In vivo Degradation and histocompatibility of a novel class of fluorescent copolyanhydrides, poly{[di(p-carboxyphenyl) succinate]-co-(sebacic anhydride)}

In this work, the in vivo degradation and tissue compatibility of a novel class of inherently fluorescent copolyanhydrides, P(dCPS:SA), were investigated. It was found that the degradation of the copolyanhydrides increased with the increase of SA content in the copolymers. The in vivo degradation rate of the copolymers was slower than that studied in vitro. A surface erosion characteristic of the copolyanhydrides was revealed by SEM and fluorescent microscopy. Mild inflammatory reactions were observed on days 6 and 10 after implantation for all the studied copolymers. By the end of 30 d, there were almost no inflammation reactions taking place.     

Multi-compartment containers from a mixture of natural and synthetic lipids

Small anionic liposomes were electrostatically adsorbed on the surface of larger cationic liposomes thus forming multi- compartment complexes composed exclusively of natural and synthetic lipids. The complexes contained two dozen anionic liposomes per a single cationic liposome and showed low cytotoxicity and ability to enzyme-induced bio-degradation. The liposomal multi-compartment complexes demonstrate great application potential as containers for drug encapsulation and delivery.     

Decolorization of textile dye effluent by genetically improved bacterial strains

Synthetic dyes are released into the environment from textile industrial effluents. The discharge of this colored wastewater into rivers and lakes leads to a reduction in sunlight penetration in natural water bodies, which, in turn, decreases both photosynthetic activity and dissolved oxygen concentration and is toxic to living beings. Bacterial isolates are optimized for growth and biomass production before using them for decolorizing dye effluent. The bacterial isolates Bacillus sp. 1 and Bacillus sp. 2 were employed at different percentages by volume with standard nutrient concentration. Of these bacterial isolates Bacillus sp. 2 recorded maximum color reduction. The pH and electrical conductivity (EC) were reduced in the decolorized effluent, and a reduction in biologic oxygen demand, chemical oxygen demand, total suspended solids, and total dissolved solids (TDS) were also observed.     

Modeling Microbial Transport and Biodegradation in a Dual-porosity System

A mathematical model describing microbial transport and growth in a heterogeneous aquifer domain, composed of overlapping subdomains of high-permeability and low-permeability materials, is developed. Each material is conceptually visualized as a continuum which occupies the entire considered spatial aquifer domain. Based on the assumption that advection in the low-permeability domain is negligible, the mathematical model is solved by using a publically available reactive transport code. The importance of modeling microbial transport and growth in such a dual-porosity system is demonstrated through a hypothetical case study.     

Electrospun Non-Woven Fabrics of Poly(ϵ-caprolactone) and Their Biodegradation by Pure Cultures of Soil Filamentous Fungi

The biodegradation of electrospun nano-fibers of poly(ϵ-caprolactone) was firstly investigated, using pure-cultured soil filamentous fungi. In the biochemical oxygen demand test, the biodegradation of the nano-fiber exceeded 20-30% carbon dioxide generation. The biodegradabilities decrease with increase of the mean fiber diameter.     

Unprecedented Biodegradable Cellulose-Derived Polyesters with Pendant Citronellol Moieties: From Monomer Synthesis to Enzymatic Degradation

Levoglucosenone (LGO) is a cellulose-derived molecule that is present commercially on a multi-ton/year scale. Taking advantage of the α,β-conjugated ketone of LGO, a new citronellol-containing 5-membered lactone (HBO-citro) was synthesized through a one-pot two-step pathway involving oxa-Michael addition and Baeyer-Villiger oxidation. The solvent-free treatment of HBO-citro with NaBH₄ at room temperature led to the full reduction of the lactone moiety which gave a novel fully renewable triol monomer having a citronellol side chain (Triol-citro). Noticeably, by simply changing the reducing agent, temperature and reaction duration, the partial reduction of HBO-citro can be achieved to yield a mixture of 5- and 6-membered Lactol-citro molecules. Triol-citro was chosen to prepare functional renewable polyesters having citronellol pendant chains via polycondensation reactions with diacyl chlorides having different chain lengths. Good thermal stability (T_d5% up to 170 °C) and low glass transition temperatures (as low as −42 °C) were registered for the polyesters obtained. The polymers were then hydrolyzed using a commercial lipase from Thermomyces lanuginosus (Lipopan^® 50 BG) to assess their biodegradability. A higher degradation profile was found for the polyesters prepared using co-monomers (acyl chlorides) having longer chain lengths. This is likely due to the decreased steric hindrance around the ester bonds which allowed enhanced accessibility of the enzyme.     

Synthesis and characterization of a family of biodegradable poly(ester amide)s derived from glycine

A series of aliphatic poly(ester amide)s derived from 1,6-hexanediol, glycine, and diacids with a variable number of methylenes (from 2 to 8) have been synthesized and characterized. Infrared spectroscopy shows that the studied polymers present a unique kind of hydrogen bond that is established between their amide groups. Thermal properties as melting, glass transition, and decomposition temperatures are reported. The data indicate that all the polymers are highly crystalline. Thus, different kinds of spherulites (positive and/or negative) were obtained depending on the preparation conditions and on the polymer samples. Moreover, all the polymers crystallized from dilute diol solutions as ribbonlike crystals where a regular folding habit and a single hydrogen bond direction could be deduced. A test of enzymatic hydrolysis was employed to assess the potential biodegradability of these polymers. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1271–1282, 1998     

电子穿梭体介导的微生物胞外电子传递:机制及应用

厌氧条件下微生物将电子传递给胞外电子受体的现象非常普遍,电子穿梭体(electron shuttle,ES)是介导胞外电子传递过程的重要途径之一,但其具体的机制尚未明晰。一部分微生物自身能分泌一些物质作为内生ES,另一部分微生物能利用天然存在或人工合成的某些物质作为外生ES,并将其携带的电子传递至微生物胞外电子受体。ES介导微生物胞外电子传递的基本过程为:氧化态电子穿梭体(ES_ox)接受电子变成还原态(ES_red),ES_red传递电子给胞外电子受体,自身再次氧化成ES_ox,从而循环往复。本文重点介绍不同种类ES及其电子穿梭机制,以及ES的分子扩散、氧化还原电势及电子转移能力对胞外电子传递过程的影响。ES介导的胞外电子传递过程直接影响污染物转化和微生物产电,因此在污染修复及生物能源等方面具有重要的应用前景。     

改性淀粉/PVA生物降解材料性能的研究

以BPO为引发剂、正庚烷为溶剂在66℃下制得马来酸酐接枝淀粉。将其与聚乙烯醇(PVA)、增塑剂及加工助剂等于HAAKE密炼机中共混,制备了可生物降解热塑性淀粉塑料。研究了接枝改性淀：粉／PVA共混物的力学性能、生物降解性能及热性能等,并用SEM研究了共混物的微观形态。结果表明接枝改性淀粉／PVA共混物拉伸强度为27．57Mpa,60d失重率达65．1％。     

Environmental biodegradation of synthetic polymers I. Test methodologies and procedures

Biodegradation of synthetic polymers is an important property that is used in many applications. Evaluation of the extent of biodegradation has used different methods in recent years. For each environmental compartment, different approaches have to be made in order to obtain valuable data on biodegradability.This review describes validated and accepted methods based on standardized biodegradation tests, analytical tests, enzymatic tests or tests of physical properties to evaluate the biodegradability of synthetic polymers for different types of environmental compartments (e.g., soil, compost or aqueous media).Part II of this review will subsequently report on the environmental biodegradation of different groups of synthetic polymers.