Sunlight-driven activation of molecular oxygen(O_(2))for organic oxidation reactions offers an appealing strategy to cut down the reliance on fossil fuels in chemical industry,yet it remains a great challenge to simul...Sunlight-driven activation of molecular oxygen(O_(2))for organic oxidation reactions offers an appealing strategy to cut down the reliance on fossil fuels in chemical industry,yet it remains a great challenge to simultaneously tailor the charge kinetics and promote reactant chemisorption on semiconductor catalysts for enhanced photocatalytic performance.Herein,we report iron sites immobilized on defective BiOBr nanosheets as an efficient and selective photocatalyst for activation of O_(2) to singlet oxygen(^(1)O_(2)).These Fe^(3+) species anchored by oxygen vacancies can not only facilitate the separation and migration of photogenerated charge carrier,but also serve as active sites for effective adsorption of 02.Moreover,low-temperature phosphorescence spectra combined with X-ray photoelectron spectroscopy(XPS)and electronic paramagnetic resonance(EPR)spectra under illumination reveal that the Fe species can boost the quantum yield of excited triplet state and accelerate the energy transfer from excited triplet state to adsorbed O2 via a chemical loop of Fe^(3+)/Fe^(2+),thereby achieving highly efficient and selective generation of ^(1)O_(2).As a result,the versatile iron sites on defective BiOBr nanosheets contributes to near-unity conversion rate and selectivity in both aerobic oxidative coupling of amines to imines and sulfoxidation of organic sulfides.This work highlights the significant role of metal sites anchored on semiconductors in regulating the charge/energy transfer during the heterogeneous photocatalytic process,and provides a new angle for designing high-performance photocatalysts.展开更多
Infectious microbes that spread easily in healthcare facilities remain as the severe threat for the public health,especially among immunocompromised populations.Given the intricate problem of dramatic increase in resi...Infectious microbes that spread easily in healthcare facilities remain as the severe threat for the public health,especially among immunocompromised populations.Given the intricate problem of dramatic increase in resistance to common biocides,the development of safe and efficient biocide formulated agents to alleviate drug resistance is highly demanding.In this study,Schiff-base ligands were successfully formed on natural biopolymer of epsilon-poly-L-lysine(ε-PL)decorated aldehyde functionalized mesoporous silica SBA-15(CHO-SBA-15)for the selective coordination of silver ions,which was affirmed by various physicochemical methods.Besides the identified broad-spectrum antibacterial activities,the as-prepared Schiff-base silver nanocomplex(CHO-SBA-15/ε-PL/Ag,CLA-1)exhibited an improved inhibitory effect on infectious pathogen growth typified by Escherichia coli and Staphylococcus aureus in comparison with two control silver complexes without Schiff-base conjugates,SBA-15/ε-PL/Ag and CHO-SBA-15/Ag,respectively.In addition,CLA-1 remarkably inhibited the growth of Mycobacterium tuberculosis due to the excellent antimicrobial activity of silver species.Significantly,CLA-1 kills Candida albicans cells,inhibits biofilm formation,and eliminates preformed biofilms,with no development of resistance during continuous serial passaging.The antifungal activity is connected to disruption of bacterial cell membranes and increased levels of intracellular reactive oxygen species.In mouse models of multidrug-resistant C.albicans infection,CLA-1 exhibited efficient in vivo fungicidal efficacy superior to two antifungal drugs,amphotericin B and fluconazole.Moreover,CLA-1 treatment induces negligible toxicity against normal tissues with safety.Therefore,this study reveals the pivotal role of the molecular design of Schiff-base silver nanocomplex formation on biopolymer surface-functionalized silica mesopores as a green and efficient nanoplatform to tackle infectious microbes.展开更多
基金supported by the National Key R&D Program of China(No.2017YFA0700104)the National Natural Science Foundation of China(Nos.21905204,21931007,and 21790052)111 Project of China(No.D17003).
文摘Sunlight-driven activation of molecular oxygen(O_(2))for organic oxidation reactions offers an appealing strategy to cut down the reliance on fossil fuels in chemical industry,yet it remains a great challenge to simultaneously tailor the charge kinetics and promote reactant chemisorption on semiconductor catalysts for enhanced photocatalytic performance.Herein,we report iron sites immobilized on defective BiOBr nanosheets as an efficient and selective photocatalyst for activation of O_(2) to singlet oxygen(^(1)O_(2)).These Fe^(3+) species anchored by oxygen vacancies can not only facilitate the separation and migration of photogenerated charge carrier,but also serve as active sites for effective adsorption of 02.Moreover,low-temperature phosphorescence spectra combined with X-ray photoelectron spectroscopy(XPS)and electronic paramagnetic resonance(EPR)spectra under illumination reveal that the Fe species can boost the quantum yield of excited triplet state and accelerate the energy transfer from excited triplet state to adsorbed O2 via a chemical loop of Fe^(3+)/Fe^(2+),thereby achieving highly efficient and selective generation of ^(1)O_(2).As a result,the versatile iron sites on defective BiOBr nanosheets contributes to near-unity conversion rate and selectivity in both aerobic oxidative coupling of amines to imines and sulfoxidation of organic sulfides.This work highlights the significant role of metal sites anchored on semiconductors in regulating the charge/energy transfer during the heterogeneous photocatalytic process,and provides a new angle for designing high-performance photocatalysts.
基金supported by the National Key R&D Programs of China(No.2018YFC0311003 to H.B.)the National Natural Science Foundation of China(No.U1703118 to J.C.)+5 种基金the Natural Science Foundation of Jiangsu Province(No.BK20181364 to J.C.)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD,to J.C.)the Cooperative Project between Southeast University and Nanjing Medical University(No.2018DN0004 to J.C.)the National Science Foundation of the Jiangsu Higher Education Institutions of China(No.18KJA310002 to H.B.,No.19KJA310003 to J.C)the Jiangsu Specially Appointed Professor and Jiangsu Medical Specialist Programs of China(to H.B.)Jiangsu Province“Innovative and Entrepreneurial Team”Program.
文摘Infectious microbes that spread easily in healthcare facilities remain as the severe threat for the public health,especially among immunocompromised populations.Given the intricate problem of dramatic increase in resistance to common biocides,the development of safe and efficient biocide formulated agents to alleviate drug resistance is highly demanding.In this study,Schiff-base ligands were successfully formed on natural biopolymer of epsilon-poly-L-lysine(ε-PL)decorated aldehyde functionalized mesoporous silica SBA-15(CHO-SBA-15)for the selective coordination of silver ions,which was affirmed by various physicochemical methods.Besides the identified broad-spectrum antibacterial activities,the as-prepared Schiff-base silver nanocomplex(CHO-SBA-15/ε-PL/Ag,CLA-1)exhibited an improved inhibitory effect on infectious pathogen growth typified by Escherichia coli and Staphylococcus aureus in comparison with two control silver complexes without Schiff-base conjugates,SBA-15/ε-PL/Ag and CHO-SBA-15/Ag,respectively.In addition,CLA-1 remarkably inhibited the growth of Mycobacterium tuberculosis due to the excellent antimicrobial activity of silver species.Significantly,CLA-1 kills Candida albicans cells,inhibits biofilm formation,and eliminates preformed biofilms,with no development of resistance during continuous serial passaging.The antifungal activity is connected to disruption of bacterial cell membranes and increased levels of intracellular reactive oxygen species.In mouse models of multidrug-resistant C.albicans infection,CLA-1 exhibited efficient in vivo fungicidal efficacy superior to two antifungal drugs,amphotericin B and fluconazole.Moreover,CLA-1 treatment induces negligible toxicity against normal tissues with safety.Therefore,this study reveals the pivotal role of the molecular design of Schiff-base silver nanocomplex formation on biopolymer surface-functionalized silica mesopores as a green and efficient nanoplatform to tackle infectious microbes.
