Biologically Engineered Quantum Dots for Biomedical Applications
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1095-EE08-05
Biologically Engineered Quantum Dots for Biomedical Applications Ganna Chornokur1, Sergei Ostapenko1, Yusuf Emirov1, Nadezhda Korsunska2, Abraham Wolcott3, Jin Zhang3, Catherine Phelan4, Abhilasha Nagaram4, and Thomas Sellers4 1 Nanomaterials and Nanomanufacturing Research Center, University of South Florida, ENB 118, 4202 E. Fowler Ave, Tampa, FL, 33620 2 Institute of Semiconductor Physics, Ukrainian Academy of Sciences, pr. Nauki 45, Kiev, Ukraine 3 University of California Santa Cruz, Santa Cruz, CA, 95064 4 H. Lee Moffitt Cancer Center and Research Institute, Tampa, FL, 33620 ABSTRACT We report on a short-wavelength, “blue” spectral shift of the photoluminescence (PL) spectrum in CdSeTe/ZnS core/shell quantum dots (QDs) caused by bioconjugation with several monoclonal cancer related antibodies (ABs). Scanning PL spectroscopy was performed on samples dried on solid substrates at various temperatures. The influence of the AB chemical origin on the PL spectral shift was observed. The conjugation QD-AB reaction was confirmed using the agarose gel electrophoresis technique. The spectral shift is strongly increased and the process facilitated when the samples are dried above room temperature. The PL spectroscopic mapping revealed a profile of the PL spectral shift across the dried QD-AB spot. Transmission Electron Microscopy analyses of the samples were performed to reveal the shape and size of individual QDs. A mechanism of the “blue” shift is attributed to changes in the QD electronic energy levels caused by local stress field applied to the bio-conjugated QD. INTRODUCTION Cancer is a major cause of illness and death in the US [1]. Clinical outcome of cancer is strongly related to the stage, at which the malignancy is detected, however, most solid tumors are detectable with standard diagnostic methods during a late phase of disease when it may have already metastasized. Therefore, there is a critical need to develop sensitive probes for early cancer detection. Quantum dots (QDs) represent state-of-the-art nano-scale devices that exhibit promising results toward the development of a sensitive probe for screening cancer markers. It’s anticipated that QDs could be successfully used for the purpose of early cancer detection to substitute organic dyes in many biological techniques including ELISA (Enzyme-Linked ImmunoSorbent Assay) which provides low detection limits for target biomolecules due to high sensitivities which can detect, for instance, PSA antigen concentrations as low as 1 ng/ml [2]. Our recent experiments demonstrated that PL spectra of QDs are changed by the bio-conjugation [3]. This is revealed as a “blue” or short wavelength spectral shift of the PL maximum, which can be clearly observed as a color change of the dried bio-conjugated sample. This PL spectroscopic feature of the bio-conjugated QDs may serve as a fingerprint of the bio-conjugation reaction. Ultimately, this will dramatically improve sensitivity of the cancer antigen detection using QDs because a background PL from the non-conj
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