Advances in Physicochemical Properties of Biopolymers (Part 2)

A chitosan biopolymer is a reactive functional polymer, which gives possibilities for chemical modifications to generate new properties and functions. Biocompatibility, biodegradability, non-toxicity to mammals, and potential biological activities make this compound with its derivatives advantageous for many applications in different fields, such as agriculture, food and nutrition, biomedicine, pharmaceutics, and biotechnology. In this chapter, we provide collaborative studies of the biological activity of chitosan and its major derivatives in different applications. In addition, the chapter provides the latest technological applications and prospects of products based on chitosan molecule.

Synthetic polymers play a significant role in the technological development of humankind and are obtained from petroleum by-products. Because of their physical properties, they can be used for the manufacture of a diversity of products ranging from simple garbage bags or contact lenses up to products for construction. Based on plastic skills such as low price, low weight, resistance to abrasion, impact and corrosion, inertia and versatility, they gradually replaced traditional materials like wood, stone and metal. However, these same advantages nowadays have become their worst drawback, turning them into wastes of difficult disposal and consequently, in a serious environmental problem. Additionally, their multiple usage in daily life has caused a massive increase in consumption and the consequent pollution problems. In this context, biopolymers have emerged as an ideal alternative to the synthetic polymer industry. Biopolymers provide a solution to the origin of the problem as coming from renewable resources, practically all of them being biodegradable, which is not the case for most synthetic polymers. Eco-friendly waste disposal of biopolymers takes advantage of their property of being degraded by soil microbiota, which significantly reduces CO2 emission as compared to conventional incineration. Therefore, the use of biodegradable biopolymers is also relevant from the point of view of global warming prevention. Based on this rationale, biopolymers based on renewable resources are generating an increasing interest, both in the overall society and particularly, in the plastic industry.

Polysaccharides, which can be obtained from a variety of different sources, have important industrial applications owing to their properties in solution. Considering the wide variety of plant species found in Brazilian flora, the achievement of these biopolymers from plant seeds is highly promising. In view of this potential, various research groups from Brazil have been investigating several plant species as a source of these natural polymers. These studies include structural elucidation, modification, and industrial application using several approaches. Therefore, the aim of this chapter is to review the results from studies of native Brazilian sources of polysaccharides, especially galactomannans and xyloglucans, to inspire commercial exploitation of these unconventional sources.

Industrial activity associated with processing of crustaceans generates large quantities of waste. The main residue corresponds to its exoskeletons constituted primarily of chitin. Through a modification on its structure, chitosan is derived, the only polycationic polymer in nature. This work aims to review a wide variety of aspects concerning chitosan. First it studies the chitosan properties: biodegradability, biocompatibility and non-toxicity. Its high density of positive charges makes it a versatile material, being able to be used in practically all the industrial fields. Agriculture, biotechnology, food, wastewater treatment and medicine are the main examples. Then it compares different chitin and chitosan obtaining methods being mostly used chemical treatments. The biological methods are presented as an alternative. Several techniques are necessary for chitosan´s characterization. Molecular weight and deacetylation degree are the most important characteristics which define its potential applications. This chapter analyzes different methods according to the necessity of each situation. An examination on the regulatory status and the global market of this biopolymer is made. A report in 2010 projected its market in 21.4 thousand tons by 2015, placing Japan as the biggest contributor. The main industries are placed in Asia and US. In Latin America, there are plants in Brazil, Chile and México. In Argentina, despite the crustaceans fishing industry continuously growing, there is no industrial chitosan production. This review concludes with a description of the work that is being carried out at the National Institute of Industrial Technology of Argentina in this regard.

The use of biomaterials as drug carriers is being extensively investigated as a drug delivery strategy in pharmaceutical research. However, the selection of materials for such systems is rather complicated. Lately, the advent of biomaterials brought the use of polymers as drug vehicles into the spotlight. Chitosan and albumin are two of the most promising biomaterials for the development of drug delivery systems. These are widely available in nature and can be used as scaffolds of unprecedented novel structure, presenting high biocompatibility and biodegradability and reduced toxicity. Moreover, these molecules promote optimized pharmacokinetics for targeted drug delivery and controlled release, and avoid accumulation or undesired side effects in healthy tissues Chitosan is a linear polysaccharide obtained from chitin and, when used as drug carrier, demonstrates to improve drugs pharmacokinetic profiles when comparing with the drug alone. Albumin is the most abundant protein in blood plasma, which has been receiving renewed interest in the development of drug delivery systems. Importantly, albumin is already an “off-the-shelf” product. Advances in the study of engineered biomaterials represent a step forward in the exploitation, development and commercialization of new therapies for old, poorly served medical needs.

Microencapsulation is a technology that physically wraps sensitive ingredients in a protective matrix. This may be required for several reasons, such as: 1) to contain aromatic compounds that can be rapidly evaporated or aromas that may be lost during storage, 2) to avoid undesirable interactions between the matrix and the aromas, 3) to minimize interactions between volatile compounds (flavor/flavor), 4) to protect substances against oxidative reactions, 5) to control and prolong the release of probiotics, drugs and/or flavor. Materials that have been microencapsulated include: enzymes, probiotics and microorganisms, acids, bases, oils, vitamins, antioxidants, salts, gases, pharmacologically active peptides and amino acids, flavorings and colorings. Several materials have been employed as microencapsulants, such as: gums (carrageenan, alginate and gum arabic), carbohydrates (starch, maltodextrin, β-cyclodextrin and chitosan), celluloses (cellulose acetate phthalate) and proteins (gelatin and dairy protein isolates). In this chapter we discuss some of the variables, such as the concentrations of the reactants used, that affect the formation of microencapsulation materials.

Biopolymer hydrogels present diverse applications in medicine due to their biocompatibility, biodegradability and low immunogenicity. The specific features related to swelling, holding a large amount of water while maintaining the structure, in addition to the ease of taking different shapes, make them the selected biomaterials as component for diverse bio-applications: contact lenses, injectable or implantable drug delivery devices and as platforms intended for wound healing and tissue engineering. In general, the restriction associated to the use of hydrogels in biomedicine lies in the poor mechanical properties associated to the natural biopolymers. This problem can be solved by the use of other materials during the synthesis procedure. In this chapter, general synthesis methodologies and latest innovations in terms of gelatin, collagen and hyaluronic acid hydrogels for wound care and tissue engineering are reviewed. The selection of the biopolymers is based on their suitable features for biomedical applications. The focusing of specific clinical challenges for wound healing and tissue engineering can prove to be beneficial for rapid development in science and marketing. This implies considering the current increasing market associated to hydrogel employment for wound care and treatment as well as the requirement to develop concise clinical hydrogels implementation on the replacement of diverse tissue and organs.

Collagen is a natural constituent of the extracellular matrix of tissues. It is well known that, when prepared without additives, diluted collagen hydrogels present poor mechanical properties limiting their use in tissue engineering. Hence, collagen's structural properties need to be enhanced. For this purpose, this chapter presents an overview of the recent advances and alternatives developed to improve the mechanical properties of collagen biomaterials.

The development of protein-based biopolymers has been driven by the increasing global demand for polymer products, the need for sustainable practice within this industry and the availability of low cost by-products, such as high protein content meals. The continuing development of new and existing protein-based biopolymers will enable these materials to help supplement the increasing global demand for polymer products and to develop new markets with their niche applications. To date various compositions of protein-based biopolymers have been successfully used to produce injection moulded articles, films and foams. Biopolymers typically display poor foaming behavior and commonly produce foams with irregular morphology and high densities. Protein-based biopolymers are no exception, therefore it is important to fully understand how the foaming mechanisms of bubble nucleation, growth and stabilization are affected by the inherently different properties of these materials. This chapter aims to review the production of stable protein-based foams for use in applications such as cushioning, insulation and packaging through a variety of methods. The review specifically focuses on the production of protein-based foams through thermosetting, the emerging role of proteins as a renewable substitute in polyurethane production and the application of thermoplastic foam technologies to protein-based thermoplastics, with an emphasis on batch and extrusion foaming methods. The similarities and differences between the production of traditional foams and those produced from proteins are highlighted here. Discussion of foam morphologies, properties and processing conditions is also included. Overall, this chapter intends to provide the reader with a greater understanding of the existing research and the current challenges associated with the production of protein-based thermoplastic and thermoset foams.

Electrospinning is a useful tool for producing fine fibers of about 10 nanometers to 10 microns in diameter from both natural and synthetic polymers. Historical developments, theory, and the types equipment used to produce aligned and non-aligned fibres in electrospinning are discussed. Collector composition or substrates, dimension of the collector, electrospinning materials and configurations of nozzle in electrospinning are discussed with their respective importance. The electrospinning process is influenced by the following solution parameters like viscosity, polymer molecular weight, polymer concentration, surface tension, polymer solution conductivity or surface charge density, rate of evaporation of solvents, dielectric constant and vapour pressure. Voltage, needle tip to collector distance, feedrate, collector material, electrospinning setup, diameter of needle orifice, environmental (ambient) parameters like temperature, humidity, type of atmosphere and pressure also determine electrospun fiber size and morphology.

In this work, we prepared and characterized water insoluble Tara gum films. Tara gum (TG) is a polysaccharide extracted from the endosperm of Caesalpinia spinosa seeds with a performance of 12% wt. TG films were evaluated as barrier material for agricultural and food industries. The films were modified in order to improve water resistance by using glutaraldehyde (Glu) as crosslinker. The crosslinking process consisted of placing the TG films in a bath containing Glu in an acidic medium for a period of 12 and 24 hours (TG-12 and TG-24) at 25ºC. Film properties were structurally studied through XRD, TGA and SEM images and operationally evaluated by measuring water vapor permeability (WVP), gas permeation and mechanical properties. WVP values decreased with increasing crosslinking time. This is due to crosslinking which hinders the diffusion of vapor molecules through the polymer matrix. Gas permeability tests showed permeabilities in the order CO2>> N2> O2. Mechanical tests indicated an increase in the elastic modulus of the film with increasing crosslinking time; this effect is due to the loss of flexibility of the crosslinked polymeric matrix.