Attempts have been made to use cell transplantation and biomaterials to promote cell proliferation,differentiation,migration,and survival,as well as angiogenesis,in the context of brain injury.However,whether bioactiv...Attempts have been made to use cell transplantation and biomaterials to promote cell proliferation,differentiation,migration,and survival,as well as angiogenesis,in the context of brain injury.However,whether bioactive materials can repair the damage caused by ischemic stroke by activating endogenous neurogenesis and angiogenesis is still unknown.In this study,we applied chitosan gel loaded with basic fibroblast growth factor to the stroke cavity 7 days after ischemic stroke in rats.The gel slowly released basic fibroblast growth factor,which improved the local microenvironment,activated endogenous neural stem/progenitor cells,and recruited these cells to migrate toward the penumbra and stroke cavity and subsequently differentiate into neurons,while enhancing angiogenesis in the penumbra and stroke cavity and ultimately leading to partial functional recovery.This study revealed the mechanism by which bioactive materials repair ischemic strokes,thus providing a new strategy for the clinical application of bioactive materials in the treatment of ischemic stroke.展开更多
The chitosan/β-glycerophosphate( CS/β-GP),a physical hydrogel system with thermosensitive and injectable features combined with biocompatibility and biodegradability, has great potentials as matrices for drug or cel...The chitosan/β-glycerophosphate( CS/β-GP),a physical hydrogel system with thermosensitive and injectable features combined with biocompatibility and biodegradability, has great potentials as matrices for drug or cell encapsulation and delivery,or as in situ gel-forming materials for tissue repair. Here,the chitin nanocrystal( Chi NC) was introduced into the aforementioned system, and its effects on solution behavior and mechanical properties was investigated. The results showed the incorporation of Chi NC complicated sol-to-gel transition process; a higher loading ratio( 20%) speeded up sol-to-gel transition rate,reduced the solto-gel transition temperature,while still maintained shear-thinning behavior or injectable feature. Moreover,the mechanical properties of gels were significantly enhanced by Chi NC, accompanied by decreased water uptake. The above mentioned behavior favored better applications as injectable tissue-repair implants.展开更多
In situ forming hydrogels with simple sol–gel transition are more practicable as injectable hydrogels for drug delivery and tissue regeneration. State-of-the-art in situ gelling systems can easily and efficiently be ...In situ forming hydrogels with simple sol–gel transition are more practicable as injectable hydrogels for drug delivery and tissue regeneration. State-of-the-art in situ gelling systems can easily and efficiently be formed by different mechanisms in situ. Chitosan is a kind of natural polysaccharide that is widely exploited for biomedical applications due to its good biocompatibility, low immunogenicity and specific biological activities. Chitosan-based in situ gelling systems have already gained much attention as smart biomaterials in the development of several biomedical applications, such as for drug delivery systems and regeneration medicine. Herein, we review the typical in situ gelling systems based on chitosan and mechanisms involved in hydrogel forming, and report advances of chitosan-based in situ gels for the applications in drug delivery and tissue regeneration. Finally, development prospects of in situ forming hydrogels based on chitosan are also discussed in brief.展开更多
The procedure for preparing a new type of uniform and porous chitosan gel from citric acid medium is described. Its swelling behavior in different media was compared with those of the gels prepared by other methods. T...The procedure for preparing a new type of uniform and porous chitosan gel from citric acid medium is described. Its swelling behavior in different media was compared with those of the gels prepared by other methods. The ultrastructure of the xerogel prepared from citric acid was characterized using electron microscopy (SEM).展开更多
Hydrogel has high water content and structural similarity with natural extracellular matrix.So it has been widely studied and applied in the field of biomedicine.In order to further develop multifunctional hydrogels,w...Hydrogel has high water content and structural similarity with natural extracellular matrix.So it has been widely studied and applied in the field of biomedicine.In order to further develop multifunctional hydrogels,we prepared mixed gels with antiultraviolet properties.This study found that the addition of polysaccharides and polyphenols was beneficial to the rheological,me-chanical properties,and biological activity of the protein.Chitosan(CS)could significantly improve the viscoelasticity,hardness,gel strength,thermal stability and crystallinity of gelatin.Interestingly,the addition of gallic acid(GA)could not only provide significant cross-linking effect,improve gel properties and microstructure,but also improve the UV resistance of the mixed gel.展开更多
The aim of this study was to fabricate composite gel beads based on natural polysaccharides. Hyaluronic acid（HA） and Chitosan（CS） were successfully admixed with Ca^2＋/alginate（SA） gel system to produce SA/HA/CS...The aim of this study was to fabricate composite gel beads based on natural polysaccharides. Hyaluronic acid（HA） and Chitosan（CS） were successfully admixed with Ca^2＋/alginate（SA） gel system to produce SA/HA/CS gel beads by dual crosslinking： the ionic gelation and the polyelectrolyte complexation. The preparation procedure was that the weight ratio of SA（2%, m/v） to HA（2%, m/v） was kept at 2：1, then the mixture was dripped into the Ca^2＋ solution for ion-crosslinking, and finally polyelectrolyte crosslinked with 2% low molecular weight CS（LMW-CS） for 1.5 hours. The optimal formulation was achieved by adjusting the concentration and the weight ratio of SA, HA and LMW-CS. Due to the incorporation of HA and LMWCS, the swelling ratio of the beads at pH 7.4 was increased up to 120, and the time for the maximum swelling degree was prolonged to 7.5 h. The swelling behavior was obviously improved compared to the pure SA/Ca^2＋ system. The preliminary results clearly suggest that the SA/HA/CS gel beads may be a potential candidate for biomedical delivery vehicles.展开更多
Recently, potential applications for β-chitosan (β-CS) have been examined. In the present study, calcium-induced alginate gel beads (Alg-Ca) containing weak acid salts of β-CS were prepared and examined with regard...Recently, potential applications for β-chitosan (β-CS) have been examined. In the present study, calcium-induced alginate gel beads (Alg-Ca) containing weak acid salts of β-CS were prepared and examined with regard to their ability to adsorb bile acids in vitro. More than 70% of taurocholate dissolved in solution was taken up by Alg-Ca containing 100 mg β-CS, sim. ilar to the degree of uptake observed with Alg-Ca containing α-CS salt. The adsorption of bile acid was affected by the absolute amount of β-CS and/or the acid concentration of the preparation. A secondary bile acid, taurodeoxycholate, was also adsorbed by Alg-Ca containing weak acid salts of β-CS. Therefore, β-CS might be used to adsorb bile acids within the gastrointestinal tract in the same manner as an anion-exchange resin, and thus serve as a complementary means by which to prevent hyperlipidemia.展开更多
Sucrose ester( SE) was fixed on surface of poly( ethylene terephthalate)( PET) fibers to improve surface activity. Chitosan( CS) was used to graft onto pretreated PET fibers by sol-gel method. The transformations of s...Sucrose ester( SE) was fixed on surface of poly( ethylene terephthalate)( PET) fibers to improve surface activity. Chitosan( CS) was used to graft onto pretreated PET fibers by sol-gel method. The transformations of surface chemical structure,microcosmic morphology and thermodynamic property were investigated by Fourier transform infrared spectroscopy( FTIR),X-ray photoelectron spectroscopy( XPS), scanning electron microscope( SEM), X-ray diffraction technique( XRD), and thermo gravimetric analysis( TGA),respectively. The wettability and antistatic property of PET fiber were significantly improved after modification by SE and CS.展开更多
Chitosan/α,β-glycerophosphate （CS/α,β-GP） thermo-sensitive hydrogels presented flowable solution state at low temperature and semisolid hydrogel when the ambient temperature increased. In this research, differen...Chitosan/α,β-glycerophosphate （CS/α,β-GP） thermo-sensitive hydrogels presented flowable solution state at low temperature and semisolid hydrogel when the ambient temperature increased. In this research, different concentrations of metronida- zole encapsulated, CS and α,β-GP, as well as different acid solvents, were chosen to evaluate their influences on the drug release behaviors from CS/α,β-GP hydrogels. It was found that there was a sustaining release during the first 3 h followed by a plateau. SEM images showed that drugs were located both on the surface and in the interior of hydrogels. The optimal preparation conditions of this hydrogel for drug release were as follows： 1.8% （w/v） CS in HAc solvent, 5.6% （w/v） a, 13-GP and 5g/L metronidazole encapsulation. Cytotoxicity evaluation found no toxic effect. In order to control the release rate, 2.5 g/L chitosan microspheres with spherical shape and smooth surface were incorporated, and it was found that the initial release process was alleviated, while drug concentration had no obvious effect on the release rate. It could be concluded that the metronidzole release behaviors could be optimized according to practical applica- tions.展开更多
基金supported by the National Natural Science Foundation of China,Nos.81941011(to XL),31771053(to HD),31730030(to XL),31971279(to ZY),31900749(to PH),31650001(to XL),31320103903(to XL),31670988(to ZY)the Natural Science Foundation of Beijing,Nos.7222004(to HD)+1 种基金a grant from Ministry of Science and Technology of China,Nos.2017YFC1104002(to ZY),2017YFC1104001(to XL)a grant from Beihang University,No.JKF-YG-22-B001(to FH)。
文摘Attempts have been made to use cell transplantation and biomaterials to promote cell proliferation,differentiation,migration,and survival,as well as angiogenesis,in the context of brain injury.However,whether bioactive materials can repair the damage caused by ischemic stroke by activating endogenous neurogenesis and angiogenesis is still unknown.In this study,we applied chitosan gel loaded with basic fibroblast growth factor to the stroke cavity 7 days after ischemic stroke in rats.The gel slowly released basic fibroblast growth factor,which improved the local microenvironment,activated endogenous neural stem/progenitor cells,and recruited these cells to migrate toward the penumbra and stroke cavity and subsequently differentiate into neurons,while enhancing angiogenesis in the penumbra and stroke cavity and ultimately leading to partial functional recovery.This study revealed the mechanism by which bioactive materials repair ischemic strokes,thus providing a new strategy for the clinical application of bioactive materials in the treatment of ischemic stroke.
基金National Natural Science Foundation of China(No.51303024)
文摘The chitosan/β-glycerophosphate( CS/β-GP),a physical hydrogel system with thermosensitive and injectable features combined with biocompatibility and biodegradability, has great potentials as matrices for drug or cell encapsulation and delivery,or as in situ gel-forming materials for tissue repair. Here,the chitin nanocrystal( Chi NC) was introduced into the aforementioned system, and its effects on solution behavior and mechanical properties was investigated. The results showed the incorporation of Chi NC complicated sol-to-gel transition process; a higher loading ratio( 20%) speeded up sol-to-gel transition rate,reduced the solto-gel transition temperature,while still maintained shear-thinning behavior or injectable feature. Moreover,the mechanical properties of gels were significantly enhanced by Chi NC, accompanied by decreased water uptake. The above mentioned behavior favored better applications as injectable tissue-repair implants.
文摘In situ forming hydrogels with simple sol–gel transition are more practicable as injectable hydrogels for drug delivery and tissue regeneration. State-of-the-art in situ gelling systems can easily and efficiently be formed by different mechanisms in situ. Chitosan is a kind of natural polysaccharide that is widely exploited for biomedical applications due to its good biocompatibility, low immunogenicity and specific biological activities. Chitosan-based in situ gelling systems have already gained much attention as smart biomaterials in the development of several biomedical applications, such as for drug delivery systems and regeneration medicine. Herein, we review the typical in situ gelling systems based on chitosan and mechanisms involved in hydrogel forming, and report advances of chitosan-based in situ gels for the applications in drug delivery and tissue regeneration. Finally, development prospects of in situ forming hydrogels based on chitosan are also discussed in brief.
基金Sponsored by a Girant-in-Aid from the Ministry of Education of China.
文摘The procedure for preparing a new type of uniform and porous chitosan gel from citric acid medium is described. Its swelling behavior in different media was compared with those of the gels prepared by other methods. The ultrastructure of the xerogel prepared from citric acid was characterized using electron microscopy (SEM).
基金supported by the National Natural Sci-ence Foundation of China(No.31922072)the China Agri-culture Research System(No.CARS-48)+1 种基金the Fundamen-tal Research Funds for the Central Universities(No.201941002)the Taishan Scholar Project of Shandong Province(No.tsqn201812020).
文摘Hydrogel has high water content and structural similarity with natural extracellular matrix.So it has been widely studied and applied in the field of biomedicine.In order to further develop multifunctional hydrogels,we prepared mixed gels with antiultraviolet properties.This study found that the addition of polysaccharides and polyphenols was beneficial to the rheological,me-chanical properties,and biological activity of the protein.Chitosan(CS)could significantly improve the viscoelasticity,hardness,gel strength,thermal stability and crystallinity of gelatin.Interestingly,the addition of gallic acid(GA)could not only provide significant cross-linking effect,improve gel properties and microstructure,but also improve the UV resistance of the mixed gel.
基金Funded by the National Natural Science Foundation of China(No.81401510)
文摘The aim of this study was to fabricate composite gel beads based on natural polysaccharides. Hyaluronic acid（HA） and Chitosan（CS） were successfully admixed with Ca^2＋/alginate（SA） gel system to produce SA/HA/CS gel beads by dual crosslinking： the ionic gelation and the polyelectrolyte complexation. The preparation procedure was that the weight ratio of SA（2%, m/v） to HA（2%, m/v） was kept at 2：1, then the mixture was dripped into the Ca^2＋ solution for ion-crosslinking, and finally polyelectrolyte crosslinked with 2% low molecular weight CS（LMW-CS） for 1.5 hours. The optimal formulation was achieved by adjusting the concentration and the weight ratio of SA, HA and LMW-CS. Due to the incorporation of HA and LMWCS, the swelling ratio of the beads at pH 7.4 was increased up to 120, and the time for the maximum swelling degree was prolonged to 7.5 h. The swelling behavior was obviously improved compared to the pure SA/Ca^2＋ system. The preliminary results clearly suggest that the SA/HA/CS gel beads may be a potential candidate for biomedical delivery vehicles.
文摘Recently, potential applications for β-chitosan (β-CS) have been examined. In the present study, calcium-induced alginate gel beads (Alg-Ca) containing weak acid salts of β-CS were prepared and examined with regard to their ability to adsorb bile acids in vitro. More than 70% of taurocholate dissolved in solution was taken up by Alg-Ca containing 100 mg β-CS, sim. ilar to the degree of uptake observed with Alg-Ca containing α-CS salt. The adsorption of bile acid was affected by the absolute amount of β-CS and/or the acid concentration of the preparation. A secondary bile acid, taurodeoxycholate, was also adsorbed by Alg-Ca containing weak acid salts of β-CS. Therefore, β-CS might be used to adsorb bile acids within the gastrointestinal tract in the same manner as an anion-exchange resin, and thus serve as a complementary means by which to prevent hyperlipidemia.
文摘Sucrose ester( SE) was fixed on surface of poly( ethylene terephthalate)( PET) fibers to improve surface activity. Chitosan( CS) was used to graft onto pretreated PET fibers by sol-gel method. The transformations of surface chemical structure,microcosmic morphology and thermodynamic property were investigated by Fourier transform infrared spectroscopy( FTIR),X-ray photoelectron spectroscopy( XPS), scanning electron microscope( SEM), X-ray diffraction technique( XRD), and thermo gravimetric analysis( TGA),respectively. The wettability and antistatic property of PET fiber were significantly improved after modification by SE and CS.
文摘Chitosan/α,β-glycerophosphate （CS/α,β-GP） thermo-sensitive hydrogels presented flowable solution state at low temperature and semisolid hydrogel when the ambient temperature increased. In this research, different concentrations of metronida- zole encapsulated, CS and α,β-GP, as well as different acid solvents, were chosen to evaluate their influences on the drug release behaviors from CS/α,β-GP hydrogels. It was found that there was a sustaining release during the first 3 h followed by a plateau. SEM images showed that drugs were located both on the surface and in the interior of hydrogels. The optimal preparation conditions of this hydrogel for drug release were as follows： 1.8% （w/v） CS in HAc solvent, 5.6% （w/v） a, 13-GP and 5g/L metronidazole encapsulation. Cytotoxicity evaluation found no toxic effect. In order to control the release rate, 2.5 g/L chitosan microspheres with spherical shape and smooth surface were incorporated, and it was found that the initial release process was alleviated, while drug concentration had no obvious effect on the release rate. It could be concluded that the metronidzole release behaviors could be optimized according to practical applica- tions.
