Influence of manufacturing variables on the characteristics and effectiveness of chitosan products. I. Chemical composition, viscosity, and molecular-weight distribution of chitosan products

Effect of milling intensity on the properties of chitin, chitosan and chitosan films obtained from grasshopper

To obtain high-quality insect products, milling was used as a modification tool and its effect on grasshopper chitin, chitosan and chitosan films was investigated. Three grasshopper powders were obtained and classified into coarse-milled powder (CMP, D90 = 956 μm), medium-milled powder (MMP, D90 = 492 μm), and ultrafine-milled powder (UMP, D90 = 79.1 μm). Fourier transform infrared spectroscopy illustrated that no drastic change due to milling was observed, but the crystallinity (X-ray diffraction) and thermal stability (Thermogravimetric analysis) of the chitin, chitosan and chitosan films reduced with increasing milling intensity. Besides, the purity of the chitin and the yield of chitosan obtained from UMP were improved. Chitosan prepared from UMP was also characterized by high degree of deacetylation (65.6 %) and solubility and rather low molecular weight (11.5 kDa), viscosity and water/fat binding capacity. The finer the powder used as the extraction material, the thinner the chitosan films and the more compact the structure. On the whole, the chitosan films prepared from the MMP had higher mechanical properties and better moisture-keeping ability on strawberries compared with CMP and UMP films. This study establishes the role milling intensity played in the modification of grasshopper products and provides a reference for practical applications.

Chitosan as an Underrated Polymer in Modern Tissue Engineering

Chitosan is one of the most well-known and characterized materials applied in tissue engineering. Due to its unique chemical, biological and physical properties chitosan is frequently used as the main component in a variety of biomaterials such as membranes, scaffolds, drug carriers, hydrogels and, lastly, as a component of bio-ink dedicated to medical applications. Chitosan's chemical structure and presence of active chemical groups allow for modification for tailoring material to meet specific requirements according to intended use such as adequate endurance, mechanical properties or biodegradability time. Chitosan can be blended with natural (gelatin, hyaluronic acid, collagen, silk, alginate, agarose, starch, cellulose, carbon nanotubes, natural rubber latex, κ-carrageenan) and synthetic (PVA, PEO, PVP, PNIPPAm PCL, PLA, PLLA, PAA) polymers as well as with other promising materials such as aloe vera, silica, MMt and many more. Chitosan has several derivates: carboxymethylated, acylated, quaternary ammonium, thiolated, and grafted chitosan. Its versatility and comprehensiveness are confirming by further chitosan utilization as a leading constituent of innovative bio-inks applied for tissue engineering. This review examines all the aspects described above, as well as is focusing on a novel application of chitosan and its modifications, including the 3D bioprinting technique which shows great potential among other techniques applied to biomaterials fabrication.

Sustainable and eco-friendly strategies for shrimp shell valorization

Among the seafood used globally, shellfish consumption is in great demand. The utilization of these shellfish such as prawn/shrimp has opened a new market for the utilization of the shellfish wastes. Considering the trends on the production of wealth from wastes, shrimp shell wastes seem an important resource for the generation of high value products when processed on the principles of a biorefinery. In recent years, various chemical strategies have been tried to valorize the shrimp shell wastes, which required harsh chemicals such as HCl and NaOH for demineralization (DM) and deproteination (DP) of the shrimp wastes. Disposal of chemicals by the chitin and chitosan industries into the aquatic bodies pose harm to the aquatic flora and fauna. Thus, there has been intensive efforts to develop safe and sustainable technologies for the management of shrimp shell wastes. This review provides an insight about environmentally-friendly methods along with biological methods to valorize the shrimp waste compared to the strategies employing concentrated chemicals. The main objective of this review article is to explain the utilization shrimp shell wastes in a productive manner such that it would be offer environment and economic sustainability. The application of valorized by-products developed from the shrimp shell wastes and physical methods to improve the pretreatment process of shellfish wastes for valorization are also highlighted in this paper.

Comparison of the Quality of Chitin and Chitosan from Shrimp, Crab and Squilla Waste

Chitin and Chitosan obtained from the crustaceans are having more biological value such as physiological compatibility, non-toxicity, bio digestibility, adsorption and chelating capacity. These biological values of chitosan depend on the quality parameters which are directly related to the source of the raw material. In this study, three commercially available crustacean shell waste such as shrimp, crab and squilla were used for the extraction of chitin and chitosan. The chemical treatment of demineralization, deproteinization and deacetylation were used for the production of chitosan. The viscosity quality parameter of the shrimp chitosan (5300cPs) was better than the crab and squilla chitosan. It is due the high solubility (97.65%) of the shrimp chitosan in 1% acetic acid. The degree of deacetylation of the shrimp chitosan (81.24%) directly relates the solubility of the chitosan. The chitosan with these quality parameters considered to be the excellent biological value. The yield of shrimp chitosan (15.4%) was also more when compare to crab and squilla chitosan. These result showed that utilisation of shrimp shell waste for the production of chitin and chitosan will give more economical and biological value along with reduction of environmental pollution.

Synthesis and Properties of Hyaluronic Acid Conjugated Nucleic Acid Analogs—1: Synthesis of Deacetylhyaluronan and Introduction of Nucleic Acid Bases

The conjugation of nucleic acid base with hyaluronan was achieved by using the activated ester of pentachlorophenyl trichloroacetate. The conditions of de-N-acetylation of sodium hyaluronic acid were studied. In low concentrations of NaOH, the degree of deacetylation was 26%, while in 7.4N NaOH, the degree of deacetylation was 76% and the viscosity was 1.12 dL/g. Thymine and 5-fluorouracil bases were quantitatively conjugated to deacetylhyaluronan in 65% and 51%, respectively. The interaction of thymine hyaluronan conjugate with the complementary base of polyadenylate showed a small hypochromicity.

Applications and Properties of Chitosan

Chitosan, a polycationic polymer and waste product from the sea food processing industry, is an abundant natural resource that has, as yet, not been fully utilized. Advantages of this polymer include availability, low cost, high biocompatibility, biodegradability and ease of chemical modification. In this paper, the physicochemical properties of chitosan, as well as its numerous applications, are reviewed with particular emphasis on its use in water treat ment, pharmaceutics, agriculture and membrane formation.

Environmental scanning electron microscopy analysis of Proteus mirabilis biofilms grown on chitin and stainless steel

Proteus mirabilis is a human pathogen able to form biofilms on the surface of urinary catheters. Little is known about P. mirabilis biofilms on natural or industrial surfaces and the potential consequences for these settings. The main aim of this work was to assess and compare the adhesion and biofilm formation of P. mirabilis strains from different origins on chitin and stainless steel surfaces within 4 to 96 h. Using environmental scanning electron microscopy, the biofilms of a clinical strain grown on chitin at 4 h showed greater adhesion, aggregation, thickness, and extracellular matrix production than those grown on stainless steel, whereas biofilms of an environmental strain had less aggregation on both surfaces. Biofilms of both P. mirabilis strains developed different structures on chitin, such as pillars, mushrooms, channels, and crystalline-like precipitates between 24 and 96 h, in contrast with flat-layer biofilms produced on stainless steel. Significant differences (p < 0.05) were found in the frequency of pillars and channels. Images of transmission electron microscopy demonstrated abundant fimbriae in 100 % of cells from both strains, which could be related to surface adherence and biofilm formation. This represents the first study of P. mirabilis showing adhesion, biofilm formation, and development of different structures on surfaces found outside the human host.

Chitin and chitosan preparation from marine sources. Structure, properties and applications

This review describes the most common methods for recovery of chitin from marine organisms. In depth, both enzymatic and chemical treatments for the step of deproteinization are compared, as well as different conditions for demineralization. The conditions of chitosan preparation are also discussed, since they significantly impact the synthesis of chitosan with varying degree of acetylation (DA) and molecular weight (MW). In addition, the main characterization techniques applied for chitin and chitosan are recalled, pointing out the role of their solubility in relation with the chemical structure (mainly the acetyl group distribution along the backbone). Biological activities are also presented, such as: antibacterial, antifungal, antitumor and antioxidant. Interestingly, the relationship between chemical structure and biological activity is demonstrated for chitosan molecules with different DA and MW and homogeneous distribution of acetyl groups for the first time. In the end, several selected pharmaceutical and biomedical applications are presented, in which chitin and chitosan are recognized as new biomaterials taking advantage of their biocompatibility and biodegradability.

Isolation of chitosan from Ganoderma lucidum mushroom for biomedical applications

Chitin biopolymer production and its by-product chitosan show great potential. These biomaterials have great applicability in various fields because they are non-toxic, biodegradable, biocompatible, and have antimicrobial effects. The most common source of chitin and chitosan is the crustaceous shell; however, mushrooms are an alternative source for isolating these biopolymers because their cellular wall has a high content of chitin, which may be transformed into chitosan through a deacetylation reaction. The main objective of this research was to obtain chitosan through the deacetylation of chitin isolated from the Ganoderma lucidum basidiomycetes mushroom, which is obtained through biotechnological culture. The material characterization was performed using X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, and an evaluation of cytotoxicity comparing the results obtained with results for commercial chitosan. Protocol results showed that chitosan obtained from this mushroom had a significant similitude with commercial chitosan, yet the one obtained using P2 protocol was the one that rendered the best results: including diffractogram peaks, characteristic infrared analysis bands, and an 80.29 % degree of deacetylation. Cytotoxicity in vitro testing showed that the material was non-toxic; furthermore, it rendered very promising information regarding the evaluation of future applications of this biomaterial in the field of biomedicine.

Glycoprotein IIb/IIIa and P2Y12 induction by oligochitosan accelerates platelet aggregation

Platelet membrane receptor glycoprotein IIb/IIIa (gpiibiiia) is a receptor detected on platelets. Adenosine diphosphate (ADP) activates gpiibiiia and P2Y₁₂, causing platelet aggregation and thrombus stabilization during blood loss. Chitosan biomaterials were found to promote surface induced hemostasis and were capable of activating blood coagulation cascades by enhancing platelet aggregation. Our current findings show that the activation of the gpiibiiia complex and the major ADP receptor P2Y₁₂ is required for platelet aggregation to reach hemostasis following the adherence of various concentrations of chitosan biomaterials [7% N,O-carboxymethylchitosan (NO-CMC) with 0.45 mL collagen, 8% NO-CMC, oligochitosan (O-C), and oligochitosan 53 (O-C 53)]. We studied gpiibiiia and P2Y₁₂ through flow cytometric analysis and western blotting techniques. The highest expression of gpiibiiia was observed with Lyostypt (74.3 ± 7.82%), followed by O-C (65.5 ± 7.17%). Lyostypt and O-C resulted in gpiibiiia expression increases of 29.2% and 13.9%, respectively, compared with blood alone. Western blot analysis revealed that only O-C 53 upregulated the expression of P2Y₁₂ (1.12 ± 0.03-fold) compared with blood alone. Our findings suggest that the regulation of gpiibiiia and P2Y₁₂ levels could be clinically useful to activate platelets to reach hemostasis. Further, we show that the novel oligochitosan is able to induce the increased expression of gpiibiiia and P2Y₁₂, thus accelerating platelet aggregation in vitro.

Natural Polysaccharides as Treatment Agents for Wastewater

This chapter gives an account of recent developments in biopolymers with an emphasis on natural polysaccharides as treatment agents in wastewater remediation. Almost all sources of water around the world are polluted to some degree, owing to a heavy influx of industrial effluents, domestic and agricultural wastes. These discharges vary from simple nutrients to highly toxic hazardous chemicals. Numerous approaches have been studied for the development of cheaper and more effective water remediation agents containing natural polymers. Among these, natural polysaccharides deserve particular attention. These materials have proved to be better treatment alternatives compared to their synthetic counterparts because of their particular structure, physicochemical characteristics, chemical stability, high reactivity and excellent selectivity towards aromatic compounds, metals and other contaminants that cause water pollution.

Femtosecond laser induced synthesis of Au nanoparticles mediated by chitosan

This paper reports the synthesis of Au nanoparticles by 30-fs pulses irradiation of a sample containing HAuCl4 and chitosan, a biopolymer used as reducing agent and stabilizer. We observed that it is a multi-photon induced process, with a threshold irradiance of 3.8 × 10(11) W/cm2 at 790 nm. By transmission electron microscopy we observed nanoparticles from 8 to 50 nm with distinct shapes. Infrared spectroscopy indicated that the reduction of gold and consequent production of nanoparticles is related to the fs-pulse induced oxidation of hydroxyl to carbonyl groups in chitosan.

A review on chemical coagulation/flocculation technologies for removal of colour from textile wastewaters

Textile industry is one of the most chemically intensive industries on the earth and the major polluter of potable water. It generates huge quantities of complex chemical substances as a part of unused materials including dyes in the form of wastewater during various stages of textile processing. The direct discharge of this wastewater into environment affects its ecological status by causing various undesirable changes. As environmental protection becomes a global concern, industries are finding novel solutions for developing technologies that can diminish the environmental damage. However, colour removal from textile wastewater by means of cheaper and environmental friendly technologies is still a major challenge. In this manuscript, several options of decolourisation of textile wastewater by chemical means have been reviewed. Based on the present review, some novel pre-hydrolysed coagulants such as Polyaluminium chloride (PACl), Polyaluminium ferric chloride (PAFCl), Polyferrous sulphate (PFS) and Polyferric chloride (PFCl) have been found to be more effective and suggested for decolourisation of the textile wastewater. Moreover, use of natural coagulants for textile wastewater treatment has also been emphasised and encouraged as the viable alternative because of their eco-friendly nature.

A Biopolymer Chitosan and Its Derivatives as Promising Antimicrobial Agents against Plant Pathogens and Their Applications in Crop Protection

Recently, much attention has been paid to chitosan as a potential polysaccharide resource. Although several efforts have been reported to prepare functional derivatives of chitosan by chemical modifications, few attained their antimicrobial activity against plant pathogens. The present paper aims to present an overview of the antimicrobial effects, mechanisms, and applications of a biopolymer chitosan and its derivatives in crop protection. In addition, this paper takes a closer look at the physiochemical properties and chemical modifications of chitosan molecule. The recent growth in this field and the latest research papers published will be introduced and discussed.

Characteristics of deacetylation and depolymerization of β-chitin from jumbo squid (Dosidicus gigas) pens

This study evaluated the deacetylation characteristics of β-chitin from jumbo squid (Dosidicus gigas) pens by using strongly alkaline solutions of NaOH or KOH. Taguchi design was employed to investigate the effect of reagent concentration, temperature, time, and treatment step on molecular mass (MM) and degree of deacetylation (DDA) of the chitosan obtained. The optimal treatment conditions for achieving high MM and DDA of chitosan were identified as: 40% NaOH at 90°C for 6h with three separate steps (2h+2h+2h) or 50% NaOH at 90°C for 6h with one step, or 50% KOH at 90°C for 4h with three steps (1h+1h+2h) or 6h with one step. The most important factor affecting DDA and MM was temperature and time, respectively. The chitosan obtained was then further depolymerized by cellulase or lysozyme with cellulase giving a higher degradation ratio, lower relative viscosity, and a larger amount of reducing-end formations than that of lysozyme due to its higher susceptibility. This study demonstrated that jumbo squid pens are a good source of materials to produce β-chitosan with high DDA and a wide range of MM for various potential applications.

Downstream Processing in Marine Biotechnology

Downstream processing is one of the most underestimated steps in bioprocesses and this is not only the case in marine biotechnology. However, it is well known, especially in the pharmaceutical industry, that downstreaming is the most expensive and unfortunately the most ineffective part of a bioprocess. Thus, one might assume that new developments are widely described in the literature. Unfortunately this is not the case. Only a few working groups focus on new and more effective procedures to separate products from marine organisms. A major characteristic of marine biotechnology is the wide variety of products. Due to this variety a broad spectrum of separation techniques must be applied. In this chapter we will give an overview of existing general techniques for downstream processing which are suitable for marine bioprocesses, with some examples focussing on special products such as proteins (enzymes), polysaccharides, polyunsaturated fatty acids and other low molecular weight products. The application of a new membrane adsorber is described as well as the use of solvent extraction in marine biotechnology.

Light-Induced Storage in Layer-by-Layer Films of Chitosan and an Azo Dye

The buildup of layer-by-layer (LBL) films from chitosan and the azodye Ponceau-S (PS) was investigated under various experimental conditions, and the resulting films were used in optical storage experiments. The kinetics for the writing process in optical storage was faster for LBL films prepared at low pHs, probably because the films had a larger free volume for isomerization of the chromophores. The nanostructured nature of the LBL films also affected the crystallinity of chitosan, which was considerably decreased in this type of film as chitosan became protonated because of the electrostatic interactions between adjacent layers.