The enzymatic depolymerization of polyethylene terephthalate(PET)offers a sustainable approach for the recycling of PET waste.Great efforts have been devoted to engineering PET depolymerases on the substrate binding c...The enzymatic depolymerization of polyethylene terephthalate(PET)offers a sustainable approach for the recycling of PET waste.Great efforts have been devoted to engineering PET depolymerases on the substrate binding cleft and the surrounding loops/α-helices on the surface.Here,we report the systematic engineering of whole β-sheet regions in the core of IsPETase(a PETase from Ideonella sakaiensis)via a fluorescent high-throughput screening assay.Twenty-one beneficial substitutions were obtained and iteratively recombined.The best variant,DepoPETase β,with an increase in the melting temperatures(T_(m))of 22.9℃,exhibited superior depolymerization performance and enabled complete depolymerization of100.5 g of untreated post-consumer PET(pc-PET;0.26% W_(enzyme)/W_(PET) enzyme loading)in liter-scale bioreactor at 50℃within 4 d.Crystallization and molecular dynamics simulations revealed that the improved activity and thermostability of DepoPETase β were due to enhanced hydrogen bonds and salt bridges in the β-sheet region,a more tightly packed structure of the core sheets and the surrounding helix,and improved binding of PET to the active sites.This study not only demonstrates the importance of engineering strategy in theβ-sheet region of PET hydrolases but also provides a potential PET depolymerase for large-scale PET recycling.展开更多
Chain-growth radical polymerization of vinyl monomers is essential for producing a wide range of materials with properties tailored to specific applications.However,the inherent resistance of the polymer's C―C ba...Chain-growth radical polymerization of vinyl monomers is essential for producing a wide range of materials with properties tailored to specific applications.However,the inherent resistance of the polymer's C―C backbone to degradation raises significant concerns regarding long-term environmental persistence,which also limits their potential in biomedical applications.To address these challenges,researchers have developed strategies to either degrade preexisting vinyl polymers or incorporate cleavable units into the backbone to modify them with enhanced degradability.This review explores the various approaches aimed at achieving backbone degradability in chain-growth radical polymerization of vinyl monomers,while also highlighting future research directions for the development of application-driven degradable vinyl polymers.展开更多
Green and atom-economic depolymerization of lignin remains a great challenge due toits complex non-repetitive structure and the inert property for chemo-digestion. A redoxneutrallignin depolymerization system without ...Green and atom-economic depolymerization of lignin remains a great challenge due toits complex non-repetitive structure and the inert property for chemo-digestion. A redoxneutrallignin depolymerization system without the use of extra oxidant and/or reductantover a Co-NC catalyst has been developed in this work, providing the first non-noble metalheterogeneous catalytic system for redox-neutral valorization of lignin. Mechanistic studiesbased on control reactions and deuterium labeling experiments suggest that the reactionproceeds via ametal-catalyzed dehydrogenation of C_(α)-OH to afford a carbonyl intermediate,followed by C_(β)-O bond cleavage (via hydrogenolysis) to afford monophenols and aromaticketone products. The hydrogen used for the cleavage of the C_(β)-O bond originates from thealcoholmoiety in the substrate, and the cascade dehydrogenation and hydrogenolysis stepsare highly coupled, rendering it an efficient and atom-economic process.展开更多
Chemical recycling/upcycling of plastics has emerged as one of the most promising strategies for the plastic circular economy,enabling the depolymerization and functionalization of plastics into valuable monomers and ...Chemical recycling/upcycling of plastics has emerged as one of the most promising strategies for the plastic circular economy,enabling the depolymerization and functionalization of plastics into valuable monomers and chemicals.However,studies on the depolymerization and functionalization of challenging super engineering plastics have remained in early stage and underexplored.In this review,we would like to discuss the representative accomplishments and mechanism insights on chemical protocols achieved in depolymerization of super engineering plastics,especially for poly(phenylene sulfide)(PPS),poly(aryl ether)s including poly(ether ether ketone)(PEEK),polysulfone(PSU),polyphenylsulfone(PPSU)and polyethersulfone(PES).We anticipate that this review will provide an overall perspective on the current status and future trends of this emerging field.展开更多
Although the efficiency of poly(ethylene terephthalate)(PET)degradation has been successfully improved by depolymerase engineering,mostly by using Goodfellow-PET(gf-PET)as a substrate,efforts to degrade unpretreated P...Although the efficiency of poly(ethylene terephthalate)(PET)degradation has been successfully improved by depolymerase engineering,mostly by using Goodfellow-PET(gf-PET)as a substrate,efforts to degrade unpretreated PET materials with high crystallinity remain insufficient.Here,we endeavored to improve the degradation capability of a WCCG mutant of leaf-branch compost cutinase(LCC)on a unpretreated PET substrate(crystallinity>40%)by employing iterative saturation mutagenesis.Using this method,we developed a high-throughput screening strategy appropriate for unpretreated substrates.Through extensive screening of residues around the substrate-binding groove,two variants,WCCG-sup1 and WCCG-sup2,showed good depolymerization capabilities with both high-(42%)and low-crystallinity(9%)substrates.The WCCG-sup1 variant completely depolymerized a commercial unpretreated PET product in 36 h at 72℃.In addition to enzyme thermostability and catalytic efficiency,the adsorption of enzymes onto substrates plays an important role in PET degradation.This study provides valuable insights into the structure-function relationship of LCC.展开更多
Plastic waste puts a huge burden on the ecosystem due to the current lack of mature recycling technology.Poly(ethylene terephthalate)(PET)is one of the most produced plastics in the world.Enzymatic decomposition holds...Plastic waste puts a huge burden on the ecosystem due to the current lack of mature recycling technology.Poly(ethylene terephthalate)(PET)is one of the most produced plastics in the world.Enzymatic decomposition holds the promise of recovering monomers from PET plastic,and the monomers can be used to regenerate new PET products.However,there are still limitations in the activity and thermal stability of the existing PET hydrolases.The recent study by Lu et al.introduced a novel PET hydrolase via machine learning-aided engineering.The obtained PET hydrolase showed excellent activity and thermal stability in the hydrolysis of PET and is capable of directly degrading large amounts of postconsumer PET products.This approach provides an effective method for recycling PET waste and is expected to improve the current state of plastic pollution worldwide.展开更多
Tetrandrine(TET),a natural bisbenzyl isoquinoline alkaloid extracted from Stephania tetrandra S.Moore,has diverse pharmacological effects.However,its effects on melanoma remain unclear.Cellular prolif-eration assays,m...Tetrandrine(TET),a natural bisbenzyl isoquinoline alkaloid extracted from Stephania tetrandra S.Moore,has diverse pharmacological effects.However,its effects on melanoma remain unclear.Cellular prolif-eration assays,multi-omics analyses,and xenograft models were used to determine the effect of TET on melanoma.The direct target of TET was identified using biotin-TET pull-down liquid chromatograph-mass spectrometry(LC-MS),cellular thermal shift assays,and isothermal titration calorimetry(ITC)analysis.Our findings revealed that TET treatment induced robust cellular autophagy depending on activating transcription factor 6(ATF6)-mediated endoplasmic reticulum(ER)stress.Simultaneously,it hindered autophagic flux by inducing cytoskeletal protein depolymerization in melanoma cells.TET treatment resulted in excessive accumulation of reactive oxygen species(Ros)and simultaneously triggered mitophagy.Sirtuin 5(SIRT5)was ultimately found to be a direct target of TET.Mechanistically,TET led to the degradation of SIRT5 via the ubiquitin(Ub)-26S proteasome system.SIRT5 knockdown induced ROS accumulation,whereas SIRT5 overexpression attenuated the TET-induced ROS accumula-tion and autophagy.Importantly,TET exhibited anti-cancer effects in xenograft models depending on SIRT5 expression.This study highlights the potential of TET as an antimelanoma agent that targets SIRT5.These findings provide a promising avenue for the use of TET in melanoma treatment and underscore its potential as a therapeutic candidate.展开更多
BACKGROUND Glioma is one of the most common intracranial tumors,characterized by invasive growth and poor prognosis.Actin cytoskeletal rearrangement is an essential event of tumor cell migration.The actin dynamics-rel...BACKGROUND Glioma is one of the most common intracranial tumors,characterized by invasive growth and poor prognosis.Actin cytoskeletal rearrangement is an essential event of tumor cell migration.The actin dynamics-related protein scinderin(SCIN)has been reported to be closely related to tumor cell migration and invasion in several cancers.AIM To investigate the role and mechanism of SCIN in glioma.METHODS The expression and clinical significance of SCIN in glioma were analyzed based on public databases.SCIN expression was examined using real-time quantitative polymerase chain reaction and Western blotting.Gene silencing was performed using short hairpin RNA transfection.Cell viability,migration,and invasion were assessed using cell counting kit 8 assay,wound healing,and Matrigel invasion assays,respectively.F-actin cytoskeleton organization was assessed using F-actin staining.RESULTS SCIN expression was significantly elevated in glioma,and high levels of SCIN were associated with advanced tumor grade and wild-type isocitrate dehydrogenase.Furthermore,SCIN-deficient cells exhibited decreased proliferation,migration,and invasion in U87 and U251 cells.Moreover,knockdown of SCIN inhibited the RhoA/focal adhesion kinase(FAK)signaling to promote F-actin depolymerization in U87 and U251 cells.CONCLUSION SCIN modulates the actin cytoskeleton via activating RhoA/FAK signaling,thereby promoting the migration and invasion of glioma cells.This study identified the cancer-promoting effect of SCIN and provided a potential therapeutic target for the treatment of glioma.展开更多
NaY zeolites are synthesized using submolten salt depolymerized natural perlite mineral as the main silica and alumina sources in a 0.94 L stirred crystallizer.Effects of alkalinity ranging from 0.38 to 0.55(n(Na_(2)O...NaY zeolites are synthesized using submolten salt depolymerized natural perlite mineral as the main silica and alumina sources in a 0.94 L stirred crystallizer.Effects of alkalinity ranging from 0.38 to 0.55(n(Na_(2)O)/n(SiO_(2)))on the relative crystallinity,textural properties and crystallization kinetics were investigated.The results show that alkalinity exerts a nonmonotonic influence on the relative crystallinity and textural properties,which exhibit a maximum at the alkalinity of 0.43.The nucleation kinetics are studied by fitting the experimental data of relative crystallinity with the Gualtieri model.It is shown that the nucleation rate constant increases with increasing alkalinity,while the duration period of nucleation decreases with increasing alkalinity.For n(Na_(2)O)/n(SiO_(2))ratios ranging from 0.38 to 0.55,the as-synthesized NaY zeolites exhibit narrower crystal size distributions with the increase in alkalinity.The growth rates determined from the variations of average crystal size with time are 51.09,157.50,46.17 and 24.75 nm·h^(-1),respectively.It is found that the larger average crystal sizes at the alkalinity of 0.38 and 0.43 are attributed to the dominant role of crystal growth over nucleation.Furthermore,the combined action of prominent crystal growth and the longer duration periods of nucleation at the alkalinity of 0.38 and 0.43 results in broader crystal size distributions.The findings demonstrate that control of the properties of NaY zeolite and the crystallization kinetics can be achieved by conducting the crystallization process in an appropriate range of alkalinity of the reaction mixture.展开更多
This study analyzed the prevalent physicochemical phases of smelting slag from the perspective of data science and chemistry.Findings delineated the silicate phase as the pivotal and predominant constraining phase for...This study analyzed the prevalent physicochemical phases of smelting slag from the perspective of data science and chemistry.Findings delineated the silicate phase as the pivotal and predominant constraining phase for the resource utilization of smelting slag.An intricate correlation between metallic elements and dominant phases was constructed.Typical silicate phase olivine(OL)was synthesized as a paradigm to examine alkali depolymerization,unveiling the optimal conditions for such depolymerization to be an alkali to olivine molar ratio of 1:5,a reaction temperature of 700℃,and a duration of 3 h.The underlying mechanism of alkali depolymerization within silicate phases was elucidated under these parameters.The reaction mechanism of alkali depolymerization within silicate phases can be encapsulated in three sequential steps:(1)NaOH dissociation and subsequent adsorption of OH^(-)to cationic(Mg or Fe)sites;(2)disruption of cation-oxygen bonds,leading to the formation of hydroxide compounds,which then underwent oxidation;(3)Na^(+)occupied the resultant cation vacancy sites,instigating further depolymerization of the intermediate Na_(2)(Mg,Fe)SiO_(4).The articulated mechanism is anticipated to furnish theoretical underpinnings for the efficacious recuperation of metals from smelting slags.展开更多
Birch outer bark(BOB)from Betula pendula Roth.is a unique and valuable biomass feedstock that contains suberin.The biopolyester suberin is built from bifunctional fatty acids-suberinic acids(SA)-which can be obtained ...Birch outer bark(BOB)from Betula pendula Roth.is a unique and valuable biomass feedstock that contains suberin.The biopolyester suberin is built from bifunctional fatty acids-suberinic acids(SA)-which can be obtained through a depolymerization process in an alkaline medium and used as a binder due to their adhesive properties.The aim of this study was to develop the SA-containing binder and identify suitable pressing conditions to produce plywood that meets the shear strength requirements of the EN 314-2 standard 3rd moisture resistance class for bonding quality,ensuring durability in unprotected exterior conditions(shear strength≥1 N/mm^(2)).The raw BOB material was modified by extraction,milling,and fractionation,and the depolymerization methodology was enhanced by additional sieving to improve the adhesive properties of the obtained binders.Several analytical methods were used to characterize the feedstock and the binders.Higher heating value was used to assess the pure outer bark content of BOB.GC-MS and GPC were used to describe the monomeric and oligomeric composition of binders.TGA was used to describe the biopolymeric composition and DSC was used to determine the thermal behavior of the binders.As a result,successful modification of feedstock(extracted BOB,milled through 2 mm sieve,1-2 mm fraction used)and its depolymerization process(implementing the separation of coarse ligno-carbohydrate particles by 1 mm mesh sieve)was employed to obtain a binder for which suitable hot-pressing parameters were determined−200℃for 5 min at 1.8 MPa.Consequently,plywood with shear strength of 1.26±0.18 N/mm^(2),which adheres to the EN 314-2 standards 3rd moisture resistance class,was obtained.展开更多
The molecular recyclability of poly (ethylene terephthalate) (PET) and three semi-aromatic polyesters poly (phloretic acid) (poly-H), poly (dihydroferulic acid) (poly-G), and poly (dihydrosinapinic acid) (poly-S) is e...The molecular recyclability of poly (ethylene terephthalate) (PET) and three semi-aromatic polyesters poly (phloretic acid) (poly-H), poly (dihydroferulic acid) (poly-G), and poly (dihydrosinapinic acid) (poly-S) is evaluated in this study. PET is an extensively used aromatic polyester, and poly-H, poly-G, and poly-S can be considered semi-aromatic poly (lactic acid) modifications. All these polyesters have been depolymerized at neutral pH and by acid- and base-catalyzed hydrolysis at two temperatures, i.e., 50˚C and 80˚C. Base-catalyzed depolymerization of virgin PET leads to an isolated yield of 38% after 48 hours of reaction at 80˚C. Contrary to these results for PET, almost all the monomers of the semi-aromatic polyesters poly-H, poly-G, and poly-S are recovered with isolated yields larger than 90% at the same temperature after 15 minutes in a facile manner. A shrinking particle model used to determine the global kinetics of the base-catalyzed depolymerization showed that the rate rises with increasing temperature. Using the shrinking particle model, the intrinsic reaction rate constants were determined. It has been demonstrated that the rate coefficients of the depolymerization of the semi-aromatic polyesters poly-H, poly-G, and poly-S are between 2 and 3 orders of magnitude higher than those for PET.展开更多
Lignin is the only nature renewable resource which can provide large quantities of aromatic compounds. In the work, transformation of lignin into benzene, toluene, and xylenes （BTX） was investigated over the HZSM-5,...Lignin is the only nature renewable resource which can provide large quantities of aromatic compounds. In the work, transformation of lignin into benzene, toluene, and xylenes （BTX） was investigated over the HZSM-5, HY, and MCM-22 catalysts, and the HZSM-5 catalyst showed the highest carbon yield of BTX. The reaction condition, including temperature, the gas flow rate, and the catalyst/lignin ratio, was also investigated. The carbon yield of BTX reached about 25.3 C-mol% over HZSM-5 catalyst under T=550℃, f（N2）=300 cm^3/min, and catalyst/lignin ratio of 2.展开更多
OBJECTIVE:To investigate the effect of manipulation treatment on knee osteoarthritis rats and the effect on Rho-associated protein kinase(ROCK)/LIM-kinase1(LIMK1)/Cofilin signaling pathway.METHOD:Fifty Specific pathog...OBJECTIVE:To investigate the effect of manipulation treatment on knee osteoarthritis rats and the effect on Rho-associated protein kinase(ROCK)/LIM-kinase1(LIMK1)/Cofilin signaling pathway.METHOD:Fifty Specific pathogen Free Sprague-Dawley rats were randomly divided into five groups(n=8 each):blank group,model group,manipulation group,celecoxib group,and manipulation combined with celecoxib group(MC group).The osteoarthritis model was established by injecting 0.2 m L 4%papain into the articular disc of the rats.After successfully establishing the model,we treated the manipulation group with pushing manipulation using one-finger-meditation to the Neixiyan(EX-LE4),Waixiyan(EX-LE5),Xuehai(SP10),Liangqiu(ST34),and Zusanli(ST36)acupoints for 10 min each time.Also,the celecoxib group was gavaged with 24 mg·kg^(-1)·d^(-1 )celecoxib,while the MC group was treated using both of these two methods.After four weeks,the cartilage of the right femur was removed for hematoxylin-eosin staining of the cartilage tissue.The expressions of interleukin-1β(IL-1β)and tumor necrosis factor-α(TNF-α)in serum were observed using the enzyme-linked immunosorbent assay.Besides,we detected the expressions of ROCK,LIMK1,Phospho-LIM-kinase1(Phospho-LIMK1),Cofilin,and Phospho-Cofilin by Western blot.RESULTS:Compared to the model group,the manipulation group,celecoxib group,and MC group all exhibited superior results concerning pathological morphologic changes of cartilage,as observed by hematoxylin-eosin staining and calculated using the Mankin score.Besides,in contrast to the blank group,the model group exhibited elevated serum levels of IL-1βand TNF-α(P<0.01),while the expression of ROCK,LIMK1,Phospho-LIMK1,Cofilin,and Phospho-Cofilin in cartilage were all higher(P<0.01).Also,the serum levels of IL-1βand TNF-αin each treatment group were lower(P<0.01)than in the model group.Moreover,there were lower expressions of ROCK,LIMK1,Phospho-LIMK1,Cofilin,and Phospho-Cofilin in cartilage in the manipulation group and the MC group(P<0.01).Compared with the model group,the expression of ROCK,LIMK1,PhosphoLIMK1,Cofilin,and Phospho-Cofilin in cartilage in the celecoxib group were not statistically different(P>0.05).CONCLUSION:In this study,we established that manipulation has a better curative effect than celecoxib.Manipulation inhibits the development of cytoskeleton damage in cartilage and slows articular degeneration by regulating the expression of related proteins in the cytoskeletal signaling pathway.展开更多
Fiber productivity and quality of cotton are severely affected by abiotic stresses.In this study,we identified the role of GhADF1,an actin depolymerizing factor,in cotton response to drought stress.GhADF1 expression i...Fiber productivity and quality of cotton are severely affected by abiotic stresses.In this study,we identified the role of GhADF1,an actin depolymerizing factor,in cotton response to drought stress.GhADF1 expression in cotton could be induced by PEG6000.GhADF1-RNAi transgenic cotton showed increased tolerance to drought stress during seed germination and seedling development as well as at the reproductive stage.In contrast,overexpression of GhADF1 led to a drought-sensitive phenotype in transgenic plants.GhADF1-RNAi plants produced an enlarged root system with longer primary roots,more lateral roots,increased root dry biomass,and increased cell size.In leaves of GhADF1-RNAi cotton,proline content and activities of reactive oxygen species-scavenging enzymes were increased following drought stress compared with those in wild type.GhADF1-RNAi lines showed higher water-use efficiency than the wild type,accompanied by reduced leaf stomatal density and conductance.GhADF1-RNAi cotton produced higher fiber yield in the field under both normal and drought conditions.Transcriptomic analyses identified 124 differentially expressed genes in leaves of GhADF1-RNAi lines compared with the wild type following drought treatment.Upregulated genes included those encoding transcription factors,protein kinases,heat shock proteins,and other proteins known to be involved in stress responses.We conclude that GhADF1 reduces the expression of abiotic stress-associated genes in cotton response to drought stress and may be a promising candidate gene for crop improvement by genetic manipulation.展开更多
Konjac glucomannan（KGM） is a water-soluble polysaccharide obtained from the roots and tubers of konjac plants. Recently, a degraded product of KGM, depolymerized KGM（DKGM）, has attracted attention because of its l...Konjac glucomannan（KGM） is a water-soluble polysaccharide obtained from the roots and tubers of konjac plants. Recently, a degraded product of KGM, depolymerized KGM（DKGM）, has attracted attention because of its low viscosity, improved hydrophily, and favorable physiological functions. In this review, we describe the preparation of DKGM and its prebiotic effects. Other health benefits of DKGM, covering antioxidant and immune activity, are also discussed, as well as its safety. DKGM could be a candidate for use as a tool for the treatment of various diseases, including intestinal flora imbalance, and oxidative-and immune-related disorders.展开更多
Depolymerization of agar was performed using agarase, which was extracted from the cell-free medium of a culture of marine bacterial Alterornonas sp. nov. SY 37-12. After ethanol fractionation and lyophilization, the ...Depolymerization of agar was performed using agarase, which was extracted from the cell-free medium of a culture of marine bacterial Alterornonas sp. nov. SY 37-12. After ethanol fractionation and lyophilization, the water-soluble agar polysaccharide （WSAP3） was collected. The anti-tumor activity of the product was determined by using Sarcoma 180 tumor in mouse. The tumor inhibition rate of WSAP3 the product was determined by using Sarcoma 180 tumor in mouse. The tumor inhibition rate of WSAP3 reached 48.7% at a dose of 64mg kg^-1 after 15 days treatment. WSAP3 enhanced the aetivities of superoxide dismutase and catalase, which suggests that WSAP3 was effective in promoting the antioxidation ability and eliminating danger from free radicals. The result of flow cytometry showed that the WSAP3 had no activities of cell cycle inhibition or apoptosis-inducing activities. The anti-oxidation of WSAP3 was further confirmed by test in vitro, which might play an important role in anti-tumor activity. The immunological regulation of WSAP3, especially its effect on the phagocytosis ratio and phagocytosis index of rophage was also assayed in test in vivo.展开更多
As one of the three major components of woody biomass,lignin is a kind of natural organic polymer and the only abundant natural renewable resource with aromatic nucleus.Chemical catalysis induced depolymerization is a...As one of the three major components of woody biomass,lignin is a kind of natural organic polymer and the only abundant natural renewable resource with aromatic nucleus.Chemical catalysis induced depolymerization is an important and effective approach for lignin utilization.In particular,photocatalysis and electrocatalysis show great potential in accurately activating C-O/C-C bonds,which is a critical point of selective cleavage of lignin.In this contribution,we focus on radical and(photo)electron transfer induced reaction mechanisms of the photo(electro)catalytic depolymerization of lignin.Primarily,the general situation of Carbon-centered radicals and active oxygen species mediated lignin conversion has been discussed.Then the mechanisms for(photo)electron transfer mediated lignin depolymerization have been summarized.At the end of this review,the challenges and opportunities of photo(electro)catalysis in the applications of lignin valorization have been forecasted.展开更多
As the most abundant source of biomass in nature for sustainable production of fuels and chemicals,efficient depolymerization of cellulose under mild conditions,due to the difficulty in selective cleavage of itsβ-1,4...As the most abundant source of biomass in nature for sustainable production of fuels and chemicals,efficient depolymerization of cellulose under mild conditions,due to the difficulty in selective cleavage of itsβ-1,4-glycosidic bonds,still remains challenging.Here,we report a novel method for oxidative cleavage of the glycosidic bonds by free radicals.Probed by the cellobiose reaction,it was found that·OH radicals,generated from the decomposition of H2O2 catalyzed by CuSO4 or CuO/SiO2,were efficient for selective conversion of cellobiose to glucose and gluconic acid at a low temperature of 333 K,and their selectivities reached 30.0%and 34.6%,respectively,at 23.4%cellobiose conversion.Other radicals,such as·SO4?,also exhibited high efficacy in the cellobiose reaction.Mechanistic studies suggest that the oxidative cleavage of theβ-1,4-glycosidic bond by the free radicals involve formation of the carbon radical intermediate via abstraction of the H atom dominantly at the C1 position.Following this oxidative mechanism,treatment of microcrystalline cellulose with·OH by impregnation with H2O2 and CuSO4 catalyst at 343 K led to significant enhancement in its hydrolysis efficiency.These results demonstrate the effectiveness of this new method in the oxidative cleavage of glycosidic bonds,and its viability for the efficient depolymerization of cellulose at low temperatures,which can be further improved,for example,by exploring new free radicals and optimizing their reactivity and selectivity.展开更多
Biomass wastes(almond shell and olive tree pruning) were used in this work as raw materials for the extraction of high purity lignin by different delignification methods. A pretreatment stage was carried out to remove...Biomass wastes(almond shell and olive tree pruning) were used in this work as raw materials for the extraction of high purity lignin by different delignification methods. A pretreatment stage was carried out to remove the major hemicelluloses content in the solid feedstocks. Afterward, two sulfur-free pulping processes(soda and organosolv) were applied to extract the largest fraction of lignin. The extracted lignin contained in the liquors was isolated using selective precipitation methods to design a tailor-made technique for obtaining high-purity lignin(in all cases more 90% of purity was reached). Soda process allowed the extraction of more lignin(around 40%–47%) than organosolv process(lower than 20%) regardless of the lignocellulosic source employed.Once the different lignin samples were isolated and characterized, they were depolymerized for the obtaining of small phenolic compounds. Three main streams were produced after the reaction: phenolic enriched oil, residual lignin and coke. After the purification of these fractions, their quantifications and characterization were conducted.The most abundant product of the reaction was residual lignin generated by the undesirable repolymerization of the initial lignin with yields around 30%–45%. The yield of the stream enriched in phenolic oil was higher than 20%. Coke, the lowest added-value product, presented a yield lower than 12% in all the cases. Lignin from organosolv presented higher phenolic oil yields, mainly due to their lower molecular size. This parameter was, thus, considered a key factor to obtain higher yields.展开更多
基金funded by the National Key Research and Development Program of China(2023YFC3903300)the Tianjin Synthetic Biotechnology Innovation Capacity Improvement Project(TSBICIPIJCP-003,TSBICIP-KJGG-009-0203,and TSBICIP-BRFI-005)the Innovation Fund of Haihe Laboratory of Synthetic Biology(22HHSWSS00018)。
文摘The enzymatic depolymerization of polyethylene terephthalate(PET)offers a sustainable approach for the recycling of PET waste.Great efforts have been devoted to engineering PET depolymerases on the substrate binding cleft and the surrounding loops/α-helices on the surface.Here,we report the systematic engineering of whole β-sheet regions in the core of IsPETase(a PETase from Ideonella sakaiensis)via a fluorescent high-throughput screening assay.Twenty-one beneficial substitutions were obtained and iteratively recombined.The best variant,DepoPETase β,with an increase in the melting temperatures(T_(m))of 22.9℃,exhibited superior depolymerization performance and enabled complete depolymerization of100.5 g of untreated post-consumer PET(pc-PET;0.26% W_(enzyme)/W_(PET) enzyme loading)in liter-scale bioreactor at 50℃within 4 d.Crystallization and molecular dynamics simulations revealed that the improved activity and thermostability of DepoPETase β were due to enhanced hydrogen bonds and salt bridges in the β-sheet region,a more tightly packed structure of the core sheets and the surrounding helix,and improved binding of PET to the active sites.This study not only demonstrates the importance of engineering strategy in theβ-sheet region of PET hydrolases but also provides a potential PET depolymerase for large-scale PET recycling.
基金funding from the National Natural Science Foundation of China(No.22401037)funding from JST CREST(No.JPMJCR23L1)。
文摘Chain-growth radical polymerization of vinyl monomers is essential for producing a wide range of materials with properties tailored to specific applications.However,the inherent resistance of the polymer's C―C backbone to degradation raises significant concerns regarding long-term environmental persistence,which also limits their potential in biomedical applications.To address these challenges,researchers have developed strategies to either degrade preexisting vinyl polymers or incorporate cleavable units into the backbone to modify them with enhanced degradability.This review explores the various approaches aimed at achieving backbone degradability in chain-growth radical polymerization of vinyl monomers,while also highlighting future research directions for the development of application-driven degradable vinyl polymers.
基金supported by the National Key R&D Program of China(No.2023YFA1507902)the Science and Technology Bureau of Dalian City(No.2021RT04)+3 种基金the Shaanxi Provincial Science and Technology Department(Nos.2024JC-YBQN-0100 and QCYRCXM-2023-079)the Youth innovation team project of Shaanxi Province Education Department(No.23JP199)the Science and Technology Plan Project of Yulin Government(No.2023-CXY-137)the Initial Scientific Research Fund of High Level Talents in Yulin University(No.2023GK44).
文摘Green and atom-economic depolymerization of lignin remains a great challenge due toits complex non-repetitive structure and the inert property for chemo-digestion. A redoxneutrallignin depolymerization system without the use of extra oxidant and/or reductantover a Co-NC catalyst has been developed in this work, providing the first non-noble metalheterogeneous catalytic system for redox-neutral valorization of lignin. Mechanistic studiesbased on control reactions and deuterium labeling experiments suggest that the reactionproceeds via ametal-catalyzed dehydrogenation of C_(α)-OH to afford a carbonyl intermediate,followed by C_(β)-O bond cleavage (via hydrogenolysis) to afford monophenols and aromaticketone products. The hydrogen used for the cleavage of the C_(β)-O bond originates from thealcoholmoiety in the substrate, and the cascade dehydrogenation and hydrogenolysis stepsare highly coupled, rendering it an efficient and atom-economic process.
基金supported by the National Natural Science Foundation of China(Nos.22125103 and 22301077)STCSM(22JC140100)Shanghai Pujiang Program(No.22PJ1403200)。
文摘Chemical recycling/upcycling of plastics has emerged as one of the most promising strategies for the plastic circular economy,enabling the depolymerization and functionalization of plastics into valuable monomers and chemicals.However,studies on the depolymerization and functionalization of challenging super engineering plastics have remained in early stage and underexplored.In this review,we would like to discuss the representative accomplishments and mechanism insights on chemical protocols achieved in depolymerization of super engineering plastics,especially for poly(phenylene sulfide)(PPS),poly(aryl ether)s including poly(ether ether ketone)(PEEK),polysulfone(PSU),polyphenylsulfone(PPSU)and polyethersulfone(PES).We anticipate that this review will provide an overall perspective on the current status and future trends of this emerging field.
文摘Although the efficiency of poly(ethylene terephthalate)(PET)degradation has been successfully improved by depolymerase engineering,mostly by using Goodfellow-PET(gf-PET)as a substrate,efforts to degrade unpretreated PET materials with high crystallinity remain insufficient.Here,we endeavored to improve the degradation capability of a WCCG mutant of leaf-branch compost cutinase(LCC)on a unpretreated PET substrate(crystallinity>40%)by employing iterative saturation mutagenesis.Using this method,we developed a high-throughput screening strategy appropriate for unpretreated substrates.Through extensive screening of residues around the substrate-binding groove,two variants,WCCG-sup1 and WCCG-sup2,showed good depolymerization capabilities with both high-(42%)and low-crystallinity(9%)substrates.The WCCG-sup1 variant completely depolymerized a commercial unpretreated PET product in 36 h at 72℃.In addition to enzyme thermostability and catalytic efficiency,the adsorption of enzymes onto substrates plays an important role in PET degradation.This study provides valuable insights into the structure-function relationship of LCC.
基金support from the Beijing Municipal Natural Science Foundation(2222012)the National Natural Science Foundation of China(Grant No.52070116)+1 种基金the Key-Area Research and Development Program of Guangdong Province(2020B1111380001)the Tsinghua University-Shanxi Clean Energy Research Institute Innovation Project Seed Fund is gratefully acknowledged.
文摘Plastic waste puts a huge burden on the ecosystem due to the current lack of mature recycling technology.Poly(ethylene terephthalate)(PET)is one of the most produced plastics in the world.Enzymatic decomposition holds the promise of recovering monomers from PET plastic,and the monomers can be used to regenerate new PET products.However,there are still limitations in the activity and thermal stability of the existing PET hydrolases.The recent study by Lu et al.introduced a novel PET hydrolase via machine learning-aided engineering.The obtained PET hydrolase showed excellent activity and thermal stability in the hydrolysis of PET and is capable of directly degrading large amounts of postconsumer PET products.This approach provides an effective method for recycling PET waste and is expected to improve the current state of plastic pollution worldwide.
基金This work was supported by funding from Natural Science Foundation of China(Grant Nos.:82372519 and 81902664)the PostdoctoralFellowshipProgramof CPSF(GrantNo.:GZB20240544)+3 种基金the China Postdoctoral Science Foundation(Grant No.:2024M752432)the Natural Science Foundation of Hebei Province(Grant Nos.:H2022206368 and H2022206446)Medical Science Research Program of the Hebei Provincial Health Commission(Grant No.:20241603)Pilot Program of Southwest University(Program No.:SWU-XDZD22006)。
文摘Tetrandrine(TET),a natural bisbenzyl isoquinoline alkaloid extracted from Stephania tetrandra S.Moore,has diverse pharmacological effects.However,its effects on melanoma remain unclear.Cellular prolif-eration assays,multi-omics analyses,and xenograft models were used to determine the effect of TET on melanoma.The direct target of TET was identified using biotin-TET pull-down liquid chromatograph-mass spectrometry(LC-MS),cellular thermal shift assays,and isothermal titration calorimetry(ITC)analysis.Our findings revealed that TET treatment induced robust cellular autophagy depending on activating transcription factor 6(ATF6)-mediated endoplasmic reticulum(ER)stress.Simultaneously,it hindered autophagic flux by inducing cytoskeletal protein depolymerization in melanoma cells.TET treatment resulted in excessive accumulation of reactive oxygen species(Ros)and simultaneously triggered mitophagy.Sirtuin 5(SIRT5)was ultimately found to be a direct target of TET.Mechanistically,TET led to the degradation of SIRT5 via the ubiquitin(Ub)-26S proteasome system.SIRT5 knockdown induced ROS accumulation,whereas SIRT5 overexpression attenuated the TET-induced ROS accumula-tion and autophagy.Importantly,TET exhibited anti-cancer effects in xenograft models depending on SIRT5 expression.This study highlights the potential of TET as an antimelanoma agent that targets SIRT5.These findings provide a promising avenue for the use of TET in melanoma treatment and underscore its potential as a therapeutic candidate.
文摘BACKGROUND Glioma is one of the most common intracranial tumors,characterized by invasive growth and poor prognosis.Actin cytoskeletal rearrangement is an essential event of tumor cell migration.The actin dynamics-related protein scinderin(SCIN)has been reported to be closely related to tumor cell migration and invasion in several cancers.AIM To investigate the role and mechanism of SCIN in glioma.METHODS The expression and clinical significance of SCIN in glioma were analyzed based on public databases.SCIN expression was examined using real-time quantitative polymerase chain reaction and Western blotting.Gene silencing was performed using short hairpin RNA transfection.Cell viability,migration,and invasion were assessed using cell counting kit 8 assay,wound healing,and Matrigel invasion assays,respectively.F-actin cytoskeleton organization was assessed using F-actin staining.RESULTS SCIN expression was significantly elevated in glioma,and high levels of SCIN were associated with advanced tumor grade and wild-type isocitrate dehydrogenase.Furthermore,SCIN-deficient cells exhibited decreased proliferation,migration,and invasion in U87 and U251 cells.Moreover,knockdown of SCIN inhibited the RhoA/focal adhesion kinase(FAK)signaling to promote F-actin depolymerization in U87 and U251 cells.CONCLUSION SCIN modulates the actin cytoskeleton via activating RhoA/FAK signaling,thereby promoting the migration and invasion of glioma cells.This study identified the cancer-promoting effect of SCIN and provided a potential therapeutic target for the treatment of glioma.
基金supports from National Natural Science Foundation of China(21938009,22308358,22208346,22078332)National Key Research and Development Program(2022YFC3902701)+2 种基金Ningxia Natural Science Foundation(2021AAC01002)the External Cooperation Program of BIC,Chinese Academy of Sciences(122111KYSB20190032)CAS Project for Young Scientists in Basic Research(YSBR-038)are gratefully acknowledged.
文摘NaY zeolites are synthesized using submolten salt depolymerized natural perlite mineral as the main silica and alumina sources in a 0.94 L stirred crystallizer.Effects of alkalinity ranging from 0.38 to 0.55(n(Na_(2)O)/n(SiO_(2)))on the relative crystallinity,textural properties and crystallization kinetics were investigated.The results show that alkalinity exerts a nonmonotonic influence on the relative crystallinity and textural properties,which exhibit a maximum at the alkalinity of 0.43.The nucleation kinetics are studied by fitting the experimental data of relative crystallinity with the Gualtieri model.It is shown that the nucleation rate constant increases with increasing alkalinity,while the duration period of nucleation decreases with increasing alkalinity.For n(Na_(2)O)/n(SiO_(2))ratios ranging from 0.38 to 0.55,the as-synthesized NaY zeolites exhibit narrower crystal size distributions with the increase in alkalinity.The growth rates determined from the variations of average crystal size with time are 51.09,157.50,46.17 and 24.75 nm·h^(-1),respectively.It is found that the larger average crystal sizes at the alkalinity of 0.38 and 0.43 are attributed to the dominant role of crystal growth over nucleation.Furthermore,the combined action of prominent crystal growth and the longer duration periods of nucleation at the alkalinity of 0.38 and 0.43 results in broader crystal size distributions.The findings demonstrate that control of the properties of NaY zeolite and the crystallization kinetics can be achieved by conducting the crystallization process in an appropriate range of alkalinity of the reaction mixture.
基金financially supported by the National Natural Science Foundation of China(Nos.22006040 and 22376070)the National Key Research and Development Program of China(No.2019YFA0210404)the Research Project on Characteristic Innovation of University Teachers(No.2022XJZZ02)。
文摘This study analyzed the prevalent physicochemical phases of smelting slag from the perspective of data science and chemistry.Findings delineated the silicate phase as the pivotal and predominant constraining phase for the resource utilization of smelting slag.An intricate correlation between metallic elements and dominant phases was constructed.Typical silicate phase olivine(OL)was synthesized as a paradigm to examine alkali depolymerization,unveiling the optimal conditions for such depolymerization to be an alkali to olivine molar ratio of 1:5,a reaction temperature of 700℃,and a duration of 3 h.The underlying mechanism of alkali depolymerization within silicate phases was elucidated under these parameters.The reaction mechanism of alkali depolymerization within silicate phases can be encapsulated in three sequential steps:(1)NaOH dissociation and subsequent adsorption of OH^(-)to cationic(Mg or Fe)sites;(2)disruption of cation-oxygen bonds,leading to the formation of hydroxide compounds,which then underwent oxidation;(3)Na^(+)occupied the resultant cation vacancy sites,instigating further depolymerization of the intermediate Na_(2)(Mg,Fe)SiO_(4).The articulated mechanism is anticipated to furnish theoretical underpinnings for the efficacious recuperation of metals from smelting slags.
基金supported according to contract No.5.1.1.2.i.0/1/22/A/CFLA/007 between“Forest Sector Competence Centre of Latvia”Ltd.,and the Central Finance and Contracting Agency which dated 20th January of 2023.
文摘Birch outer bark(BOB)from Betula pendula Roth.is a unique and valuable biomass feedstock that contains suberin.The biopolyester suberin is built from bifunctional fatty acids-suberinic acids(SA)-which can be obtained through a depolymerization process in an alkaline medium and used as a binder due to their adhesive properties.The aim of this study was to develop the SA-containing binder and identify suitable pressing conditions to produce plywood that meets the shear strength requirements of the EN 314-2 standard 3rd moisture resistance class for bonding quality,ensuring durability in unprotected exterior conditions(shear strength≥1 N/mm^(2)).The raw BOB material was modified by extraction,milling,and fractionation,and the depolymerization methodology was enhanced by additional sieving to improve the adhesive properties of the obtained binders.Several analytical methods were used to characterize the feedstock and the binders.Higher heating value was used to assess the pure outer bark content of BOB.GC-MS and GPC were used to describe the monomeric and oligomeric composition of binders.TGA was used to describe the biopolymeric composition and DSC was used to determine the thermal behavior of the binders.As a result,successful modification of feedstock(extracted BOB,milled through 2 mm sieve,1-2 mm fraction used)and its depolymerization process(implementing the separation of coarse ligno-carbohydrate particles by 1 mm mesh sieve)was employed to obtain a binder for which suitable hot-pressing parameters were determined−200℃for 5 min at 1.8 MPa.Consequently,plywood with shear strength of 1.26±0.18 N/mm^(2),which adheres to the EN 314-2 standards 3rd moisture resistance class,was obtained.
文摘The molecular recyclability of poly (ethylene terephthalate) (PET) and three semi-aromatic polyesters poly (phloretic acid) (poly-H), poly (dihydroferulic acid) (poly-G), and poly (dihydrosinapinic acid) (poly-S) is evaluated in this study. PET is an extensively used aromatic polyester, and poly-H, poly-G, and poly-S can be considered semi-aromatic poly (lactic acid) modifications. All these polyesters have been depolymerized at neutral pH and by acid- and base-catalyzed hydrolysis at two temperatures, i.e., 50˚C and 80˚C. Base-catalyzed depolymerization of virgin PET leads to an isolated yield of 38% after 48 hours of reaction at 80˚C. Contrary to these results for PET, almost all the monomers of the semi-aromatic polyesters poly-H, poly-G, and poly-S are recovered with isolated yields larger than 90% at the same temperature after 15 minutes in a facile manner. A shrinking particle model used to determine the global kinetics of the base-catalyzed depolymerization showed that the rate rises with increasing temperature. Using the shrinking particle model, the intrinsic reaction rate constants were determined. It has been demonstrated that the rate coefficients of the depolymerization of the semi-aromatic polyesters poly-H, poly-G, and poly-S are between 2 and 3 orders of magnitude higher than those for PET.
基金ACKNOWLEDGMENTS This work was supported by the National Key Basic Program of China （No.2013CB228105） and the National Natural Science Foundation of China （No.51161140331）.
文摘Lignin is the only nature renewable resource which can provide large quantities of aromatic compounds. In the work, transformation of lignin into benzene, toluene, and xylenes （BTX） was investigated over the HZSM-5, HY, and MCM-22 catalysts, and the HZSM-5 catalyst showed the highest carbon yield of BTX. The reaction condition, including temperature, the gas flow rate, and the catalyst/lignin ratio, was also investigated. The carbon yield of BTX reached about 25.3 C-mol% over HZSM-5 catalyst under T=550℃, f（N2）=300 cm^3/min, and catalyst/lignin ratio of 2.
基金Supported by the National Natural Science Foundation of China(No.81273870)Chongqing Municipal Health and Family Planning Commission and Chongqing Municipal Science and Technology Commission Jointly Funded Key Research Projects in Traditional Chinese Medicine(No.ZY201801007)Beibei District Chongqing Basic Research and Frontier Exploration Project(No.2019-6)。
文摘OBJECTIVE:To investigate the effect of manipulation treatment on knee osteoarthritis rats and the effect on Rho-associated protein kinase(ROCK)/LIM-kinase1(LIMK1)/Cofilin signaling pathway.METHOD:Fifty Specific pathogen Free Sprague-Dawley rats were randomly divided into five groups(n=8 each):blank group,model group,manipulation group,celecoxib group,and manipulation combined with celecoxib group(MC group).The osteoarthritis model was established by injecting 0.2 m L 4%papain into the articular disc of the rats.After successfully establishing the model,we treated the manipulation group with pushing manipulation using one-finger-meditation to the Neixiyan(EX-LE4),Waixiyan(EX-LE5),Xuehai(SP10),Liangqiu(ST34),and Zusanli(ST36)acupoints for 10 min each time.Also,the celecoxib group was gavaged with 24 mg·kg^(-1)·d^(-1 )celecoxib,while the MC group was treated using both of these two methods.After four weeks,the cartilage of the right femur was removed for hematoxylin-eosin staining of the cartilage tissue.The expressions of interleukin-1β(IL-1β)and tumor necrosis factor-α(TNF-α)in serum were observed using the enzyme-linked immunosorbent assay.Besides,we detected the expressions of ROCK,LIMK1,Phospho-LIM-kinase1(Phospho-LIMK1),Cofilin,and Phospho-Cofilin by Western blot.RESULTS:Compared to the model group,the manipulation group,celecoxib group,and MC group all exhibited superior results concerning pathological morphologic changes of cartilage,as observed by hematoxylin-eosin staining and calculated using the Mankin score.Besides,in contrast to the blank group,the model group exhibited elevated serum levels of IL-1βand TNF-α(P<0.01),while the expression of ROCK,LIMK1,Phospho-LIMK1,Cofilin,and Phospho-Cofilin in cartilage were all higher(P<0.01).Also,the serum levels of IL-1βand TNF-αin each treatment group were lower(P<0.01)than in the model group.Moreover,there were lower expressions of ROCK,LIMK1,Phospho-LIMK1,Cofilin,and Phospho-Cofilin in cartilage in the manipulation group and the MC group(P<0.01).Compared with the model group,the expression of ROCK,LIMK1,PhosphoLIMK1,Cofilin,and Phospho-Cofilin in cartilage in the celecoxib group were not statistically different(P>0.05).CONCLUSION:In this study,we established that manipulation has a better curative effect than celecoxib.Manipulation inhibits the development of cytoskeleton damage in cartilage and slows articular degeneration by regulating the expression of related proteins in the cytoskeletal signaling pathway.
基金supported by the National Natural Science Foundation of China(31601350)the Project of Transgenic Research from the Ministry of Science and Technology of China(2016ZX08005-004-007)+1 种基金the Fundamental Research Project of Shanxi Province(20210302123381)the Science and Technology Innovation Project of Higher Education Institutions of Shanxi Province(2021L115).
文摘Fiber productivity and quality of cotton are severely affected by abiotic stresses.In this study,we identified the role of GhADF1,an actin depolymerizing factor,in cotton response to drought stress.GhADF1 expression in cotton could be induced by PEG6000.GhADF1-RNAi transgenic cotton showed increased tolerance to drought stress during seed germination and seedling development as well as at the reproductive stage.In contrast,overexpression of GhADF1 led to a drought-sensitive phenotype in transgenic plants.GhADF1-RNAi plants produced an enlarged root system with longer primary roots,more lateral roots,increased root dry biomass,and increased cell size.In leaves of GhADF1-RNAi cotton,proline content and activities of reactive oxygen species-scavenging enzymes were increased following drought stress compared with those in wild type.GhADF1-RNAi lines showed higher water-use efficiency than the wild type,accompanied by reduced leaf stomatal density and conductance.GhADF1-RNAi cotton produced higher fiber yield in the field under both normal and drought conditions.Transcriptomic analyses identified 124 differentially expressed genes in leaves of GhADF1-RNAi lines compared with the wild type following drought treatment.Upregulated genes included those encoding transcription factors,protein kinases,heat shock proteins,and other proteins known to be involved in stress responses.We conclude that GhADF1 reduces the expression of abiotic stress-associated genes in cotton response to drought stress and may be a promising candidate gene for crop improvement by genetic manipulation.
基金Project supported by the National First-Class Discipline Program of Light Industry Technology and Engineering(Nos.LITE2018-18 and LITE2018-11) of Chinathe Transformation Project for Major Scientific and Technological Achievements in Jiangsu Province(No.BA2015006)+1 种基金the Industry-Academia Cooperation Innovation Fund Project of Jiangsu Province(No.BY2016022-19)the National Key Technologies R&D Program of China for the 12th Five-year Plan(No.2012BAD33B06)
文摘Konjac glucomannan（KGM） is a water-soluble polysaccharide obtained from the roots and tubers of konjac plants. Recently, a degraded product of KGM, depolymerized KGM（DKGM）, has attracted attention because of its low viscosity, improved hydrophily, and favorable physiological functions. In this review, we describe the preparation of DKGM and its prebiotic effects. Other health benefits of DKGM, covering antioxidant and immune activity, are also discussed, as well as its safety. DKGM could be a candidate for use as a tool for the treatment of various diseases, including intestinal flora imbalance, and oxidative-and immune-related disorders.
文摘Depolymerization of agar was performed using agarase, which was extracted from the cell-free medium of a culture of marine bacterial Alterornonas sp. nov. SY 37-12. After ethanol fractionation and lyophilization, the water-soluble agar polysaccharide （WSAP3） was collected. The anti-tumor activity of the product was determined by using Sarcoma 180 tumor in mouse. The tumor inhibition rate of WSAP3 the product was determined by using Sarcoma 180 tumor in mouse. The tumor inhibition rate of WSAP3 reached 48.7% at a dose of 64mg kg^-1 after 15 days treatment. WSAP3 enhanced the aetivities of superoxide dismutase and catalase, which suggests that WSAP3 was effective in promoting the antioxidation ability and eliminating danger from free radicals. The result of flow cytometry showed that the WSAP3 had no activities of cell cycle inhibition or apoptosis-inducing activities. The anti-oxidation of WSAP3 was further confirmed by test in vitro, which might play an important role in anti-tumor activity. The immunological regulation of WSAP3, especially its effect on the phagocytosis ratio and phagocytosis index of rophage was also assayed in test in vivo.
基金financial support of the National Natural Science Foundation of China,China(Grant No.21736003,21975082)the Guangdong Basic and Applied Basic Research Foundation(Grant Number:2019A1515011472)the Science and Technology Program of Guangzhou(Grant Number:202102080479)。
文摘As one of the three major components of woody biomass,lignin is a kind of natural organic polymer and the only abundant natural renewable resource with aromatic nucleus.Chemical catalysis induced depolymerization is an important and effective approach for lignin utilization.In particular,photocatalysis and electrocatalysis show great potential in accurately activating C-O/C-C bonds,which is a critical point of selective cleavage of lignin.In this contribution,we focus on radical and(photo)electron transfer induced reaction mechanisms of the photo(electro)catalytic depolymerization of lignin.Primarily,the general situation of Carbon-centered radicals and active oxygen species mediated lignin conversion has been discussed.Then the mechanisms for(photo)electron transfer mediated lignin depolymerization have been summarized.At the end of this review,the challenges and opportunities of photo(electro)catalysis in the applications of lignin valorization have been forecasted.
文摘As the most abundant source of biomass in nature for sustainable production of fuels and chemicals,efficient depolymerization of cellulose under mild conditions,due to the difficulty in selective cleavage of itsβ-1,4-glycosidic bonds,still remains challenging.Here,we report a novel method for oxidative cleavage of the glycosidic bonds by free radicals.Probed by the cellobiose reaction,it was found that·OH radicals,generated from the decomposition of H2O2 catalyzed by CuSO4 or CuO/SiO2,were efficient for selective conversion of cellobiose to glucose and gluconic acid at a low temperature of 333 K,and their selectivities reached 30.0%and 34.6%,respectively,at 23.4%cellobiose conversion.Other radicals,such as·SO4?,also exhibited high efficacy in the cellobiose reaction.Mechanistic studies suggest that the oxidative cleavage of theβ-1,4-glycosidic bond by the free radicals involve formation of the carbon radical intermediate via abstraction of the H atom dominantly at the C1 position.Following this oxidative mechanism,treatment of microcrystalline cellulose with·OH by impregnation with H2O2 and CuSO4 catalyst at 343 K led to significant enhancement in its hydrolysis efficiency.These results demonstrate the effectiveness of this new method in the oxidative cleavage of glycosidic bonds,and its viability for the efficient depolymerization of cellulose at low temperatures,which can be further improved,for example,by exploring new free radicals and optimizing their reactivity and selectivity.
基金the Spanish Ministry of Economy and Competitiveness(CTQ2013-41246-R)the Department of Education of the Basque Government(project IT1008-16)the University of the Basque Country(postdoctoral fellowship no.ESPDOC15/044)for financially supporting this work
文摘Biomass wastes(almond shell and olive tree pruning) were used in this work as raw materials for the extraction of high purity lignin by different delignification methods. A pretreatment stage was carried out to remove the major hemicelluloses content in the solid feedstocks. Afterward, two sulfur-free pulping processes(soda and organosolv) were applied to extract the largest fraction of lignin. The extracted lignin contained in the liquors was isolated using selective precipitation methods to design a tailor-made technique for obtaining high-purity lignin(in all cases more 90% of purity was reached). Soda process allowed the extraction of more lignin(around 40%–47%) than organosolv process(lower than 20%) regardless of the lignocellulosic source employed.Once the different lignin samples were isolated and characterized, they were depolymerized for the obtaining of small phenolic compounds. Three main streams were produced after the reaction: phenolic enriched oil, residual lignin and coke. After the purification of these fractions, their quantifications and characterization were conducted.The most abundant product of the reaction was residual lignin generated by the undesirable repolymerization of the initial lignin with yields around 30%–45%. The yield of the stream enriched in phenolic oil was higher than 20%. Coke, the lowest added-value product, presented a yield lower than 12% in all the cases. Lignin from organosolv presented higher phenolic oil yields, mainly due to their lower molecular size. This parameter was, thus, considered a key factor to obtain higher yields.
