Biodegradable blends of poly(ε‐caprolactone) with α‐chitin and chitosan: specific interactions,thermal properties and crystallization behavior

Films of poly(ε‐caprolactone) (PCL) blends with α‐chitin and chitosan were prepared as completely biodegradable polyester/polysaccharide composites. DSC thermal analysis revealed that the crystallization of PCL was suppressed by blending with α‐chitin and chitosan. The specific interaction between PCL and polysaccharides was investigated by FTIR spectroscopy. The PCL carbonyl vibration bands could be resolved into three components: crystalline, amorphous and interacting. The FTIR spectra indicated that there were hydrogen bonding interactions between PCL and polysaccharides, and that polysaccharides suppressed the crystallization of PCL, consistent with the results obtained by DSC. © 2001 Society of Chemical Industry     

Effects of culture temperature on the production of bioactive polysaccharides by Agaricus blazei in batch cultures

Effects of culture temperature ranging from 20 to 34 °C on cell growth, polysaccharide biosynthesis and the bioactivity of polysaccharides of Agaricus blazei were evaluated via eight batch cultures in steps of 2 °C in a stirred tank bioreactor. Results indicated that the optimal temperature for the biomass was 28 °C with a cell yield of 780 mg g^?1, while that for polysaccharide formation was 30 °C with a product yield of 230 mg g^?1. Both the β‐glucan content and average molecular weight of the polysaccharides from different temperature‐controlled cultures were closely correlated with their tumour necrosis factor‐α (TNF‐α) release capability on macrophage cells. The polysaccharides from the low temperature range (20–24 °C) not only had higher relative content of β‐glucan and average molecular weight but also exhibited higher bioactivity compared with those from the high temperature range (30–34 °C). The optimal temperature for the production of bioactive polysaccharides of A. blazei was 24 °C, at which their relatively high molecular weight, β‐glucan content and TNF‐α release capability on macrophage cells were 1650 kDa, 188 mg g^?1 and 1560 pg per 5 × 10⁴ cells respectively. Copyright © 2007 Society of Chemical Industry     

Thermal properties and crystallization behaviour of blends of poly(ε‐caprolactone) with chitin and chitosan

Blend films of poly(ε‐caprolactone) (PCL) with chitin and chitosan were prepared as completely biodegradable polyester/polysaccharide composites. Differential scanning calorimetry and Fourier‐transform infrared (FTIR) spectroscopy revealed that the crystallization of PCL, which had been suppressed by blending with chitin and chitosan, progressed with the elapse of time after film preparation. The suppression of crystallization of PCL by blending with polysaccharides was also observed by solid‐state ¹³C NMR spectroscopy. Furthermore, FTIR spectra indicated that the extent of hydrogen bonding between PCL and polysaccharides, which suppressed the crystallization of PCL, decreased with elapse of time after film preparation. Wide‐angle X‐ray diffraction indicated that the polysaccharides affected the crystallization of PCL and slightly deformed its crystalline lattice. Copyright © 2003 Society of Chemical Industry     

Microbial polysaccharide‐based membranes: Current and future applications

Microbial polysaccharides are characterized by high molecular structure variability which translates into a wide range of different properties offering interesting opportunities for application in many different areas, including membrane‐based products and processes. Due to their new or improved properties, microbial polysaccharides can replace plant, algae, and animal products, either in their traditional or in new applications. The main constraint to their wider use is the production costs that are still higher than that of other natural and synthetic polymers. The current applications of microbial polysaccharide membranes in medical, food, and industrial processes are outlined. The limitations still faced by these membranes and the requirements for obtaining innovative products and processes are also addressed. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 40047.     

两亲性海藻多糖在乳化和分散中应用的研究进展

海藻多糖是一种天然的凝胶多糖,其分子链上原生的亲水、疏水基团赋予其天然的两亲性,能够在一定程度上改善非均相之间的界面相容性,具有天然凝胶网络结构的海藻多糖还可在溶胶体系中有效阻止分散相之间的再聚集,因而海藻多糖在乳化及分散中具有极佳的应用潜能。本文介绍了海藻酸盐、岩藻多糖、卡拉胶、琼脂、石莼多糖等常见海藻多糖的化学组成、结构与性质,并从其糖基单元上的羧基、硫酸酯基等亲水基团与甲氧基、乙酰基、蛋白质等疏水基团构成的两亲性结构出发,总结了两亲性结构对海藻多糖分子构型、表面活性及流变性质的影响,进而综述海藻多糖两亲性结构在乳化和分散中的应用。同时,还总结了通过物理或化学手段增强海藻多糖两亲性能的相关研究,例如带电疏水粒子的静电耦合、长碳链疏水化合物的化学接枝等,介绍了衍生化海藻多糖在乳化和分散中应用的研究进展,并对海藻多糖界面吸附活性增强的方向进行了展望。     

Biomimetic gels with chemical and physical interpenetrating networks

This study aimed to create and to characterize the functional properties of gels with semi‐interpenetrating network (semi‐IPN) with focus on possible use of these composites in biomedical engineering. Polyacrylamide as a synthetic biocompatible polymer was chosen for the chemical network. The physical network comprised the gel‐forming polysaccharides xanthan gum or gellan gum. Gels were synthesized by radical polymerization of acrylamide in aqueous solutions of polysaccharides. Mechanical and electrical properties of gels with 0.2, 0.4, 0.6, 0.8 and 1.0 wt% content of polysaccharide were investigated. It was found that the inclusion of a small amount of xanthan or gellan into the polymeric network of a polyacrylamide gel significantly shifts the gel electrical potential towards the rest potential of living cells and Young's modulus towards the elasticity limits of biological soft tissues like non‐activated muscles. From the viewpoint of biomedical applications, the main advantage of the proposed composites is that the semi‐IPN structure provides a nonlinear dependence of gel tension on gel deformation, which mimics the elasticity of natural tissues. This feature opens the possibility for the promising use of the proposed gels for musculoskeletal minibioimplants or scaffolds for tissue engineering. © 2018 Society of Chemical Industry     

Preparation,characterization, and swelling and drug release properties of a crosslinked chitosan‐polycaprolactone gel

For applications in biotechnology to prepare biopolymers containing functional groups is essential. In addition, these materials have to be strong to provide physical support for practical applications. Recently, chitosan, polycaprolactone (PCL), and their various combinations were used for this purpose. In this work, we described the preparation and characterization of a new biodegradable polymeric gel containing chitosan and PCL. The gel preparation reactions were performed in suitable acetic acid solutions to obtain the products in high yields. A crosslinking agent was added to produce crosslinked gels. Swelling behavior of chitosan/PCL gels in different compositions was studied, and the results were compared. The chitosan/PCL gels show a rather large equilibrium swelling in water and in the phosphate buffered saline solution. Acrylic acid (AA) was added to these gels during preparation process to obtain a stable material for various applications. These polymeric gels were characterized by Fourier transform infrared. Their physical and morphological properties were investigated by using differential scanning calorimeter and scanning electron microscope techniques, respectively. Cell growth experiments indicate that chitosan, a positively charged polysaccharide, is not suitable for cell proliferation studies. On the other hand, the drug release studies were successful and, 59% of lidocaine, was released from a chitosan/PCL/AA hydrogel in buffer solution at pH = 7.4 at 37°C. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and characterization of polyurethane elastomers based on chitosan and poly(ε‐caprolactone)

Biodegradable polyurethane (PU) elastomers with potential for biomedical and industrial applications were synthesized by the reaction of poly(ε‐caprolactone) (PCL) and isophorone diisocyanate (IPDI), extended with different mass ratio of chitosan and 1,4‐butane diol (BDO). Their chemical structures were characterized using FTIR, ¹HNMR, and ¹³CNMR, and thermal properties were determined by TGA and DMTA. Incorporation of chitosan contents into the polyurethane backbone caused improvement in thermal stability and thermal degradation rate. Optimum thermal properties and degradation profile were obtained from elastomer extended with chitosan. The crystallinity and hydrophilicity of the prepared polymers were also examined by X‐ray and contact angle measurements. The results showed that hydrophilicity decreased and crystallinity increased with increasing of chitosan content in polyurethane backbone. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Recent Progress on the Design and Applications of Polysaccharide‐Based Graft Copolymer Hydrogels as Adsorbents for Wastewater Purification

Gum polysaccharides are one of the most abundant bio‐based polymers. They are generally derived from plants as exudates or from microorganisms and have diverse applications in many industries, especially in the food industries where they are used as emulsifiers and thickeners. In their natural form, gum polysaccharides have poor mechanical and physical properties; therefore, they are frequently modified with various synthetic monomers such as acrylamide and acrylic acid using graft copolymerization. Graft copolymerization is one of the most trusted and widely used synthetic methods for the modification of gum polysaccharides. Gum polysaccharides modified in this way have improved mechanical and physicochemical properties. Furthermore, gum polysaccharides contain a variety of functional groups, for example, carboxylic acid and hydroxyl groups; therefore, they have been used extensively as adsorbents for the removal of different impurities from wastewater such as toxic heavy metal cations and synthetic dyes. Here, the chemical and physical properties of gum polysaccharides, different methods of graft copolymerization, and the use of graft copolymer gum‐polysaccharide‐based hydrogels are reviewed in detail for the removal of toxic heavy metal cations and synthetic dyes from aqueous solutions.

     

Advancements in non-starch polysaccharides research for frozen foods and microencapsulation of probiotics

Conventionally used in the food industry as stabilizing, thickening, gelling, and suspending or dispersing agents, non-starch polysaccharides such as xanthan gum are known to improve the texture of certain frozen products. Another polysaccharide that has received significant attention in recent years is chitosan, a natural biopolymer derived from chitin. In the wake of growing interest in finding ideal encapsulating agents for probiotics, non-starch polysaccharides have been investigated. Scattered research can be found on the effect of each individual polysaccharide, but there remains a void in the literature in terms of closely comparing the characteristics of non-starch polysaccharides for these applications, especially when more than one biopolymer is employed. A good understanding of the tools capable of elucidating the underlying mechanisms involved is essential in ushering further development of their applications. Therefore, it is this review’s intention to focus on the selection criteria of non-starch polysaccharides based on their rheological properties, resistance to harsh conditions, and ability to improve sensory quality. A variety of critical tools is also carefully examined with respect to the attainable information crucial to frozen food and microencapsulation applications.     

Advancements in non-starch polysaccharides research for frozen foods and microencapsulation of probiotics

Conventionally used in the food industry as stabilizing, thickening, gelling, and suspending or dispersing agents, non-starch polysaccharides such as xanthan gum are known to improve the texture of certain frozen products. Another polysaccharide that has received significant attention in recent years is chitosan, a natural biopolymer derived from chitin. In the wake of growing interest in finding ideal encapsulating agents for probiotics, non-starch polysaccharides have been investigated. Scattered research can be found on the effect of each individual polysaccharide, but there remains a void in the literature in terms of closely comparing the characteristics of non-starch polysaccharides for these applications, especially when more than one biopolymer is employed. A good understanding of the tools capable of elucidating the underlying mechanisms involved is essential in ushering further development of their applications. Therefore, it is this review’s intention to focus on the selection criteria of non-starch polysaccharides based on their rheological properties, resistance to harsh conditions, and ability to improve sensory quality. A variety of critical tools is also carefully examined with respect to the attainable information crucial to frozen food and microencapsulation applications.     

Characterization of mechanical properties of γAl2O3 dispersed epoxy resin cured by γ‐ray radiation

Epoxy resins are widely utilized as high performance thermosetting resins for many industrial applications, but they are characterized by relatively low toughness. Incorporation of rigid inorganics is suggested to improve the mechanical properties of epoxy resins. An attempt is made to disperse nanosized γ‐Al₂O₃ particles into diglycidyl ether of bisphenol A epoxy resins for the improvement of the mechanical properties. These hybrid epoxy–alumina composites are prepared using by the γ‐ray curing technique conducted at 100 kGy under nitrogen at room temperature. The composites are characterized by determining the gel content, flexural strength, Youngis modulus, and toughness at room temperature using scanning electron microscopy and FTIR studies. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1898–1903, 2004     

From Cancer Therapy to Winemaking: The Molecular Structure and Applications of β-Glucans and β-1, 3-Glucanases

β-glucans are a diverse group of polysaccharides composed of β-1,3 or β-(1,3-1,4) linked glucose monomers. They are mainly synthesized by fungi, plants, seaweed and bacteria, where they carry out structural, protective and energy storage roles. Because of their unique physicochemical properties, they have important applications in several industrial, biomedical and biotechnological processes. β-glucans are also major bioactive molecules with marked immunomodulatory and metabolic properties. As such, they have been the focus of many studies attesting to their ability to, among other roles, fight cancer, reduce the risk of cardiovascular diseases and control diabetes. The physicochemical and functional profiles of β-glucans are deeply influenced by their molecular structure. This structure governs β-glucan interaction with multiple β-glucan binding proteins, triggering myriad biological responses. It is then imperative to understand the structural properties of β-glucans to fully reveal their biological roles and potential applications. The deconstruction of β-glucans is a result of β-glucanase activity. In addition to being invaluable tools for the study of β-glucans, these enzymes have applications in numerous biotechnological and industrial processes, both alone and in conjunction with their natural substrates. Here, we review potential applications for β-glucans and β-glucanases, and explore how their functionalities are dictated by their structure.     

Adsorption of guanosine,cytidine, and uridine on a β‐cyclodextrin derivative grafted chitosan

A β‐cyclodextrin derivative grafted chitosan (CDD‐C) was synthesized with chitosan and carboxymethyl‐β‐cyclodextrin (β‐CD). Its structure was characterized by elemental, infrared spectra, and X‐ray diffraction analyses. The degree of substitution by the carboxymethyl‐β‐CD moiety achieved 0.27 with the addition of DMF to the reaction solution. The results are in agreement with the expectations. The static adsorption properties for guanosine, cytidine, and uridine were studied. Experimental results demonstrated that CDD‐C had higher adsorption capability for guanosine than cytidine and uridine, and the adsorption capacity for guanosine was 74.20 mg/g. The adsorption capacity was greatly influenced by pH, time, and temperature. The introduction of chitosan enhanced the adsorption ability and adsorption selectivity of β‐CD for guanosine. This novel derivative of chitosan is expected to have wide applications in separation, concentration, and analysis of guanosine, cytidine, and uridine in biological sample. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3050–3055, 2007     

Preparation and characterization of chitosan/α‐zirconium phosphate nanocomposite films

Nano‐fillers play an important role in the final structure and properties of nanocomposites. The objective of the work presented here was to prepare nanocomposite films of chitosan/α‐zirconium phosphate using a casting process, with α‐zirconium phosphate (α‐ZrP) as nano‐filler and chitosan as matrix. The effects of α‐ZrP on the structure and properties of the nanocomposites were investigated. X‐ray diffraction patterns showed that α‐ZrP crystals were intercalated by n‐butylamine. The results from scanning electron microscopy and transmission electron microscopy indicated that α‐ZrP could be uniformly dispersed in the chitosan matrix when α‐ZrP loading in the composites was less than 2 wt%. A strong interaction between α‐ZrP and chitosan formed during the film‐forming process. Tensile testing showed that the tensile strength and elongation at break of nanocomposite films achieved maximum values of 61.6 MPa and 58.1%, respectively, when α‐ZrP loading was 2 wt%. The parameter B calculated from tensile yield stress according to the Pukanszky model was used to estimate the interfacial interaction between the chitosan matrix and α‐ZrP. Films with a loading of 2 wt% α‐ZrP had the highest B value (3.2), indicating the strongest interfacial interaction. The moisture uptake of the nanocomposites was reduced with addition of α‐ZrP. It can be concluded that α‐ZrP as nano‐filler in a chitosan matrix can enhance the mechanical properties of nanocomposites due to the strong interactions between α‐ZrP and chitosan. Copyright © 2010 Society of Chemical Industry     

Degradable natural polymer hydrogels for articular cartilage tissue engineering

Articular cartilage has poor ability to heal once damaged. Tissue engineering with scaffolds of polymer hydrogels is promising for cartilage regeneration and repair. Polymer hydrogels composed of highly hydrated crosslinked networks mimic the collagen networks of the cartilage extracellular matrix and thus are employed as inserts at cartilage defects not only to temporarily relieve the pain but also to support chondrocyte proliferation and neocartilage regeneration. The biocompatibility, biofunctionality, mechanical properties, and degradation of the polymer hydrogels are the most important parameters for hydrogel‐based cartilage tissue engineering. Degradable biopolymers with natural origin have been widely used as biomaterials for tissue engineering because of their outstanding biocompatibility, low immunological response, low cytotoxicity, and excellent capability to promote cell adhesion, proliferation, and regeneration of new tissues. This review covers several important natural proteins (collagen, gelatin, fibroin, and fibrin) and polysaccharides (chitosan, hyaluronan, alginate and agarose) widely used as hydrogels for articular cartilage tissue engineering. The mechanical properties, structures, modification, and structure–performance relationship of these hydrogels are discussed since the chemical structures and physical properties dictate the in vivo performance and applications of polymer hydrogels for articular cartilage regeneration and repair. © 2012 Society of Chemical Industry     

Effect of degree of deacetylation on solubility of low‐molecular‐weight chitosan produced via enzymatic breakdown of chitosan

Chitosan has emerged as a unique biomaterial, possessing scope in diverse applications in the biomedical, food and chemical industries. However, its high molecular weight is a concern when handling the polymer. Various techniques have been explored for depolymerization of this polymer, wherein enzymes have emerged as the most economic method having minimum degrading effect on the polymer and resulting in formation of side products. Chitosan can be depolymerized using a broad range of enzymes. In this study, various enzymes like α‐amylase, papain, pepsin and bromelain were employed to depolymerize chitosan and convert it into its lower molecular weight counterpart. Further, attempts were made to elucidate the process of depolymerization of chitosan, primarily by determining the change in its viscosity and hence its molecular weight. The process of depolymerization was optimized using a one‐factor‐at‐a‐time approach. The molecular weight of the resultant chitosan was estimated using gel permeation chromatography and infrared spectroscopy. These studies revealed a considerable decrease in molecular weights of chitosan depolymerized by pepsin, papain, bromelain and α‐amylase, resulting in recovery of the low‐molecular‐weight chitosan of 76.09 ± 5, 74.18 ± 5, 55.75 ± 5 and 49.18 ± 5%, respectively. Maximum yield and depolymerization were obtained using pepsin and papain due to their enzymatic recognition pattern, which was also validated using studies involving molecular dynamics. © 2019 Society of Chemical Industry     

A new approach for the preparation of chitosan from γ‐irradiation of prawn shell: effects of radiation on the characteristics of chitosan

Chitosan is a biodegradable polymer composed of randomly distributed β‐(1,4)‐linked D ‐glucosamine (deacetylated unit) and N‐acetyl‐D ‐glucosamine (acetylated unit). It is produced commercially by deacetylation of chitin, which is the structural element in the exoskeleton of crustaceans (such as crabs and shrimps) and the cell walls of fungi. In the work reported, we developed a facile technique for the preparation of chitosan by irradiating prawn shell at various intensities from 2 to 50 kGy. It was observed that γ‐irradiation of prawn shell increased the degree of deacetylation (DD) of chitin at a relatively low alkali concentration during the deacetylation process. Among the various irradiation doses applied to prawn shell, a dose of 50 kGy and 4 h heating in 50% NaOH solution yielded 84.56% DD while the chitosan obtained from non‐irradiated prawn shell with the same reaction conditions had only 74.70% DD. In order to evaluate the effect of γ‐irradiation on the various physicochemical, thermomechanical and morphological properties, the chitosan samples were again irradiated (2–100 kGy) with γ‐radiation. Molecular weight, DD, thermal properties with differential scanning calorimetry and thermogravimetric analysis, particle morphology by scanning electron microscopy, water binding capacity (WBC), fat binding capacity (FBC) and antimicrobial activity were determined and the effects of various γ‐radiation doses were assessed. The DD, WBC, FBC and antimicrobial activity of the chitosan were found to improve on irradiation. It was obvious that irradiation caused a decrease of molecular weight from 187 128 to 64 972 g mol^?1 after applying a radiation dose of 100 kGy which occurred due to the chain scission of chitosan molecules at glycosidic linkages. The decrease of molecular weight increased the water solubility of the chitosan, the extent of which was explored for biomedical applications. Copyright © 2012 Society of Chemical Industry     

Preparation of chitosan‐based thermosensitive hydrogels for drug delivery

The thermosensitive material that could be transformed into gel at 37°C was prepared from chitosan (dissolved in acetic acid/sodium acetate buffer solution) and a mixture of α‐ and β‐glycerophosphate (αβ‐GP). The thermosensitive characteristics, appearance, and structure of the hydrogel were all affected by the pH, ionic strength, and CS/αβ‐GP ratio. The optimal conditions for the preparation of a transparent CS‐αβ‐GP thermosensitive hydrogel were pH 4.6, ionic strength 0.15 mol/L, and a CS/αβ‐GP ratio of 8.8/1.2 (v/v). The hydrogel was stable for at least 3 months at 4°C. We believe that hydrogen bonding interactions between the N? H (and C?O) groups of chitosan and the O? H groups of αβ‐GP play an important role during the process of sol‐to‐gel transition. The cumulative release of adriamycin from the CS‐αβ‐GP hydrogel, measured in PBS at pH 7.4, reached only 60 to 70% over 24 h, indicating that this material could be potentially used in a sustained drug delivery system. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation and characterization of hyaluronan/chitosan scaffold cross‐ linked by 1‐ethyl‐3‐(3‐dimethylaminopropyl) carbodiimide

A novel biocompatible scaffold was prepared by cross‐linking hyaluronan (HA) and chitosan (CS). The carboxyl groups of HA were activated by 1‐ethyl‐3‐(3‐dimethylaminopropyl)carbodiimide (EDC) and then cross‐linked with amino groups of CS by forming amide bonds. The HA/CS scaffold thus prepared was characterized using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and differential scanning calorimetry. FTIR spectra showed that the absorbance of the amide (1550 cm^?1) and carbonyl (1633 cm^?1) bond in the cross‐linked scaffold was stronger than that in HA or CS. SEM micrographs showed that the cross‐linked scaffold produced at low EDC concentration had an intertwisted ribbon‐like microstructure, while the product prepared at higher EDC concentration had a porous structure. The concentration of EDC in the reaction system greatly affected the structure and properties of the HA/CS scaffold. The prepared scaffold could strongly resist degradation by hyaluronidase, free radicals in vitro and stress. Copyright © 2007 Society of Chemical Industry