Functional Modifications Of Copper Chalcogenide For Biomedical Application

As a minimally invasive treatment, photothermal ablation employing near-infrared (NIR) light for cancer treatment has been extensively studied because it could greatly improve treatment efficacy. However, high costs, involuted synthesis and poor photostability of traditional photothermal agents limit their further application. Because of strong absorption in NIR region, high photothermal conversion efficiency, good photostability, low cost and good biocompatibility, copper chalcogenide (Cu2-xS) nanocrystals have become a kind of new-style and promising photothermal agents. In this thesis, a kind of multi-functional nanocomposites based on copper chalcogenides for photothermal-triggered drug delivery systems (DDSs) and multimodal biological imaging has been developed. Research progresses are as follows:1. In order to design a remotely-controlled and noninvasive drug delivery system for reducing side effect and improving treatment efficiency, we have developed a kind of "smart" nanocarriers by grafting a lay of thermo-sensitive polymer, poly(N-isopropylacrylamide) (poly-NIPAAm) on the surface of Cu7S4 nanocrystals. The as-synthesized nanocarriers demonstrated sufficient drug loading content (19.4%), high photothermal conversion efficiency (25.4%) and appropriate critical temperature for drug release. At normal physiological conditions (pH=7.4,37 °C), negligible drug leakage was observed. Once under the irradiation of 808 nm laser (1.0 W cm-2), loaded drugs were explosively due to the drastic shrunk of the polymer matrix on the surface of Cu7S4 nanoparticles (NPs), as a result, the goal of NIR light-triggered drug release was achieved. And synergetic treatment of combining photothermal ablation and chemotherapy greatly promoted treatment efficacy of cancer.2. To monitor the treatment effect via a real-time and visualization style, a kind of multifunctional nanocomposites (Cu2S-Bi2S3@PSIOAm) have been fabricated. Cu2S nanoparticles and Bi2S3 nanorods were successfully encapsulated in the hydrophobic cavity of the nanospheres of oleylamine functionalized poly(amino acid) via van der Waals force between hydrophobic nanoparticles and amphiphilic polymer. The Cu2S-Bi2S3@PSIOAm demonstrated both good photothermal conversion efficiency and high CT imaging effect. In addition, as the NCs were modified with target peptide (RGD), the treatment and imaging efficiency of cancer would be greatly enhanced. Good biocompatibility, proper hydrated size, high efficiency of photothermal conversion and CT imaging made these as-synthesized NCs promising candidates for theranostics application.