysis of Raman scattering spectra of CdSe/ZnS QDs covered by the amine-derivatized polyethylene glycol (PEG) polymer with and without bioconjugation to bio-molecules: mouse ovarian cancer (OC 125) antibodies (mab). Commercial CdSe/ZnS QDs used in the study are characterized by the color emission with the maximum at 525 nm (2.36 eV) at 300K. Samples of CdSe/ZnS QDs (bio-conjugated and non-conjugated) in the form of an 5 mm-size spot were dried on a polished surface of crystalline Si substrate to ensure a low level of light scattering background. Raman scattering spectra of non-conjugated QDs can be presented as a superposition of Raman lines: 212.2, 222.5, 308.3, 440.3, 521.0, 618.0, 667.8 943.5, 986.7, cm-1 related to the CdSe core and silicon substrate. The Raman lines 1003.9, 1317.8, 1452.9, 1656.8, 2870.4, 2931.8 and 3059.9 cm-1 deal with the vibration of COH, CH and OH groups of polymer, which covered QDs, were detected additionally. It is revealed that the QD bio-conjugation to the OC 125 antibodies is accompanied with the changes in the intensity of all types of Raman lines: related to the CdSe core, silicon substrate and polymer groups. The explanation of bioconjugation effects has been proposed and discussed. INTRODUCTION Semiconductor CdSe/ZnS core/shell quantum dots (QDs) are a novel class of inorganic fluorophore that is interesting for the investigation owing their exceptional luminescent properties [1-7]. Semiconductor CdSe/ZnS core/shell quantum dots (QDs) with the high intensity of QD-size tunable photoluminescence (PL) can be used as bio-luminescent markers. PL intensity and/or the shapes of PL spectra vary when QDs are coupled to different biomolecules that can testify on the changes of the concentration of these biomolecules [6-10]. The conjugation of biomolecules with QDs has been achieved by the covalent bond formation and/or with the help of electrostatic interaction [11,12]. But the mechanism of bioconjugation still does not understand complitely. Moreover it is important to look for other optical effects related to QDs, such as Raman scattering, which can offer the additional information concerning the structure of bio-conjugated CdSe/ZnS QDs. This paper presents the results of the analysis of Raman scattering spectra of CdSe/ZnS QDs covered by the amine-derivatized polyethylene glycol (PEG) polymer in the nonconjugated state and at the bioconjugation to the ovarian cancer (OC 125) antibodies.
EXPERIMENT Commercially available core-shell CdSe/ZnS QDs covered with the amine-derivatized polyethylene glycol (PEG) polymer are used in a form of colloidal particles diluted i
Data Loading...
