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1.
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.  相似文献   

2.
A novel thermoresponsive hydrogel based on chitosan.   总被引:2,自引:0,他引:2  
Injectable thermosetting chitosan hydrogels are attractive systems for drug delivery and tissue engineering that combine biodegradability, biocompatibility and the ability to form in situ gel-like implants. Thermally-induced gelation relies advantageously on biopolymer secondary interactions, avoiding potentially toxic polymerization reactions that may occur with in situ polymerizing formulations. In view of a biomedical use, such formulations have to be sterilizable and storable on extended periods without losing their thermosetting properties. These two key features have been studied in the present paper. Chitosans from two different sources were added with several phosphate-free polyols or polyoses as gelling agents. Despite a reduction in chitosan molecular weight following autoclaving, the hydrogels prepared with autoclaved chitosan showed the desired thermosetting properties. Hence, chitosan steam sterilization combined with aseptic preparation of the hydrogel allows a sterile formulation to be obtained. Whereas thermosetting hydrogels were shown to be unstable when refrigerated, freezing was shown to be conceivable as a storage method. When trehalose or mannitol was used as stabilizing agent, the formulation reconstituted from a lyophilizate displayed thermosetting properties and was still injectable, paving the way to the development of a clinically utilizable, novel chitosan thermosetting hydrogel.  相似文献   

3.
A photocrosslinkable chitosan (Az-CH-LA) aqueous solution resulted in an insoluble hydrogel like a soft rubber within 30 sec of ultraviolet light (UV)-irradiation. The photocrosslinked chitosan hydrogel showed strong sealing strength and potential use as a new tissue adhesive in surgical application. Paclitaxel, which is an anti-tumor reagent and a vascularization-inhibitor, retained in the photocrosslinked chitosan hydrogel, and were gradually released from the photocrosslinked chitosan hydrogel in vivo upon the degradation of the hydrogel. The paclitaxel-incorporated photocrosslinked chitosan hydrogels effectively inhibited tumor growth and angiogenesis in mice. On the other hand, the fibroblast growth factor (FGF)-2 molecules also retained in both the photocrosslinked chitosan and an injectable chitosan/IO(4)-heparin hydrogels, and were gradually released from the hydrogels upon their in vivo biodegradations. The activity of FGF-2 in the hydrogels was stable for long time (more than 14 days). The controlled release of biologically active FGF-2 molecules from the hydrogels caused an induction of the angiogenesis and, possibly, collateral circulation occurred in the healing-impaired diabetic (db/db) mice and the ischemic limbs of rats. The purpose of this review is to describe the effectiveness of the chitosan hydrogels (photocrosslinkable chitosan hydrogel and chitosan/IO(4)-heparin hydrogel) as a local drug delivery carrier for FGF-2 and paclitaxel to control wound repair, tumor growth, and angiogenesis. It is thus proposed that the chitosan hydrogels may be a promising new local carrier for drugs such as FGF-2 and paclitaxel.  相似文献   

4.
Intelligent hydrogel, also known as smart hydrogels, are materials with great potential for development in drug delivery system. Intelligent hydrogel also has the ability to perceive as a signal structure change and stimulation. The review introduces the temperature-, pH-, electric signal-, biochemical molecule-, light- and pressure- sensitive hydrogels. Finally, we described the application of intelligent hydrogel in drug delivery system and the recent patents involved for hydrogel in drug delivery.  相似文献   

5.
Over the past few decades, advances in hydrogel technologies have spurred development in many biomedical applications including controlled drug delivery. Many novel hydrogel-based delivery matrices have been designed and fabricated to fulfill the ever-increasing needs of the pharmaceutical and medical fields. Mathematical modeling plays an important role in facilitating hydrogel network design by identifying key parameters and molecule release mechanisms. The objective of this article is to review the fundamentals and recent advances in hydrogel network design as well as mathematical modeling approaches related to controlled molecule release from hydrogels. In the first section, the niche roles of hydrogels in controlled release, molecule release mechanisms, and hydrogel design criteria for controlled release applications are discussed. Novel hydrogel systems for drug delivery including biodegradable, smart, and biomimetic hydrogels are reviewed in the second section. Several mechanisms have been elucidated to describe molecule release from polymer hydrogel systems including diffusion, swelling, and chemically-controlled release. The focus of the final part of this article is discussion of emerging hydrogel delivery systems and challenges associated with modeling the performance of these devices.  相似文献   

6.
BACKGROUND AND THE PURPOSE OF THE STUDY: Many drugs which have narrow therapeutic window and are absorbed mainly in stomach have been developed as gastroretentive delivery system. Rosiglitazone maleate, an anti-diabetic, is highly unstable at basic pH and is extensively absorbed from the stomach. Hence there is a need to develop a gastroretentive system. In this study a superporous hydrogel was developed as a gastroretentive drug delivery system. METHODS: Chitosan/poly(vinyl alcohol) interpenetrating polymer network type superporous hydrogels were prepared using a gas foaming method employing glyoxal as the crosslinking agent for Rosiglitazone maleate. Sodium bicarbonate was applied as a foaming agent to introduce the porous structure. Swelling behaviors of superporous hydrogel in acidic solution were studied to investigate their applications for gastric retention device. The optimum preparation condition of superporous hydrogels was obtained from the gelation kinetics. FT-IR, scanning electron microscopy, porosity and swelling ratio studies were used to characterize these polymers. In vitro drug release studies were also carried out. RESULTS: The introduction of a small amount of Poly(Vinyl Alcohol) enhanced the mechanical strength but slightly reduced the swelling ratio. The prepared superporous hydrogels were highly sensitive to pH of swelling media, and showed reversible swelling and de-swelling behaviors maintaining their mechanical stability. The degradation kinetics in simulated gastric fluid showed that it had biodegradability. Swelling was dependent on the amount of chitosan and crosslinker. The drug release from superporous hydrogels was sustained for 6 hrs. MAJOR CONCLUSION: The studies showed that chitosan-based superporous hydrogels could be used as a gastroretentive drug delivery system for rosiglitazone maleate in view of their swelling and prolonged drug release characteristics in acidic pH.  相似文献   

7.
Fang JY  Chen JP  Leu YL  Hu JW 《Drug delivery》2008,15(4):235-243
New thermosensitive hydrogels of poly(N-isopropylacrylamide) (PNIPAAm) with chitosan (CPN) were prepared and evaluated for use in the delivery of the platinum drugs, cisplatin and carboplatin. The effects of polymers containing different ratios of chitosan on the physicochemical and drug release characteristics were examined. The sol-gel transition temperature of the hydrogels was determined by differential scanning calorimetry (DSC) and viscometry. Discrepancies in the transition temperature among the various polymer systems were more pronounced when determined by viscosity compared by DSC, with the CPN showing a higher transition temperature than PNIPAAm. The cross-sectional structure and surface topography of the hydrogels were examined by scanning electronic microscopy (SEM) and atomic force microscopy (AFM), respectively. The incorporation of chitosan further increased the entanglement of the hydrogel network. An increase in the chitosan ratio in the polymers (CPN-H) also increased the cross-linking structure. A smoother surface of hydrogel matrices was observed for CPN compared with PNIPAAm. All hydrogels tested significantly reduced drug release compared with an aqueous solution. The release rate of platinum drugs from PNIPAAm was retarded at the late stage. CPN matrices could continuously deliver platinum drugs during the experiment. The rate of release from CPN-H was generally slower than that from hydrogels and had a lower chitosan ratio (CPN-L), presumably due to the more-tortuous pathways in the hydrogels. Thermosensitive hydrogels like those prepared in this study may be a promising carrier for the delivery of platinum drugs, as the drug release can be controlled and sustained using CPN networks.  相似文献   

8.
Hydrogel formation from a mixture of biocompatible chitosan, beta-glycerol phosphate, and hydroxyethyl cellulose was studied. The rheological properties of the formed hydrogels were examined using a Bohlin VOR rheometer. The effect of hydrogel composition and temperature on both the gelation rate and the elastic strength of hydrogels was investigated, from which possible hydrogel formation mechanisms were inferred. The formed hydrogels as potential vehicles for delivering pilocarpine were examined. The advantages and disadvantages of chitosan/hydroxyethyl cellulose hydrogel as a delivery system are discussed.  相似文献   

9.
INTRODUCTION: Controlled drug delivery has been widely applied in areas such as cancer therapy and tissue regeneration. Thermosensitive hydrogel-based drug delivery systems have increasingly attracted the attention of the drug delivery community, as the drugs can be readily encapsulated and released by the hydrogels. AREAS COVERED: Thermosensitive hydrogels that can serve as drug carriers are discussed in this paper. Strategies used to control hydrogel properties, in order to tailor drug release kinetics, are also reviewed. This paper also introduces applications of the thermosensitive hydrogel-based drug delivery systems in cancer therapy and tissue regeneration. EXPERT OPINION: When designing a drug delivery system using thermosensitive hydrogels, one needs to consider what type of thermosensitive hydrogel needs to be used, and how to manipulate its properties to meet the desired drug release kinetics. For material selection, both naturally derived and synthetic thermosensitive polymers can be used. Various methods can be used to tailor thermosensitive hydrogel properties in order to achieve the desired drug release profile.  相似文献   

10.
N-[(2-Hydroxy-3-trimethylammonium)propyl] chitosan chloride (HTCC) was chemically modified using glycidyltrimethylammonium chloride (GTMAC). A new composite hydrogel was prepared using the mixture of HTCC and α-β-glycerophosphate (α-β-GP). The gelation of HTCC/GP mainly depended on the concentration and proportion of HTCC and GP. Thermogravimetric analysis exhibited high stability of HTCC/GP hydrogels. Surface morphology assay demonstrated that HTCC/GP hydrogels were well constructed with three-dimensional (3D) porous structures in the range of 5 of 40 μm. The insulin was entrapped during the formation of hydrogel. In vitro, the insulin release was controlled by modifying the composition, drug loading, and pH condition. The hydrogel dissolved and released drug quickly under acidic condition, whereas it absorbed water and released drug slowly under neutral or basic conditions. The hydrogels were biocompatible, and the cells could adhere to and then migrated to the hydrogels. Furthermore, these cells were viable and retained 3D morphology inside the hydrogels. Interestingly, HTCC/GP hydrogel showed both thermo- and pH-sensitive properties. There are potential applications in tissue engineering, cell encapsulation, and intelligent drug delivery systems.  相似文献   

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