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

Hairy chitin nanocrystals: Sustainable adsorbents for efficient removal of organic dyes

Chitin nanocrystals (ChNCs) are typically produced using a combination of strong acid hydrolysis and mechanical treatments. In this study, a mild, energy-efficient, and environmentally friendly method was developed to prepare a novel form of chitin nanocrystals called hairy chitin nanocrystals (HChNCs) without the need of any mechanical treatments. The HChNCs were made by sequential oxidations on partially deacetylated chitin, resulting in a unique morphology with chitin molecular chains protruding from central chitin nanorods. These HChNCs have a high content of carboxyl groups, reaching up to 2.72 mmol/g, which enhances their ability to adsorb methylene blue (MB) effectively. Within just 1 min, the HChNCs can adsorb as much as 909.11 ± 17.44 mg/g of MB, a significantly higher capacity compared to other chitin-derived materials. Additionally, the HChNCs showed remarkable synergistic removal efficiency for both MB and methyl orange (MO) in a mixed dye system, making them a promising sustainable option for treating wastewater from industrial printing and dyeing processes.

Role of chitin synthases CHS1 and CHS2 in biosynthesis of the cyst wall of Cryptocaryon irritans

Cryptocaryon irritans, a protozoan parasite that infects marine fish, is characterized by a complex life cycle that includes a cyst-forming reproductive phase. However, the composition of the cyst wall and mechanism of its formation remain unclear. In this study, we identified chitin as a key component of the cyst wall using calcofluor white and wheat germ agglutinin, with Fourier-transform infrared spectroscopy confirming its β-form structure. Two chitin synthase genes, CHS1 and CHS2, were identified as being expressed throughout the life cycle and show close phylogenetic relationships with chitin synthase from ciliates. Incubation with specific anti-CHS1 and -CHS2 antibodies significantly reduced both the thickness and chitin content of the cyst wall, highlighting the critical role of these enzymes in chitin biosynthesis. Treatment with benzoylureas, which inhibit chitin synthesis, caused thinning of the cyst wall and downregulation of CHS gene expression, resulting in an 84 % reduction in the hatching rate after treatment with 0.01 mM CuSO4 compared with control tomonts. Western blot analysis demonstrated that recombinant CHS proteins are immunogenic, and tomonts from CHS-immunized grouper exhibited reduced size. These findings bridge a crucial knowledge gap in understanding of the C. irritans cyst wall and highlight promising targets for infection prevention and control strategies.

Tenebrio Molitor breeding rejects as a high source of pure chitin and chitosan: Role of the processes, influence of the life cycle stages and comparison with Hermetia illucens

This work valorizes rejects from Tenebrio Molitor TM breeding through the production of chitin and chitosan. Two processes are proposed for extracting chitin from larval exuviae and adult. The first process P1 provides chitin with high contents compared to literature data but the characterization shows the presence of impurities in the exuviae chitin responsible for the shifts in the values of the physicochemical characteristics towards those presented by γ chitin. These impurities are removed by delipidation and pure α chitin is obtained. The effective delipidation of this chitin would be linked to its fibrous surface structure. The analysis of the results of P1 led us to develop a second extraction process P2 which provides pure chitin with improved yields using delipidation followed by deproteinization. The N-deacetylation of chitin according to Kurita or Broussignac process makes possible the preparation of pure, highly deacetylated chitosan samples (2 % < DA < 12 %) with high yields and controlled molar masses (Mv). A kinetic study of molecular degradation during deacetylation is carried out. A comparison with Hermetia illucens allows to extend the use of insects as a potential source of chitin and chitosan and confirms the role of the source and the processes in the determination of their characteristics.

Exploring the potential of chitosan from royal shrimp waste for elaboration of chitosan/bioglass biocomposite: Characterization and "in vitro" bioactivity

Exploiting royal shrimp waste to produce value-added biocomposites offers environmental and therapeutic benefits. This study proposes biocomposites based on chitosan and bioglass, using shrimp waste as the chitosan source. Chitin extraction and chitosan preparation were characterized using various analytical techniques. The waste composition revealed 24 % chitin, convertible to chitosan, with shells containing 77.33-ppm calcium. (X-ray diffraction) XRD analysis showed crystallinity index of 54.71 % for chitin and 49.14 % for chitosan. Thermal analysis indicated degradation rates of 326 °C and 322 °C, respectively. The degree of deacetylation of chitosan was 97.08 % determined by proton nuclear magnetic resonance (1H-NMR) analysis, with an intrinsic viscosity of 498 mL.g-1 and molar mass of 101,720 g/mol, showing improved solubility in 0.3 % acetic acid. Royal chitosan (CHR) was combined with bioglass (BG) via freeze-drying to create a CHR/BG biocomposite for bone surgery applications. The bioactivity of the CHR/BG was tested in simulated body fluid (SBF), revealing a biologically active apatite layer on its surface. Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) analysis confirmed enhanced bioactivity of the CHR/BG compared to commercial chitosan. The CHR/BG biocomposite demonstrated excellent apatite formation, validated by Scanning Electron Microscopy (SEM), highlighting its potential in bone surgery.

Exploring the potential of chitosan/aragonite biocomposite derived from cuttlebone waste: Elaboration, physicochemical properties and in vitro bioactivity

Cuttlefish bone biowaste is a potential source of a composite matrix based on chitin and aragonite. In the present work, we propose for the first time the elaboration of biocomposites based on chitosan and aragonite through the valorization of bone waste. The composition of the ventral and dorsal surfaces of bone is well studied by ICP-OES. An extraction process has been applied to the dorsal surface to extract β-chitin and chitosan with controlled physico-chemical characteristics. In parallel, aragonite isolation was carried out on the ventral side. The freeze-drying method was used to incorporate aragonite into the chitosan polymer to form CHS/ArgS biocomposites. Physicochemical characterizations were performed by FT-IR, SEM, XRD, 1H NMR, TGA/DSC, potentiometry and viscometry. The ICP-OES method was used to evaluate in vitro the bioactivity level of biocomposite in simulated human plasma (SBF), enabling analysis of the interactions between the material and SBF. The results obtained indicate that the CHS/ArgS biocomposite derived from cuttlefish bone exhibits bioactivity, and that chitosan enhances the bioactivity of aragonite. The CHS/ArgS biocomposite showed excellent ability to form an apatite layer on its surface. After three days' immersion, FTIR and SEM analyses confirmed the formation of this layer.

Valorization of Hermetia illucens breeding rejects by chitins and chitosans production. Influence of processes and life cycle on their physicochemical characteristics

Breeding of the black soldier fly is carried out to produce proteins. It is accompanied by releases during the life cycle of this insect. This work is a study of the valorization of these rejects through the production of chitins and chitosans with controlled characteristics. An extraction process is developed with an order of treatments and reaction conditions that provide chitins with high contents. These contents increase as the stages of the life cycle progress and drop for the adult. However, the exuviae chitins present organic impurities which will be eliminated at the N-deacetylation reaction for pupe and after a purification treatment for chitosan from larval stages. All these chitins have an α structure although certain physicochemical characteristics of the larval exuviae chitins are close to those presented by γ chitin. The observed shifts are linked to the effect of impurities rather than to a difference in structure. N-deacetylation of chitins makes possible the valorization of all rejects by the production of pure chitosans with high yields which retain a porous structure for the exuviae and fibrous for the adult which allow complementary applications. These chitosans are highly to completely deacetylated and their molar masses can vary depending on the process and life stage.

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

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.

Evaluating Non-Conventional Chitosan Sources for Controlled Release of Risperidone

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.