Improved biopolymers

Microbial systems have proven to be low-cost, environmentally safe methods for improved biopolymer production. Leuconostoc mesenteroid.es, Pseudomonas pseudomallei, and Bacillus spp., and biopolymers produced by microbes have received much attention due to their easy adaptability to tools of genetic engineering [15]. 

Although chemical techniques can be used to modify the properties of biopolymers in order to expand their range of applications, this is not the unique way to improve biopolymer performance. There are different methods to transform biopolymers in sources of structural polymers that may supplant traditional commodity plastics, such as genetic manipulation of some plant species, polymerization of biological starting materials, or the creation of new gene sequences that can lead to novel protein polymers through the application of recombinant DNA methods. However, only biopolymer physical/chemical modifications will be discussed in this chapter. 

The consideration made above allows us to predict good chromatographic properties of the bonded phases composed of the adsorbed macromolecules. On the one hand, steric repulsion of the macromolecular solute by the loops and tails of the modifying polymer ensures the suppressed nonspecific adsorptivity of a carrier. On the other hand, the extended structure of the bonded phase may improve the adaptivity of the grafted functions and facilitate thereby the complex formation between the adsorbent and solute. The examples listed below illustrate the applicability of the composite sorbents to the different modes of liquid chromatography of biopolymers. 

PHAs are produced by the bacteria to store carbon and energy reserves (Keshavarz, Roy, 2010). Previous works stated that an intracellular accumulation of PHAs improves the survival of general bacteria under environmental stress conditions (Kadouri et al., 2005 Zhao et al., 2007). Various microorganisms are produced in different properties of biopolymer depending on the types of microorganisms and carbon sources used. More than 150 different monomers can be combined within this family to give materials with extremely different properties (Chen Wu, 2005). 

Biopolymers have diverse roles to play in the advancement of green nanotechnology. Nanosized derivatives of polysaccharides like starch and cellulose can be synthesized in bulk and can be used for the development of bionanocomposites. They can be promising substitutes of environment pollutant carbon black for reinforcement of rubbers even at higher loadings (upto SOphr) via commercially viable process. The combined effect of size reduction and organic modification improves filler-matrix adhesion and in turn the performance of polysaccharides. The study opens up a new and green alternative for reinforcement of rubbers. 

In our previous works the fact of AR-DNA interactions, resulting in modifications of physicochemical properties of this biopolymer with formation of supramolecular complexes has been described [Davydova et al., 2005]. The AR-DNA interactions also leads to B —> A transition of DNA, increase the thermostability of these complexes and improving the resistance of DNA to some external influences [Davydova et al., 2006, 2007]. 

Improvement of the relative mobility of oil to water by biosurfactants and biopolymers... 

Naturally occurring polysaccharides and their derivatives form the predominant group of water-soluble species generally used as thickeners to impart viscosity to treating fluids [1092]. Other synthetic polymers and biopolymers have found ancillary applications. Polymers increase the viscosity of the fi ac-turing fluid in comparatively small amounts. The increase in fluid viscosity of hydraulic fracturing fluids serves for improved proppant placement and fluid loss control. Table 17 summarizes polymers suitable for fracturing fluids. 

G. Burrafato, A. Gaumeri, T. P. Lockhart, and L. Nicora. Zirconium additive improves field performance and cost of biopolymer muds. In Proceedings Volume, pages 707-710. SPE Oilfield Chem Int Symp (Houston, TX, 2/18-2/21), 1997. 

High performance capillary electrophoresis in its current form is a new technique. Its feasibility has been proven by the analysis and separation of small ions, drugs, chiral molecules, polymers, and biopolymers.93 We are learning more every day about the small tricks of the trade of the technique, and the efficiency and reproducibility of the methods are improving. 

In order to improve the mechanical properties of PHB or poly(3HB-co-3HV), many have reported on blending these biopolymers with other, both degradable as well as non-degradable, materials. However, due to the lack in compatibility between most polymers no substantial improvements in mechanical properties were reported upon, up to now [90]. 

Above we have shown the attractiveness of the so-called green nanocomposites, although the research on these materials can still be considered to be in an embryonic phase. It can be expected that diverse nano- or micro-particles of silica, silicates, LDHs and carbonates could be used as ecological and low cost nanofillers that can be assembled with polysaccharides and other biopolymers. The controlled modification of natural polymers can alter the nature of the interactions between components, affording new formulations that could lead to bioplastics with improved mechanical and barrier properties. 

However, this study is of great importance since Gill and Ballesteros demonstrated first by numerous examples [46,82,101] that the exchange of alcohol with polyols improves the compatibility of the sol-gel processing to biopolymers. This showed a method for modification of the silica precursors. 

The approach by Brennan with collaborators led to notable improvement in the biocompatibility of sol-gel processing. However, there are some disadvantages. Their approach does not exclude the hydrolytic separation of alcohol. Its presence is detrimental for sensitive biopolymers. Furthermore, the two-stage synthesis is accompanied by the significant shrinkage of sol-gel derived nanocomposites. This leads to a decrease in the pore size that sometimes can restrict the accessibility of enzymes to substrates. 

Thus, the increasing application of the various intrinsic properties of biopolymers, coupled with the knowledge of how such properties can be improved to achieve compatibility with thermoplastics processing, manufacturing, and end-use requirements, and has fueled technological and commercial interest in biopolymers. 

The growing interest for the identification and characterization of polar and large compounds caused the development and the introduction of new ionization techniques, such as electrospray ionization (ESI)[4], and matrix assisted laser desorption ionization (MALDI),[5] and their more recent improvements, thus establishing new MS based approaches for studying large molecules, polymers and biopolymers, such as proteins, carbohydrates, nucleic acids. 

In view of the conductive and electrocatalytic features of carbon nanotubes (CNTs), AChE and choline oxidases (COx) have been covalently coimmobilized on multiwall carbon nanotubes (MWNTs) for the preparation of an organophosphorus pesticide (OP) biosensor [40, 41], Another OP biosensor has also been constructed by adsorption of AChE on MWNTs modified thick film [8], More recently AChE has been covalently linked with MWNTs doped glutaraldehyde cross-linked chitosan composite film [11], in which biopolymer chitosan provides biocompatible nature to the enzyme and MWNTs improve the conductive nature of chitosan. Even though these enzyme immobilization techniques have been reported in the last three decades, no method can be commonly used for all the enzymes by retaining their complete activity. 

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