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Antimicrobials and Biocides

Octa(3-chloropropylsilsesquioxane) and a soluble, low molec.wt. poly(3-chloropropylsilsesquioxane) were subjected to a reaction with dimethyl n-octylamine to convert part or almost all of the chloropropyl groups to corresponding quaternary ammonium salt(QAS) groups. Polysilsesquioxanes containing secondary n-amylammonium salt(SAS) groups were synthesised by reaction of n-alkyl bromides with poly(3-aminopropylsilsesquioxane) of limited molec.wt. or by amination of n-amyl bromide with 3-aminopropyltriethoxysilane, followed by hydrolysis and polycondensation. The antibacterial activity of these QAS- and SAS-containing silsesquioxane materials against two representative Gram-positive and three representative Gram-negative bacterium strains were tested. Most of these materials showed high or moderate activity against Gram-positive bacteria and moderate or weak activity against Gram-negative bacteria. They could be of use, for example, as fillers and biocides in polymeric materials or in paints. 28 refs.

The need for and effectiveness of antimicrobials for protecting PU from microbial degradation and the variables to be taken into account when considering antimicrobials for PU substrates are discussed. Methods of determining the ability of PU products to resist microbial attack and test methods to characterise the antimicrobial effect of products are described and discussed and soil burial applications are briefly considered. 4 refs.

The mechanical properties of polymers containing milled soda-lime-glass foam were investigated and compared with those of polymers containing mineral fillers and glass fibres. The biocidal action of silver containing glass foam fillers was also investigated and potential applications for the filled polymers, such as anti-slip coatings and plastics colouring, indicated. (22nd International Conference on Fillers of Polymers, 21-22 March, 2006, Koeln, Rapra Technology Ltd., Germany)

The antimicrobial and antifungal properties of samples of a knitted polyamide/polyurethane composite fabric, treated with gentamine sulphate and a natural antimicrobial preparation, were evaluated in vitro against various bacteria and a fungus. The effects of the treatment on the tensile and tear strengths, stiffness and elasticity of the fabric were also evaluated. An increase in tensile properties was observed after treatment. Testing of the fabrics in vivo against human skin indicated that the materials were suitable in both treated and untreated forms for use as a compression textile. 19 refs.

Chemically modified chitosan (QTS) was characterised using Fourier transform infrared spectroscopy, and its microbiocidal activity was examined with respect to its molecular weight, concentration in solution, solution pH, and presence of surfactant. QTS was soluble in water, whereas the original chitosan was not, and its water solubility was estimated. Biocidal activity was high towards gram-positive bacteria, but decreased with decreasing molecular weight, and biocidal activity towards gram-negative bacteria was not special. Presence of surfactant had no significant effect. 22 refs.

Graft polymerisation of vinylimidazole onto polypropylene was used to prepare antimicrobial sutures. Sutures were characterised using tensile tests, thermogravimetric analysis, water absorption measurements and drug immobilisation and release studies. Antimicrobial properties were evaluated against E.coli. It was shown that grafting increases the thermal stability of the suture, and water uptake of sutures was reasonable. Initial drug release was quite fast, but slowed down after the initial burst. 24 refs.

A novel wound dressing material was prepared by electrospinning poly(vinyl alcohol) (PVA)/AgNO3 aqueous solution into nonwoven webs and then treating the webs by heat or UV radiation. Through SEM, TEM, and XPS analyses, it was observed that the silver (Ag) nanoparticles were generated and existed in the near surface of the electrospun nanofibres. It was found that heat treatment as well as UV radiation reduced the Ag+++ ions in the electrospun PVA/AgNO3 fibre web into the Ag nanoparticles. Also the heat treatment improved the crystallinity of the electrospun PVA fibre web and so it made the web unsolved in moisture environment. Therefore, it was concluded that the only heat treated electrospun PVA/AgNO3 fibre web was a good material as wound dressings because it had structural stability in moisture environment as well as excellent antimicrobial ability and, quick and continuous release of the effectiveness. 13 refs.

Twenty-one papers are presented at this first international conference on food contact in polymers. Papers are divided into the following sessions: regulatory developments, migration research, food contact materials, sustainable design and recycling of food packaging, biodegradable food contact materials, and innovations in food packaging.

The benefits and risks of active and intelligent food packaging are examined, and the differences between the two types of packaging are explained. Intelligent packaging does not affect food. It provides information on the conditions of the packaged food. This information can be related to storage conditions, gas composition (generation of carbon dioxide, or leakage detector). It can also detect metabolites or chemical reaction products. It is placed either inside or outside the primary food packaging. Typical examples of the information provided by intelligent packaging include time-temperature indicators, oxygen, carbon dioxide, microbial growth and ripening indicators. Active packaging involves the use of active absorbers/scavengers which are designed to remove constituents from the food or from its environment. Chemicals include oxygen, excessive water, ethylene, carbon dioxide, taints, and other specific food compounds. Typical applications include oxygen absorbers/scavengers, moisture absorbers/regulators, ethylene, aldehyde, amine, and sulphite scavengers, bitter taste removers, and carbon dioxide absorbers. EU regulations relating to active and intelligent packaging are reviewed. 44 refs.

In the US, components of food contact materials are regulated as food additives under the Federal Food, Drug, and Cosmetic Act (FFDCA). The FDA has the responsibility for the administration and enforcement of the FFDCA with regard to food contact materials. This chapter gives an overview of the FDA's current approach to toxicology review and risk assessment for components of food contact materials. The regulatory framework is described, and methods for the safety assessment of food additives, including threshold approaches to safety assessment, are discussed. The carcinogenicity risk assessment for constituents of food additives is examined, together with the use of a structure-activity relationship analysis technique. 44 refs.

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