Construction Of Vasculature-Targeted Near-Infrared Nanodrug System And Research In Enhanced Drug Delivery To Solid Tumors

Tumor angiogenesis is a hallmark of tumor growth and metastasis, and the inhibition of tumor angiogenesis is an effective strategy for tumor therapy. The high expression levels of specific biomarkers such as integrin receptors (e.g. ?v?3) in the endothelium of tumor vessels makes angiogenesis an ideal target for drug delivery and thus tumor therapy.In this work, we constructed successfully a new vasculature-targeted near-infrared nanodrug delivery system TNP-470&DOX@RGD-Ag2S (T&D@RGD-Ag2S) for tumor therapy. The integrin-specific recognition peptide cyclic RGD (cRGD) is integrated onto Ag2S quantum dots (QDs) surface to allow tumor vasculature targeting, and the broad-spectrum endothelial inhibitor TNP-470 and the chemotherapeutic drug doxorubicin (DOX) is incorporated into the phospholipid PEG-Ag2S QDs for tumor therapy. Results show that the T&D@RGD-Ag2S nanodrug rapidly and specifically binds to the tumor vasculature after intravenous injection, due to its RGD-targeting ability. Tumor vascular density greatly reduced following effective angiogenesis inhibition by TNP-470. Meanwhile, increased delivery of DOX deep into the tumor induce extensive tumor apoptosis, resulting in marked tumor growth inhibition in a human U87-MG malignant glioma xenograft model. In addition, the therapeutic effects of T&D@RGD-Ag2S on inhibiting tumor growth and decreasing vessel density are monitored in situ using NIR-? fluorescence imaging of Ag2S QDs.This dissertation includes four chapters:Chapter one:IntroductionWe summarized the limitation of traditional drugs for tumor therapy; we summarized the research progress of targeted nanodrug delivery systems for tumor therapy, the advantages of nanomaterials being drug carriers, the delivery of targeted nanodrug delivery systems in vivo and the research progress of the application of the near-infrared quantum dots in targeted nanodrug delivery systems; we analyzed the feasibility of vasculature-targeted strategy for tumor therapy, summarized the commonly used angiogenesis inhibitors and angiogenesis models and reviewed on the research progress of the vasculature-targeted strategy in nanodrug delivery systems. Based on the reviews, we proposed the topic and research contents of this dissertation.Chapter two:Construction of the vasculature-targeted near-infrared nanodrug systemWe introduced detail the synthesis of T&D@RGD-Ag2S nanodrug and the optimization of synthetic conditions. Meanwhile, we studied the characterizations T&D@RGD-Ag2S nanodrug including morphology, optical properties, stability, drug loading and release.Chapter three:The in vitro evaluation of vasculature-targeted near-infrared nanodrug systemWe studied the vasculature-targeted properties of T&D@RGD-Ag2S nanodrug at the cellular level; we used a tubing formation assay to simulate and verify the anti-angiogenesis properties of T&D@RGD-Ag2S nanodrug; we used a standard MTT assay to verify the cytotoxicity of T&D@RGD-Ag2S nanodrug; we used a Caspase-3 activity assay to study the molecular mechanism of T&D@RGD-Ag2S nanodrug in inducing cell apoptosis.Chapter four:Property studies of vasculature-targeted near-infrared nanodrug in enhanced drug penetration in solid tumors and tumor inhibitionFirstly, we studied the in vivo toxicity, biocompatibility, half life of blood circulation, vasculature-targeting and metabolic pathway of T&D@RGD-Ag2S nanodrug. Inspired by the excellent cellular and in vivo experiments, we studied the properties of T&D@RGD-Ag2S nanodrug in inhibition of tumor blood vessels and growth. Meanwhile, we used the NIR-II fluorescence of Ag2S QDs to monitor the therapeutic effects in situ. We used the immunohistochemistry and TUNEL assay to verify the ability of T&D@RGD-Ag2S nanodrug in anti-angiogenesis and inducing cell apoptosis; we used the combination of NIR-II and normal fluorescence imaging to describe the distribution and enrichment of T&D@RGD-Ag2S nanodrug in tumor.