Recent advances in the use of nonporous silica nanoparticles as theranostic platforms for various biomedical applications, particularly in drug delivery, bioimaging and bio-adhesives.

Polymeric prodrug based on therapeutic nanomedicine has demonstrated great promise for effective tumor growth inhibition, however, the drawbacks of low drug-loading and weak micellar stability limit its application for clinical cancer therapy. Herein, a reduction-responsive starburst block copolymer prodrug CCP [β-cyclodextrin (β-CD)-PCPT XX -POEGMA, XX: SS or CC] has been developed for cancer therapy. And CCP is composed of β-CD-Br core with multiple reactive sites, as well as a diblock copolymer containing hydrophobic polymerized camptothecin (PCPT) prodrug chain and hydrophilic poly[(ethylene glycol) methyl ether methacrylate] (OEGMA) chain. A family of CCP polymeric prodrugs with different drug loading contents (up to 25%) and various sizes of unimolecular micelles (UMs) (around 30 nm) were obtained by adjusting the block ratio of PCPT XX and POEGMA. On account of the amphiphilic structure feature, CPP could take shape water-soluble UMs in aqueous medium with excellent micellar stability. Under imitatively reductive tumor microenvironment, anticancer drug CPT could rapidly escape from CCP UMs in terms of disulfide bond breakage. However, this behavior is strongly refrained in the physiological environment. In vitro and in vivo outcome confirmed that CCP UMs showed excellent performance of sufficient tumor accumulation, high-efficiency tumor growth inhibition and low-toxicity for healthy tissues. Based on these gratifying therapeutic efficacy, it is believed that as-present starburst prodrug strategy can offer a brand-new insight for highefficiency therapeutic nanoplatforms for chemotherapy application.

Drug self-delivery systems represent an important approach to enhance the therapeutic efficacy for cancer therapy. We report the design, synthesis and characterization of a new amphiphilic small molecule prodrug based on two types of anticancer drugs, the hydrophilic gemcitabine and hydrophobic camptothecin, linked by a disulfide bond and abbreviated as GT-CPT. The obtained amphiphilic prodrug conjugates self-assembled into nanoparticles in water and showed strong micellar stability and excellent blood compatibility in vivo. The GT-CPT prodrug conjugates could realize precise drug loading as high as ∼75 wt% demonstrating a carrier-free model for efficient drug delivery. Furthermore, the reduction-responsive disulfide bond enabled controlled drug release in the presence of tumour-specific microenvironment. It was found that each of these hybrid drug components (CPT and GT) not only showed enhanced cytotoxicity individually but also exhibited a prominent synergistic effect on HeLa and MCF-7 cancer cells. This study demonstrated the promising potential of this stimuli-responsive hybrid prodrug conjugate for highly efficient co-delivery of multiple anticancer chemotherapeutics, which could inspire further applications using such hybrid prodrug conjugates for combination cancer chemotherapy.

A theranostic nanoplatform based on pH-responsive amphiphilic star-like copolymers for theranostic and NIR imaging applications.