Preparation Of Quantum Dots Fluorescent Probes And Their Applications In Cellular And In Vivo Imaging

Quantum dots (QDs) are fluorescent nanocrystals which characterized unique optical properties such as size-and composition-dependent tunable emission spectra, high levels of brightness and photostability, broad excitation spectra and narrow emission bands. Since the first reports on the biological application of quantum dots in1998, they have been extensively applied to molecular, cellular, in vivo imaging, bio-analytical assays, and biosensing.In this paper, the optical properties and cytotoxicity of Au-doped visible-near-infrared quantum dots, noninvasive living cell imaging and in vivo imaging using QDs fluorescent probes, were researched. The tumor targeting multispectral fluorescence imaging was performed using QDs fluorescent probes, the fluorescent signals were successfully unmixed, and the in vivo simultinously detection of multiple tumor markers was achieved. The detail content is as follows:Gold was firstly doped into semiconductor fluorescent quantum dots. The gold-doped cadmium telluride (Au:CdTe) quantum dots were synthesized by aqueous solution route using L-glutathione and L-cysteine as stabilizers. As-prepared Au:CdTe NCs were used as probes for living cells fluorescence imaging. They were endocytic uptaken by cells and long-term noninvasive labeled the cells. The Au:CdTe quantum dots exhibited improved photostability, higher cellular affinity, and lower cytotoxicity, and were suitable for long-term noninvasive labeling and fluorescence imaging living cells.Bioluminescence resonance energy transfer quantum dot conjugates were synthesized and used for small animal in vivo imaging. The Renilla reniformis luciferase (RLuc8) protein was expressed in BL21bacterial cytoplasm. The purified RLuc8was congjugated to RGD (arginine-glycine-aspartic acid containing) peptides capped CdTe quantum dots, and the RGD-QD-Rluc8self-illuminating quantum dots successfully used for mice in vivo tumor-targeted imaging, indicating that as prepared RGD-QD-Rluc8self-illuminating quantum dots could used as bioprobes for in vivo tumor labeling and fluorescence imaging.The "one step synthesis" of quantum dots bioconjugates was developed. The RGD peptides capped, water-soluble near infrared gold-doped CdHgTe quantum dots were directly synthesized by aqueous solution route using Cys-RGD peptides and L-cysteine as stabilizers. The polyethylene glycol (PEG) was congjugated to the RGD-CdHgTe QDs. The tumor-targeting fluorescence imaging using PEG-QD-RGD congjugates as probes obtained idea efficiency, indicating that as prepared near infrared PEG-QD-RGD congjugates, which with good fluorescent signal in vivo, had great potential in tumor detection an in vivo imaging applications.Near infrared gold-doped CdHgTe quantum dots were firstly synthesized and used for in vivo tumor-targeted multispectral fluorescence imagin. As prepared Au:CdHgTe QDs were characterized, and their photostability, cytotoxicity, and tissue penetration were tested. The results indicated that Au:CdHgTe QDs have improved photoluminescence, enhanced photostability againsting photobleaching, lower cytotoxicity, and deeper tissue penetration. Three Au:CdHgTe quantum dots were conjugated to RGD peptides, anti-epidermal growth factor receptor (EGFR) monoclonal antibody (MAb), and anti-carcinoembryonic antigen-related cell adhesion molecule1(CEACAM1) MAb respectively. Three bioconjugates (QD800-RGD, QD820-anti-CEACAM1and QD840-anti-EGFR) were successfully used as probes for in vivo tumor targeted multispectral fluorescence imaging; the fluorescent signals labeling tumor markers were spectrally unmixed, and the in vivo simultinously detection of multiple tumor markers was achieved. The results indicated that Au:CdHgTe QDs bioconjugates could be used as fluorescence probes for tumor targeted multispectral fluorescence imaging, and could potentially serve as a powerful tool for in vivo conjoined detection of multiple tumor markers, leading to improved accuracy of diagnosis of early stage cancer.