目的:研究制备方法对乳清分离蛋白(whey protein isolate,WPI)-绿原酸(chlorogenic acid,CA)共价接枝物结构和功能性质的影响。方法:分别以碱法、自由基法和酶法制备WPI-CA共价接枝物,对其反应基团含量、CA接枝量、分子结构、表面疏水...目的:研究制备方法对乳清分离蛋白(whey protein isolate,WPI)-绿原酸(chlorogenic acid,CA)共价接枝物结构和功能性质的影响。方法:分别以碱法、自由基法和酶法制备WPI-CA共价接枝物,对其反应基团含量、CA接枝量、分子结构、表面疏水性、热稳定性、抗氧化活性和乳化性等进行分析。结果:游离氨基、色氨酸和巯基均参与了反应,游离氨基为主要反应基团。碱法、自由基法和酶法接枝物的CA接枝量分别为(52.70±1.81)、(42.57±1.85)μmol/g和(63.75±2.50)μmol/g。CA的共价接枝使WPI二级结构中α-螺旋相对含量减少,无规卷曲结构相对含量增加,分子内源荧光强度降低。碱法和酶法接枝会降低WPI表面疏水性,增强其热稳定性,自由基法的影响则与两者相反。与WPI相比,WPI-CA共价接枝物的抗氧化活性和乳化性显著增强(P<0.05),且抗氧化活性与CA接枝量成正比。结论:酶法接枝效率最高,且所得WPI-CA接枝物热稳定性和抗氧化活性最强。本研究可为蛋白质-多酚共价接枝物类抗氧化性载体材料的制备及应用提供参考。展开更多
Photocatalytic hydrogen(H_(2))evolution using covalent organic frameworks(COFs)is an attractive and promising avenue for exploration,but one of its big challenges is low photo-induced charge separation.In this study,w...Photocatalytic hydrogen(H_(2))evolution using covalent organic frameworks(COFs)is an attractive and promising avenue for exploration,but one of its big challenges is low photo-induced charge separation.In this study,we present a straightforward and facile dipole polarization engineering strategy to enhance charge separation efficiency,achieved through atomic modulation(O,S,and Se)of the COF monomer.Our findings demonstrate that incorporating atoms with varying electronegativities into the COF matrix significantly influences the local dipole moment,thereby affecting charge separation efficiency and photostability,which in turn affects the rates of photocatalytic H_(2) evolution.As a result,the newly developed TMT-BO-COF,which contains highly electronegative O atoms,exhibits the lowest exciton binding energy,the highest efficiency in charge separation and transportation,and the longest lifetime of the active charges.This leads to an impressive average H_(2) production rate of 23.7 mmol g^(−1) h^(−1),which is 2.5 and 24.5 times higher than that of TMT-BS-COF(containing S atoms)and TMT-BSe-COF(containing Se atoms),respectively.A novel photocatalytic hydrogen evolution mechanism based on proton-coupled electron transfer on N in the structure of triazine rings in vinylene-linked COFs is proposed by theoretical calculations.Our findings provide new insights into the design of highly photoactive organic framework materials for H_(2) evolution and beyond.展开更多
文摘目的:研究制备方法对乳清分离蛋白(whey protein isolate,WPI)-绿原酸(chlorogenic acid,CA)共价接枝物结构和功能性质的影响。方法:分别以碱法、自由基法和酶法制备WPI-CA共价接枝物,对其反应基团含量、CA接枝量、分子结构、表面疏水性、热稳定性、抗氧化活性和乳化性等进行分析。结果:游离氨基、色氨酸和巯基均参与了反应,游离氨基为主要反应基团。碱法、自由基法和酶法接枝物的CA接枝量分别为(52.70±1.81)、(42.57±1.85)μmol/g和(63.75±2.50)μmol/g。CA的共价接枝使WPI二级结构中α-螺旋相对含量减少,无规卷曲结构相对含量增加,分子内源荧光强度降低。碱法和酶法接枝会降低WPI表面疏水性,增强其热稳定性,自由基法的影响则与两者相反。与WPI相比,WPI-CA共价接枝物的抗氧化活性和乳化性显著增强(P<0.05),且抗氧化活性与CA接枝量成正比。结论:酶法接枝效率最高,且所得WPI-CA接枝物热稳定性和抗氧化活性最强。本研究可为蛋白质-多酚共价接枝物类抗氧化性载体材料的制备及应用提供参考。
文摘Photocatalytic hydrogen(H_(2))evolution using covalent organic frameworks(COFs)is an attractive and promising avenue for exploration,but one of its big challenges is low photo-induced charge separation.In this study,we present a straightforward and facile dipole polarization engineering strategy to enhance charge separation efficiency,achieved through atomic modulation(O,S,and Se)of the COF monomer.Our findings demonstrate that incorporating atoms with varying electronegativities into the COF matrix significantly influences the local dipole moment,thereby affecting charge separation efficiency and photostability,which in turn affects the rates of photocatalytic H_(2) evolution.As a result,the newly developed TMT-BO-COF,which contains highly electronegative O atoms,exhibits the lowest exciton binding energy,the highest efficiency in charge separation and transportation,and the longest lifetime of the active charges.This leads to an impressive average H_(2) production rate of 23.7 mmol g^(−1) h^(−1),which is 2.5 and 24.5 times higher than that of TMT-BS-COF(containing S atoms)and TMT-BSe-COF(containing Se atoms),respectively.A novel photocatalytic hydrogen evolution mechanism based on proton-coupled electron transfer on N in the structure of triazine rings in vinylene-linked COFs is proposed by theoretical calculations.Our findings provide new insights into the design of highly photoactive organic framework materials for H_(2) evolution and beyond.
