Preparation of super-hydrophobic surface on biodegradable polymer by transcribing microscopic pattern of water-repellent leaf

Super-hydrophobic surface has been prepared onto biodegradable polymer by a combination of transcribing microscopic structure of a water-repellent leaf and a chemical treatment. An aroid leaf has been chosen for the preparation of the super-hydrophobic surface since the leaf has concavity microscopic structure, which is easy to handle for a material use. The microscopic pattern was transcribed onto poly(ε-caprolactone) (PCL) sheet by using replica method, then it was further treated by soaking in a mixture of acetone/methanol solution. The resultant PCL having the microscopic concavity pattern showed high water contact angle of 148° and also showed antibacterial property for filamentous fungi.     

Biodegradable fraction of organic carbon estimated under oxic and anoxic conditions

The biodegradability of water samples is usually estimated with bioassays under oxic conditions. In order to overcome some of the drawbacks linked to the incubation of the samples in aerobic batches, a new protocol is proposed and tested, which is based on an organic carbon (OC) balance after a 45 days incubation under anoxic conditions with excess nitrate. The biodegradable fractions of organic matter obtained with the anoxic protocol are slightly lower than those obtained under oxic conditions. Several possible reasons for a systematic underestimation of the biodegradable organic matter under anoxic conditions are evaluated and discussed: a reduced microbial metabolic potential, significantly reduced degradation rates for the slowly biodegradable organic matter, an additional production of refractory organic compounds during the incubation, or the inhibition of the recycling of the organic matter stored in bacterial biomass. Nevertheless, the 7% difference observed on the biodegradable total OC estimations keeps low enough so that the anoxic protocol can be proposed as a convenient alternative to the oxic one.     

Osteointegration of poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) scaffolds incorporated with violacein

This work reports on the production and in vivo evaluation of biodegradable scaffolds of poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) incorporated with violacein, an antibiotic and antitumoral agent. PHBV produced in a bioreactor by Chromobacterium violaceum was pressed and partially sintered to produce scaffolds with 3 mm of diameter and 3 mm of height. The scaffolds were microstructurally characterized and exhibited suitable micromorphology for bone ingrowth. The PHBV-violacein scaffolds were implanted in femur of Wistar rats, extracted and analyzed after 30 and 60 days of surgery. Histological evaluation revealed that no inflammatory reaction occurred and new bone tissue was formed in the implant. The results indicated that PHBVs with violacein are potential candidates for application in regenerative bone tissue engineering.     

Biodegradation Study on the Starch-LDPE Film by Soil Micro-organism

Abstract

Degradation of low density polyethylene (LDPE) film containing starch as the biodegradable additive has been studied by isolating a soil microbe identified as Pseudomonous species. The degradation of the film was monitored by mechanical property and the surface starch concentration by UV-spectrophotometry at different intervals of time. The degradation depends on the accessibility of starch i.e., the carbon source in the starch-LDPE film. By adding external carbon source like, monosaccharide and disaccharide sugars some changes in the rate of biodegradation was observed. The ultimate fall in tensile strength was higher for the film when exposed to a nutrient medium without any external carbon source. Mostly the added sugar helps in the growth of micro-organisms. Among the various external carbon sources, maltose was found to be the best. In case of maltose the loss of tensile strength was 50% in 58 days, but the film without additional sugar showed a fall in tensile strength of 48% in the same period.     

In vitro degradation properties of ion-beam irradiated poly(lactide-co-glycolic acid) mesh

Scaffolds for tissue regeneration must be biocompatible and biodegradable. Ion-beam irradiation is useful for making polymers biocompatible, but the process by which the irradiated polymers biodegradable is not yet well understood. We investigated this phenomenon by Kr⁺-irradiated poly(lactide-co-glycolic acid) (PLGA) mesh substrate at an acceleration energy of 50 keV with fluences of 1 × 10¹³ and 1 × 10¹⁴ ions/cm². We then measured the electronic states of the constituent elements on the irradiated surface by X-ray photoelectron microscopy (XPS) and evaluated the hydrolytic degradation properties (weight loss, media pH, and tensile strength) of the mesh in phosphate buffer solution. New functional groups and carbonization were induced on the irradiated surface. Degradation rate and tensile strength remain unchanged by ion-beam irradiation. Ion-beam irradiation should, thus, be a promising modification technique for tissue engineering scaffolds.     

PLA—PEG共聚物的合成与性能研究

采用熔融缩聚法合成一定分子量的聚乳酸（PLA）,并用聚乙二醇（PEG）的聚氨酯预聚体进行扩链。研究了扩链反应条件对产物分子量的影响及产物的热性能。结果表明,扩链反应后PLA的分子量有大幅度提高,且扩链前后的PLA都具有良好的热稳定性。     

生物降解型聚氨酯材料的研究进展

论述了国内外生物降解型聚氨酯材料的种类及其性能,以及在各个应用领域中的发展前景。     

Local antibiotic delivery systems for the treatment of osteomyelitis – A review

Osteomyelitis, an inflammatory process accompanied by bone destruction, is caused by infective microorganisms. The high success rates of antimicrobial therapy by conventional routes of administration in controlling most infectious diseases have not yet been achieved with osteomyelitis for several reasons. Local and sustained availability of drugs have proven to be more effective in achieving prophylactic and therapeutic outcomes. This review introduces osteomyelitis – its present options for drug delivery and their limitations, and the wide range of carrier materials and effective drug choices. Local drug delivery for osteomyelitis is a topic of importance for more than 20 years. Carrier materials used for local delivery of antibiotics may be classified as nonbiodegradable and biodegradable. Commonly used non biodegradable carrier materials are polymethyl methacrylate (PMMA), Acrylic beads, PMMA bone cement etc. and biodegradable materials are hydroxyapatite block, bioactive glass ceramics, collagen sponge, polylactide/ployglycolide implants. Both the systems release antibiotic at concentrations exceeding the minimum inhibitory concentrations (MICs) for the most common pathogens involved in osteomyelitis without causing any adverse systemic effects although non biodegradable beads are to be removed from the surgical site after completion of antibiotic release.     

Matrix Tablets of Carrageenans. II. Release Behavior And Effect of Added Cations

Carrageenans are hydrocolloids in the rubbery state at standard conditions. They are useful excipients for controlled-release tablets. Three carrageenans, two κ-carrageenans (Gelcarin® GP-812 NF and GP-911 NF) and one ι-carrageenan (Gelcarin GP-379 NF), are analyzed regarding their release behavior in combination with sorption, swelling, and rheology. The l-carrageenan has a higher substitution by sulfate groups. The κ-carrageenan Gelcarin GP-812 NF contains a small amount of potassium chloride left over from processing. Water sorption of the pure materials was studied gravimetrically, and the rheology of different solutions (2% and 5% w/w) was studied by cup-cylinder rotation viscosimetry. Swelling was determined as the vertical expansion of the tablets with a specially designed swelling apparatus. Drug release from the tablets was performed by the USP paddle method for 8 hr. The data indicate that drug release increases when water sorption and swelling extent decrease and as viscosity increases. The order of release is nearly zero-order kinetics for theophylline monohydrate, a nonionic drug. Diffusion of the anionic drug diclofenac sodium is anomalous. In addition, the influence of the added salts potassium and calcium chloride on swelling and release was studied. Before tableting, physical mixtures of these salts with and without theophylline monohydrate were prepared. Swelling and release change in the same order, but this is only valid when the ionic interactions responsible for this are strong enough. Besides this, physical mixing of salts with the carrageenans can result in an increased release of drug caused by decreased cohesion of the matrix during drug release, mainly for calcium chloride.     

红外光谱法快速鉴别可降解一次性塑料制品

研究了快速鉴别可降解一次性塑料制品成分的方法。首先利用衰减全反射红外光谱方法采集市场常见生物降解塑料的红外光谱图,作为标准对照谱图。然后收集市场一次性可降解塑料制品,包括塑料袋、餐盒、餐具、杯子、吸管等,用手术刀切下制品薄层,采用衰减全反射红外光谱法对薄层进行表征,结合生物降解塑料标准对照谱图及常见塑料填料标准谱图确定一次性塑料制品成分。在此基础上选择有代表性的一次性塑料制品的红外谱图,建立一次性可降解塑料制品标准红外谱图库。结果表明:采集样品材质可分三大类,分别以聚乳酸、淀粉、聚对苯二甲酸/己二酸/丁二酯为主体添加适当填料。未知样品与谱库数据匹配度,可作为未知样品的初步判定依据。可见通过红外光谱衰减全反射分析方法可以对可降解一次性塑料制品材质成分进行分析,该方法无需前处理,操作简单,为大批量可降解包装制品检测提供了一种简便、快捷、准确的方法。