manganese(III) oxide (Mn 2 O 3 ), and Prussian blue nanozyme (PBzyme), etc., have multienzyme-like activities, which enable either the efficient production of reactive oxygen species (ROS) to kill tumor cells and bacteria, or the clearance of ROS to reduce oxidative stress and inflammation. [9][10][11][12][13][14] These metal-based nanozymes display multiple antitumor, anti-infective, and anti-inflammatory activities, and offer promise as potential adjuvants, cotreatments, or alternatives to cytotoxic chemotherapeutics, antibiotics, and nonsteroidal anti-inflammatory drugs. [15][16][17] Most nanozymes in preclinical development have single-enzyme-like activity, and are thus limited by insufficient catalytic efficiency, restricted availability of substrate types and concentrations, and activity under single identifiable catalytic conditions. In comparison, those with multienzyme-like activities carry advantages of high catalytic efficiency via amplification or cascade reactions, adaptive responses to dissimilar catalytic conditions, multifunctionality in diverse pathological processes, and capacities to overcome the impediment of insufficient substrates via "self-provision." [18] At present, most reported nanozymes with multienzyme-like activities are metal-based, owing to their unsaturated sites from the inherent structure of metal atoms and the valence changes of the metal centers in case of transition metals. [4] In the last decade, researchers have studied catalytic effects and regulation rules and design schemes of metal-based nanozymes with multienzyme-like activities (MNMs), with goals to remarkably improve their therapeutic efficiency and broaden their range of applications. [15,[19][20][21][22][23][24][25] Previous review articles have discussed the spatial structures and catalytic mechanisms of nanozymes from the perspective of their physical properties, or have summarized the effects of a few types of nanozymes with potential medical applications. [4,6,[26][27][28][29][30][31][32] However, clinical relevance stands as the core motivator of nanozyme research. Therefore, this review concentrates on MNMs. This work focuses on the biological effects of nanozymes based on their intracellular interactions, intending to analyze mechanisms of action and potential therapeutic applications. Herein, we summarize MNMs, their impacts on pathogenesis, underlying mechanisms, potential medical Most nanozymes in development for medical applications only exhibit singleenzyme-like activity, and are thus limited by insufficient catalytic activity and dysfunctionality in complex pathological microenvironments. To overcome the impediments of limited substrate availabilities and concentrations, some metal-based nanozymes may mimic two or more activities of natural enzymes to catalyze cascade reactions or to catalyze multiple substrates simultaneously, thereby amplifying catalysis. Metal-based nanozymes with multienzyme-like activities (MNMs) may adapt to dissimilar catalytic conditions to exert different enzyme-like effects. ...

The rapid degradation of magnesium (Mg) alloy implants erodes mechanical performance and interfacial bioactivity, thereby limiting their clinical utility. Surface modification is among the solutions to improve corrosion resistance and bioefficacy of Mg alloys. Novel composite coatings that incorporate nanostructures create new opportunities for their expanded use. Particle size dominance and impermeability may increase corrosion resistance and thereby prolong implant service time. Nanoparticles with specific biological effects may be released into the peri‐implant microenvironment during the degradation of coatings to promote healing. Composite nanocoatings provide nanoscale surfaces to promote cell adhesion and proliferation. Nanoparticles may activate cellular signaling pathways, while those with porous or core–shell structures may carry antibacterial or immunomodulatory drugs. Composite nanocoatings may promote vascular reendothelialization and osteogenesis, attenuate inflammation, and inhibit bacterial growth, thus increasing their applicability in complex clinical microenvironments such as those of atherosclerosis and open fractures. This review combines the physicochemical properties and biological efficiency of Mg‐based alloy biomedical implants to summarize the advantages of composite nanocoatings, analyzes their mechanisms of action, and proposes design and construction strategies, with the purpose of providing a reference for promoting the clinical application of Mg alloy implants and to further the design of nanocoatings.

Polyurethane (PU) has wide application and popularity as medical apparatus due to its unique structural properties relationship. However, there are still some problems with medical PUs, such as a lack of functionality, insufficient long-term implantation safety, undesired stability, etc. With the rapid development of nanotechnology, the nanomodification of medical PU provides new solutions to these clinical problems. The introduction of nanomaterials could optimize the biocompatibility, antibacterial effect, mechanical strength, and degradation of PUs via blending or surface modification, therefore expanding the application range of medical PUs. This review summarizes the current applications of nano-modified medical PUs in diverse fields. Furthermore, the underlying mechanisms in efficiency optimization are analyzed in terms of the enhanced biological and mechanical properties critical for medical use. We also conclude the preparation schemes and related parameters of nano-modified medical PUs, with discussions about the limitations and prospects. This review indicates the current status of nano-modified medical PUs and contributes to inspiring novel and appropriate designing of PUs for desired clinical requirements.

Abstract. Based on the panel data of seven economically developed regions in China from 2006 to 2015, the STATA 15.0 is used to study the direct and indirect effects of the R&D center aggregation level on regional innovation capability by the fixed-effect regression method. The results show that, from its direct impact, active establishment of multinational companies R&D centers and their agglomeration would positively influence regional technological innovation ability. From the indirect effect, the aggregation of R&D center of MNCs improves regional innovation ability through the flow and agglomeration of talents, research and development funds. Finally, based on the research results, relevant suggestions are put forward. IntroductionInnovation is the key to determining the competitiveness of a region. In order to further open up the host country market, multinational companies have been increasingly focusing on R&D in host countries. In recent years, more and more R&D centers, which possess advanced technology and research resources, have been established in China. The knowledge spillover effects they generate provides a good opportunity for improving regional technological innovation levels. However, because of the knowledge blockade and insufficient absorptive capacity of local companies, high-aggregation foreign R&D centers may cause pressure on local companies and negative effects such as the loss of talents and R&D resources.In order to study how agglomeration of MNCs' R&D centers affects the innovation capability of a region, this paper selected seven regions in China, where the agglomeration effect of multinational companies' R&D centers is obvious, theoretically analyzes the impact mechanism of R&D center concentration on regional innovation capability based on provincial panel data from 2006 to 2015.