To achieve real-time monitoring of humidity in various applications,we prepared facile and ultra-thin CoAl layered double hydroxide(CoAl LDH)nanosheets to engineer quartz crystal microbalances(QCM).The characteristics...To achieve real-time monitoring of humidity in various applications,we prepared facile and ultra-thin CoAl layered double hydroxide(CoAl LDH)nanosheets to engineer quartz crystal microbalances(QCM).The characteristics of CoAl LDH were investigated by transmission electron microscopy(TEM),X-ray diffraction(XRD),X-ray photoelectric spectroscopy(XPS),Brunauer–Emmett–Telle(BET),atomic force microscopy(AFM)and zeta potential.Due to their large specific surface area and abundant hydroxyl groups,CoAl LDH nanosheets exhibit good humidity sensing performance.In a range of 11.3%and 97.6%relative humidity(RH),the sensor behaved an ultrahigh sensitivity(127.8 Hz/%RH),fast response(9.1 s)and recovery time(3.1 s),low hysteresis(3.1%RH),good linearity(R^(2)=0.9993),stability and selectivity.Besides,the sensor can recover the initial response frequency after being wetted by deionized water,revealing superior self-recovery ability under high humidity.Based on in-situ Fourier transform infrared spectroscopy(FT-IR),the adsorption mechanism of CoAl LDH toward water molecules was explored.The QCM sensor can distinguish different respiratory states of people and wetting degree of fingers,as well as monitor the humidity in vegetable packaging,suggesting excellent properties and a promising application in humidity sensing.展开更多
It is difficult to achieve macroscale superlubricity under high contact pressures and high normal loads.Layered double hydroxide(LDH)nanoadditives were introduced into an ionic liquid alcohol solution(IL(as))with cont...It is difficult to achieve macroscale superlubricity under high contact pressures and high normal loads.Layered double hydroxide(LDH)nanoadditives were introduced into an ionic liquid alcohol solution(IL(as))with contact pressures up to 1.044 GPa,which resulted in a friction coefficient(COF)of 0.004 and a robust superlubricity state lasting for 2 h.Compared with the LDH particles(LDH-Ps)with ca.90-nm widths and 18-nm thickness,micron-scale LDH nanosheet(LDH-N)additives with ca.1.5-pm width and 6-nm thickness increased the load-bearing capacity by approximately three times during superlubricity.The lubricant film thickness and the ultrathin longitudinal dimension of the LDH-N additives did not influence the continuity of the fluid film on the contact surface.These improvements resulted from the protective adsorption layer and ion distribution formed on the contact interface,as revealed by detailed surface analyses and simulation studies.In particular,the sliding energy barrier and Bader charge calculation revealed that weak shear sliding between the nanosheet and the solid surface formed easily and the anions in the liquid adsorbed on the solid surface exhibited electrostatic repulsion forces,which generated stable tribological properties synergistically.This research provides a novel method for obtaining macroscale superlubricity for practical industrial applications.展开更多
In contrast to reactive oxygen species(ROS),the generation of oxygen-irrelevant free radicals is oxygen-and H2O2-independent in cell,which can offer novel opportunities to maximum the chemodynamic therapy(CDT)efficacy...In contrast to reactive oxygen species(ROS),the generation of oxygen-irrelevant free radicals is oxygen-and H2O2-independent in cell,which can offer novel opportunities to maximum the chemodynamic therapy(CDT)efficacy.Herein,an H2O2-independent“functional reversion”strategy based on tumor microenvironment(TME)-toggled C-free radical generation for CDT is developed by confining astaxanthin(ATX)on the NiFe-layered double hydroxide(LDH)nanosheets(denoted as ATX/LDH).The unique ATX/LDH can demonstrate outstanding TME-responsive C-free radical generation performance by proton coupled electron transfer(PCET),owing to the specific ATX activation by unsaturated Fe sites on the LDH nanosheets formed under TME.Significantly,the Brönsted base sites of LDH hydroxide layers can promote the generation of neutral ATX C-free radicals by capturing the protons generated in the ATX activation process.Conversely,ATX/LDH maintain antioxidant performance to prevent normal tissue cancerization due to the synergy of LDH nanosheets and antioxidative ATX.In addition,C-free radical can compromise the antioxidant defense in cells to the maximum extent,compared with ROS.The free radicals burst under TME can significantly elevate free radical stress and induce cancer cell apoptosis.This strategy can realize TME-toggled C free radical generation and perform free radical stress enhanced CDT.展开更多
基金supported by the Shanghai Natural Science Foundation(No.21ZR1427500)the Agricultural Project of Shanghai Science and Technology Innovation Action Plan(No.19391901600).
文摘To achieve real-time monitoring of humidity in various applications,we prepared facile and ultra-thin CoAl layered double hydroxide(CoAl LDH)nanosheets to engineer quartz crystal microbalances(QCM).The characteristics of CoAl LDH were investigated by transmission electron microscopy(TEM),X-ray diffraction(XRD),X-ray photoelectric spectroscopy(XPS),Brunauer–Emmett–Telle(BET),atomic force microscopy(AFM)and zeta potential.Due to their large specific surface area and abundant hydroxyl groups,CoAl LDH nanosheets exhibit good humidity sensing performance.In a range of 11.3%and 97.6%relative humidity(RH),the sensor behaved an ultrahigh sensitivity(127.8 Hz/%RH),fast response(9.1 s)and recovery time(3.1 s),low hysteresis(3.1%RH),good linearity(R^(2)=0.9993),stability and selectivity.Besides,the sensor can recover the initial response frequency after being wetted by deionized water,revealing superior self-recovery ability under high humidity.Based on in-situ Fourier transform infrared spectroscopy(FT-IR),the adsorption mechanism of CoAl LDH toward water molecules was explored.The QCM sensor can distinguish different respiratory states of people and wetting degree of fingers,as well as monitor the humidity in vegetable packaging,suggesting excellent properties and a promising application in humidity sensing.
基金This project was supported by the National Natural Science Foundation of China(Nos.51875303,51905294,and 52105194)the Tribology Science Fund of the State Key Laboratory of Tribology(No.SKLTKF20A01).
文摘It is difficult to achieve macroscale superlubricity under high contact pressures and high normal loads.Layered double hydroxide(LDH)nanoadditives were introduced into an ionic liquid alcohol solution(IL(as))with contact pressures up to 1.044 GPa,which resulted in a friction coefficient(COF)of 0.004 and a robust superlubricity state lasting for 2 h.Compared with the LDH particles(LDH-Ps)with ca.90-nm widths and 18-nm thickness,micron-scale LDH nanosheet(LDH-N)additives with ca.1.5-pm width and 6-nm thickness increased the load-bearing capacity by approximately three times during superlubricity.The lubricant film thickness and the ultrathin longitudinal dimension of the LDH-N additives did not influence the continuity of the fluid film on the contact surface.These improvements resulted from the protective adsorption layer and ion distribution formed on the contact interface,as revealed by detailed surface analyses and simulation studies.In particular,the sliding energy barrier and Bader charge calculation revealed that weak shear sliding between the nanosheet and the solid surface formed easily and the anions in the liquid adsorbed on the solid surface exhibited electrostatic repulsion forces,which generated stable tribological properties synergistically.This research provides a novel method for obtaining macroscale superlubricity for practical industrial applications.
基金the financial support from the National Natural Science Foundation of China(No.21571013,52073023,and 21805293)the National Basic Research Program(No.2014CB932101)+2 种基金the Program for Chang Jiang Scholars,Innovative Research Team in University(No.IRT1205)the Youth Innovation Promotion Association of Chinese Academy of Sciences(No.2019027)the Director Foundation of the Technical Institute of Physics and Chemistry,Chinese Academy of Sciences.
文摘In contrast to reactive oxygen species(ROS),the generation of oxygen-irrelevant free radicals is oxygen-and H2O2-independent in cell,which can offer novel opportunities to maximum the chemodynamic therapy(CDT)efficacy.Herein,an H2O2-independent“functional reversion”strategy based on tumor microenvironment(TME)-toggled C-free radical generation for CDT is developed by confining astaxanthin(ATX)on the NiFe-layered double hydroxide(LDH)nanosheets(denoted as ATX/LDH).The unique ATX/LDH can demonstrate outstanding TME-responsive C-free radical generation performance by proton coupled electron transfer(PCET),owing to the specific ATX activation by unsaturated Fe sites on the LDH nanosheets formed under TME.Significantly,the Brönsted base sites of LDH hydroxide layers can promote the generation of neutral ATX C-free radicals by capturing the protons generated in the ATX activation process.Conversely,ATX/LDH maintain antioxidant performance to prevent normal tissue cancerization due to the synergy of LDH nanosheets and antioxidative ATX.In addition,C-free radical can compromise the antioxidant defense in cells to the maximum extent,compared with ROS.The free radicals burst under TME can significantly elevate free radical stress and induce cancer cell apoptosis.This strategy can realize TME-toggled C free radical generation and perform free radical stress enhanced CDT.
