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.

Biodegradation of typical azole fungicides in activated sludge under aerobic conditions

Widespread use of azole fungicides and low removal efficiency in wastewater treatment plants(WWTPs) have led to the elevated concentration of azole fungicides in receiving environment. However, there was limited research about the removal mechanism of azole fungicides in the biological treatment of WWTPs. Imidazole fungicide climbazole and triazole fungicide fluconazole were selected to investigate the biodegradation mechanism of azole fungicides in activated sludge under aerobic conditions. Climbazole was found to be adsorbed to solid sludge and resulted in quick biodegradation. The degradation of climbazole in the aerobic activated sludge system was fitted well by the first-order kinetic model with a half-life of 5.3 days, while fluconazole tended to stay in liquid and had only about 30% of loss within 77 days incubation. Ten biotransformation products of climbazole were identified by high resolution mass spectrometry using suspect and non-target screening method. But no biodegradation products of fluconazole were identified due to its limited removal. The possible biodegradation pathways for climbazole were proposed based on the products identification and pathway prediction system, and involves oxidative dehalogenation, side chain oxidation and azole ring loss. The findings from this study suggest that it should be a concern for the persistence of fluconazole in the environment.