Lignin is the most abundant heteropolymer based on aromatic subunits in nature.Large quantities of lignin are annually produced from pulping processes and biorefinery industries.Its unclearly defined structure and dif...Lignin is the most abundant heteropolymer based on aromatic subunits in nature.Large quantities of lignin are annually produced from pulping processes and biorefinery industries.Its unclearly defined structure and difficult biodegradation mainly limit its utilization.This work focused on the effect of hydroxylation of lignin on its microbial degradation.Butyloxy carbonyl-modified lignin,and hydroxylated-lignin were synthesized with di-tert-butyl dicarbonate and hydrogen peroxide,respectively,using lignin as raw material.The degradation of the modifiedlignins both by P.chrysosporium and B.subtilis were analyzed using UV-vis spectroscopy.Results revealed that the lignin degradation velocity raises with the increase hydroxylation level of lignin.Moreover,FTIR and 1H NMR analysis of the biodegradation products of lignin further indicated that higher content of hydroxyl groups in lignin facilitated the demethylation combined with the aromatic ring cracking in the presence of fungus and bacteria.展开更多
Surface modification of different functional molecules onto NaREF_(4)(RE=rare earth)upconversion nanoparticles(UCNPs)impart their multiple functionalities.Functional molecules can be loaded onto NaREF_(4) UCNPs throug...Surface modification of different functional molecules onto NaREF_(4)(RE=rare earth)upconversion nanoparticles(UCNPs)impart their multiple functionalities.Functional molecules can be loaded onto NaREF_(4) UCNPs through the formation of coordination bonds between the surface-exposed RE^(3+) ions and the appropriate chemical groups of functional molecules.The density of surface RE^(3+) ions directly determines the loading efficiency of Na REF4 UCNPs.However,NaREF_(4) is a binary cation system,rendering the surface-distributed Na;and RE^(3+) ions remains a mystery.Here,we develop an effective strategy to significantly enhance the density of surface RE^(3+) ions,thus maximizing the loading capacity of NaREF_(4) UCNPs.This strategy is based on a heterovalent cation exchange(HCE)reaction in the surface region in which Na^(+)ions are replaced by RE^(3+) ions.The density of surface ligands enhances from 3.6 to 8.8 molecules/nm^(2) after reaction,suggesting that the loading efficiency increases by approximately 150%.Benefiting from the improved loading capacity,we demonstrate such surface-RE-rich nanoparticles have the ability to offer higher colloidal stability and more desirable photodynamic therapy(PDT)efficacy.This work not only advances our understanding of cation exchange reactions in RE-based nanoparticles,but also provides significant value for considerable applications such as sensing,bioimaging,and therapy.展开更多
基金This work was financially supported by the Science and Technology Innovation Program of Hunan Province(Contract Grant No.2018RS3101).
文摘Lignin is the most abundant heteropolymer based on aromatic subunits in nature.Large quantities of lignin are annually produced from pulping processes and biorefinery industries.Its unclearly defined structure and difficult biodegradation mainly limit its utilization.This work focused on the effect of hydroxylation of lignin on its microbial degradation.Butyloxy carbonyl-modified lignin,and hydroxylated-lignin were synthesized with di-tert-butyl dicarbonate and hydrogen peroxide,respectively,using lignin as raw material.The degradation of the modifiedlignins both by P.chrysosporium and B.subtilis were analyzed using UV-vis spectroscopy.Results revealed that the lignin degradation velocity raises with the increase hydroxylation level of lignin.Moreover,FTIR and 1H NMR analysis of the biodegradation products of lignin further indicated that higher content of hydroxyl groups in lignin facilitated the demethylation combined with the aromatic ring cracking in the presence of fungus and bacteria.
基金financially supported by the National Natural Science Foundation of China(Nos.61805083,31801968,and 51802281)。
文摘Surface modification of different functional molecules onto NaREF_(4)(RE=rare earth)upconversion nanoparticles(UCNPs)impart their multiple functionalities.Functional molecules can be loaded onto NaREF_(4) UCNPs through the formation of coordination bonds between the surface-exposed RE^(3+) ions and the appropriate chemical groups of functional molecules.The density of surface RE^(3+) ions directly determines the loading efficiency of Na REF4 UCNPs.However,NaREF_(4) is a binary cation system,rendering the surface-distributed Na;and RE^(3+) ions remains a mystery.Here,we develop an effective strategy to significantly enhance the density of surface RE^(3+) ions,thus maximizing the loading capacity of NaREF_(4) UCNPs.This strategy is based on a heterovalent cation exchange(HCE)reaction in the surface region in which Na^(+)ions are replaced by RE^(3+) ions.The density of surface ligands enhances from 3.6 to 8.8 molecules/nm^(2) after reaction,suggesting that the loading efficiency increases by approximately 150%.Benefiting from the improved loading capacity,we demonstrate such surface-RE-rich nanoparticles have the ability to offer higher colloidal stability and more desirable photodynamic therapy(PDT)efficacy.This work not only advances our understanding of cation exchange reactions in RE-based nanoparticles,but also provides significant value for considerable applications such as sensing,bioimaging,and therapy.
