Imaging-Guided Nanoplatform for Tumor Targeting Delivery and Combined Chemo-, Gene- and Photothermal Therapy.

Currently, a large number of anti-tumor drug delivery systems have been widely used in cancer therapy. However, due to the molecular complexity and multidrug resistance of tumors, monotherapies remain suboptimal. Thus, this study aimed to develop a multifunctional theranostic nanoplatform for effective cancer therapy. Folic acid-modified silver sulfide@mesoporous silica core-shell nanoparticle was first modified with desthiobiotin (db) on the surface, then doxorubicin (DOX) was loaded into pore. Avidin was employed as "gatekeeper" to prevent leakage of DOX desthiobiotin-avidin interaction. Db-modified survivin antisense oligonucleotide (db-DNA) which could inhibit survivin expression was then grafted on avidin at the outer layer of nanoparticle. DOX release and db-DNA dissociation were simultaneously triggered by overexpressing biotin in cancer cells, then combining PTT from AgS QD to inhibit tumor growth. This nanoprobe had satisfactory stability and photothermal conversion efficiency up to 33.86% which was suitable for PTT. Due to the good targeting ability and fluorescent anti-bleaching, its signal still existed at the tumor site after tail vein injection of probe into HeLa tumor-bearing nude mice for 48 h. and antitumor experiments both demonstrated that drug, gene and photothermal synergistic therapy significantly enhanced antitumor efficacy with minimal systemic toxicity. Our findings demonstrate that this novel nanoplatform for targeted image-guided treatment of tumor and tactfully integrated chemotherapy, photothermal therapy (PTT) and gene therapy might provide an insight for cancer theranostics.