The Synthesis Of Water-Soluble CdTe/CdS Near-Infrared-Emitting Quantum Dots And Their Bioimaging Application

Quantum dots (QDs), that emit in the near-infrared (NIR) range of650to900nm are particularly interesting for bioimaging applications because at these wavelengths light has deep tissue penetration and induces minimal autofluorescence. Despite several strategies have been employed to prepare QDs with NIR emission in aqueous or organic medium, high-quality NIR-emitting QDs have remained a have remained elusive:(1) QDs prepared using high-temperature organic routes have no intrinsic aqueous solubility, thus the phase transfer to aqueous solution requires surface functionalization with hydrophilic ligands, which the processes are primarily driven by mass action, and some chemicals used in the organic reaction are toxic and expensive;(2) by using aqueous approaches, almost the protocol involves complicated multistep processes, most especially the precursor injection that is always out of control because of that the precursor go to oxidation extremely easy. Therefore, the goal of our present study to design a facile aqueous method to obtain NIR-emitting QDs for high-sensitivity targeted bioimaging. The main concents and results are listed as below.1. A simple one-pot aqueous approach based on lattice-mismatch strain tuning theory of producing highly fluorescent and ultrasmall size NIR-emitting CdTe/CdS QDs was reported. The as-prepared products have been characterized by Ultraviolet-visible (UV-vis) absorption and photoluminescence (PL) spectra, X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM), et al.2. The photostability and cytotoxicity of the QD700(QDs with emission maximum at700nm) were performed to examine the ability of the QDs for biological applications. After successfully coupled folate to QD700to creat a QD-folate (QD-FA) construct, we demonstrated the QD-FA conjugates application for targeted bioimaging in human cervical cancer cells line.3. Studied the acute toxicity in vivo and the histological analysis of the QD-FA probes, we demonstrated the progress of identification of folate-receptor-positive tumors in the human hepatocellular carcinoma xenograft growing tumor model by QD-FA. The QD-FA probes could correctly recognize the tumor and emit bright fluorescence in vivo, which confirmed the high targeting specificity and excellent biocompatibiliry of these probes. In conclusion, a facile aqueous synthesis of highly fluorescent and ultrasmall size CdTe/CdS QDs with broadly tunable near-infrared emission was reported. The QD probes allowed high-sensitive imaging in vitro and in vivo. It should be noted that this is the first time to use water-dispersed NIR-emitting QDs for receptor targeting in vivo. We believe that our unique nanocrystals can serve as next-generation near-infrared optical imaging probes and may impact actively for the development of cancer diagnosis.