Versatile acid base sustainable solvent for fast extraction of various molecular weight chitin from lobster shell

Identifying barriers to scaled-up production and commercialization of chitin and chitosan using green technologies: A review and quantitative green chemistry assessment

Chitosan (CHT) production from Chitin (CH) is a billion-dollar industry but is constrained by multi-step chemical extractions that are energy and wastewater-intensive. Numerous green recovery technologies (GRT)s have paved the path for sustainable extraction, however, these have not been adopted for scale-up or mainstream commercialization. Therefore, this review critically evaluates the chemical, biological, combined biological-chemical and GRTs for CH/CHT recovery on commercially important criteria such as yields, molecular properties, cost/gram, water & energy use and wastewater & GHG emissions to identify barriers that hinder (i) the scaled-up, cost-effective commodity production of CH/CHT using GRTs (ii) the preparation of CH/CHT standards and (iii) the successful pathway from CH/CHT recovery to commercialization of chitosan-based products, supporting United Nations Sustainable Development Goals (UN SDG)s, particularly SDG 12. To arrive at the data-driven assessment, techno-economic and green chemistry metrics such as PMI and E-factor were calculated. The industry-developed quantitative green chemistry evaluator DOZN™ was used to assess resource & energy efficiency and human & environmental health hazards for CHT production. Mechanochemistry was identified as a viable GRT based on the limited literature available for quantitative assessment, and increasing the yield from GRT processes was identified as key to improving economic performance while also reducing environmental impacts.

Efficient and green extraction of chitin from Hermetia illucens using deep eutectic solvents and its application for rapid hemostasis

Hermetia illucens, with a short growth cycle, is promising as a valuable source of chitin. However, the optimal method for extracting chitin from this insect and its application for hemostasis has not been addressed. This work employed an environmentally friendly choline chloride-lactic acid deep eutectic solvent technology to extract chitin effectively from the Hermetia illucens pupae shells, realizing one-step removal of inorganic salts and proteins. The extraction process was optimized through the response surface methodology, which identified the optimal temperature (92 °C), time (5.6 h), and liquid-solid ratio (20 mL/g) as the conditions that yielded the highest chitin yield (28.40 %) and the highest purity (96.93 %). The structural characterization of the extracted chitin revealed an α-type structure with favorable thermal stability. Furthermore, by regulating the degree of deacetylation, we optimized the degree of protonation of chitin for producing a series of chitosan (Cts), thereby enabling the production of Cts2 with excellent in vitro hemostatic properties. The superior hemostatic performance of Cts2 can be attributed to significantly superior platelet adhesion, achieved preferred adsorption of fibrinogen, and improved blood coagulation. This work provides a theoretical basis for the efficient extraction and high-value application of chitin from Hermetia illucens.

Advances and challenges in green extraction of chitin for food and agriculture applications: A review

Chitin, the second most abundant polysaccharide in nature, offers numerous practical applications due to its versatile functional properties. However, its utilization is constrained by significant challenges in extraction, as well as low solubility and high crystallinity. While traditional chemical and biological fermentation methods can achieve high-purity chitin, these processes are often environmentally harmful or time/energy-consuming. Ionic liquids and deep eutectic solvents have emerged as more sustainable alternatives for chitin extraction, though both methods still face certain limitations, which are comprehensively discussed in this review. Besides extraction, chitin or modified chitin is increasingly being used to create a variety of biomaterials, which have shown considerable potential in food applications, including food packaging, preservation, stabilization, and nutrient encapsulation and delivery. Furthermore, the applications of chitin-based biomaterials are also reviewed in agriculture, where they are utilized as fertilizers, biocides, the elicitation of plants, or to treat seeds. This review not only provides a deeper understanding of the advancements and limitations in green chitin extraction methods but also highlights the broad potential of chitin-based biomaterials in both food and agriculture.

Catalytic conversion of chitin biomass into key platform chemicals

Chitin is the most abundant nitrogen-containing biomass on Earth and presents a compelling alternative to fossil fuels for chemical production. The catalytic conversion of chitin offers a viable approach for harnessing its inherent carbon and nitrogen contents, contributing to developing a green and sustainable society. This feature article reviews recent advances in shell waste biorefinery, with an emphasis on the contributions from our group. Efficient and sustainable chitin extraction methods are highlighted, along with the conversion of chitin biomass (N-acetyl-D-glucosamine (NAG), D-glucosamine, chitosan, and chitin) into key platform chemicals, mainly including furans, amino/amide sugars, organic acids and amino/amide acids. Catalytic strategies and production pathways are detailed, and current challenges and future research directions in chitin valorization are discussed.

Waste-to-resource: Extraction and transformation of aquatic biomaterials for regenerative medicine

The fisheries and aquaculture industry are known for generating substantial waste or by-products, often underutilized, or relegated to low-value purposes. However, this overlooked segment harbors a rich repository of valuable bioactive materials of which have a broad-spectrum of high-value applications. As the blue economy gains momentum and fisheries expand, sustainable exploitation of these aquatic resources is increasingly prioritized. In this review, we present a comprehensive overview of technology-enabled methods for extracting and transforming aquatic waste into valuable biomaterials and their recent advances in regenerative medicine applications, focusing on marine collagen, chitin/chitosan, calcium phosphate and bioactive-peptides. We discuss the inherent bioactive qualities of these "waste-to-resource" aquatic biomaterials and identify opportunities for their use in regenerative medicine to advance healthcare while achieving the Sustainable Development Goals.

Green extraction of chitin from hard spider crab shells

A green protocol to extract chitin from crab shells using water soluble ionic liquids (ILs) is here reported. Compared to conventional multistep acid-base extraction methods, this one-pot procedure achieves pulping of recalcitrant crustacean waste shells by employing ammonium acetate, ammonium formate and hydroxylammonium acetate as water-soluble, low-cost and easy to prepare ILs. An extensive parametric analysis of the pulping process has been carried out with different ILs, different ratios, temperature and time. The optimized protocol provides a high-quality chitin comparable, if not better, to commercial chitin. The best results were obtained at 150 °C with ammonium formate prepared in-situ from aqueous ammonia and formic acid: chitin was isolated in a 17 wt% yield (based on dried crab shells as starting biowaste), a degree of acetylation (DA) > 94 %, a crystallinity index of 39-46 %, a molecular weight up to 6.6 × 105 g/mol and a polydispersity of ca 2.0.

Exploring the Sustainable Utilization of Deep Eutectic Solvents for Chitin Isolation from Diverse Sources

Deep eutectic solvents (DES) represent an innovative and environmentally friendly approach for chitin isolation. Chitin is a natural nitrogenous polysaccharide, characterized by its abundance of amino and hydroxyl groups. The hydrogen bond network in DES can disrupt the crystalline structure of chitin, facilitating its isolation from bioresources by dissolving or degrading other components. DES are known for their low cost, natural chemical constituents, and recyclability. Natural deep eutectic solvents (NADES), a subclass of DES made from natural compounds, offer higher biocompatibility, biodegradability, and the lowest biotoxicity, making them highly promising for the production of eco-friendly chitin products. This review summarized studies on chitin isolation by DES, including reviews of biomass resources, isolation conditions (raw materials, DES compositions, solid-liquid ratios, temperature, and time), and the physicochemical properties of chitin products. Consequently, we have concluded that tailoring an appropriate DES-based process on the specific composition of the raw material can notably improve isolation efficiency. Acidic DES are particularly effective for extracting chitin from materials with high mineral content, such as crustacean bio-waste; for instance, the choline chloride-lactic acid DES achieved purity levels comparable to those of commercial chemical methods. By contrast, alkaline DES are better suited for chitin isolation from protein-rich sources, such as squid pens. DES facilitate calcium carbonate removal through H+ ion release and leverage unique hydrogen bonding interactions for efficient deproteination. Among these, potassium carbonate-glycerol DES have demonstrated optimal efficacy. Nonetheless, further comprehensive research is essential to evaluate the environmental impact, economic feasibility, and safety of DES application in chitin production.

Dissolving Chitin by Novel Deep Eutectic Solvents for Effectively Enzymatic Hydrolysis

Chitin is the most productive nitrogen-containing polysaccharide in nature with immense potential for transforming into a range of chemicals. However, its dense crystal structure poses a challenge for depolymerization, limiting its applications. To overcome these challenges, a novel series of deep eutectic solvents (DESs) based on benzyltrimethylammonium chloride (TMBAC) as the hydrogen bond acceptor was developed. These TMBAC-based DESs, in combination with lactic acid, oxalic acid, and malic acid as the hydrogen bond donor demonstrated efficient chitin dissolution, achieving a solubility of up to 12% and an 88% recovery rate of regenerated chitin. The regenerated chitin was characterized using XRD, FT-IR, SEM, and 13C CP-MAS NMR, which indicated the preservation of chitin's chemical structure, a significant decrease in crystallinity, and a reduction in the molecular weight. Furthermore, the enzymatic hydrolysis efficiency of chitin was nearly doubled after treatment with TMBAC-based DESs, surpassing the effectiveness of untreated chitin. This approach holds promise for facilitating subsequent transformation and utilization of chitin.

Comparative efficiency of different polyol-based deep eutectic solvents for chitin extraction from lobster shells

In this study, deep eutectic solvent (DES) prepared from choline chloride, lactic acid, and one of the four polyols (ethylene glycol, glycerol, xylitol, and sorbitol) were compared and assessed for their effectiveness in extracting chitin from lobster shells. Our results revealed that as the number of hydroxyl groups in polyols increased, the hydrogen bond network within the DESs became denser. However, this led to a corresponding increase in viscosity, which impacted the efficiency of chitin extraction. Among all prepared DESs, choline chloride-lactic acid/glycerol (CCLaGly) exhibited superior extractive ability, resulting in the extraction of pure chitin from lobster shells. The purity, crystallinity, and molecular weight of the extracted chitin using CCLaGly DES were comparable to those of chemically-isolated chitin, with purity reaching 94.76 ± 0.33 %, crystallinity at 78.78 %, and a molecular weight of 655 kDa. Additionally, the physicochemical properties of the DES-extracted chitins were characterized using Fourier-transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy. This study conducted a comparative analysis of polyol effects on chitin extraction from lobster shells, thereby opening a promising avenue for the utilization of various crustacean shells in sustainable biomaterial production.

Valorization of the Invasive Blue Crabs (Callinectes sapidus) in the Mediterranean: Nutritional Value, Bioactive Compounds and Sustainable By-Products Utilization

The blue crab (Callinectes sapidus), originally from the western Atlantic Ocean, has recently spread to the Mediterranean and is now considered one of the one hundred most invasive species in that region. This opportunistic species, known for its adaptability to different temperatures and salinities, negatively impacts biodiversity and human activities such as fishing and tourism in the Mediterranean. However, the blue crab is gaining interest as a potential food resource due to its high nutritional value and delicate, sweet flavor. Its meat is rich in protein (14% to 30%), omega-3 fatty acids (EPA and DHA) and other essential nutrients beneficial for human health such as vitamins, and minerals. Utilizing this species in the production of new foods could help mitigate the negative impact of its invasiveness and offer economic opportunities. One challenge with this potential resource is the generation of waste. Approximately 6-8 million tonnes of crab shells are produced worldwide each year, leading to disposal problems and concerns regarding environmental sustainability. To improve economic and environmental sustainability, there is a need to valorize these residues, which are an important source of proteins, lipids, chitin, minerals, and pigments that can be processed into high-value-added products. However, especially in areas with industrial pollution, attention should be paid to the heavy metal (Cd and As) contents of blue crab shells. Studies suggest that blue crab by-products can be used in various sectors, reducing environmental impacts, promoting a circular economy, and creating new industrial opportunities.

Valorization of Seafood Waste for Food Packaging Development

Packaging plays a crucial role in protecting food by providing excellent mechanical properties as well as effectively blocking water vapor, oxygen, oil, and other contaminants. The low degradation of widely used petroleum-based plastics leads to environmental pollution and poses health risks. This has drawn interest in renewable biopolymers as sustainable alternatives. The seafood industry generates significant waste that is rich in bioactive substances like chitin, chitosan, gelatins, and alginate, which can replace synthetic polymers in food packaging. Although biopolymers offer biodegradability, biocompatibility, and non-toxicity, their films often lack mechanical and barrier properties compared with synthetic polymer films. This comprehensive review discusses the chemical structure, characteristics, and extraction methods of biopolymers derived from seafood waste and their usage in the packaging area as reinforcement or base materials to guide researchers toward successful plastics replacement and commercialization. Our review highlights recent advancements in improving the thermal durability, mechanical strength, and barrier properties of seafood waste-derived packaging, explores the mechanisms behind these improvements, and briefly mentions the antimicrobial activities and mechanisms gained from these biopolymers. In addition, the remaining challenges and future directions for using seafood waste-derived biopolymers for packaging are discussed. This review aims to guide ongoing efforts to develop seafood waste-derived biopolymer films that can ultimately replace traditional plastic packaging.

Pretreatment of shrimp shells with an acidic deep eutectic solvent system for chitin extraction and its enhanced performance as a carrier for immobilized lipase

Existing methods for chitin extraction usually produce substantial waste, which poses ecological hazards. Natural deep eutectic solvent (NADES) offers a promising one-step pretreatment alternative, replacing the resource-intensive demineralization (DM) and deproteinization (DP) process. Hence, in this study, the influence of various acidic NADES, on achieving a simplified one-step DM and DP in the chitin extraction process was investigated. The study yielded chitin with 87.73 % purity, and microstructural analysis showed that NADES pretreatment minimally affected chitin quality without deacetylation. In addition, chitin extracted using choline chloride-oxalic acid as a carrier displayed excellent performance in the immobilization of Geobacillus thermocatenulatus lipase 2 (GTL2) because of obvious Ca2+ activation effect. This process contributed to enhancement of immobilized enzyme activity. The immobilized GTL2 showed excellent hydrolytic capabilities, with its highest activity reaching 547.80 ± 20.62 U/mg, significantly better than the five commercial lipases that exhibited <40 % of the enzyme activity. Furthermore, the hydrolytic capacity of immobilized GTL2 was notably high for 4-nitrophenyl butyrate, measuring 935.47 ± 51.60 U/mg. This study provided a constructive approach for the one-step pretreatment of shrimp shells with organic acid-based NADES to isolate and purify chitin and its potential application as an immobilized carrier to enhance enzyme activity.

Preparation of nanochitin using deep eutectic solvents

Chitin is an abundant and renewable non-wood biopolymer. Nanochitin is formed by the assembly of chitin molecules, which has the advantages of large tensile strength, high specific surface area, and biodegradability, so it has been widely used. However, the traditional methods of preparing nanochitin have many drawbacks. As the new generation of green solvents, deep eutectic solvents (DESs) have been successfully applied in the fields of chitin dissolution, extraction, and nanochitin preparation. In this review, the relevant knowledge of chitin, nanochitin, and DESs was first introduced. Then, the application status of DESs in the fields of chitin was summarized, with a focus on the preparation of nanochitin using DESs. In conclusion, this review provided a comprehensive analysis of the published literature and proposed insights and development trends in the field of preparation of nanochitin using DESs, aiming to provide guidance and assistance for future researchers.

Glycerol/organic acid-based ternary deep eutectic solvents as a green approach to recover chitin with different molecular weight from seafood waste

In this study, we designed a green and efficient approach for the fractionation of high-purity chitin with tunable molecular weights from seafood waste. This was achieved by using ternary deep eutectic solvents (TDESs) composed of choline chloride as a hydrogen bond acceptor, glycerol as the polyol-based hydrogen bond donor, together with lactic acid or malic acid. Two binary DESs and four TDESs were evaluated for their ability to recover chitin. The extracted chitin exhibited not only high yield with excellent protein and mineral removal, but also high purity with similar crystallinity patterns as standard chitin. However, the average molecular weights, viscosity behavior and morphology of chitin extracted by DESs were varied and influenced by organic acid to glycerol molar ratios. The molecular weights of chitin extracted by lactic acid-based TDES ranged from 264 kDa to 541 kDa, but malic acid-based TEDS displayed a stronger depolymerization effect, resulting in chitin with a smaller molecular weight of less than 300 kDa. Lactic acid-based TDES revealed that the purity of chitin remained higher than 92 % after three cycles. This sustainable and environmentally friendly extraction system holds great potential to recover chitin from seafood waste, opening a new era for chitin extraction and applications.

Harnessing the Potential of Chitosan and Its Derivatives for Enhanced Functionalities in Food Applications

As one of the most abundant natural polysaccharides that possess good biological activity, chitosan is extracted from chitin. Its application in the food field is being increasingly valued. However, chitosan extraction is difficult, and its poor solubility limits its application. At present, the extraction methods include the acid-base method, new chemical methods, and biological methods. The extraction rates of chitin/chitosan are 4-55%, 13-14%, and 15-28%, respectively. Different chemical modifications have different effects on chitosan, making it applicable in different fields. This article reviews and compares the extraction and chemical modification methods of chitosan, emphasizing the importance of green extraction methods. Finally, the application prospects of chitosan in the food industry are discussed. This will promote the understanding of the advantages and disadvantages of different extraction methods for chitosan as well as the relationship between modification and application, providing valuable insights for the future development of chitosan.

Fabrication of chitin-glucan nanofibers: Insights into mushroom pretreatment and subsequent acidic deep eutectic solvent-based esterification

Mushrooms contain chitin-glucan complex (CGC), a natural copolymer of chitin and glucan, and nanofibrillation enhances its applicability. Here, a novel method was used to fabricate chitin-glucan nanofibers (CGNFs) from white button mushrooms. The first stage was to pretreat the raw mushroom using hot water and alkali to remove water-soluble glucans and alkali-soluble proteins, respectively, producing a CGC amenable to nanofibrillation. The second stage was nanofibrillation via esterification using acidic deep eutectic solvents (DESs) and subsequent ultrasonication. Five choline chloride-based DESs containing mono- or dicarboxylic acid were tested for the CGC esterification. DESs with strong dicarboxylic acids expedited nanofibrillation by homogeneously dispersing the solid CGC, swelling CGC fibrils, and facilitating acidity-dependent esterification leading to steric and electrostatic repulsions. One CGNF, namely CGNF_CCMnA, was characterized: it contained chitin and glucan at an approximate ratio of 8:2 and exhibited desirable properties as nanomaterials, including small diameter (11 nm) and high colloidal (zeta potential < -30 mV above pH 5.8) and thermal stability (Tm, 315 °C). CGNF_CCMnA was tested for the adsorption to methylene blue, revealing a maximum adsorption capacity of 82.58 mg/g. The proposed approach is an efficient and readily applicable method to fabricate various mushroom-derived safe CGNFs and to produce related nanomaterials.

Sustainable valorization approaches on crustacean wastes for the extraction of chitin, bioactive compounds and their applications - A review

The unscientific disposal of the most abundant crustacean wastes, especially those derived from marine sources, affects both the economy and the environment. Strategic waste collection and management is the need of the hour. Sustainable valorization approaches have played a crucial role in solving those issues as well as generating wealth from waste. The shellfishery wastes are rich in valuable bioactive compounds such as chitin, chitosan, minerals, carotenoids, lipids, and other amino acid derivatives. These value-added components possessed pleiotropic applications in different sectors viz., food, nutraceutical, cosmeceutical, agro-industrial, healthcare, and pharmaceutical sectors. The manuscript covers the recent status, scope of shellfishery management, and different bioactive compounds obtained from crustacean wastes. In addition, both sustainable and conventional routes of valorization approaches were discussed with their merits and demerits along with their combinations. The utilization of nano and microtechnology was also included in the discussion, as they have become prominent research areas in recent years. More importantly, the future perspectives of crustacean waste management and other potential valorization approaches that can be implemented on a large scale.

Hydrogels based on seafood chitin: From extraction to the development

Chitin is extensively applied in vast applications due to its excellent biological properties, such as biodegradable and non-toxic. About 50 % of waste generated during seafood processing is chitin. Conventionally, chitin is extracted via chemical method. However, it has many shortcomings. Many novel extraction methods have emerged, including enzymatic hydrolysis, microbial fermentation, ultrasonic or microwave-assisted, ionic liquids, and deep eutectic solvents. Chitin and its derivatives-based hydrogels have attracted much attention due to their excellent properties. Nevertheless, they all have many limitations. Therefore, the preparation and application of chitin and its derivatives-based hydrogels are still facing great challenges. This review focuses on the challenges and prospects for sustainable chitin extraction from seafood waste and the preparation and application of chitin and its derivatives-based hydrogels. First section summarizes the mechanism and application of several methods of extracting chitin. The different extraction methods were evaluated from the aspects of yield, degree of acetylation, and protein and mineral residuals. The shortcomings of the extraction methods are also discussed. Next section summarizes the preparation and application of chitin and its derivatives-based hydrogels. Overall, we hope this mini-review can provide a practical reference for selecting chitin extraction methods from seafood and applying chitin and its derivatives-based hydrogels.

Synthesis of Mixed Chitin Esters via Acylation of Chitin in Deep Eutectic Solvents

The development of efficient derivatization methods of chitin, such as acylation, has been identified to confer new properties and functions to chitin. In this study, we investigate the synthesis of mixed chitin esters via the acylation of chitin in deep eutectic solvents (DESs) comprising 1-allyl-3-methylimidazolum chloride and 1,1,3,3-tetramethylguanidine based on a previous study that reported the development of efficient acylation of chitin in the DES to obtain single chitin esters. A stearoyl group was selected as the first substituent, which was combined with several bulky acyl and long oleoyl groups as the second substituents. After dissolution of chitin in the DES (2 wt%), the acylation reactions were conducted using stearoyl and the desired acyl chlorides for 1 h + 24 h at 100 °C in the resulting solutions. The IR and 1H NMR spectra of the isolated products confirmed the structures of mixed chitin esters with two different substituents. The substituent ratios in the derivatives, which were estimated via the 1H NMR analysis, were changed according to the feed ratios of two acyl chlorides.

Trash to Treasure: An Up-to-Date Understanding of the Valorization of Seafood By-Products, Targeting the Major Bioactive Compounds

Fishery production is exponentially growing, and its by-products negatively impact industries' economic and environmental status. The large amount of bioactive micro- and macromolecules in fishery by-products, including lipids, proteins, peptides, amino acids, vitamins, carotenoids, enzymes, collagen, gelatin, chitin, chitosan, and fucoidan, need to be utilized through effective strategies and proper management. Due to the bioactive and healthy compounds in fishery discards, these components can be used as functional food ingredients. Fishery discards have inorganic or organic value to add to or implement in various sectors (such as the agriculture, medical, and pharmaceutical industries). However, the best use of these postharvest raw materials for human welfare remains unelucidated in the scientific community. This review article describes the most useful techniques and methods, such as obtaining proteins and peptides, fatty acids, enzymes, minerals, and carotenoids, as well as collagen, gelatin, and polysaccharides such as chitin-chitosan and fucoidan, to ensure the best use of fishery discards. Marine-derived bioactive compounds have biological activities, such as antioxidant, anticancer, antidiabetic, anti-inflammatory, and antimicrobial activities. These high-value compounds are used in various industrial sectors, such as the food and cosmetic industries, owing to their unique functional and characteristic structures. This study aimed to determine the gap between misused fishery discards and their effects on the environment and create awareness for the complete valorization of fishery discards, targeting a sustainable world.

The synergistic action of two chitinases from Vibrio harveyi on chitin degradation

In this study, two chitinases (VhChit2 and VhChit6) from Vibrio harveyi possessed specific activity of 36.5 and 20.8 U/mg, respectively. Structure analysis indicates that their amino acid composition of active sites is similar, but the substrate binding cleft of VhChit2 is deeper than that of VhChit6. They were shown to have a synergistic effect on chitin degradation, and the optimized degree of synergy and the degradation ratio of chitin reached 1.75 and 23.6 %, respectively. The saturated adsorption capacity of VhChit2 and VhChit6 adsorbed in 1 g of chitin was 48.5 and 33.4 mg. It was found that VhChit2 and VhChit6 had different adsorption sites on chitin, making more enzymes absorbed by chitin. Furthermore, the combined use of VhChit2 and VhChit6 increased their binding force of chitinases with the substrate. The synergistic action of VhChit2 and VhChit6 may be attributed to their different adsorption sites on chitin and the increased binding force with chitin.

Preparation of polysubstituted imidazoles using AC-SO3H/[Urea]7[ZnCl2]2 as an efficient catalyst system: a novel method, and α-glucosidase inhibitor activity

Deep eutectic solvents (DESs) act as both an organic solvent and a useful catalyst for organic synthesis reactions, especially the synthesis of heterocyclic compounds containing the element nitrogen. DESs exhibit many important properties namely large liquid fields, biodegradability, outstanding thermal stability, and moderate vapor pressure. Amorphous carbon-bearing sulfonic acid groups (AC-SO3H) are one of the new-generation solid acids showing strong acid activity. Based on the simultaneous presence of acidic functional groups such as carboxylic acid, phenolic, and sulfonic acid groups, they exhibit many important activities namely strong Brønsted acid, high surface area, high stability, reusability, and recyclability. In this study, AC-SO3H was made from rice husk via the carbonization and sulfonation processes, and the surface properties and structure were examined using contemporary methods such as FT-IR, P-XRD, TGA, SEM, and EDS. And, [Urea]7[ZnCl2]2 was synthesized from urea and ZnCl2 with a mole ratio of 7 : 2; the structure is defined using FT-IR and TGA. By combining AC-SO3H and [Urea]7[ZnCl2]2 we aim to form an effective catalyst/solvent system for the preparation of polysubstituted imidazole derivatives through the multi-component cyclization reaction from nitrobenzenes, benzil, aldehydes, and ammonium acetate. The major products are obtained with high isolation yields above 60%. To assess the catalyst system's activity, the recovery and reusability of the AC-SO3H/[Urea]7[ZnCl2]2 system were examined with hardly any performance modification. In an effort to create potential enzyme α-glucosidase inhibitors, several novel polysubstituted imidazoles were created. Five of these compounds showed good enzyme α-glucosidase inhibitor activity. The most effective substances were IMI-13, IMI-15, and IMI-20, with IC50 values that were greater than the acarbose at 16.5, 15.8, and 11.6 μM, respectively - the acarbose (IC50, 214.5 μM) as the positive control.

Evaluating the status quo of deep eutectic solvent in food chemistry. Potentials and limitations

Conventional organic solvents (e.g., methanol, ethanol, ethyl acetate) are widely used for extraction, reaction, and separation of valuable compounds. Although these solvents are effective, they have disadvantages, including flammability, toxicity, and persistence in the environment. Deep eutectic solvents (DESs) are valued for their biodegradability/low impact on the environment, low cost, and ease of manufacture. The objective of this review was to provide an overview of applications of DES in food chemistry, specifically in regard of extraction of polyphenols (e.g., anthocyanin, rutin, kaempferol, quercetin, resveratrol), protein, carbohydrates (e.g., chitin, pectins), lipids and lipid-soluble compounds (e.g., free fatty acids, astaxanthin, β-carotene, terpenoids), biosensor development, and use in food safety (pyrethroids, Sudan I, bisphenol A, Pb²⁺, Cd²⁺, etc.) over the past five years. A comprehensive analysis and discussion of DES types, preparation, structures, and influencing factors is provided. Furthermore, the potential and disadvantages of using DESs to extract biomolecules were assessed. We concluded that DES is a viable alternative for extracting polyphenols, carbohydrates, and lipids as well as use in food safety monitoring and biosensor development. However, more work is needed to address shortcomings, and determine whether using compounds extracted with DES can be consumed safely.

Chitosan electrospun nanofibers derived from Periplaneta americana residue for promoting infected wound healing

Periplaneta americana has been used medicinally for years to treat a wide variety of skin lesions or ulcers. However, a sizable portion of the drug residues that are retained after extraction are routinely thrown away, thus posing a hazard to the environment and depleting resources. In this study, low molecular weight Periplaneta americana chitosan (LPCS) and high molecular weight Periplaneta americana chitosan (HPCS) were extracted from Periplaneta americana residue (PAR) based on the conventional acid-base method and two deacetylation methods. Moreover, the physicochemical properties and structural differences between the above two chitosan and commercial chitosan (CS) were compared using different methods. Next, two nanofibers comprising different ratios of Periplaneta americana chitosan (LPCS or HPCS), polyvinyl alcohol (PVA), and polyethylene oxide (PEO) were prepared and optimized. The above nanofibers exhibited excellent mechanical properties, antibacterial properties, and biocompatibility while facilitating wound healing in an infected rat whole-layer wound model by promoting wound closure, epithelialization, collagen deposition, and inflammation reduction. In brief, this study produced an effective and affordable wound dressing and offered a suggestion for the comprehensive utilization of Periplaneta americana residue.

Double Valorization for a Discard-α-Chitin and Calcium Lactate Production from the Crab Polybius henslowii Using a Deep Eutectic Solvent Approach

Polybius henslowii, an abundant yet unexploited species of swimming crab, was investigated as a potential source of α-chitin and calcium lactate using deep eutectic solvents (DES) as extracting solvents. Choline chloride-malonic acid (CCMA) and choline chloride-lactic acid (CCLA) were used to obtain high purity α-chitin from ball-milled P. henslowii exoskeleton in 2 h at 120 °C, with yields of 12.05 ± 2.54% and 12.8 ± 1.54%, respectively. The physical and chemical characteristics of the obtained chitins were assessed using CHN elemental analysis, attenuated total reflectance-Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. Furthermore, the CCLA solvent was reusable three times with little effect on the extract purity, and calcium lactate was produced at the end of the recycling cycles. The ensuing calcium lactate was also characterized in terms of chemical and physical properties. The obtained chitin is a promising raw material for downstream processing and the double valorization pathway with the obtention of calcium salts may increase the viability of a DES-based approach for the processing of mineralized substrates.

Nanochitin: Chemistry, Structure, Assembly, and Applications

Chitin, a fascinating biopolymer found in living organisms, fulfills current demands of availability, sustainability, biocompatibility, biodegradability, functionality, and renewability. A feature of chitin is its ability to structure into hierarchical assemblies, spanning the nano- and macroscales, imparting toughness and resistance (chemical, biological, among others) to multicomponent materials as well as adding adaptability, tunability, and versatility. Retaining the inherent structural characteristics of chitin and its colloidal features in dispersed media has been central to its use, considering it as a building block for the construction of emerging materials. Top-down chitin designs have been reported and differentiate from the traditional molecular-level, bottom-up synthesis and assembly for material development. Such topics are the focus of this Review, which also covers the origins and biological characteristics of chitin and their influence on the morphological and physical-chemical properties. We discuss recent achievements in the isolation, deconstruction, and fractionation of chitin nanostructures of varying axial aspects (nanofibrils and nanorods) along with methods for their modification and assembly into functional materials. We highlight the role of nanochitin in its native architecture and as a component of materials subjected to multiscale interactions, leading to highly dynamic and functional structures. We introduce the most recent advances in the applications of nanochitin-derived materials and industrialization efforts, following green manufacturing principles. Finally, we offer a critical perspective about the adoption of nanochitin in the context of advanced, sustainable materials.

Nano-fertilizers: A sustainable technology for improving crop nutrition and food security

Excessive use of synthetic fertilizers cause economic burdens, increasing soil, water and atmospheric pollution. Nano-fertilizers have shown great potential for their sustainable uses in soil fertility, crop production and with minimum or no environmental tradeoffs. Nano-fertilizers are of submicroscopic sizes, have a large surface area to volume ratio, can have nutrient encapsulation, and greater mobility hence they may increase plant nutrient access and crop yield. Due to these properties, nano-fertilizers are regarded as deliverable 'smart system of nutrients'. However, the problems in the agroecosystem are broader than existing developments. For example, nutrient delivery in different physicochemical properties of soils, moisture, and other agro-ecological conditions is still a challenge. In this context, the present review provides an overview of various uses of nanotechnology in agriculture, preference of nano-fertilizers over the conventional fertilizers, nano particles formation, mobility, and role in heterogeneous soils, with special emphasis on the development and use of chitosan-based nano-fertilizers.

Chitosan: Sources, Processing and Modification Techniques

Chitosan, a copolymer of glucosamine and N-acetyl glucosamine, is derived from chitin. Chitin is found in cell walls of crustaceans, fungi, insects and in some algae, microorganisms, and some invertebrate animals. Chitosan is emerging as a very important raw material for the synthesis of a wide range of products used for food, medical, pharmaceutical, health care, agriculture, industry, and environmental pollution protection. This review, in line with the focus of this special issue, provides the reader with (1) an overview on different sources of chitin, (2) advances in techniques used to extract chitin and converting it into chitosan, (3) the importance of the inherent characteristics of the chitosan from different sources that makes them suitable for specific applications and, finally, (4) briefly summarizes ways of tailoring chitosan for specific applications. The review also presents the influence of the degree of acetylation (DA) and degree of deacetylation (DDA), molecular weight (M_w) on the physicochemical and biological properties of chitosan, acid-base behavior, biodegradability, solubility, reactivity, among many other properties that determine processability and suitability for specific applications. This is intended to help guide researchers select the right chitosan raw material for their specific applications.

Application Progress of Modified Chitosan and Its Composite Biomaterials for Bone Tissue Engineering

In recent years, bone tissue engineering (BTE), as a multidisciplinary field, has shown considerable promise in replacing traditional treatment modalities (i.e., autografts, allografts, and xenografts). Since bone is such a complex and dynamic structure, the construction of bone tissue composite materials has become an attractive strategy to guide bone growth and regeneration. Chitosan and its derivatives have been promising vehicles for BTE owing to their unique physical and chemical properties. With intrinsic physicochemical characteristics and closeness to the extracellular matrix of bones, chitosan-based composite scaffolds have been proved to be a promising candidate for providing successful bone regeneration and defect repair capacity. Advances in chitosan-based scaffolds for BTE have produced efficient and efficacious bio-properties via material structural design and different modifications. Efforts have been put into the modification of chitosan to overcome its limitations, including insolubility in water, faster depolymerization in the body, and blood incompatibility. Herein, we discuss the various modification methods of chitosan that expand its fields of application, which would pave the way for future applied research in biomedical innovation and regenerative medicine.

Extraction and characterization of chitin from Oratosquilla oratoria shell waste and its application in Brassica campestris L.ssp

Mantis shrimp waste (Oratosquilla oratoria) is a good source of chitin. The applicability of microwave-assisted organic acids and proteases for extracting chitin from mantis shrimp shell waste was evaluated, and the extracted-chitin was characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). Moreover, the effects of nanochitin on the growth of pak choi (Brassica campestris L.ssp.) were also investigated. The results indicated that alkaline protease (4000 U/g, microwave heating at 60 °C, 10 min) and malic acid (5%, 320 W, 5 min) exhibited excellent potential for deproteinizing and demineralizing shells. The deproteinization and demineralization yields were 92.78% and 94.11%, respectively, and the chitin yield was 15.6%. The extracted-chitin had a highly porous structure and exhibited excellent crystallinity and thermostability compared with chitin prepared by traditional chemical methods. Furthermore, 0.003% nanochitin significantly enhanced photosynthesis, which improved the pak choi fresh weight by 22.94%, and improved the accumulation of isothiocyanates in its leaves. This study provides an alternative approach for the high-value utilization of mantis shrimp waste, and reveals the potential of chitin for application in agricultural production.

Adsorption properties of heavy metals and antibiotics by chitosan from larvae and adult Trypoxylus dichotomus

Chitosan was prepared by hydrothermal deacetylation from multi-step protein purification chitin based on Trypoxylus dichotomus, for treating heavy metals and antibiotics. Chitosan with higher deacetylation degree and lower molecular weight were synthesized. The adult chitosan was composed of nanofibers arranged more evenly, showing higher yield, thermal stabilities and antimicrobial properties. The adsorption capacities of Cu²⁺ and Fe³⁺ were 462 and 270 mg/g, lower than 934 mg/g of Pb²⁺. Levofloxacin and tetracycline hydrochloride adsorption capacity were 26 and 22 mg/g, lower than 67 mg/g of sulfamethoxazole. In addition, compared with single pollutants, the adsorption of sulfamethoxazole and Pb²⁺ can increase by 6% and 5% when they act as composite contaminants. The adsorption procedure can be well described by pseudo-second-order kinetics and Langmuir isothermal model, indicating it a homogeneous monolayer chemisorption. Therefore, the Trypoxylus dichotomus source chitosan prepared by hydrothermal deacetylation has potential applications in the adsorption of complex pollutants.

Chitin and derivative chitosan-based structures - Preparation strategies aided by deep eutectic solvents: A review

The high molecular weight of chitin, as a biopolymer, challenges its extraction due to its insolubility in the solvents. Also, chitosan, as the N-deacetylated form of chitin, can be employed as a primary material for different industries. The low mechanical stability and poor plasticity of chitosan films, as a result of incompatible interaction between chitosan and the used solvent, have limited its industrialization. Deep eutectic solvents (DESs), as novel solvents, can solve the extraction difficulties of chitin, and the low mechanical stability and weak plasticity of chitosan films. Also, DESs can be considered for the different chitosan and chitin productions, including chitin nanocrystal and nanofiber, N,N,N-trimethyl-chitosan, chitosan-based imprinted structures, and DES-chitosan-based beads and monoliths. This review aims to focus on the preparation and characterization (chemistry and morphology) of DES-chitin-based and DES-chitosan-based structures to understand the influence of the incorporation of DESs into the chitin and chitosan structure.

A Comparative Analysis of Conventional and Deep Eutectic Solvent (DES)-Mediated Strategies for the Extraction of Chitin from Marine Crustacean Shells

Chitin, the second most abundant biopolymer on earth, is utilised in a wide range of applications including wastewater treatment, drug delivery, wound healing, tissue engineering, and stem cell technology among others. This review compares the most prevalent strategies for the extraction of chitin from crustacean sources including chemical methods that involve the use of harsh solvents and emerging methods using deep eutectic solvents (DES). In recent years, a significant amount of research has been carried out to identify and develop environmentally friendly processes which might facilitate the replacement of problematic chemicals utilised in conventional chemical extraction strategies with DES. This article provides an overview of different experimental parameters used in the DES-mediated extraction of chitin while also comparing the purity and yields of associated extracts with conventional methods. As part of this review, we compare the relative proportions of chitin and extraneous materials in different marine crustaceans. We show the importance of the species of crustacean shell in relation to chitin purity and discuss the significance of varying process parameters associated with different extraction strategies. The review also describes some recent applications associated with chitin. Following on from this review, we suggest recommendations for further investigation into chitin extraction, especially for experimental research pertaining to the enhancement of the "environmentally friendly" nature of the process. It is hoped that this article will provide researchers with a platform to better understand the benefits and limitations of DES-mediated extractions thereby further promoting knowledge in this area.

Low-Phytotoxic Deep Eutectic Systems as Alternative Extraction Media for the Recovery of Chitin from Brown Crab Shells

The versatility of chitin and its derivatives has allowed their utilization in a wide range of applications, from wastewater treatment to pharmaceutical or biomedical industries. However, even though the extraction method used industrially is extremely efficient, it involves the use of strong acids and bases and results in the disposal of large quantities of toxic effluents. Deep eutectic systems (DESs) have emerged as a promising new class of alternative solvents, including for chitin recovery. Yet, the assessment of their toxicity has often been neglected. Therefore, in this work, the phytotoxicity of choline chloride (ChCl)/organic acid-based DESs toward wheat seeds was evaluated by measuring different growth parameters and stress biomarkers. DESs were then explored for the efficient recovery of chitin contained in brown crab shell residues at varying conditions of temperature and processing time as well as with and without water addition. The obtained chitin was then characterized through different analytical techniques and compared to a standard as well as to chitin obtained by a conventional acid/alkaline hydrolysis. Results have shown that by applying a ChCl/lactic acid-based DES (which was the system that showed the least phytotoxic effects on wheat; EC50 ≥ 1.6 mg/mL) at 130 °C, it was possible to obtain pure chitin (up to 98%) with characteristics similar to those presented by commercial chitin or chitin recovered by conventional hydrolysis in a shorter time (more than 8-fold faster), thus suggesting that ChCl/organic acid-based DESs can truly represent a low-phytotoxic alternative extraction media for the recovery of chitin from the crab shell biomass.

Chitosan for biomedical applications, promising antidiabetic drug delivery system, and new diabetes mellitus treatment based on stem cell

Since chitosan's excellent pharmacokinetic and chemical properties, it is an attractive and promising carbohydrate biopolymer in biomedical applications. Chitosan's beneficial function in the defense and propagation of pancreatic β cells, reducing hyperglycemia, and avoiding diabetes mellitus associated with impaired lipid metabolism has been demonstrated in several studies. Additionally, chitosan has also been used in various nanocarriers to deliver various antidiabetic drugs to reduce glucose levels. Herein, the first to provide the currently available potential benefits of chitosan in diabetes mellitus treatment focuses on chitosan-based nanocarriers for oral administration of various antidiabetic drugs nasal and subcutaneous passages. Moreover, chitosan is used to activate and deliver stem cells and differentiate them into cells similar to pancreatic beta cells as a new type of treatment for type one diabetes mellitus. The results of this review will be helpful in the development of promising treatments and better control of diabetes mellitus.

IL versus DES: Impact on chitin pretreatment to afford high quality and highly functionalizable chitosan

Chitin is mainly extracted from crustaceans, but this resource is seasonally dependent and can represent a major drawback to satisfy the traceability criterion for high valuable applications. Insect resources are valuable alternatives due to their lower mineral content. However, the deacetylation of chitin into chitosan is still an expensive process. Therefore, we herein compare the impact of both DES/IL-pretreatments on the efficiency of the chemical deacetylation of chitin carried out over two insect sources (Bombyx eri, BE and Hermetia illucens, HI) and shrimp shells (S). The results showed that chitosans obtained from IL-pretreated chitins from BE larva, present lower acetylation degrees (13-17%) than DES-pretreated samples (18-27%). A selective N-acylation reaction with oleic acid has also been performed on the purest and most deacetylated chitosans leading to high substitution degrees (up to 27%). The overall approach validates the proper chitin source and processing methodology to achieve high quality and highly functionalizable chitosan.

A review on the potential uses of deep eutectic solvents in chitin and chitosan related processes

Ionic liquids (ILs) as well as closely related deep eutectic solvents (DESs) have been the most promising discoveries in the "Green Chemistry" world in recent years as types of solvents. Deep eutectic solvents are received as potential alternatives to the conventional organic solvents with other advantages such as renewability, reusability, biodegradability, nontoxicity, large-scale availability, having very low vapour pressure, low flammability and easy in preparation. Chitin is the second most abundant biopolymers in the nature that can be extracted from many aquatic and terrestrial organisms also some of the microorganisms. Chitin and its derivatives have applications in many fields such as medical, food-beverages, agriculture and cosmetics. This review reports the major contributions of DESs in chitin and chitosan related studies and summarizes recent advances in some applications such as extraction media, bio-film fabrication, nanomaterial preparation, chitosan methylation, chitin dissolution, composite material preparation.

Review of chitosan composite as a heavy metal adsorbent: Material preparation and properties

A large amount of wastewater is typically discharged into water bodies and has extremely harmful effects to aquatic environments. The removal of heavy metals from water bodies is necessary for the safe consumption of water and human activities. The demand for seafood has considerably increased, and millions of tons of crustacean waste are discarded every year. These waste products are rich in a natural biopolymer known as chitin. The deacetylated form of chitin, chitosan, has attracted attention as an adsorbent. It is a biocompatible and biodegradable polymer that can be modified and converted to various derivatives. This review paper focuses on relevant literature on strategies for chemically modifying the biopolymer and its use in the removal of heavy metals from water and wastewater. The different aspects of chitosan-based derivatives and their preparation and application are elucidated. A list of chitosan-based composites, along with their adsorptivity and experimental conditions, are compiled.

Preparation of Antioxidant and Antibacterial Chitosan Film from Periplaneta americana

Simple Summary

The American cockroach (Periplaneta americana) is a kind of insect distributed worldwide. Commonly, it is considered as a pest. However, nowadays, it has been developed as a potential resource of protein, lipid, and antibacterial peptide. Besides, it also contains chitin, which could be used to produce chitosan by deacetylation. Chitosan is a valuable biomaterial containing amino groups, and has been applied in various fields. However, the researches focusing on the applications of P. americana chitosan are rare, which might hinder the exploration of the value of P. americana. In this paper, we prepared and characterized the chitosan film from P. americana. The performances relating to food packaging of the obtained film were also examined. As the results showed, P. americana chitosan film could resist UV light effectively. It could also keep scavenging 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals in 8 h, proving its ability of antioxidant. In addition, it exhibited antibacterial activity by resisting the growth of Serratia marcescens and Escherichia coli. The results showed that P. americana chitosan film could work as a potential food packaging material, which implicated the value of P. americana chitosan and provided a new clue for the exploration of the value of more insects, especially pests.

Abstract

Among different insects, the American cockroach (Periplaneta americana) has been bred in industrial scale successfully as a potential resource of protein, lipid, and antibacterial peptide. However, the application of its chitosan has not been studied widely, which has hindered the sufficient utilization of P. americana. In this paper, the chitosan from P. americana was separated, characterized, and processed into film (PaCSF) to examine its potential of being applied in food packaging. As the results of different characterizations showed, PaCSF was similar to shrimp chitosan film (SCSF). However, concerning the performances relating to food packaging, the two chitosan films were different. PaCSF contained more water (42.82%) than SCSF did, resulting in its larger thickness (0.08 mm). PaCSF could resist UV light more effectively than SCSF did. Concerning antioxidant activity, the DPPH radical scavenging ability of PaCSF increased linearly with time passing, reaching 72.46% after 8 h, which was better than that of SCSF. The antibacterial activity assay exhibited that PaCSF resisted the growth of Serratia marcescens and Escherichia coli more effectively than SCSF did. The results implied that P. americana chitosan could be a potential raw material for food packaging, providing a new way to develop P. americana.