In vitro chondrogenesis with lysozyme susceptible bacterial cellulose as a scaffold

A current focus of tissue engineering is the use of adult human mesenchymal stem cells (hMSCs) as an alternative to autologous chondrocytes for cartilage repair. Several natural and synthetic polymers (including cellulose) have been explored as a biomaterial scaffold for cartilage tissue engineering. While bacterial cellulose (BC) has been used in tissue engineering, its lack of degradability in vivo and high crystallinity restricts widespread applications in the field. Recently we reported the formation of a novel bacterial cellulose that is lysozyme‐susceptible and ‐degradable in vivo from metabolically engineered Gluconacetobacter xylinus. Here we report the use of this modified bacterial cellulose (MBC) for cartilage tissue engineering using hMSCs. MBC's glucosaminoglycan‐like chemistry, combined with in vivo degradability, suggested opportunities to exploit this novel polymer in cartilage tissue engineering. We have observed that, like BC, MBC scaffolds support cell attachment and proliferation. Chondrogenesis of hMSCs in the MBC scaffolds was demonstrated by real‐time RT–PCR analysis for cartilage‐specific extracellular matrix (ECM) markers (collagen type II, aggrecan and SOX9) as well as histological and immunohistochemical evaluations of cartilage‐specific ECM markers. Further, the attachment, proliferation, and differentiation of hMSCs in MBC showed unique characteristics. For example, after 4 weeks of cultivation, the spatial cell arrangement and collagen type‐II and ACAN distribution resembled those in native articular cartilage tissue, suggesting promise for these novel in vivo degradable scaffolds for chondrogenesis. Copyright © 2013 John Wiley & Sons, Ltd.     

Fabrication of a blood compatible composite membrane from chitosan nanoparticles,ethyl cellulose and bacterial cellulose sulfate

A heparin-like composite membrane was fabricated through electrospinning chitosan nanoparticles (CN) together with an ethylcellulose (EC) ethanol solution onto a bacterial cellulose sulfate membrane (BCS). Scanning electron microscopy images revealed that there were no chitosan particles in the obtained composite CN-EC/BCS membranes (CEB), indicating CN had been stretched to nanofibers. X-ray photoelectron spectroscopy verified the existence of –NH₂ from chitosan and –SO₃⁻ from BCS on the surface of CEB membranes. Positively charged CN in the electrospinning solution and negatively charged BCS on the collector increased the electrostatic force and the electrospinning ability of the EC was increased. The membrane was hydrophobic, with a water contact angle higher than 120°. CEB membranes expressed good blood compatibility according to the results of coagulation time and platelet adhesion experiments. No platelets adhered on the surface of the CEB membranes. An inflammatory response was investigated according to activation of the macrophages seeded onto the membranes. Macrophages seeded on CEB membranes are not activated after 24 h incubation.

A blood compatible membrane was fabricated through electrospinning a solution of chitosan nanoparticles and ethylcellulose onto a bacterial cellulose sulfate membrane to mimic heparin''s structure.     

Bacterial cellulose as a potential meniscus implant

Traumatic or degenerative meniscal lesions are a frequent problem. The meniscus cannot regenerate after resection. These lesions often progress and lead to osteoarthritis. Collagen meniscal implants have been used in clinical practice to regenerate meniscal tissue after partial meniscectomy. The mechanical properties of bacterial cellulose (BC) gel were compared with a collagen material and the pig meniscus. BC was grown statically in corn steep liquid medium, as described elsewhere. Pig meniscus was harvested from pigs. The collagen implant was packed in sterile conditions until use. The different materials were evaluated under tensile and compression load, using an Instron 5542 with a 500 N load cell. The feasibility for implantation was explored using a pig model. The Young's modulus of bacterial cellulose was measured to be 1 MPa, 100 times less for the collagen material, 0.01 MPa in tensile load. The Young's modulus of bacterial cellulose and meniscus are similar in magnitude under a compression load of 2 kPa and with five times better mechanical properties than the collagen material. At higher compression strain, however, the pig meniscus is clearly stronger. These differences are clearly due to a more ordered and arranged structure of the collagen fibrils in the meniscus. The combination of the facts that BC is inexpensive, can be produced in a meniscus shape, and promotes cell migration makes it an attractive material for consideration as a meniscus implant.     

Insights into the effects of synthesis techniques and crosslinking agents on the characteristics of cellulosic aerogels from Water Hyacinth

Aerogel cellulose materials were synthesised from Water hyacinth and different crosslinkers, such as kymene and a mixture of polyvinyl alcohol (PVA) and glutaraldehyde (GA). The effects of using a magnetic stirrer and ultrasonic methods were investigated. The results show that materials prepared using ultrasonic methods have higher porosity and lower density. The thermal conductivity of the synthesised aerogel cellulose could be as low as 0.0281 W m K⁻¹, showing the good heat insulation performance of this material. Absorption capacity was tested using diesel oil (DO), and the highest capacities of 58.82 and 52.03 g g⁻¹ of DO were found with kymene and PVA + GA as crosslinkers, respectively. The reusability of the materials was tested. After 10 cycles, the DO absorption capacity was 62.8% of the value of the first cycle for the aerogel cellulose sample with kymene as the crosslinker and 72.7% for the sample with PVA + GA as the crosslinking agent.

Aerogel cellulose materials were synthesised from Water hyacinth and different crosslinkers, such as kymene and a mixture of polyvinyl alcohol (PVA) and glutaraldehyde (GA).     

细菌纤维素在组织工程中的应用

背景：细菌纤维素是纳米级纤维,具有许多独特的理化和机械性能及良好的生物相容性和可降解性等特性,目前已成为国际上新型组织工程材料的研究热点。 目的：分析细菌纤维素在组织工程中的应用。 方法：检索2004至2013年PubMed数据库和中国知网数据库中相关文献,英文检索词为＂bacterial cellulose; tissue engineering＂,中文检索词为＂细菌纤维素;组织工程＂。选取有关细菌纤维素在组织工程中应用方面密切相关文献48篇进行分析。 结果与结论：细菌纤维素具有高结晶度、高持水性、高机械强度、可降解性、良好的生物相容性和超细三维纳米网状纤维结构等独特特性,能作为生物活性分子的载体,维持生物活性分子的活性。同时,细菌纤维素通过改性修饰能提高其机械和生物特性,促进损伤组织的修复重建。目前已开始将细菌纤维素应用于组织器官重建中。细菌纤维素能作为生物活性分子的载体,但存在难以降解和功能单一等缺点,通过对细菌纤维素的改性修饰可以改善它的功能和促进降解。     

Fabrication of green poly(vinyl alcohol) nanofibers using natural deep eutectic solvent for fast-dissolving drug delivery

Fast-dissolving drug delivery systems are essential to drug delivery owing to the enhanced drug solubility, controlled drug concentration, target and rapid drug delivery. In this study, we developed fast-dissolving drug delivery systems using honey and acetylsalicylic acid-embedded poly(vinyl alcohol) (PVA) nanofibers based on natural deep eutectic solvent (DES). The efficacy of our fast-dissolving drug delivery system was tested by incorporating honey and acetylsalicylic acid in the PVA nanofibers. Firstly, the morphology and structure of the functional PVA–DES nanofibers (PVA–DES–honey and PVA–DES–ASA) were observed and analyzed, which proved the successful preparation of functional PVA–DES nanofibers. NIH/3T3 and HepG2 cells incubated on the nanofiber had more than 90% of cell viability, suggesting our materials were biocompatible and non-toxic. The nanofiber materials dissolved rapidly in artificial saliva solutions, suggesting potential use of our materials for fast dissolving drug delivery in oral cavities. The honey incorporated PVA nanofiber (PVA–DES–honey) showed a total bacterial reduction of 37.0% and 37.9% against E. coli and S. aureus, respectively, after 6 hour incubation in bacterial cultures. Furthermore, in vivo study proved that the PVA–DES–honey nanofibers accelerated the wound healing process, and they improved the wound healing rate on rat skin to 85.2% after 6 days of surgery, when compared to the control PVA (68.2%) and PVA–DES (76.3%) nanofibers. Overall, the nanofiber materials reported in our study showed potential as a green and biocompatible fast-dissolving drug delivery system and can be used for pharmaceutical fields, such as antibacterial wound dressing and oral ulcer stickers.

We report an environmental friendly method to construct honey/ASA embedded poly(vinyl alcohol) nanofibers based on natural deep eutectic solvent for fast-dissolving drug delivery firstly.     

Fused sphere carbon monoliths with honeycomb-like porosity from cellulose nanofibers for oil and water separation

Carbon monoliths with a unique hierarchical surface structure from carbonized cellulose nanofibers were synthesized in pursuit of developing carbon materials from sustainable natural resources. Through a 2-step hydrothermal – carbonization method, TEMPO-oxidized cellulose nanofibers were turned into carbon-rich hydrochar embedded with polystyrene latex as template for 80 nm-sized pores in a honeycomb pattern, while the triblock copolymer Pluronic F-127 was used for a dual purpose not reported before: (1) an interface between the cellulose nanofibers and polystyrene particles, as well as (2) act as a secondary template as ∼1 μm micelles that form hollow carbon spheres. The use of nanofibers allowed more contact between the carbon spheres to coalesce into a working monolith while optimizing the pore structure. Oil–water separation studies have shown that carbon monoliths have high adsorption capacity due to surface area and hydrophobicity. Testing against commercially available activated carbon pellets show greater performance due to highly-developed macropores.

Carbon monoliths with a unique hierarchical surface structure from carbonized cellulose nanofibers were synthesized in pursuit of developing carbon materials from sustainable natural resources.     

Investigating cellulose derived glycosaminoglycan mimetic scaffolds for cartilage tissue engineering applications

Articular cartilage has a limited capacity to heal and, currently, no treatment exists that can restore normal hyaline cartilage. Creating tissue engineering scaffolds that more closely mimic the native extracellular matrix may be an attractive approach. Glycosaminoglycans, which are present in native cartilage tissue, provide signalling and structural cues to cells. This study evaluated the use of a glycosaminoglycan mimetic, derived from cellulose, as a potential scaffold for cartilage repair applications. Fully sulfated sodium cellulose sulfate (NaCS) was initially evaluated in soluble form as an additive to cell culture media. Human mesenchymal stem cell (MSC) chondrogenesis in pellet culture was enhanced with 0.01% NaCS added to induction media as demonstrated by significantly higher gene expression for type II collagen and aggrecan. NaCS was combined with gelatine to form fibrous scaffolds using the electrospinning technique. Scaffolds were characterized for fibre morphology, overall hydrolytic stability, protein/growth factor interaction and for supporting MSC chondrogenesis in vitro. Scaffolds immersed in phosphate buffered saline for up to 56 days had no changes in swelling and no dissolution of NaCS as compared to day 0. Increasing concentrations of the model protein lysozyme and transforming growth factor‐β3 were detected on scaffolds with increasing concentrations of NaCS (p < 0.05). MSC chondrogenesis was enhanced on the scaffold with the lowest NaCS concentration as seen with the highest collagen type II production, collagen type II immunostaining, and expression of cartilage‐specific genes. These studies demonstrate the feasibility of cellulose sulfate as a scaffolding material for cartilage tissue engineering. Copyright © 2016 John Wiley & Sons, Ltd.     

Nanocellulose-based polymer hybrids and their emerging applications in biomedical engineering and water purification

Nanocellulose, derived from cellulose hydrolysis, has unique optical and mechanical properties, high surface area, and good biocompatibility. It is frequently used as a reinforcing agent to improve the native properties of materials. The presence of functional groups in its surface enables the alteration of its behavior and its use under different conditions. Nanocellulose is typically used in the form of cellulose nanocrystals (CNCs), cellulose nanofibers (CNFs), or bacterial nanocellulose (BNC). CNCs and CNFs have a high aspect ratio with typical lengths of ∼100–250 nm and 0.1–2 μm, respectively; BNC is nanostructured cellulose produced by bacteria. Nanohybrid materials are a combination of organic or inorganic nanomaterials with macromolecules forming a single composite and typically exhibit superior optical, thermal, and mechanical properties to those of native polymers, owing to the greater interactions between the macromolecule matrix and the nanomaterials. Excellent biocompatibility and biodegradability make nanocellulose an ideal material for applications in biomedicine. Unlike native polymers, nanocellulose-based nanohybrids exhibit a sustained drug release ability, which can be further optimized by changing the content or chemical environment of the nanocellulose, as well as the external stimuli, such as the pH and electric fields. In this review, we describe the process of extraction of nanocellulose from different natural sources; its effects on the structural, morphological, and mechanical properties of polymers; and its various applications.

Nanocellulose, derived from cellulose hydrolysis, has unique optical and mechanical properties, high surface area, and good biocompatibility.     

Waste brewed tea leaf derived cellulose nanofiber reinforced fully bio-based waterborne polyester nanocomposite as an environmentally benign material

Bio-resources have carved a unique niche for the ever-increasing thrust of the global scientific community to impart green credentials to various research outputs along with the demands for advanced materials. In this milieu, the authors wish to fabricate a fully bio-based waterborne polyester nanocomposite as an advanced material using different bio-based reactants and cellulose nanofibers as the nanomaterial. Three different compositions of the nanocomposite were prepared at different loadings of cellulose nanofibers (0.25, 0.5 and 1 weight%) which were isolated from waste brewed green tea leaves. The structural attributes of the nanocomposites were evaluated by Fourier transform infrared spectroscopic, X-ray diffraction, scanning electron microscopic and transmission electron microscopic studies. The nanocomposites were further cured with glycerol based epoxy and fatty acid based poly(amido amine) as the hardener to obtain the respective thermosets. The significant improvements in mechanical properties including tensile strength (13.71–22.33 MPa), elongation at break (128–290%), toughness (15.65–45.18 MJ m⁻³) and scratch hardness (8 to >10 kg) were observed for the thermosetting nanocomposites and the thermogravimetric analysis supports their high thermostability (234–265 °C). Further, the thermosetting nanocomposites were found to be highly biodegradable by Bacillus subtilis and Pseudomonas aeruginosa bacterial strains, hemocompatible with the erythrocytes present in RBCs and showed antioxidant properties. Thus, this nanocomposite could be used as a promising eco-friendly material for different related applications.

A fully bio-based waterborne polyester/cellulose nanofiber nanocomposite was fabricated by an environmentally benign route as a safe and biodegradable material.     

Preparation of asiaticoside-loaded coaxially electrospinning nanofibers and their effect on deep partial-thickness burn injury

Sodium alginate and chitosan were in favor of wound healing. However, the two polymers were not compatible in one formulation due to the electrostatic interaction. Coaxially electrospinning technology could make two or more noneletrospun polymers to be electrospun in independent core and shell layer. Asiaticoside-loaded coaxially electrospinning nanofibers of alginate, polyvinyl alcohol (PVA) and chitosan (alginate/PVA/chitosan) were prepared and evaluated. Morphologies and microstructure of nanofibers were observed with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Drug release in vitro of coaxial nanofibers was also evaluated. Deep partial-thickness burn injury were established and used to evaluate the improved healing effect of asiaticoside-loaded coaxial nanofibers. Drug-loaded coaxial nanofibers prepared with the optimized formulations and technologies had the obvious core-shell structure. Coaxial nanofibers showed faster drug release profiles in vitro and this facilitated wound healing. Its healing effect on rats with deep partial-thickness burn injury was also significant based on morphology, wound healing ratio, and pathological sections. Positive expression of vascular endothelial growth factor (VEGF), cluster of differentiation 31 (CD31), and proliferating cell nuclear antigen (PCNA), and down regulation of tumor necrosis factor (TNF) and interleukin-6 (IL-6) also validated the improved effect of wound healing. In general, the asiaticoside-loaded coaxial nanofibers had obvious core-shell structure with smooth surface and uniform diameter. Its healing effect on deep partial-thickness burn injury of rats was obvious. Asiaticoside-loaded coaxial nanofibers provide a novel promising option for treatment of deep partial-thickness burn injury.     

A green approach to prepare hierarchical porous carbon nanofibers from coal for high-performance supercapacitors

A green method is designed to obtain hierarchical porous carbon nanofibers from coal. In the work, deionized water, coal, polyvinyl alcohol and Pluronic F127 are used as the aqueous solution, carbon source, spinning assistant and soft template for spinning, respectively. As electrode materials for supercapacitors, the obtained hierarchical porous carbon nanofibers exhibit a high specific capacitance of 265.2 F g⁻¹ at 1.0 A g⁻¹ in 6 M KOH, a good rate performance with a capacitance of 220.3 F g⁻¹ at 20.0 A g⁻¹ with the retention of 83.1% and a superior cycle stability without capacitance loss after 20 000 charge/discharge cycles at 10.0 A g⁻¹. Compared with the carbon nanofibers constructed without Pluronic F127, the enhanced electrochemical performance of the sample benefits from a larger contact surface area and the mesoporous structure formed by decomposition of Pluronic F127 and good structural stability. This work not only provides a green route for high-value utilization of coal in energy storage, but also paves a new way to make hierarchical porous carbon nanofibers from coal for supercapacitor electrodes with high specific capacitance and long cycle life.

A green method is designed to obtain hierarchical porous carbon nanofibers from coal for supercapacitor electrodes with high specific capacitance and long cycle life.     

不同生物止血材料研究进展及复合型止血材料的临床应用

背景:随着生物医用高分子材料如纤维素、甲壳素等天然高分子材料以及聚乙烯醇、胶原等合成高分子材料的研发,止血材料的运用和发展获得了飞跃.目的:文章综述了近年来不同种类高分子止血敷料的研究进展,评价了不同种类复合止血敷料的临床应用价值.方法:应用计算机检索万方和PubMed数据库中1996-01/2010-12关于医用高分子止血敷料研究应用的文章,在标题和摘要中以"止血材料;纤维蛋白;高分子材料;胶原蛋白;明胶海绵"或"biological;occlude the flow of blood;gelatin sponge; fibrae sanguis"为检索词进行检索.选择医用高分子止血敷料领域发表在近期文献或权威杂志上的文章.初检得到126篇文献,根据纳入标准选择28篇文章进行综述.结果与结论:近年来国内外主要应用的可吸收止血材料包括壳聚糖、纤维蛋白胶、吸收性明胶海绵、微纤维胶原等以及常用的按材质和用途分类的藻酸盐类和水胶体类,不同的止血材料其止血机制和止血效果均不相同.文章通过对多种复合止血材料的效果进行比较观察,说明了各种止血材料止血途径和止血机制还有待进一步的研究,以便于开发出更卓越、更有效的止血材料.     

Bacterial community structure and diversity in the gut of the muga silkworm,Antheraea assamensis (Lepidoptera: Saturniidae), from India

The muga silkworm, Antheraea assamensis, is exclusively present in the northeastern regions of India and rearing of this silkworm is a vocation unique to this region in the world. Through culture‐dependent techniques, generic identification using 16S ribosomal RNA probes, diversity analysis and qualitative screening for enzyme activities, our studies have identified a number of bacterial isolates, viz. Bacillus spp., Serratia marcescens, Stenotrophomonas maltophilia, Pseudomonas stutzeri, Acinetobacter sp. and Alcaligens sp., inhabiting the gut of the muga silkworm. Analysis of the culturable bacterial community from the gut of An. assamensis revealed that Bacillus (54%) was the predominant bacterial genus followed by Serratia (24%), Pseudomonas (10%) and Alcaligens (6%). Significant differences in the Shannon–Wiener (H') and Simpson (D) diversity indices of gut bacteria were recorded for An. assamensis collected from different regions. H' and D values were found to be highest for An. assamensis from the Titabar region (H' = 4.73 ± 0.43; D = 10.00 ± 0.11) and lowest for individuals from the Mendipathar region (H' = 2.1 ± 0.05; D = 0.04 ± 0.00) of northeastern India. Qualitative screening for enzyme activities identified about 26 gut bacterial isolates having significantly higher cellulose, amylase and lipase activities. These isolates probably contribute to the digestion and nutrition of their host insect, An. assamensis.     

Hybrids based on borate-functionalized cellulose nanofibers and noble-metal nanoparticles as sustainable catalysts for environmental applications

Polymeric supports from renewable resources such as cellulose nanomaterials are having a direct impact on the development of heterogenous sustainable catalysts. Recently, to increase the potentiality of these materials, research has been oriented towards novel functionalization possibilities. In this study, to increase the stability of cellulose nanofiber films as catalytic supports, by limiting the solubility in water, we report the synthesis of new hybrid catalysts (HC) based on silver, gold, and platinum nanoparticles, and the corresponding bimetallic nanoparticles, supported on cellulose nanofibers (CNFs) cross-linked with borate ions. The catalysts were prepared from metal precursors reduced by the CNFs in an aqueous suspension. Metal nanoparticles supported on CNFs with a spherical shape and a mean size of 9 nm were confirmed by TEM, XRD, and SAXS. Functionalized films of HC-CNFs were obtained by adding a borate solution as a cross-linking agent. Solid-state ¹¹B NMR of films with different cross-linking degrees evidenced the presence of four different boron species of which the bis-chelate is responsible for the cross-linking of the CNFs. Also, it may be concluded that the bis-chelate and the mono-chelates modify the microstructure of the film increasing the water uptake and enhancing the catalytic activity in the reduction of 4-nitrophenol.

We report the synthesis of supported noble metal nanoparticles on cellulose nanofibers cross-linked with borate as highly efficient sustainable catalysts.     

Cross-linked polyvinyl alcohol-xanthan gum hydrogel fabricated by freeze/thaw technique for potential application in soft tissue engineering

The search for materials and process parameters capable of generating hydrogels for soft tissue engineering applications, based on an experimental design strategy that allows the evaluation of several factors involved in their development and performance, has greatly increased. Nevertheless, the fabrication technique can influence their mechanical properties, swelling, crystallinity, and even their susceptibility to contamination by microorganisms, compromising their performance within the tissue or organ. This study aimed to evaluate the influence of the freeze/thaw technique on different characteristics of polyvinyl alcohol–xanthan gum hydrogel. Methods: this research analyzed the critical variables of the freeze/thaw process through a systematic study of a 2^k factorial design of experiments, such as the proportion and concentration of polymers, freezing time and temperature, and freeze/thaw cycles. Additionally, physicochemical analysis, susceptibility to bacterial growth, and cell viability tests were included to approximate its cytotoxicity. The optimized hydrogel consisted of polyvinyl alcohol and xanthan gum at a 95 : 5 ratio, polymer mixture concentration of 15%, and 12 h of freezing with three cycles of freeze/thaw. The hydrogel was crystalline, flexible, and resistant, with tensile strengths ranging from 9 to 87 kPa. The hydrogel was appropriate for developing scaffolds for soft tissue engineering such as the cardiac and skeletal muscle, dermis, thyroid, bladder, and spleen. Also, the hydrogel did not expose an in vitro cytotoxic effect, rendering it a candidate for biomedical applications.

A polyvinyl alcohol–xanthan gum hydrogel was developed and the influence of the freeze/thaw technique on different characteristics was evaluated.     

Engineering microporosity in bacterial cellulose scaffolds

The scaffold is an essential component in tissue engineering. A novel method to prepare three-dimensional (3D) nanofibril network scaffolds with controlled microporosity has been developed. By placing paraffin wax and starch particles of various sizes in a growing culture of Acetobacter xylinum, bacterial cellulose scaffolds of different morphologies and interconnectivity were prepared. Paraffin particles were incorporated throughout the scaffold, while starch particles were found only in the outermost area of the resulting scaffold. The porogens were successfully removed after culture with bacteria and no residues were detected with electron spectroscopy for chemical analysis (ESCA) or Fourier transform infra-red spectroscopy (FT-IR). Resulting scaffolds were seeded with smooth muscle cells (SMCs) and investigated using histology and organ bath techniques. SMC were selected as the cell type since the main purpose of the resulting scaffolds is for tissue engineered blood vessels. SMCs attached to and proliferated on and partly into the scaffolds.     

Bacterial cellulose modified with xyloglucan bearing the adhesion peptide RGD promotes endothelial cell adhesion and metabolism--a promising modification for vascular grafts

Today, biomaterials such as polytetrafluorethylene (ePTFE) are used clinically as prosthetic grafts for vascular surgery of large vessels (>5 mm). In small diameter vessels, however, their performance is poor due to early thrombosis. Bacterial-derived cellulose (BC) is a new promising material as a replacement for blood vessels. This material is highly biocompatible in vivo but shows poor cell adhesion. In the native blood vessel, the endothelium creates a smooth non-thrombogenic surface. In order to sustain cell adhesion, BC has to be modified. With a novel xyloglucan (XG) glycoconjugate method, it is possible to introduce the cell adhesion peptide RGD (Arg-Gly-Asp) onto bacterial cellulose. The advantage of the XG-technique is that it is an easy one-step procedure carried out in water and it does not weaken or alter the fiber structure of the hydrogel. In this study, BC was modified with XG and XGRGD to asses primary human vascular endothelial cell adhesion, proliferation, and metabolism as compared with unmodified BC. This XG-RGD-modification significantly increased cell adhesion and the metabolism of seeded primary endothelial cells as compared with unmodified BC whereas the proliferation rate was affected only to some extent. The introduction of an RGD-peptide to the BC surface further resulted in enhanced cell spreading with more pronounced stress fiber formation and mature phenotype. This makes BC together with the XG-method a promising material for synthetic grafts in vascular surgery and cardiovascular research.     

榄香烯透皮凝胶的制备及体外透皮性能

背景:选择合适的载体材料对药物透皮性能的影响是制备榄香烯透皮制剂首先要解决的问题。目的:建立一种榄香烯透皮凝胶并观察其体外透皮性能。方法:采用具有良好生物相容性的亲水性高分子材料聚乙烯醇和羧甲基纤维素钠制备榄香烯透皮制剂。在体外透皮实验装置上,用鼠背皮肤为屏障进行经皮渗透实验,高效气相色谱检测榄香烯的经皮渗透量。结果与结论:聚乙烯醇和羧甲基纤维素钠的使用比例对榄香烯的透皮能力没有显著影响;两种高分子骨架材料在凝胶基质中的浓度对榄香烯透皮能力有一定的影响,以30%含量(聚乙烯醇与羧甲基纤维素钠总量)为最佳。提示此种透皮凝胶可用作榄香烯的良好载体。