Phosphate Glass Fibre Composites for Bone Repair

We investigate high-modulus degradable materials intended to replace metals in biomedical applications.These are typicallycomposites comprising a polylactide(PLA)matrix reinforced with phosphate glass fibres,which provide reinforcementsimilar to E-glass but are entirely degradable in water to produce,principally,calcium phosphate.We have made compositesusing a variety of fibre architectures,from non-woven random mats to unidirectional fibre tapes.Flexural properties in theregion of 30 GPa modulus and 350 MPa strength have been achieved-directly comparable to quoted values for human corticalbone.In collaboration with other groups we have begun to consider the development of foamed systems with structures mimickingcancellous bone and this has shown significant promise.The fibres in these foamed structures provide improved creepresistance and reinforcement of the pore walls.To date the materials have exhibited excellent cellular responses in vitro andfurther studies are due to include consideration of the surface character of the materials and the influence of this on cell interaction,both with the composites and the glass fibres themselves,which show promise as a standalone porous scaffold.     

生物复合絮凝剂处理深圳湾污染水体的研究

深圳市西部海域近岸水体污染严重,水体发黑,淤泥沉积,气味恶臭,严重影响了海洋生态、周边居民生活质量与城市海岸线景观。采用高效环保的生物复合絮凝剂处理深圳近海污染水体。通过絮凝沉降技术,研究了复合絮凝剂对深圳湾近海污水处理的最佳絮凝、混凝条件,筛选了最佳絮凝剂配方及最佳浓度,结果表明壳聚糖乙酸溶液、聚合硫酸铁分别与海藻酸钠复合,终浓度为12—16ppm时处理近海污染水体效果最佳,同时可以有效抑制海洋有害弧茵。研究表明该生物复合絮凝剂可以有效处理近海污染水体。     

Effects of Surface Oxidation Treatment of Carbon Fibers on Biotribological Properties of CF/PEEK Materials

Carbon Fiber (CF) reinforced polyetheretherketone (PEEK) composite is one of the most promising implant biomaterials used in orthopedics.In this article,unfilled PEEK and CF/PEEK specimens were prepared by vacuum hot pressing method,and their tribological properties were evaluated by sliding against a cobalt-chromium-molybdenum (Co-Cr-Mo) alloy block.The influences of mass fraction of carbon fibers in CF/PEEK and the surface oxidation treatment of carbon fibers were explored.The results showed that the water contact angles on the surfaces of CF/PEEK specimens decreased,indicating that their surface wettability was improved.The hardness value of CF/PEEK was significantly improved,the friction coefficients of CF/PEEK were effectively reduced and its wear resistance was enhanced compared with unfilled PEEK.The leading effect on CF/PEEK tribological properties was the mass fraction of CF,followed by surface oxidation of CF,and the calf serum solution had better lubricity than that of saline and deionized water.     

In vitro antistaphylococcal effects of a novel 45S5 bioglass/agar–gelatin biocomposite films

Aims

To assess the antibacterial efficacy of new composite materials developed from microparticles of 45S5 bioactive glass (BG) and agar–gelatin films.

Methods and Results

In vitro antibacterial activity was evaluated against Staphylococcus spp. because of the importance of this pathogen in damaged tissues and in failures associated with biomaterial implants. To our knowledge, this is the first paper reporting on the suitable combination of BG and agar–gelatin for bioactive and antibacterial films. Bacterial suspensions up or below 10⁵ CFU ml^?1 reflecting situations of wound infection and of noninfection, respectively, were prepared and then put in contact with the biomaterials at 37°C. After 24 and 48 h of incubation, the pH value was measured and the staphylococci strains viability was determined by counting in Mueller–Hinton agar plates. Moreover, the biomaterials were prepared for observation under scanning electron microscopy (SEM). Biocomposites (BCs) showed a strong antibacterial effect against all staphylococci strains tested. Some differences were found depending on the strain, the inoculum size and the contact time. This effect was correlated with an alkalinization of the media. By SEM analyses, no bacterial presence was observed on the surface of BCs in any of the cell concentrations tested at any time.

Conclusions

Overall, the coating of 45S5 BG on agar–gelatin films promoted BCs with strong antistaphylococcal activity. The effect was efficient under bacterial concentration up or below 10⁵ CFU ml^?1. Additionally, none of the strains were found on BCs surfaces.

Significance and Impact of Study

45S5 bioglass/agar–gelatin biocomposite films are reported for the first time. The results suggest a potential application as wound dressing.     

Easy alignment and effective nucleation activity of ramie fibers in injection-molded poly(lactic acid) biocomposites

The poly(lactic acid) (PLA)/ramie fiber biocomposites were fabricated, which exhibited considerable reinforcement effect comparable to the glass fiber at the same loading. The attempts were made to understand the flow-induced morphology of ramie fibers and PLA crystals in the injection-molded PLA/ramie fiber biocomposites, thus revealing its relationship to biocomposite mechanical properties. The polarized optical microscopy (POM) and two-dimensional wide-angle X-ray diffraction (2D-WAXD) were for the first time used to determine the distribution of nature fibers, which interestingly showed the ramie fibers aligned well along the flow direction over the whole thickness of injection-molded parts, instead of skin-core structure. This easy alignment of ramie fibers during the common processing was ascribed to the intrinsically high flexibility of ramie fibers and strong interfacial interaction between PLA chains and cellulose molecules of ramie fibers. Both 2D-WAXD and differential scanning calorimeter (DSC) measurements suggested that the PLA matrix in its ramie biocomposites had rather high orientation degree and crystallinity, which was attributed to effective heterogeneous nucleation induced by ramie fibers and local shearing field in the vicinity of fiber surface. Remarkable improvement of mechanical and thermo-mechanical properties was achieved for PLA/ramie fiber biocomposites, without sacrifice of toughness and ductility. Addition of 30wt% ramie fibers increased the tensile strength and modulus of PLA/ramie fiber biocomposites from 65.6 and 1468 MPa for pure PLA to 91.3 and 2977 MPa, respectively. These superior mechanical properties were ascribed to easy alignment of ramie fibers, high crystallinity of PLA, and favorable interfacial adhesion as revealed by scanning electron microscopy (SEM) observation and theoretical analysis based on dynamic mechanical analysis (DMA) data.     

Mechanical characteristics of antibacterial epoxy resin adhesive wood biocomposites against skin disease

Moldy wood can cause some skin disease. However epoxy resin adhesive (EP) can inhibit mold growth. Therefore, antibacterial EP/wood biocomposites were reinforced and analyzed by the nonlinear finite element. Results show that glass fiber cloth and aluminum foil have the obvious reinforced effect under flat pressure, but this was not the case under side pressure. And when the assemble pattern was presented in 5A way, the strengthening effect was better. The nonlinear finite element showed that the aluminum foil and glass fiber cloth have the obvious reinforced effect. The mutual influence and effect of span, thickness and length on the ultimate bearing capacity of specimen were studied. And the simulation results agreed with the test. It provided a theoretical basis on the preparation of antibacterial EP/wood biocomposites against skin disease.     

Laminated Epoxy Biocomposites Based on Clay and Jute Fibers

Jute/epoxy hybrid laminated biocomposites were manufactured by using Illite clay particles at various content (5 wt.％-20 wt.％).The effects of hybridization on the morphology,structure,and mechanical properties were investigated.The properties of the biocomposites reinforced with jute fibers were mainly influenced by the interfacial adhesion between the jute fibers and the epoxy matrix.An alkali treatment was applied to improve the interfacial fiber-matrix adhesion and thus obtaining better mechanical properties.Besides the chemical treatment,epoxy hybridization using clay particles also had a strong effect on the overall properties of laminated biocomposites.The mechanical properties of the jute/epoxy biocomposites reinforced with Illite clay increased with clay content,up to an optimum value at 15 wt.％.The average technique and the laminates theory were performed to validate the coherence of the elastic moduli between the calculated and experimental values.A difference between the experimental and predicted data was observed,which was attributed to the simplifying assumptions made in both models.The laminates theory gave better overall predictions.     

Biosensitive and antibacterial coatings on metallic material for medical applications

Metallic materials are commonly used for load-bearing implants and as internal fixation devices. It is customary to use austenitic stainless steel, especially surgical grade type 316L SS as temporary and Ti alloys as permanent implants. However, long-term, poor bonding with bone, corrosion, and release of metal ions, such as chromium and nickel occur. These ions are powerful allergens and carcinogens and their uncontrolled leaching may be avoided by surface coatings. Therefore, bioactive glasses (BGs) became a vital biomedical material, which can form a biologically active phase of hydroxycarbonate apatite on their surface when in contact with physiological fluids. To reduce the high coefficient of friction and the brittle nature of BGs, polymers are normally incorporated to avoid the high-temperature sintering/densification of ceramic-only coatings. For medical application, electrophoretic deposition (EPD) is now used for polymer (organic) and ceramic (inorganic) components at room temperature due to its simplicity, control of coating thickness and uniformity, low cost of equipment, ability to coat substrates of intricate shape and to supply thick films in composite form, high purity of deposits as well as no phase transformation during coating. Although extensive research has been conducted on polymer/inorganic composite coatings, only some studies have reported multifunctional properties, such as biological antibacterial activity, enhanced cell adhesion, controlled drug release ability, and mechanical properties. This review will focus on biodegradable coatings, including zien, chitosan, gelatin, cellulose loaded with antibacterial drugs/metallic ions/natural herbs on biostable substrates (PEEK/PMMA/PCL/PLLA layers), which have the potential of multifunctional coating for metallic implants.