Advanced Materials Research Vol. 506

Abstract: The successful development of biomaterials is increasingly influenced by biomimesis essentially the use of biological structures as design templates. This approach has been used here in the design of injectable systems for the nucleus of the intervertebral disc, corneal inlays and intraocular lenses (IOLs). The strategy is based on the use of C-linked sulphonates to mimic the O-linked sulphate groups that are the hydration drivers in proteoglycans. The elastic modulus of the materials can be tailored for specific applications.

Abstract: Laser activated SurgiLux^® technology was examined to determine its suitability as an ocular wound sealant. SurgiLux showed suitable strength and flexibility as well as moisture content for applications in the eye. In comparison to conventional microsuturing complemented with fibrin sealant, application of the SurgiLux technology was up to 5 times faster and the strength of the repaired wounds up to 7 times greater, with a 6 mm incision withstanding 235 mm Hg pressure compared to 120 mm Hg for sutures with fibrin.

Abstract: Polymers have a major contribution to make in the field of regenerative medicine in order to develop and deploy biological substitutes that restore, maintain, or improve tissue function. There are realistic opportunities to create tissues using an engineered extracellular matrix or scaffold and biologically active molecules. A number of different approaches to preparing scaffolds have been explored and the requirements for materials and personalization identified. We review the methodologies and materials available and report on recent work at the CDRSP to integrate and provide control of the processes to provide a realistic biomanufacturing process.

Abstract: Nowadays, polymers are finding increasing use in a bewildering array of specialist applications. A good example of this is in the biomedical field. In this paper, some of the research work which is being carried out in Chiang Mai will be described. In its wider context, this paper also aims to show how the development of new polymers for such specialist applications depends on being able to control the polymers microstructure at each stage of its synthesis and processing.

Abstract: Extracellular matrices (ECM) derived from urinary bladder membrane (UBM) have demonstrated substantial potential for applications in tissue repair and reconstruction. However, these materials are limited by the requirement of suturing following surgery. In this paper, the coalescence of UBM with an advanced surgical adhesive demonstrated a suitable alternative to sutures for wound closure, prevention of fluid leakage and improvement of cell growth. This novel bioadhesive contains favourable characteristics that are suitable for tissue repair, support of cell growth, and influence cellular microenvironments that are biocompatible with peripheral nerve regeneration in the spinal cord.

Abstract: Several factors affect the indoor air quality, among which ventilation, human occupancy, cleaning products, equipment and material; they might induce the presence of aerosols (or bioaerosols in the presence of biological components) nitrogen oxides, ozone, carbon monoxide and dioxide, volatile organic compounds, radon and microorganisms. Microbiological pollution involves hundreds of bacteria and fungi species that grow indoors under specific conditions of temperature and humidity. Exposure to microbial contaminants is clinically associated with allergies, asthma, immune responses and respiratory infections, such as Legionnaires Disease and Pontiac Feaver, which are due to contamination by Legionella pneumophila. Legionnaire's Disease has increased over the past decade, because of the use of central air conditioning. In places such as homes, kindergartens, nursing homes and hospitals, indoor air pollution affects population groups that are particularly vulnerable because of their health status or age, making indoor air pollution a public health issue of high importance. Therefore, the implementation of preventive measures, as the application of air filters, is fundamental. Currently, High Efficiency Particulate Air (HEPA) filters are the most used to capture microorganisms in ventilation, filtration and air conditioning systems; nevertheless, as they are not completely secure, new filters should be developed. This work aims to present how the efficiency of a textile nanostructure in a non-woven material based on synthetic textiles (high hydrophobic fibers) incorporating appropriate biocides to control Legionella pneumophila, is going to be measured. These bioactive structures, to be used in ventilation systems, as well as in respiratory protective equipment, will reduce the growth of microorganisms in the air through bactericidal or bacteriostatic action. The filter nanostructure should have good air permeability, since it has to guarantee minimum flows of fresh air for air exchange as well as acceptable indoor air quality.

Abstract: Removal of low levels of arsenic from contaminated water using the polyelectrolyte-enhanced ultrafiltration or PEUF process technology has been studied. The cationic polyelectrolyte poly (diallyldimethyl ammonium chloride), PDADMAC, was utilized to bind arsenic (in the form of arsenate anion) in contaminated water and the polyelectrolyte-arsenate complex solution was then filtered off (as retentate) by ultrafiltration. The 99-99.9% arsenic removal from synthetic low level arsenic (100 ppb) contaminated water demonstrates that the technology can easily achieve the relatively new international arsenic maximum concentration level of 10 ppb. To make the PEUF process more economical and environmentally friendly, the PDADMAC in the retentate must be recovered. Precipitation of PDADMAC-arsenate solutions with divalent cations has been studied to separate out metal-arsenate compounds leaving free PDADMAC to reuse in the process. The metal-arsenate compound precipitation is strongly affected by divalent metal:As molar ratio, and pH of the solution. The precipitation results also suggest that polyelectrolyte retards formation of the metal-arsenate compounds and affects the size and morphology of the particles formed, thus directly affecting the sedimentation rate of the resulting precipitate.

Abstract: Oligochitosan salt-based antibacterial wound gels were developed and evaluated in both in vitro and in vivo models. The antibacterial activities of the oligochitosan salts and the wound gels were investigated against Staphylococcus epidermidis RP625 and Escherichia coli ATCC 11775. The minimum inhibitory concentrations (MIC) of the oligochitosan salts were found in the range of 16-256 μg/mL. The wound gels demonstrated their in vitro activities on inhibiting the growth of bacteria. The 3-D collagen gel matrix containing human dermal fibroblasts cultured with each test gel was used as an in vitro model for the examination of cell proliferation and secretion of interleukin-8 (IL-8). The gels appeared to promote the proliferation and formation of cellular process of the fibroblasts in the 3-D collagen gels and stimulate the fibroblasts to produce more IL-8. In the in vivo model, it was noted that the gels could accelerate the wound closure process. The wounds were completely closed within 14 days.

Abstract: The effect of physical aging on the properties of starch is important to understand structural relaxation and to control the physicochemical changes after pregelatinization which induced by aging. In this study, the effect of physical aging on the physicochemical properties of pregelatinized tapioca starch was investigated. The tapioca starch was pregelatinized by either heating at 80°C or using high power (400 W) ultrasonic treatment. After pregelatinization, dextrose equivalent (DE), viscosity, turbidity, swelling power and solubility were determined and compared with native tapioca starch. Compared to fresh tapioca starch, the aged starch exhibited an increase in DE, turbidity and solubility. The viscosity and swelling power were decreased after storage. Similar results were found for both tapioca starches pregelatinized by heat and ultrasonic treatments. The results of the physicochemical properties of pregelatinized starches obtained from ultrasonic treatment related to the formation of low molecular weight components that aging starch are easily changed by disruption of molecular structure within the starch granule.