Physical properties and biocompatibility of chitosan/soy blended membranes

Blends of polysaccharides and proteins are a source for the development of novel materials with interesting and tailorable properties, with potential to be used in a range of biomedical applications. in this work a series of blended membranes composed by chitosan and soy protein isolate was prepared by solvent casting methodology. in addition, cross-linking was performed in situ with glutaraldehyde solutions in the range 5 × 10^–3 – 0.1 M. Furthermore, the influence of the composition and cross-linking on the degradation behaviour, water uptake and cell adhesion was investigated. The obtained results showed that the incorporation of chitosan, associated to network formation by cross linking, promoted a slight decrease of water absorption and a slower degradability of the membranes. Moreover, direct contact biocompatibility studies, with L929 cells, indicate that the cross-linking enhances the capability of the material to support cell growth.     

Preparation,fabrication and biocompatibility of novel injectable temperature-sensitive chitosan/glycerophosphate/collagen hydrogels

This paper introduces a novel type of injectable temperature-sensitive chitosan/glycerophosphate/collagen (C/GP/Co) hydrogel that possesses great biocompatibility for the culture of adipose tissue-derived stem cells. The C/GP/Co hydrogel is prepared by mixing 2.2% (v/v) chitosan with 50% (w/w) β-glycerophosphate at different proportions and afterwards adding 2 mg/ml of collagen. The gelation time of the prepared solution at 37°C was found to be of around 12 min. The inner structure of the hydrogel presented a porous spongy structure, as observed by scanning electron microscopy. Moreover, the osmolality of the medium in contact with the hydrogel was in the range of 310–330 mmol kg⁻¹. These analyses have shown that the C/GP/Co hydrogels are structurally feasible for cell culture, while their biocompatibility was further examined. Human adipose tissue-derived stem cells (ADSCs) were seeded into the developed C/GP and C/GP/Co hydrogels (The ratios of C/GP and C/GP/Co were 5:1 and 5:1:6, respectively), and the cellular growth was periodically observed under an inverted microscope. The proliferation of ADSCs was detected using cck-8 kits, while cell apoptosis was determined by a Live/Dead Viability/Cytotoxicity kit. After 7 days of culture, cells within the C/GP/Co hydrogels displayed a typical adherent cell morphology and good proliferation with very high cellular viability. It was thus demonstrated that the novel C/GP/Co hydrogel herein described possess excellent cellular compatibility, representing a new alternative as a scaffold for tissue engineering, with the added advantage of being a gel at the body’s temperature that turns liquid at room temperature.     

The biodegradation of a biopolymeric additive in building materials

A summary is given of a series of studies performed in order to explain one cause of bad odour and spoilage of floor covering materials (‘sick building syndrome’). Bad odours as well as spoilage of floor covering materials, i.e. blackening etc., inside buildings with self-levelling concrete containing casein are due to the biodegradation of the protein molecule by different species ofClostridia, which have adapted themselves to the extreme environment, i.e. a high pH and a relatively low temperature (pH 12 and 17°C). These new characteristics ofClostridia make it possible, under these extreme conditions, for theClostridia to degrade the casein molecule to volatile organic acids and monoamines. Organic acids such as propionic acid, butyric acid etc, and monoamines such as triethylamine, di-iso-butylamine etc. have been detected in biodegraded concrete. The monoamines are odorous and contribute strongly to the bad odour experienced inside some buildings constructed between 1979 and 1982. The acids are chemically bound in the concrete and can therefore not be observed as bad odour. A simulation of the biodegradative attack on concrete showed that the same acids were produced in the laboratory (in vitro) as the one detected in the floor covered with concrete.

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Résumé On résume une série d'études destinées à déterminer la cause de l'odeur désagréable et de la détérioration de matériaux de revêtements de sols (‘sick building syndrome”). Les odeurs désagréables et la détérioration des revêtements de sols, c'est-à-dire le noircissement, etc... dans des batiments où pour la confection de chapes on s'est servi d'un béton contenant de la caséine sont imputables à la biodégradation de la molécule de protéine par différentes espèces deClostridia, qui se sont adaptées aux conditions extrêmes (haut pH: 12 et températures relativement basses: 17°C). Ces nouvelles propriétés desClostridia leur permenttent dans ces conditions extrêmes de transformer la molécule de caséine en acides organiques volatiles et en monoamines. On a discerné des acides organiques, tels que l'acide propionique, butyrique, etc... et des monoamines comme la triéthylène et di-iso-butylamine dans le béton biodétérioré. Les monoamines sont odorigènes et contribuent largement à l'odeur désagréable qui se dégage dans certains batiments construits entre 1979 et 1982. Les acides se trouvent chimiquement liés dans le béton. On ne peut donc les déceler par leur odeur désagréable. Une simulation de l'attaque du béton par une action biodégradante a montré qu'on obtenait en laboratoire (in vitro) les mêmes acides que ceux dont la présence avait été détectée dans un sol recouvert de béton.

     

In vitro biodegradation and biocompatibility of gelatin/montmorillonite-chitosan intercalated nanocomposite

The intercalated nanocomposite of gelatin/montmorillonite-chitosan (Gel/MMT-CS) was prepared via the solution intercalation process. In vitro degradation tests showed that the nanocomposite had a lower degradation rate than Gel-CS composite. And the introduced intercalation structure endowed Gel/MMT-CS nanocomposite with a controllable degradation rate when changing the MMT content. Cells attachment, spread and proliferation on the Gel/MMT-CS membranes were investigated by scanning electron microscopy (SEM) and mitochondrial activity assay. The results provided evidences of good adhesion, proliferation and morphology of rat stromal stem cells on Gel/MMT-CS membranes compared to the tissue culture plates (TCPs), making the Gel/MMT-CS nanocomposite a promising candidate towards tissue engineering.     

Synthesis and biocompatibility of porous nano-hydroxyapatite/collagen/alginate composite

Porous nano-hydroxyapatite/collagen/alginate (nHAC/Alginate) composite containing nHAC and Ca-crosslinked alginate is synthesized biomimetically. This composite shows a significant improvement in mechanical properties over nHAC material. Mechanical test results show that the compressive modulus and yield strength of this composite are in direct proportion to the percentage of Ca-crosslinked alginate in the composite. Primary biocompatibility experiments in vitro including fibroblasts and osteoblasts co-culture with nHAC/alginate composite indicated the high biocompatibility of this composite. Therefore the composite can be a promising candidate of scaffold material for bone tissue engineering.     

Preparation and characterization of collagen/PLA,chitosan/PLA,and collagen/chitosan/PLA hybrid scaffolds for cartilage tissue engineering

In this study, three-dimensional (3D) porous scaffolds were developed for the repair of articular cartilage defects. Novel collagen/polylactide (PLA), chitosan/PLA, and collagen/chitosan/PLA hybrid scaffolds were fabricated by combining freeze-dried natural components and synthetic PLA mesh, where the 3D PLA mesh gives mechanical strength, and the natural polymers, collagen and/or chitosan, mimic the natural cartilage tissue environment of chondrocytes. In total, eight scaffold types were studied: four hybrid structures containing collagen and/or chitosan with PLA, and four parallel plain scaffolds with only collagen and/or chitosan. The potential of these types of scaffolds for cartilage tissue engineering applications were determined by the analysis of the microstructure, water uptake, mechanical strength, and the viability and attachment of adult bovine chondrocytes to the scaffolds. The manufacturing method used was found to be applicable for the manufacturing of hybrid scaffolds with highly porous 3D structures. All the hybrid scaffolds showed a highly porous structure with open pores throughout the scaffold. Collagen was found to bind water inside the structure in all collagen-containing scaffolds better than the chitosan-containing scaffolds, and the plain collagen scaffolds had the highest water absorption. The stiffness of the scaffold was improved by the hybrid structure compared to plain scaffolds. The cell viability and attachment was good in all scaffolds, however, the collagen hybrid scaffolds showed the best penetration of cells into the scaffold. Our results show that from the studied scaffolds the collagen/PLA hybrids are the most promising scaffolds from this group for cartilage tissue engineering.     

纳米羟基磷灰石/聚酰胺复合材料屏障膜的体外生物相容性

用相转移法制备了用于引导骨再生的纳米磷灰石/聚酰胺66(n-HA/PA66)和载银纳米羟基磷灰石/二氧化钛/聚酰胺66(Ag-HA-TiO₂/PA66)复合生物材料屏障膜, 并通过与骨髓基质干细胞(BMSC)共培养评价了其体外生物相容性。扫描电子显微镜(SEM)观察显示,制备的复合材料膜为不对称多孔膜,一面是孔径小于10μm的微孔层,另一面是孔径在30～200μm的大孔结构。四唑盐比色(MTT)和流式细胞术(FCM)试验结果表明：n-HA/PA66膜具有良好的细胞亲和力,有利于BMSC的黏附、生长和减少凋亡;Ag-HA-TiO₂/PA66 膜也具有良好的生物相容性,但加速了BMSC的凋亡。2种膜的结构和生物相容性能够满足引导骨组织再生膜材料的要求。     

磷酰胆碱共聚物的合成及膜的生物相容性

为了研究磷酰胆碱类聚合物的生物相容性,以偶氮二异丁腈(AIBN)为引发剂,采用自由基聚合制备了系列2-甲基丙烯酰氧乙基磷酰胆碱(MPC)与甲基丙烯酸丁酯(BMA)、甲基丙烯酸异辛酯(EHMA)的共聚物PMB、PMEH.用红外光谱、元素分析、核磁共振等方法对其结构进行了表征并探讨了其在不同溶剂中的溶解性,为该类物质的提纯提供依据;通过溶剂挥发法制备了共聚物薄膜,血小板黏附实验显示,含有MPC的聚合物薄膜比不含MPC的聚合物薄膜有更好的血液相容性;溶胀度测试显示MPC聚合物薄膜有非常好的吸收水的能力,且平衡含水量(EWC)会随着MPC在聚合物薄膜中含量的增加而增加,当MPC在PMB20中的摩尔含量为18%时,平衡含水量可以达到47%,这是磷酰胆碱类聚合物薄膜具有优良生物相容性的原因之一.     

Biomimetic properties of an injectable chitosan/nano-hydroxyapatite/collagen composite

To meet the challenges of designing an injectable scaffold and regenerating bone with complex three-dimensional (3D) structures, a biomimetic and injectable hydrogel scaffold based on nano-hydroxyapatite (HA), collagen (Col) and chitosan (Chi) is synthesized. The chitosan/nano-hydroxyapatite/collagen (Chi/HA/Col) solution rapidly forms a stable gel at body temperature. It shows some features of natural bone both in main composition and microstructure. The Chi/HA/Col system can be expected as a candidate for workable systemic minimally invasive scaffolds with surface properties similar to physiological bone based on scanning electron microscopic (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) results.     

Evaluation of batch adsorption of chromium ions on natural and crosslinked chitosan membranes

Removal of chromium ions from aqueous solutions by using natural and crosslinked chitosan membranes was achieved using batch adsorption experiments. The effect of pH (6.0 and 2.0), concentration of chromium ions and crosslinking agents (glutaraldehyde: GLA and epichlorohydrin: ECH) on the adsorption properties of chitosan membranes was analyzed. The experimental equilibrium data was fitted to Langmuir and Freundlich models. Through the model curves, it was possible to observe that the amount of chromium ions adsorbed was significantly higher for crosslinked membranes compared to non-crosslinked chitosan. The maximum adsorbed amount was about 1400 mg g(-1) for ECH-crosslinked chitosan at pH 6.0. The adsorption rates for crosslinked chitosan membranes with glutaraldehyde and epichlorohydrin were similar for natural chitosan. Desorption study using NaCl (1 mol L(-1)) solution was performed on chitosan membranes, in order to recover chromium ions and to determine the suitable number of cycles for repeated use of these membranes without considerable decrease in their adsorption capacity. The desorption results showed that chromium ions could be more effectively removed at pH 2.0 than pH 6.0, mainly for ECH-crosslinked chitosan.     

纳米羟基磷灰石-胶原蛋白-壳聚糖复合生物材料

采用共沉淀法制备了纳米羟基磷灰石．胶原蛋白．壳聚糖复合生物材料，用IR、XRD、TEM及万能材料实验机等方法对材料性能进行了分析表征。结果表明：羟基磷灰石．胶原蛋白．壳聚糖复合生物材料在晶相组成、化学成分、羟基磷灰石尺寸上具有类骨结构，并具有良好的力学性能．其抗压强度达到128MPa，可满足骨组织修复与替代的要求。有望成为治疗骨缺损的承力替代物。     

Carboxymethyl chitosan as a polyampholyte mediating intrafibrillar mineralization of collagen via collagen/ACP self-assembly

The significant role of the polyelectrolytic nature of non-collagenous proteins (NCPs) in regulating the in vivo mineralization of collagen provides important insights for scientists searching for analogues of NCPs to achieve in vitro collagen mineralization. Polyampholyte carboxymethyl chitosan (CMC) has both carboxyl and amino groups, which allows it to act as a cationic or anionic polyelectrolyte below or above its isoelectric point (IP), respectively. In this study, CMC was employed as the analogue of NCPs to stabilize amorphous calcium phosphate (ACP) under acidic conditions (pH < 3.5) via the formation of CMC/ACP nanocomplexes. In the presence of both ACP nanoparticles and acid collagen molecules, ACP nanoparticles could be integrated into collagen fibrils during the process of collagen self-assembly and achieve intrafibrillar mineralization of collagen in vitro (i.e., synchronous self-assembly/mineralization (SSM) of collagen). This mode of mineralization is different from established mechanisms in which mineralization follows the self-assembly (MFS) of collagen. Thus, SSM provides a new strategy for developing materials from mineralized collagen scaffolds.     

PPO/SiO_2碱性阴离子交换膜的制备与表征

本研究是基于聚(2,6-二甲基-1,4-苯撑氧)(PPO)所进行的系列改性工作.PPO进行溴化,得到两种溴化度的溴化PPO(BPPO),再进行羟基化和季铵化反应,随后与小分子烷氧基硅烷进行sol-gel反应,热处理后将膜浸泡在碱液中转化为OH-型,得到两种系列的碱性阴离子交换膜.膜具有平整均一的外观形貌和良好的机械性能(4.5~12 MPa,36%~58%),膜的厚度范围为0.09~0.12 mm.水含量(WROH)范围为62%~145%,离子交换容量为1.6~2.2 mmol/g.膜具有良好的抗碱能力,在2 mol/L NaOH中浸泡192 h后,其IEC仍能保持在原有的82%以上.低溴化度BPPO制备的膜具有更高的抗溶胀能力,在60℃水中浸泡44 h后,溶胀度范围为117%~297%,高溴化度BPPO制备的膜有高的电导率(室温条件下为0.036~0.041 S/cm),说明所制备的碱性阴离子交换膜有潜力应用于碱性膜燃料电池领域.     

Immobilizing collagen type I to TiO2 film for improvement of biocompatibility

In this work, using a bio-chemical modification method, collagen type I was immobilized on the TiO₂ film surface by a silane coupling reagent of aminopropyltriethoxysilane. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy were used to investigate the characteristics of the modified TiO₂ film. The thrombus formation ability of the films was studied by in vitro platelet adhesion test. Furthermore, the biological behavior of cultured human umbilical vein endothelial cells (HUVECs) onto different films was investigated by in vitro HUVECs cultured experiment. The results show that the modification can improve the biocompatibility of TiO₂ film for applications of biomedical microcoil hemangioma treatment, etc.     

壳聚糖中空纤维膜的制备及其结构研究

采用干湿相转化成膜的方法,纺制了壳聚糖中空纤维膜,研究了干燥方法及成膜条件对膜结构的影响.实验发现自然干燥导致膜的严重收缩,最终形成整体致密的膜结构;采用乙醇-正己烷液-液交换干燥,能够有效地避免膜结构的完全致密化,最终形成整体非对称的膜结构.成膜条件的研究结果表明,壳聚糖浓度的提高,更易形成致密层增厚的膜结构;而凝胶温度及凝胶液组成中氢氧化钠浓度的升高,有利于形成致密层更薄,支撑层孔径更大的整体非对称膜结构.进一步的研究表明,整体非对称结构的壳聚糖中空纤维膜可以应用于渗透汽化分离碳酸二甲酯/甲醇混合物,突破恒沸组成的限制,具有较好的应用前景.     

Dual delivery of hydrophilic and hydrophobic drugs from chitosan/diatomaceous earth composite membranes

Oral administration of drugs presents important limitations, which are frequently not granted the importance that they really have. For instance, hepatic metabolism means an important drug loss, while some patients have their ability to swell highly compromised (i.e. unconsciousness, cancer…). Sublingual placement of an accurate Pharmaceutical Dosage Form is an attractive alternative. This work explores the use of the β-chitosan membranes, from marine industry residues, composed with marine sediments for dual sublingual drug delivery. As proof of concept, the membranes were loaded with a hydrophilic (gentamicin) and a hydrophobic (dexamethasone) drug. The physico-chemical and morphological characterization indicated the successful incorporated of diatomaceous earth within the chitosan membranes. Drug delivery studies showed the potential of all formulations for the immediate release of hydrophilic drugs, while diatomaceous earth improved the loading and release of the hydrophobic drug. These results highlight the interest of the herein developed membranes for dual drug delivery.

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In vivo bone regeneration with injectable chitosan/hydroxyapatite/collagen composites and mesenchymal stem cells

For reconstruction of irregular bone defects, injectable biomaterials are more appropriate than the preformed biomaterials. We herein develop a biomimetic in situ-forming composite consisting of chitosan (CS) and mineralized collagen fibrils (nHAC), which has a complex hierarchical structure similar to natural bone. The CS/nHAC composites with or without mesenchymal stem cells (MSCs) are injected into cancellous bone defects at the distal end of rabbit femurs. Defects are assessed by radiographic, histological diagnosis and Raman microscopy until 12 weeks. The results show that MSCs improve the biocompatibility of CS/nHAC composites and enhance new bone formation in vivo at 12 weeks. It can be concluded that the injectable CS/nHAC composites combined with MSCs may be a novel method for reconstruction of irregular bone defects.     

Hydrophilic and hydrophobic interactions in cross-linked chitosan membranes

Chitosan membranes with different cross-linking density were prepared by modifying cross-linking time. Sodium tripolyphosphate was the cross-linking agent. A pulsed nuclear magnetic resonance study was performed on uncross-linked and cross-linked membranes. Different fraction of water molecules were identified in different zones within the membranes. The ratio of water molecules per chitosan repeating unit were calculated. A maximum of twelve water molecules were tightly coordinated to the chitosan repeating unit. Also, a very small water molecule fraction was identified but it was mobile enough as not to contribute to the dipolar interactions. The cross-linking reaction could lead to the formation of hydrophilic and hydrophobic interactions. These two types of interactions could result in the coexistence of a network formed by hydrophilic and hydrophobic micropores. This knowledge could be useful for the interpretation of results of hydrophobic drugs permeation across hydrophilic membranes. For example, the increment of estradiol fluxes across chitosan membranes with an increase in cross-linking density.