Microbial conductive polymers

Canhato and Magan [39] have also described the detection of microbial and chemical contamination of potable water. Two electronic noses consisting of conducting polymer sensor arrays were compared for the early detection and discrimination of bacterial species, fungal spores, and trace concentrations of pesticides. Using PCA and CA allowed differentiation of the bacterial and fungal species after 24 hours of incubation at 25°C. However, this was not possible with the pesticides. 

In particular, redox chemicals (serving as electron shuttles) naturally synthesized by bacteria or exogenously added synthetic molecules have been proved to be directly involved in promoting extracellular electron transfer between the cells and the electrode. Moreover, electrode modification with conductive polymers or carbon nanomaterials showed great potential for the enhancement of nanoscale topological interactions and hence the extracellular electron transfer between the cells and the electrode.Extracellular electron transfer manipulation (a microbial process) with chemical electron shuttles or electrode modifiers can be considered as a typical application of chemical bioengineering. 

A. Mulchandani, W. Chen, N.V. Myung, and M.V. Yates, Conducting-Polymer Nanowire hnmunosensor Arrays for Microbial Pathogens, EPA Grant Number GR832375,2005. 

J Chem Soc Chem Commun 17 954-955 Ballard DGH, Moran KT, Shirley IM (1984) Conducting polymers. EP 122079 Ballard DGH, Courtis A, Shirley IM, Taylor SC (1988) Synthesis of polyphenylene from a cis-dihydrocatechol biologically produced monomer. Macromolecules 21 294-304 Ballard DGH, Blacker AJ, Woodley JM, Taylor SC (1994) Polyphenylenes from biosynthetic cis-dihydroxycyclohexadiene. In Mobley DP (ed) Plastics from microbes microbial synthesis of polymers and polymer precursors. Htmser, New York, pp 139-168 Berresheim AJ, Muller M, Klaus M (1999) Polyphenylene nanostructures. Chem Rev 99 1747-1785 Boyd DR, Bugg TDH (2006) Arene c/s-dihydrodiol formtition from biology to application. Org Biomol Chem 4 181-192... 

Tuncagil, S., D. Odaci, E. Yidiz, S. Timur, and L. Toppare. 2009. Design of a microbial sensor using conducting polymer of 4-(2,5-di(thiophen-2-yl)-lH-pyrrole-l-l) benzenamine. 137 (l) 42-47. 

Enhanced performance was also reported for anode modification with conductive polymers. A commonly used conductive polymer, polyaniline, can increase the current densities of MFC anodes. But it is also susceptible to microbial attack and degradation [39]. Schroder et al. [18] reported that a platinum electrode covered with polyaniline achieved a current density up to l.SmAcm in an MFC. Modification of polyaniline can improve its performance and stability, such as fluorinated PANI [40], PANI/carbon nanotube (CNT) composite [41], and PANI/titanium dioxide composite [42]. 

Anode performance Add redox mediators in anode chamber Use anode materials of high conductivity, good microbial compatibility and large surface area Anode modification with conductive polymers, metal oxides, etc. 

Most often, the rates for feedstock destruction in anaerobic digestion systems are based upon biogas production or reduction of total solids (TS) or volatile solids (VS) added to the system. Available data for analyses conducted on the specific polymers in the anaerobic digester feed are summarized in Table II. The information indicates a rapid rate of hydrolysis for hemicellulose and lipids. The rates and extent of cellulose degradation vary dramatically and are different with respect to the MSW feedstock based on the source and processing of the paper and cardboard products (42). Rates for protein hydrolysis are particularly difficult to accurately determine due the biotransformation of feed protein into microbial biomass, which is representative of protein in the effluent of the anaerobic digestion system. 

Peter Teasdale, Ph.D., is a senior lecturer in environmental chemistry at Australian Rivers Institute, Griffith University Gold Coast Campus. His current research interests include in situ sensors for metals and nutrients, natural, recycled and potable water quality, microbial toxicology, and sediment biogeochemistry. Peter is the current chair of the Royal Australian Chemical Institute Environment Division. He has published over 40 refereed publications. Coauthoring this book reflects his interest in the field of conducting electroactive polymers, the area in which he completed his Ph.D. in 1993 at the University of Wollongong. 

The increasing occurrence of microbial and nosocomial infection has stimulated research activities into antimicrobial polymers and textiles [19, 25, 34]. Most medical textiles and polymeric materials used in hospitals are conductive to crosstransmission of diseases, as most microorganisms can survive on these materials for hours to several months [17, 26]. Thus, it would be advantageous for polymeric surfaces and textile materials to exhibit antibacterial properties so as to reduce and prevent disease transmission and cross-contamination within and from hospitals. N-halamines exhibit a similar antimicrobial potency to chlorine bleach, one of the most widely used disinfectants, but they are much more stable, less corrosive and have a considerably reduced tendency to generate halogenated hydrocarbons, making them attractive candidates for the production of antimicrobial polymeric materials. N-halamine compounds are currently used as antimicrobial additives to produce polymers with antimicrobial and biofilm-limiting activities. 

Furthermoie, these natural polymer are relatively inexpensive. One example is the use of guar gum. Tliis natural carbohydrate is crosslinked with potassium tetraborate in the presence of KQ and propylene ycol to produce a high water content, crosslinked conductive geL The natural lymers tend to have limitations based on thdr phyacal and chemicd incon tendes, undesirable support for microbial growth, potential for creating adverse skin sensitivities, and the amount of impurities present in the raw material. 

Conductivity of the anode is important to MF C performance. One method that has been suecess-fully used to increase conductivity and current densities of MFC is the application of the eonductive polymer polyaniline (Schroder etal., 2003). However, performance was only improved temporarily as polyaniline was shown to be unstable and susceptible to microbial degradation (Niessen et al., 2004). While these findings would seemingly limit polyaniline s potential contribution to future MFC designs research has suggested that it may be possible to improve both the stability and performance of polyaniline by making composites combined with fluorine, carbon nanotubes (Qiao et al., 2007) and titanium dioxide (Qiao et al., 2008). 

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