Carbon-based single-atom catalysts(SACs)have been widely studied in the field of biomedicine due to their excellent catalytic performance.However,carbon-based SACs usually aggregate during pyrolysis,which leads to the...Carbon-based single-atom catalysts(SACs)have been widely studied in the field of biomedicine due to their excellent catalytic performance.However,carbon-based SACs usually aggregate during pyrolysis,which leads to the reduction of catalytic activity.Here,we describe a method to improve the monodispersion of SACs using silicon dioxide as a protective layer.The decoration of silicon dioxide serves as a buffer layer for individual nanoparticles,which is not destroyed during the pyrolysis process,ensuring the single-particle dispersion of the nanoparticles after etching.This approach increased the hydroxyl groups on the surface of Fe-SAC(Fe-SAC-SE)and improved its water solubility,resulting in a four times enhancement of the peroxidase(POD)-like activity of Fe-SAC-SE(58.4 U/mg)than that of non-protected SACs(13.9 U/mg).The SiO_(2)-protection approach could also improve the catalytic activities of SACs with other metals such as Mn,Co,Ni,and Cu,indicating its generality for SACs preparation.Taking advantage of the high POD-like activity,photothermal properties,and large specific surface area of Fe-SAC-SE,we constructed a synergistic therapeutic system(Fe-SAC-SE@DOX@PEG)for combining the photothermal therapy,catalytic therapy,and chemotherapy.It was verified that the photothermal properties of Fe-SAC-SE@DOX@PEG could effectively improve its POD-like activity,exhibiting excellent tumor-killing performance at the cellular level.This work may provide a general approach to improve the performances of SACs for disease therapy and diagnosis.展开更多
The Al0.85Ga0.15As layers buried below the GaAs core layer with and without the SiO2 layer were successfully oxidized in a wet ambient environment.The experimental results show that the SiO2 layer has little impact on...The Al0.85Ga0.15As layers buried below the GaAs core layer with and without the SiO2 layer were successfully oxidized in a wet ambient environment.The experimental results show that the SiO2 layer has little impact on the lateral-wet-oxidation rate of the Al0.85Ga0.15 As layer.The contrast of the SEM image of the oxidized regions and the absence of As-related Raman peaks for samples with the SiO2 layer arise from the removal of As ingredients with the largest atomic number,which leads to improvements in the thermal stability of the oxidized layer.The PL intensities of samples with the SiO2 layer are much stronger than those without the SiO2 layer.The PL emission peak is almost unshifted with a slight broadening under the protection of the SiO2 layer.This is attributed to the SiO2 layer preventing oxidation damage to the GaAs capping layer.展开更多
基金the National Natural Science Foundation of China(Nos.51872030,51631001,51902023,51702016,and 22175048)Beijing Institute of Technology Research Fund Program for Young Scholars.
文摘Carbon-based single-atom catalysts(SACs)have been widely studied in the field of biomedicine due to their excellent catalytic performance.However,carbon-based SACs usually aggregate during pyrolysis,which leads to the reduction of catalytic activity.Here,we describe a method to improve the monodispersion of SACs using silicon dioxide as a protective layer.The decoration of silicon dioxide serves as a buffer layer for individual nanoparticles,which is not destroyed during the pyrolysis process,ensuring the single-particle dispersion of the nanoparticles after etching.This approach increased the hydroxyl groups on the surface of Fe-SAC(Fe-SAC-SE)and improved its water solubility,resulting in a four times enhancement of the peroxidase(POD)-like activity of Fe-SAC-SE(58.4 U/mg)than that of non-protected SACs(13.9 U/mg).The SiO_(2)-protection approach could also improve the catalytic activities of SACs with other metals such as Mn,Co,Ni,and Cu,indicating its generality for SACs preparation.Taking advantage of the high POD-like activity,photothermal properties,and large specific surface area of Fe-SAC-SE,we constructed a synergistic therapeutic system(Fe-SAC-SE@DOX@PEG)for combining the photothermal therapy,catalytic therapy,and chemotherapy.It was verified that the photothermal properties of Fe-SAC-SE@DOX@PEG could effectively improve its POD-like activity,exhibiting excellent tumor-killing performance at the cellular level.This work may provide a general approach to improve the performances of SACs for disease therapy and diagnosis.
基金supported by the National Research Project of China(Nos.60990315,60625402,61161130527)
文摘The Al0.85Ga0.15As layers buried below the GaAs core layer with and without the SiO2 layer were successfully oxidized in a wet ambient environment.The experimental results show that the SiO2 layer has little impact on the lateral-wet-oxidation rate of the Al0.85Ga0.15 As layer.The contrast of the SEM image of the oxidized regions and the absence of As-related Raman peaks for samples with the SiO2 layer arise from the removal of As ingredients with the largest atomic number,which leads to improvements in the thermal stability of the oxidized layer.The PL intensities of samples with the SiO2 layer are much stronger than those without the SiO2 layer.The PL emission peak is almost unshifted with a slight broadening under the protection of the SiO2 layer.This is attributed to the SiO2 layer preventing oxidation damage to the GaAs capping layer.