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The size and structural control of particulate carriers for imaging agents and therapeutics are constant themes in designing smart delivery systems. This is motivated by the causal relationship between geometric parameters and functionalities of delivery vehicles. Here, both in vitro and in vivo, the controlling factors for cytotoxicity, photothermal, and anti-tumor effects of biodegradable magnesium@poly(lactic-co-glycolic acid (Mg@PLGA) particulate carriers with different sizes and shell thicknesses are investigated. Mg@PLGA microspheres fabricated by microfluidic emulsification are shown to have higher Mg encapsulation efficiency, 87%, than nanospheres by ultrasonic homogenization, 50%. The photothermal and anti-tumor effects of Mg@PLGA spheres are found to be dictated by their Mg content, irrelevant to size and structural features, as demonstrated in both in vitro cell assays and in vivo mice models. These results also provide important implications for designing and fabricating stimuli-responsive drug delivery vehicles., (© 2020 Wiley-VCH GmbH.)

Wonderful black phosphorus (BP) and some BP analogs (BPAs) have been increasingly studied for their biomedical applications owing to their fascinating properties and biodegradability, but opportunities and challenges have always coexisted in their study. Poor stability upon exposure to the natural environment is the major obstacle hampering their in vivo applications. BP/polymer and BPAs/polymer nanocomposites can not only efficiently prevent their oxidation and aggregation but also exhibit "biological activity" due to synergistic effects. In this review, we briefly describe the synthesis methods and stability strategies of BP/polymer and BPAs/polymer. Then, advances pertaining to their exciting therapeutic applications in various fields are systematically introduced, such as cancer therapy (phototherapy, drug delivery, and synergistic immunotherapy), bone regeneration, and neurogenesis. Some challenges for future clinical trials and possible directions for further study are finally discussed.

Two-dimensional nanomaterial-based photothermal therapy (PTT) is currently under intensive investigation as a promising approach toward curative cancer treatment. However, high toxicity, moderate efficacy, and low uniformity in shape remain critical unresolved issues that hamper their clinical application. Thus, there is an urgent need for developing versatile nanomaterials to meet clinical expectations. To achieve this goal, we developed a stable, highly uniform in size, and nontoxic nanomaterials made of tellurium-selenium (TeSe)-based lateral heterojunction. Systemic delivery of TeSe nanoparticles in mice showed highly specific accumulation in tumors relative to other healthy tissues. Upon exposure to light, TeSe nanoparticles nearly completely eradicated lung cancer and hepatocellular carcinoma in preclinical models. Consistent with tumor suppression, PTT altered the tumor microenvironment and induced immense cancer cell apoptosis. Together, our findings demonstrate an exciting and promising PTT-based approach for cancer eradication., (Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).)

A biodegradable drug delivery system (DDS) is one the most promising therapeutic strategies for cancer therapy. Here, we propose a unique concept of light activation of black phosphorus (BP) at hydrogel nanostructures for cancer therapy. A photosensitizer converts light into heat that softens and melts drug-loaded hydrogel-based nanostructures. Drug release rates can be accurately controlled by light intensity, exposure duration, BP concentration, and hydrogel composition. Owing to sufficiently deep penetration of near-infrared (NIR) light through tissues, our BP-based system shows high therapeutic efficacy for treatment of s.c. cancers. Importantly, our drug delivery system is completely harmless and degradable in vivo. Together, our work proposes a unique concept for precision cancer therapy by external light excitation to release cancer drugs. If these findings are successfully translated into the clinic, millions of patients with cancer will benefit from our work., Competing Interests: The authors declare no conflict of interest.