Biodegradability, protein-based materials

Guilbert, S., Redl, A., Gontard, N. Mass transport within edible and biodegradable protein based materials Application to the design of acive biopackaging, CRC Press Boca Raton, 2000. 

A few examples are discussed in Chapter 9 wherein the future will see the biosynthesis of biodegradable protein-based thermoplastics, materials to prevent postsurgical adhesions, temporary functional scaffoldings to direct tissue reconstruction, and drug delivery devices for new drug release regimens. 

Desirable at this point would be an implantable naltrexone delivery system that would not depend on patient compliance. It could be a biodegradable controlled release device, for example, injectable by hypodermic syringe for relatively short-term release. Alternatively, it could be implanted by trocar or by laparoscope for release for months as a biocompatible and biodegradable yet removable vehicle should patients circumstances warrant substantial pain control. As demonstrated below (see Figure 9.39), properly designed protein-based materials exhibit this potential. 

Extensive research has been undertaken in blending different polymers to obtain new products having some of the desired properties of each component. Among protein- and polysaccharide-based green materials, those made from soy protein (Maruthi et al. 2014 Ghidelli et al. 2014 Behera et al. 2012) and starch (Katerinopoulou et al. 2014 Flores-Hemandez et al. 2014) have been extensively studied for and their physiochemical properties been analyzed. The literature review clearly shows that development of biodegradable biopolymer-based materials based on these materials can not only solve the white pollution problem but also ease the overdependence on petroleum resources. This chapter provides a brief overview of the preparation, properties, and application of cellulose fiber-reinforced soy protein-based and starch-based biocomposites. 

In recent years, soy products such as soy whole flour (SF), soy protein concentrate (SPC), and soy protein isolate (SPI) have been considered as alternatives to petroleum polymers because of their abundance, low cost, perfect adhesion, and good biodegradability (Maruthi et al. 2014). SF contains about 40-60 % protein, combined with fats and carbohydrates. Soy protein concentrate contains about 60-70 % protein. SPI contains more than 90 % of protein and is the most widely used soybean product for film processing (Ciannamea et al. 2014). Moreover, SPI-based films are clearer, smoother, and more flexible compared to other plant protein-based films, and they have impressive gas barrier properties compared to those prepared from lipids and polysaccharides. When SPI films are not moist, their O2 permeability was 500, 260, 540, and 670 times lower than that of films based on low-density polyethylene, methylceUulose, starch, and pectin, respectively (Song et al. 2011). Thus, in addition to their large availability, soy protein-based materials have interesting barrier and release properties ideal for packaging applications. 

The model determines the permeability levels for nanocomposite material at various loading levels of clay nanocomposites, which gives an understanding of barrier properties of film. Nielsen (1967) model (Equation 2) and Cussler (1988) model (Equation 3) were also compared for the prediction of barrier properties of biodegradable protein based nanocomposite material. 

Wheat protein-based materials are biodegradable and environment-friendly (27). A biodegradation study was performed in liquid medium using the standard ISO 14852 method. The wheat protein-based materials were completely degraded after 36 days (Figure 3) and no microbial inhibition due to toxic metabolite excretion was noted. 

Over the last two decades, there has been an increasing interest in the industrial use of plant proteins for non-food applications because of their renewabiUty or biodegradability Plant proteins ve thus been used for the fabrication of materials such as films and coatings, adhesives, thermoplastics and surfactants. However, for many applications, it is necessary to confer and/or to improve some specific properties by chemical modification of the native proteins. Particularly, the esterification of their carboxyl and amide groups by a fatty alcohol (Fig 1) could lead to a protein-derivative with improved functional properties. Such modification would result into a lower water sensitivity of the protein-based products and it would therefore offer... 

The materials of our approach are natural to the tissue to be restored they are protein-based polymers that are progammably biodegradable in their swollen state they degrade to natural amino acids without release of irritating acid (as occurs with the commonly used polyglycolic and polylactic acids) they are elastic and can match the compliance of the natural tissue they are biocompatible (the basic sequence in its contracted state appears to be simply ignored... 

Modification of natural polymers such as starch, cellulose, and proteins is a way of capitalizing on the well-accepted biodegradability of the base material with... 

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