Anticorrosive and antibacterial smart integrated strategy for biomedical magnesium

Biomedical magnesium is an ideal material for hard tissue repair and replacement.However,its rapid degradation and infection after implantation significantly hindersclinical applications.To overcome these two critical drawbacks,we describe an integrated strategybased on the changes in pH and Mg^(2+)triggered by magnesiumdegradation.This system can simultaneously offer anticorrosion and antibacterial activity.First,nanoengineered peptide-grafted hyperbranched polymers(NPGHPs)with excellent antibacterial activity were introduced to sodium alginate(SA)to construct a sensitive NPGHPs/SA hydrogel.The swelling degree,responsiveness,and antibacterial activity were then investigated,indicating that the system can perform dual stimulation of pH and Mg^(2+)with controllable antimicrobial properties.Furthermore,an intelligent platform was constructed by coating hydrogels on magnesium with polydopamine as the transition layer.The alkaline environment generated by the corrosion of magnesium reduces the swelling degree of the coatingso that the liquid is unfavorable for contacting the substrate,thus exhibiting superior corrosion resistance.Antibacterial testing shows that the material can effectively fight against bacteria,while hemolytic and cytotoxicity testing suggest that it is highly biocompatible.Thus,this work realizes the smart integration of anticorrosion and antibacterial properties of biomedical magnesium,thereby providing broader prospects for the use of magnesium.

Enhanced Bioenergy Transformation by Metal-Free Electrozyme-Based Mitochondrion Nanoarchitectonics

Herein,we couple a synthetic electrozyme in a supramolecule-assembled nanoarchitecture to achieve enhanced bioenergy transformation by mimicking mitochondrial oxidative phosphorylation.Different from the natural counterpart,the metal-free electrozyme is a semiconducting polymer deposited on an electrode.The wellmatched electrocatalytic property of the electrozyme permits oxidization of reduced nicotinamide adenine dinucleotide(NADH)to release protons under a much lower electric potential.As a consequence,the generated proton gradient drives rotary catalysis of adenosine 5′-triphosphate(ATP)synthase reconstituted in a lipid membrane to produce ATP.Remarkably,electrochemical bioenergy conversion of NADH to ATP is accomplished with much higher efficiency in such a bio-like system compared with the natural mitochondria.This work integrates synthetic and natural catalytic chemistry to facilitate enhanced bioenergy transformation,thereby greatly improving prospects in ATP-fueled bioapplications.

Black Phosphorus Nanosheets Enhance Photophosphorylation by Positive Feedback

We construct a natural-artificial hybrid architecture containing black phosphorus nanosheets(BPNS)to enhance photosynthesis of chloroplast in a positive-feedback manner.In this architecture,oxygen yielded by photosynthesis during water splitting by photosystemⅡpromotes the photoreaction of BPNS to produce proton and inorganic phosphate(Pi).Further,transmembrane proton gradient is increased to drive ATP synthase to synthesize ATP.Meanwhile,additional photogenerated electrons produced by BPNS are transferred to the photosynthesis process.As a consequence,photosynthesis performed by chloroplast is improved.Quantitatively,photophosphorylation efficacy of the hybrid system is increased by 1.89 times in the case of Pi deficiency.This work offers a new path to enhance solar-to-chemical energy conversion,holding promise in boosting natural photosynthesis.

Rh(Ⅲ)-Catalyzed Diverse C-H Functionalization of Iminopyridinium Ylides

Divergent synthesis of useful skeletons has been realized via rhodium(Ⅲ)-catalyzed C-H activation of iminopyridinium ylides and coupling with various unsaturated coupling reagents.Isocoumarins and isoquinolones were obtained via cleavage of the C-N or N-N bond in the ylidic di recti ng group,while fluorinated alkenes were delivered with the di recti ng group in tact.The reactions occurred with wide substrate scopes and good efficiency under redox-neutral and air-tolerant conditions.Representative products exhibit solid-state fluoresce nt property and bioactivity of in hibiti on toward huma n cancer cells.