Light‐responsive inorganic biomaterials are an emerging class of materials used for developing noninvasive, noncontact, precise, and controllable medical devices in a wide range of biomedical applications, including photothermal therapy, photodynamic therapy, drug delivery, and regenerative medicine. Herein, a range of biomaterials is discussed, including carbon‐based nanomaterials, gold nanoparticles, graphite carbon nitride, transition metal dichalcogenides, and up‐conversion nanoparticles that are used in the design of light‐responsive medical devices. The importance of these light‐responsive biomaterials is explored to design light‐guided nanovehicle, modulate cellular behavior, as well as regulate extracellular microenvironments. Additionally, future perspectives on the clinical use of light‐responsive biomaterials are highlighted.

Light‐responsive biomaterials are an emerging class of materials used for developing noninvasive, noncontact, precise, and controllable biomedical devices. Long‐wavelength near‐infrared (NIR) radiation is an attractive light source for in situ gelation due to its higher penetration depth and minimum side effects. The conventional approach to obtain crosslinked biomaterials relies heavily on the use of a photoinitiator by generating reactive species when exposed to short‐wavelength radiation, which is detrimental to surrounding cells and tissue. Here, a new class of NIR‐triggered in situ gelation system based on defect‐rich 2D molybdenum disulfide (MoS2) nanoassemblies and thiol‐functionalized thermoresponsive polymer in the absence of a photoinitiator is introduced. Exposure to NIR radiation activates the dynamic polymer–nanomaterials interactions by leveraging the photothermal characteristics of MoS2 and intrinsic phase transition ability of the thermoresponsive polymer. Specifically, upon NIR exposure, MoS2 acts as a crosslink epicenter by connecting with multiple polymeric chains via defect‐driven click chemistry. As a proof‐of‐concept, the utility of NIR‐triggered in situ gelation is demonstrated in vitro and in vivo. Additionally, the crosslinked gel exhibits the potential for NIR light‐responsive release of encapsulated therapeutics. These light‐responsive biomaterials have strong potential for a range of biomedical applications, including artificial muscle, smart actuators, 3D/4D printing, regenerative medicine, and therapeutic delivery.

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Absorbable magnesium stents have become alternatives for treating restenosis owing to their better mechanical properties than those of bioabsorbable polymer stents. However, without modification, magnesium alloys cannot provide the proper degradation rate required to match the vascular reform speed. Gallic acid is a phenolic acid with attractive biological functions, including anti-inflammation, promotion of endothelial cell proliferation, and inhibition of smooth muscle cell growth. Thus, in the present work, a small-molecule eluting coating is designed using a sandwich-like configuration with a gallic acid layer enclosed between poly (d,l-lactide-co-glycolide) layers. This coating was deposited on ZK60 substrate, a magnesium alloy that is used to fabricate bioresorbable coronary artery stents. Electrochemical analysis showed that the corrosion rate of the specimen was ~2000 times lower than that of the bare counterpart. The released gallic acid molecules from sandwich coating inhibit oxidation by capturing free radicals, selectively promote the proliferation of endothelial cells, and inhibit smooth muscle cell growth. In a cell migration assay, sandwich coating delayed wound closure in smooth muscle cells. The sandwich coating not only improved the corrosion resistance but also promoted endothelialization, and it thus has great potential for the development of functional vascular stents that prevent late-stent restenosis.

Magnesium alloy is promising new biomaterial due to its satisfactory mechanical performance, biocompatibility and degradation of non-toxic substances. However, the dual problems of corrosion and hydrogen evolution require overcoming in order to reach a practical application level. For anticorrosion modification, fluoride conversion treatment was chosen to provide varied MgF 2 coatings on the microstructure-modified Mg-Zn-Zr alloy The aim of the present study was to investigate the influence of coating structures and their corresponding corrosion resistance. The fluoride coatings were constructed with nano-crystalline composites, which demonstrated that Mg-Zn precipitates participate in the coating-growth mechanism. In addition, the improved corrosion resistance was also systematically investigated. Compared with the pristine substrate, the F24h and F48h specimens significantly improved the anti-corrosion performance. Moreover, this report is the first report to propose a non-destructive evaluation method through simultaneous evaluation of the corrosion behavior and the establishment of a correspondence surface reflectance for fluoride conversion coatings on Mg-Zn-Zr alloy.