Molybdenum-oxo-sulfide quantum dot-based nanocarrier: Efficient generation of reactive oxygen species via photo/chemodynamic therapy and stimulus-induced drug release.

The fabrication of multifunctional nano-therapies has increased gradually to strengthen the therapeutic performance and minimize adverse effects of traditional cancer treatment strategies. Currently, we have designed a facile preparation drug-loaded nanocarrier for multimodal cancer therapy upon external stimuli. First, defect-rich molybdenum oxo-sulfide (MoOxS2-x) quantum dots (QDs) was synthesized via rapid biomineralization techniques with superior optical quantum yield reaching upto 37.28%. The presence of the Fenton ion, Mo+IV/+VI, enables MoOxS2-x QDs to efficiently catalyze peroxide solutions to produce •OH radicals for chemodynamic treatment (CDT) and also deactivate the intracellular glutathione (GSH) enzymes through redox reaction for boosted reactive oxygen species (ROS)-mediated therapies. In addition, upon laser combination, MoOxS2-x QDs generate ROS for photodynamic therapy (PDT). Also, due to a large amount of sulfide content, MoOxS2-x QDs showed excellent H2S gas release in acidic pH for cancer gas therapy. Then, MoOxS2-x QDs was further conjugated with ROS-responsive thioketal linked Camptothecin (CPT-TK-COOH) drug, forming a multitargeted MoOxS2-xCPT anticancer agent with better drug-loading efficiency (38.8%). After triggering the ROS generation through the CDT and PDT mechanisms, the thioketal linkage was disrupted, releasing up to 79% of the CPT drug in 48 h. Besides, in vitro experiments verified that MoOxS2-x QDs possess higher biocompatibility with 4T1 and HeLa cells but also showed considerable toxicity in the presence of laser/H2O2, resulting in 84.45% cell death through PDT/CDT and chemotherapeutic effects. Therefore, the designed MoOxS2-xCPT exhibited outstanding therapeutic benefits for image-guided cancer therapy.

Engineering the Surface of Ti3C2 MXene Nanosheets for High Stability and Multimodal Anticancer Therapy.

The surface of Ti3C2 MXene nanosheets (TC NSs) was first modified with the antioxidants sodium ascorbate (SA) and dopamine (DA) (DSTC NS) to improve their stability in oxidative and hydration environments and thereby improve their bioapplications. This novel approach not only improved MXene stability by arresting oxidation but also increased the available functional groups for further functionalization with various biomolecules. The DSTC NSs were then sequentially conjugated with enzyme glucose oxidase (GOx) and photosensitizer Ce6 to render the obtained CGDSTC NSs with glucose starvation and photodynamic therapeutic properties and thus attain high efficiency in killing cancer cells through the cooperative effect. The as-synthesized CGDSTC NSs demonstrated tremendous photothermal effect with conversion efficiency of 45.1% and photodynamic (ROS generation) properties upon irradiation with 808 and 671 nm lasers. Furthermore, it was observed that the enzymatic activity of CGDSTC NSs increased upon laser irradiation due to enhanced solution temperature. During in vitro studies, the CGDSTC NSs exhibited cytocompatability to HePG2 and HeLa cells under nonstimulus conditions. However, they elicited more than 90% cell-killing efficiency in the presence of glucose and laser irradiation via the cooperative effect between starvation therapy and phototherapy. These results indicate that CGDSTC NSs could be used as potential therapeutic agents to eradicate cancers with no or few adverse effects. This surface modification approach is also simple and facile to adopt in MXene-based research.