Green and eco-friendly approaches for the extraction of chitin and chitosan: A review.

In this work, two chitosan samples from cuttlebone and squid pen are produced and characterized. We studied the formation of thermoresponsive hydrogels with β-glycerol phosphate and found proper formulations that form the hydrogels at 37 °C. Gel formation depended on the chitosan source being possible to produce the thermoresponsive hydrogels at chitosan concentration of 1% with cuttlebone chitosan but 1.5% was needed for squid pen. For the first time, these non-commercial chitosan sources have been used in combination with β-glycerol phosphate to prepare risperidone formulations for controlled drug delivery. Three types of formulations for risperidone-controlled release have been developed, in-situ gelling formulations, hydrogels and xerogels. The release profiles show that in-situ gelling formulations and particularly hydrogels allow an extended control release of risperidone while xerogels are not appropriate formulations for this end since risperidone was completely released in 48 h.

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Evaluating Non-Conventional Chitosan Sources for Controlled Release of Risperidone

Three-dimensional chitinous scaffolds often used in regenerative medicine, tissue engineering, biomimetics and technology are mostly isolated from marine organisms, such as marine sponges (Porifera). In this work, we report the results of the electrochemical isolation of the ready to use chitinous matrices from three species of verongiid demosponges (Aplysina archeri, Ianthella basta and Suberea clavata) as a perfect example of possible morphological and chemical dimorphism in the case of the marine chitin sources. The electrolysis of concentrated Na2SO4 aqueous solution showed its superiority over the chemical chitin isolation method in terms of the treatment time reduction: only 5.5 h for A. archeri, 16.5 h for I. basta and 20 h for the S. clavata sample. Further investigation of the isolated scaffolds by digital microscopy and SEM showed that the electrolysis-supported isolation process obtains chitinous scaffolds with well-preserved spatial structure and it can be competitive to other alternative chitin isolation techniques that use external accelerating factors such as microwave irradiation or atmospheric plasma. Moreover, the infrared spectroscopy (ATR-FTIR) proved that with the applied electrochemical conditions, the transformation into chitosan does not take place.

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Electrolysis as a Universal Approach for Isolation of Diverse Chitin Scaffolds from Selected Marine Demosponges

Chitin is a natural polysaccharide produced abundantly by biosynthesis in algae and fungi of the plant kingdom, as well as arthropods, mollusks, and other taxonomic groups of the animal kingdom. It consists of a sequence of monomers of N-acetylglucosamine and is found in three forms (α, β, and γ) which differ according to the arrangement of the chains in the crystalline region. Chitosan is the main high-value derivative of chitin. It is obtained by N-deacetylation reactions. Chitin and chitosan are copolymers consisting of units of N-acetylglucosamine and D-glucosamines linked by β- (1 → 4) glycosidic linkages. The major structural parameter is the degree of acetylation (DA), defined as the molar fraction of acetylglucosamine units. When the DA exceeds 50%, the copolymer is substantially insoluble in dilute acid solutions and corresponds to chitin. The chitosan name applies when DA is below 50%; the smaller the DA, the more soluble the copolymer is in acidic solutions. Methods for chitin and chitosan extraction from biomass are considered (Kurita, Broussignac, and laboratory processes) and compared to prepare samples with definite characteristics relative to the intended applications. The roles of the source (and the type of chitin) and the process will be discussed. Structural analysis will be presented to determine the DA using different techniques (spectroscopic, potentiometric, or conductimetric), which will be compared. The techniques to characterize the pattern of acetylation are discussed relative to the properties depending on this pattern. Finally, solution properties are addressed. Concerning these determinations and solution properties, special care must be taken to avoid macromolecular aggregates; this can be achieved by choosing appropriate solvents and solution concentration domains. 

Extraction of chitin, preparation of chitosan and their structural characterization

An overview perspective of the potential of chitin and chitosan biopolymers to promote economically and environmentally sustainable development poles, which could be exploited especially in developing countries, is presented. Their following advantages have been considered and briefly outlined: (i) the natural sources of chitin have a wide distribution on the entire planet and are usually accessible as inexpensive waste materials; (ii) the great versatility of these materials, with applications in diverse fields such as agriculture, water treatments, food industry, environment, petroleum, healthcare, energy, technology, etc., with some trials conducted even off-planet; (iii) the production and use of these materials could promote advances in the endogenous capacity of some countries to create own technologies and generate products and applications, basic and advanced, in sensitive sectors, i.e., health services, food, water treatments, etc., in addition to promoting the necessary integration of the academic sector with other sectors such as industry and business. 

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Chitosan: an overview of its multiple advantages for creating sustainable development poles

β-chitins are extracted from two different parts of cuttlefish (Sepia officinalis officinalis) bone; the shell and the thin layer. They are then subjected to N-deacetylation reactions to prepare chitosans using the Broussignac or the Kurita process. The physicochemical characteristics of chitins and chitosans are compared to those obtained in the case of squid (Loligo vulgaris) β-chitin. In this work, the role of the source in determining the reaction behavior, during the extraction of chitin and the preparation of chitosan, is confirmed, although it is a β-chitin of two taxonomically close species. In particular, we show that the differences observed can be related to the differences in molar masses of the starting chitins, their crystallinity index and the rates of molecular degradation which accompany the N-deacetylation reactions. Finally, it was demonstrated that the huge quantities of bones rejected each year by the cuttlefish processing units from Dakhla city, alone, can be valorized by the production of about 77 tons of β-chitin that can be transformed into 60 tons of chitosan (presenting low degree of acetylation and molar masses ranging from 78,000 to 340,000 g/mol).

S. Lidrissi Hassani

Papers

Investigation of β-chitin extracted from cuttlefish: comparison with squid β-chitin