Antitumor activity of chitosan from mayfly with comparison to commercially available low, medium and high molecular weight chitosans

Unravelling the Role of Chitin and Chitosan in Prebiotic Activity and Correlation With Cancer: A Narrative Review

This review describes the state of the art regarding the prebiotic role of chitin and the interactions of chitin and chitosan with cancer cells. Chitin is the second most abundant polysaccharide in nature and a constitutive component of crustacean shells and the exoskeleton of insects. Chitosan is the deacetylated form of chitin, which is obtained by chemical processing or the enzymatic activity of deacetylases found in microorganisms and insects. Edible insects have recently been introduced in Western countries, thus raising concerns regarding food safety and due to their chitin content and the release of chitosan during the digestive process. The roles of insect chitin and chitosan in the gastrointestinal tract, microbiome modulation, and cancer have been widely investigated. Several in vitro and in vivo studies have shown the possible microbiota modulation of chitin and its relevant communication with the immune system, thus confirming its prebiotic activity. No evidence has been provided on the cancerogenic activity of chitin; however, studies have suggested that chitin has a cytotoxic effect on cancer cell lines. Chitosan has been confirmed to exhibit apoptotic and cytotoxic activities on cancer cells in several in vitro studies on cancer cell lines and in vivo models. In conclusion, the literature does not show a direct connection between the presence of chitin or chitosan and the onset of cancer. However, cytotoxic and apoptotic activities in relation to cancerous lines have been demonstrated.

Hermetia illucens-derived chitosan as a promising sustainable biomaterial for wound healing applications: development of sponge-like scaffolds

Chitosan (CS), a biopolymer known for its wound-healing properties, has garnered significant interest in biomedical research. This study explores the potential of two Hermetia illucens-derived CS types-unbleached CS and bleached CS-as novel biomaterials for wound-healing applications, in comparison with commercial CS derived from the shells of Pandalus borealis (cold-water shrimp). CS was extracted from pupal exuviae, a byproduct of insect farming, which supports a circular economy by converting waste into valuable molecules for biomedical applications. Unbleached CS exhibited viscosity and viscoelastic properties comparable to those of commercial CS. The critical entanglement concentration (CEC) of unbleached CS (1.15 ± 0.05 % w/v) was similar to that of commercial CS (1.18 ± 0.09 % w/v). Moreover, both Hermetia illucens-derived CS types (unbleached and bleached) demonstrated a greater capability to enhance fibroblast viability (135 ± 7 % and 123 ± 6 %, respectively) compared to commercial CS (115 ± 7 %). Further investigation revealed that unbleached CS exhibited increased antioxidant activity, reversing >30 % of the loss of viability caused by H2O2 treatment, and demonstrated anti-inflammatory properties, decreasing IL-6 levels by 66 ± 2 %. Sponge-like scaffolds based on unbleached CS and commercial CS were prepared via freeze-drying. When comparing structural and functional properties of commercial and unbleached CS scaffolds, the unbleached CS scaffolds exhibited higher porosity (67.9 ± 2.7 %), smaller pore size (216 ± 35 nm), higher swelling ratio (25.4 ± 1.9), greater resistance to degradation, and enhanced fibroblast proliferation. These findings underscore the potential of insect-derived CS as a sustainable and bioactive material for wound healing. However, further research is required to fully understand its interactions and mechanisms in tissue repair.

Structural analysis and immunological activity of a novel low molecular weight neutral polysaccharide isolated from Hemerocallis citrina Borani

A novel neutral water-soluble polysaccharide (HCBP1-1) was isolated and purified from Hemerocallis citrina Borani by column chromatography. The fine structure of HCBP1-1 was determined by a series of physical and chemical means. HCBP1-1 was a homogeneous low molecular weight polysaccharide of 7.25 kDa. Methylation and NMR analysis revealed that HCBP1-1 consisted of α-D-Glcp-(1→, →4)-α-D-Glcp-(1→, →4)-β-D-Galp-(1→, →4,6)-α-D-Glcp-(1→, →3,4)-α-D-Glcp-(1→. In particular, the main backbone of HCBP1-1 consisted of unsubstituted (4-α-D-Glcp and 4-β-D-Galp) and monosubstituted (4,6-α-D-Glcp and 3,4-α-D-Glcp) glucose and galactose units linked by α-(1 → 4) and β-(1 → 4) glycosidic linkages. The side chain consisted of α-D-Glcp-(1 → and →4)-α-D-Glcp-(1→. Furthermore, bioactivity assays show that HCBP1-1 significantly promoted the secretion of NO, TNF-α, IL-1β, and IL-6 and the expression of NF-κB p65 in RAW264.7 cells, which had good immune-enhancing activity. These results suggest that HCBP1-1 had beneficial immunomodulatory effects and could be developed into functional foods or nutraceuticals with immune-enhancing properties.

Bioactive compounds in edible insects: Aspects of cultivation, processing and nutrition

The increasing interest in edible insects, driven by projected global population growth and environmental concerns, has led to the exploration of their potential in the food sector. Edible insects are abundant in macronutrients, such as proteins, lipids and chitin, as well as micronutrients, such as minerals, vitamins and phenolic compounds. Considering their content of bioactive compounds, they offer a sustainable solution to meet future food demands while providing potential health benefits. This review identifies bioactive peptides, phenolic compounds, chitosan, and vitamins as major bioactive ingredients derived from insects. It discusses their presence in various edible insect species, their primary bioactive properties, and methods for production and isolation. Bioactive compounds sourced from edible insects exhibit antioxidant, antimicrobial, and disease-preventing properties. Insects also serve as rich sources of vitamins A, B2, B6, B12, D, and E, albeit with variations in content among species and life stages. However, the consumption of insects poses risks related to their biological and chemical contaminants, as well as their allergenicity. Managed diets in farm-bred insects ensure controlled nutrient levels, highlighting their potential as sustainable sources of bioactive compounds for human health. Adequate processing and labeling of insect-derived products can reduce the risk of insect consumption. In conclusion, the bioactive compound profile of edible insects complements their nutritional richness and highlights their potential to address future nutrition and food security.

Mussel-inspired chitosan and its applications in the biomedical field

Chitosan (CS) has physicochemical properties including solubility, crystallinity, swellability, viscosity, and cohesion, along with biological properties like biocompatibility, biodegradation, antioxidant, antibacterial, and antitumor effects. However, these characteristics of CS are greatly affected by its degree of deacetylation, molecular weight, pH and other factors, which limits the application of CS in biomedicine. The modification of CS with catechol-containing substances inspired by mussels can not only improve these properties of CS, but also endow it with self-healing property, providing an environmentally friendly and sustainable way to promote the application of CS in biomedicine. In this paper, the properties of CS and its limitation in the biomedical filed are introduced in detail. Then, the modification methods and properties of substances with catechol groups inspired by mussels on CS are reviewed. Finally, the applications of modified CS in the biomedical field of wound healing, drug delivery, anticancer therapy, biosensor and 3D printing are further discussed. This review can provide valuable information for the design and exploitation of mussel-inspired CS in the biomedical field.

Update on Chitin and Chitosan from Insects: Sources, Production, Characterization, and Biomedical Applications

Insects, renowned for their abundant and renewable biomass, stand at the forefront of biomimicry-inspired research and offer promising alternatives for chitin and chitosan production considering mounting environmental concerns and the inherent limitations of conventional sources. This comprehensive review provides a meticulous exploration of the current state of insect-derived chitin and chitosan, focusing on their sources, production methods, characterization, physical and chemical properties, and emerging biomedical applications. Abundant insect sources of chitin and chitosan, from the Lepidoptera, Coleoptera, Orthoptera, Hymenoptera, Diptera, Hemiptera, Dictyoptera, Odonata, and Ephemeroptera orders, were comprehensively summarized. A variety of characterization techniques, including spectroscopy, chromatography, and microscopy, were used to reveal their physical and chemical properties like molecular weight, degree of deacetylation, and crystallinity, laying a solid foundation for their wide application, especially for the biomimetic design process. The examination of insect-derived chitin and chitosan extends into a wide realm of biomedical applications, highlighting their unique advantages in wound healing, tissue engineering, drug delivery, and antimicrobial therapies. Their intrinsic biocompatibility and antimicrobial properties position them as promising candidates for innovative solutions in diverse medical interventions.

Current and emerging applications of saccharide-modified chitosan: a critical review

Chitin, as the main component of the exoskeleton of Arthropoda, is a highly available natural polymer that can be processed into various value-added products. Its most important derivative, i.e., chitosan, comprising β-1,4-linked 2-amino-2-deoxy-β-d-glucose (deacetylated d-glucosamine) and N-acetyl-d-glucosamine units, can be prepared via alkaline deacetylation process. Chitosan has been used as a biodegradable, biocompatible, non-antigenic, and nontoxic polymer in some in-vitro applications, but the recently found potentials of chitosan for in-vivo applications based on its biological activities, especially antimicrobial, antioxidant, and anticancer activities, have upgraded the chitosan roles in biomaterials. Chitosan approval, generally recognized as a safe compound by the United States Food and Drug Administration, has attracted much attention toward its possible applications in diverse fields, especially biomedicine and agriculture. Even with some favorable characteristics, the chitosan's structure should be customized for advanced applications, especially due to its drawbacks, such as low drug-load capacity, low solubility, high viscosity, lack of elastic properties, and pH sensitivity. In this context, derivatization with relatively inexpensive and highly available mono- and di-saccharides to soluble branched chitosan has been considered a "game changer". This review critically reviews the emerging technologies based on the synthesis and application of lactose- and galactose-modified chitosan as two important chitosan derivatives. Some characteristics of chitosan derivatives and biological activities have been detailed first to understand the value of these natural polymers. Second, the saccharide modification of chitosan has been discussed briefly. Finally, the applications of lactose- and galactose-modified chitosan have been scrutinized and compared to native chitosan to provide an insight into the current state-of-the research for stimulating new ideas with the potential of filling research gaps.

Preparation of nanocomposite based on chitosan-PDCOEMA containing biosynthesized ZnO: Biological and thermal characterization

In this study, poly(2-(3,5-dichloroanilino)-2-oxoethyl 2-methylprop-2-enoate) (PDCOEMA), a new synthetic polymer based on methacrylate, was synthesized and characterized. The blend of PDCOEMA with chitosan (CS) was prepared by the hydrothermal method and the DSC technique confirmed its formation. It was observed that PDCOEMA increased the thermal stability and glass transition temperature (Tg) of CS. The Tg value of the PDCOEMA-CS blend was increased at about 7 °C with the highest ZnO NPs contribution rate. PDCOEMA-CS/ZnO nanocomposites were prepared by adding ZnO NPs produced by biosynthesis at different weight ratios to the PDCOEMA-CS blend by hydrothermal method. When the thermal stability of nanocomposites determined by TGA was examined, it was observed that it increased significantly compared to CS. While the initial decomposition temperature of CS was 270 °C, this value increased to 293 °C after blending with DCOEMA, and to 317 °C with the addition of 7 % ZnO NPs. Antimicrobial, anticancer, cytotoxic, antioxidant, and wound healing properties of PDCOEMA, CS, PDCOEMA-CS blend, and nanocomposites were determined. According to the obtained results, it was observed that nanocomposites containing 5 % and 7 % ZnO NPs showed good anticancer activity against A549 cells at a dose of 10 μg/mL. The results show that the produced nanocomposites can contribute to developing CS-based materials.

Chitosan-based packaging films with an integrated antimicrobial peptide: Characterization, in vitro release and application to fresh pork preservation

Chitosan (CS) films were developed incorporating peptide HX-12C. The films were studied to determine their microstructures, physical properties, release properties of peptide HX-12C and functional properties. The results indicated that there may be hydrogen bonding interactions between CS and peptide HX-12C, thereby creating a homogeneous internal microstructure and lower crystallinity (10.8-12.8 %). Compared with CS film, CS-HX-12C films displayed lower light transmission, MC (20.8-19.9 %), WVP (8.82-8.59 × 10^-11·g·m^-1·s^-1·Pa^-1), OTR (0.015-0.037 cc/(m².day)) and higher WS (15.7-32.4 %) values. Moreover, controlled-release experiments showed that pH, ionic strength and temperature could all significantly affect the release of peptide HX-12C from the films. Finally, the increase of pH value and TVC and lipid oxidation of fresh pork were delayed due to the treatment with CS-2%HX-12C film. However, incorporating peptide HX-12C into CS films did not improve the mechanical properties of the films and their effects against protein oxidation. Our results suggest that the CS-based antimicrobial packaging films integrated with peptide HX-12C exhibit the potential for fresh pork preservation.

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.

Progress in the drug encapsulation of poly(lactic-co-glycolic acid) and folate-decorated poly(ethylene glycol)-poly(lactic-co-glycolic acid) conjugates for selective cancer treatment

Poly(lactic-co-glycolic acid) (PLGA) is a US Food and Drug Administration (FDA)-approved polymer used in humans in the forms of resorbable sutures, drug carriers, and bone regeneration materials. Recently, PLGA-based conjugates have been extensively investigated for cancer, which is the second leading cause of death globally. This article presents an account of the literature on PLGA-based conjugates, focusing on their chemistries, biological activity, and functions as targeted drug carriers or sustained drug controllers for common cancers (e.g., breast, prostate, and lung cancers). The preparation and drug encapsulation of PLGA nanoparticles and folate-decorated poly(ethylene glycol)-poly(lactic-co-glycolic acid) (FA-PEG-PLGA) conjugates are discussed, along with several representative examples. Particularly, the reactions used for preparing drug-conjugated PLGA and FA-PEG-PLGA are emphasized, with the associated chemistries involved in the formation of structures and their biocompatibility with internal organs. This review provides a deeper understanding of the constituents and interactions of PLGA-conjugated materials to ensure successful conjugation in PLGA material design and the subsequent biomedical applications.

Characterization of chitin and chitosan derived from Hermetia illucens, a further step in a circular economy process

Due to their properties and applications, the growing demand for chitin and chitosan has stimulated the market to find more sustainable alternatives to the current commercial source (crustaceans). Bioconverter insects, such as Hermetia illucens, are the appropriate candidates, as chitin is a side stream of insect farms for feed applications. This is the first report on production and characterization of chitin and chitosan from different biomasses derived from H. illucens, valorizing the overproduced larvae in feed applications, the pupal exuviae and the dead adults. Pupal exuviae are the best biomass, both for chitin and chitosan yields and for their abundance and easy supply from insect farms. Fourier-transform infrared spectroscopy, X-ray diffraction and scanning electron microscope analysis revealed the similarity of insect-derived polymers to commercial ones in terms of purity and structural morphology, and therefore their suitability for industrial and biomedical applications. Its fibrillary nature makes H. illucens chitin suitable for producing fibrous manufacts after conversion to chitin nanofibrils, particularly adults-derived chitin, because of its high crystallinity. A great versatility emerged from the evaluation of the physicochemical properties of chitosan obtained from H. illucens, which presented a lower viscosity-average molecular weight and a high deacetylation degree, fostering its putative antimicrobial properties.

Surface channel patterned and endothelialized poly(glycerol sebacate) based elastomers

Prevascularization of tissue equivalents is critical for fulfilling the need for sufficient vascular organization for nutrient and gas transport. Hence, endothelial cell culture on biomaterials is of great importance for researchers. Numerous alternate strategies have been suggested in this sense, with cell-based methods being the most commonly employed. In this study, poly (glycerol sebacate) (PGS) elastomers with varying crosslinking ratios were synthesized and their surfaces were patterned with channels by using laser ablation technique. In order to determine an ideal material for cell culture studies, the elastomers were subsequently mechanically, chemically, and biologically characterized. Following that, human umbilical vein endothelial cells (HUVECs) were seeded into the channels established on the PGS membranes and cultured under various culture conditions to establish the optimal culture parameters. Lastly, the endothelial cell responses to the synthesized PGS elastomers were evaluated. Remarkable cell proliferation and impressive cellular organizations were noticed on the constructs created as part of the investigation. On the concrete output of this research, arrangements in various geometries can be created by laser ablation method and the effects of various molecules, drugs or agents on endothelial cells can be evaluated. The platforms produced can be employed as an intermediate biomaterial layer containing endothelial cells for vascularization of tissue-engineered structures, particularly in layer-by-layer tissue engineering approaches.

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.

Incorporating silver nanoshell-coated mesoporous silica nanoparticles improves physicochemical and antimicrobial properties of chitosan films

Tailoring nanomaterials with tunable properties is of great importance to develop multifunctional candidates in the biomedical field. In the present study, we aimed to develop a promising nano-hybrid system composed of chitosan (CS) and mesoporous silica nanoparticles with a silver nanoshell coat (CS-AgMSNs). The physicochemical properties of CS-AgMSNs films were characterized using various techniques. Further, the mechanical properties of CS-AgMSNs were evaluated and compared with those of undoped CS film. Moreover, the antimicrobial activities of CS-AgMSNs (with different concentrations) were assessed against E-coli, S. aureus, C. albicans, and A. niger. Our results demonstrated that increasing the concentrations of doped AgMSNs (10 to 40 mg) in CS films lowered their transparency and blocked light transmission effectively. The measured elastic modulus of CS-AgMSNs films (20 and 30 mg) showed a decrease in the stiffness of CS films. Also, the elongation at break for CS-AgMSNs (40 mg) indicated a better flexibility. CS-AgMSNs films (10-40 mg) showed an enhanced antimicrobial activity in a concentration-dependent manner compared to undoped CS films. Collectively, the results suggest that our nano-hybrid CS-AgMSNs matrix has unique and promising properties, and holds potential for use in the biomedical field, food packaging, and textile industry.

Fabrication and characterization of carbon aerogel/poly(glycerol-sebacate) patches for cardiac tissue engineering

Cardiovascular diseases (CVDs) are responsible for the major number of deaths around the world. Among these is heart failure after myocardial infarction whose latest therapeutic methods are limited to slowing the end-state progression. Numerous strategies have been developed to meet the increased demand for therapies regarding CVDs. This study aimed to establish a novel electrically conductive elastomer-based composite and assess its potential as a cardiac patch for myocardial tissue engineering. The electrically conductive carbon aerogels (CAs) used in this study were derived from waste paper as a cost-effective carbon source and they were combined with the biodegradable poly(glycerol-sebacate) (PGS) elastomer to obtain an electrically conductive cardiac patch material. To the best of our knowledge, this is the first report about the conductive composites obtained by the incorporation of CAs into PGS (CA-PGS). In this context, the incorporation of the CAs into the polymeric matrix significantly improved the elastic modulus (from 0.912 MPa for the pure PGS elastomer to 0.366 MPa for the CA-PGS) and the deformability (from 0.792 MPa for the pure PGS to 0.566 MPa for CA-PGS). Overall, the mechanical properties of the obtained structures were observed similar to the native myocardium. Furthermore, the addition of CAs made the obtained structures electrically conductive with a conductivity value of 65 × 10^-3S m^-1which falls within the range previously recorded for human myocardium. Thein vitrocytotoxicity assay with L929 murine fibroblast cells revealed that the CA-PGS composite did not have cytotoxic characteristics. On the other hand, the studies conducted with H9C2 rat cardiac myoblasts revealed that final structures were suitable for MTE applications according to the successes in cell adhesion, cell proliferation, and cell behavior.

Chitosan-based blends for biomedical applications

Polysaccharides are the most abundant naturally available carbohydrate polymers; composed of monosaccharide units covalently connected together. Chitosan is the most widely used polysaccharides because of its exceptional biocompatibility, mucoadhesion, and chemical versatility. However, it suffers from a few drawbacks, e.g. poor mechanical properties and antibacterial activity for biomedical applications. Blending chitosan with natural or synthetic polymers may not merely improve its physicochemical and mechanical properties, but may also improve its bioactivity-induced properties. This review paper summarizes progress in chitosan blends with biodegradable polymers and polysaccharides and their biomedical applications. Blends of chitosan with alginate, starch, cellulose, pectin and dextran and their applications were particularly addressed. The critical and challenging aspects as well as the future ahead of the use of chitosan-based blends were eventually enlightened.

Benefits and Challenges in the Incorporation of Insects in Food Products

Edible insects are being accepted by a growing number of consumers in recent years not only as a snack but also as a side dish or an ingredient to produce other foods. Most of the edible insects belong to one of these groups of insects such as caterpillars, butterflies, moths, wasps, beetles, crickets, grasshoppers, bees, and ants. Insect properties are analyzed and reported in the articles reviewed here, and one common feature is nutrimental content, which is one of the most important characteristics mentioned, especially proteins, lipids, fiber, and minerals. On the other hand, insects can be used as a substitute for flour of cereals for the enrichment of snacks because of their high content of proteins, lipids, and fiber. Technological properties are not altered when these insects-derived ingredients are added and sensorial analysis is satisfactory, and only in some cases, change in color takes place. Insects can be used as substitute ingredients in meat products; the products obtained have higher mineral content than traditional ones, and some texture properties (like elasticity) can be improved. In extruded products, insects are an alternative source of proteins to feed livestock, showing desirable characteristics. Isolates of proteins of insects have demonstrated bioactive activity, and these can be used to improve food formulations. Bioactive compounds, as antioxidant agents, insulin regulators, and anti-inflammatory peptides, are high-value products that can be obtained from insects. Fatty acids that play a significant role in human health and lipids from insects have showed positive impacts on coronary disease, inflammation, and cancer. Insects can be a vector for foodborne microbial contamination, but the application of good manufacturing practices and effective preservation techniques jointly with the development of appropriate safety regulations will decrease the appearance of such risks. However, allergens presented in some insects are a hazard that must be analyzed and taken into account. Despite all the favorable health-promoting characteristics present in insects and insects-derived ingredients, willingness to consume them has yet to be generalized.

Chitin and Chitosan Derivatives as Biomaterial Resources for Biological and Biomedical Applications

Chitin is a long-chain polymer of N-acetyl-glucosamine, which is regularly found in the exoskeleton of arthropods including insects, shellfish and the cell wall of fungi. It has been known that chitin can be used for biological and biomedical applications, especially as a biomaterial for tissue repairing, encapsulating drug for drug delivery. However, chitin has been postulated as an inducer of proinflammatory cytokines and certain diseases including asthma. Likewise, chitosan, a long-chain polymer of N-acetyl-glucosamine and d-glucosamine derived from chitin deacetylation, and chitosan oligosaccharide, a short chain polymer, have been known for their potential therapeutic effects, including anti-inflammatory, antioxidant, antidiarrheal, and anti-Alzheimer effects. This review summarizes potential utilization and limitation of chitin, chitosan and chitosan oligosaccharide in a variety of diseases. Furthermore, future direction of research and development of chitin, chitosan, and chitosan oligosaccharide for biomedical applications is discussed.

Long-Term Protective Effects of Single-Dose Cardioplegic Solutions in Cell Culture Models

Despite the popularity of single-dose cardioplegic techniques, the time window and targeted population for successful reperfusion remain unclear. We tested currently available techniques based on cell viability and integrity to demonstrate long-term cardioprotection and clarify whether these solutions were performed on neonatal/adult endothelium and myocardium by examining different cell lines. Cell viability with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test proliferation assay and membrane integrity with the lactic dehydrogenase (LDH) cytotoxicity test were documented in a cell culture/microscopy setting on adult (human umbilical vein endothelium [HUVEC]), neonatal (H9C2-cardiomyocytes), and myofibroblast (L929) cell lines. Apoptotic cell activity and necrosis were evaluated by acridine orange/propidium iodide (AO/PI) staining. Twenty-four hours after seeding, cells were incubated in control (Dulbecco's modified Eagle), St. Thomas and blood cardioplegia (4:1), histidine-tryptophan-ketoglutarate (HTK), and del Nido solutions at 32°C followed by an additional 6, 24, and 48 hours in standard conditions (37°C, 5% CO2). Experiments were repeated eight times. In MTT cell viability analysis, HTK protection was significantly better than the control medium in L929 cell lines at 48th hours follow-up and acted markedly better on the HUVEC cell line at 24th and 48th hours. del Nido and HTK provided significantly better protection on H9C2 (at 24th and 48th hours). Apoptotic and necrotic cell scoring as a result of AO/PI staining was found consistent with MTT results. The LDH test demonstrated that the level of cell disruption was significantly higher for St. Thomas and blood cardioplegia in H9c2 cells. Experimental studies on cardioplegia aimed at assessing myocardial protection use time-consuming and often expensive approaches that are unrealistic in clinical practice. We have focused on identifying the most effective cell types and the direct consequences of different cardioplegia solutions to document long-term effects that we believe are the most underestimated ones in the cardioplegia literature.

Pristine and modified chitosan as solid catalysts for catalysis and biodiesel production: A minireview

Chitosan is one of the readily available polymers with relatively high abundance, biodegradable and sustainable materials with divergent functional groups that are employed in broad range of applications. Chitosan is widely used in many fields like adsorption, drug carrier for therapeutic activity, environmental remediation, drug formulation and among others. One of the unique features of chitosan is that it can be transformed to other forms like beads, films, flakes, sponges and fibres depending upon the applications. This review is aimed at showing the potential applications of chitosan and its modified solids in organic transformations. The number of existing articles is organized based on the nature of materials and subsequently with the types of reactions. After a brief description on the structural features of chitosan, properties, characterization methods including various analytical/microscopic techniques and some of the best practices to be followed in catalysis are also discussed. The next section of this review describes the catalytic activity of native chitosan without any modifications while the subsequent sections provide the catalytic activity of chitosan derivatives, chitosan covalently modified with metal complexes/salts through linkers and chitosan as support for metal nanoparticles (NPs). These sections discuss number of organic reactions that include Knoevenagel condensation, oxidation, reduction, heterocycles synthesis, cross-coupling reactions and pollutant degradation among others. A separate section provides the catalytic applications of chitosan and its modified forms for the production of fatty acid methyl esters (FAME) through esterification/transesterification reactions. The final section summarizes our views on the future directions of this field in the coming years.

Dipteran Carboxymethyl Chitosan as an Inexhaustible Derivative with a Potential Antiproliferative Activity in Hepatocellular Carcinoma Cells

Traditional folk therapies indicate that insects have diverse medicinal potentials. However, the therapeutic application of insect chitosan and its derivatives has not been explored. To investigate the application of chitosan and its derivatives, the carboxymethyl derivative of chitosan (CM-Ch) was extracted from two dipteran larvae species, Chrysomya albiceps and Sarcophaga aegyptiaca. The degree of deacetylation (DD) and CM-Ch functional groups were validated using Fourier-transform infrared (FTIR) spectroscopy analysis and proton nuclear magnetic resonance spectroscopy (¹H NMR), respectively. The molecular weight was estimated using MALDI-TOF MS analysis. The effect of CM-Ch on the morphology and proliferation of human liver HepG2 cancer cells was assessed. IC₅₀ of CM-Ch induced significant growth-inhibitory effects in HepG2 cells. CM-Ch treatment altered the morphology of HepG2 in a dose-dependent manner and induced apoptosis in a caspase-dependent manner. CM-Ch treatment showed no signs of toxicity, and no alterations in liver and kidney biochemical markers were observed in albino rats. A CM-Ch derivative from commercial crustacean chitosan was used to assess the efficacy of the insect-derived CM-Ch. The data presented here introduce insect CM-Ch as a promising, inexhaustible, safe derivative of chitosan with antitumor potential in liver cancer. This is the first report highlighting the anticancer activity of insect CM-Ch in hepatocellular carcinoma cells.

Chitosan: Structural modification, biological activity and application

Many by-products that are harmful to the environment and human health are generated during food processing. However, these wastes are often potential resources with high-added value. For example, crustacean waste contains large amounts of chitin. Chitin is one of the most abundant polysaccharides in natural macromolecules, and is a typical component of crustaceans, mollusks, insect exoskeleton and fungal cell walls. Chitosan is prepared by deacetylation of chitin and a copolymer of D-glucosamine and N-acetyl-D-glucosamine through β-(1 → 4)-glycosidic bonds. Chitosan has better solubility, biocompatibility and degradability compared with chitin. This review introduces the preparation, physicochemical properties, chemical and physical modification methods of chitosan, which could help us understand its biological activities and applications. According to the latest reports, the antibacterial activity, antioxidant, immune and antitumor activities of chitosan and its derivatives are summarized. Simultaneously, the various applications of chitosan and its derivatives are reviewed, including food, chemical, textile, medical and health, and functional materials. Finally, some insights into its future potential are provided, including novel modification methods, directional modification according to structure-activity relationship, activity and application development direction, etc.

Chitosan as a Wound Dressing Starting Material: Antimicrobial Properties and Mode of Action

Fighting bacterial resistance is one of the concerns in modern days, as antibiotics remain the main resource of bacterial control. Data shows that for every antibiotic developed, there is a microorganism that becomes resistant to it. Natural polymers, as the source of antibacterial agents, offer a new way to fight bacterial infection. The advantage over conventional synthetic antibiotics is that natural antimicrobial agents are biocompatible, non-toxic, and inexpensive. Chitosan is one of the natural polymers that represent a very promising source for the development of antimicrobial agents. In addition, chitosan is biodegradable, non-toxic, and most importantly, promotes wound healing, features that makes it suitable as a starting material for wound dressings. This paper reviews the antimicrobial properties of chitosan and describes the mechanisms of action toward microbial cells as well as the interactions with mammalian cells in terms of wound healing process. Finally, the applications of chitosan as a wound-dressing material are discussed along with the current status of chitosan-based wound dressings existing on the market.

Mayflies (Ephemeroptera) and Their Contributions to Ecosystem Services

This work is intended as a general and concise overview of Ephemeroptera biology, diversity, and services provided to humans and other parts of our global array of freshwater and terrestrial ecosystems. The Ephemeroptera, or mayflies, are a small but diverse order of amphinotic insects associated with liquid freshwater worldwide. They are nearly cosmopolitan, except for Antarctica and some very remote islands. The existence of the subimago stage is unique among extant insects. Though the winged stages do not have functional mouthparts or digestive systems, the larval, or nymphal, stages have a variety of feeding approaches-including, but not limited to, collector-gatherers, filterers, scrapers, and active predators-with each supported by a diversity of morphological and behavioral adaptations. Mayflies provide direct and indirect services to humans and other parts of both freshwater and terrestrial ecosystems. In terms of cultural services, they have provided inspiration to musicians, poets, and other writers, as well as being the namesakes of various water- and aircraft. They are commemorated by festivals worldwide. Mayflies are especially important to fishing. Mayflies contribute to the provisioning services of ecosystems in that they are utilized as food by human cultures worldwide (having one of the highest protein contents of any edible insect), as laboratory organisms, and as a potential source of antitumor molecules. They provide regulatory services through their cleaning of freshwater. They provide many essential supporting services for ecosystems such as bioturbation, bioirrigation, decomposition, nutrition for many kinds of non-human animals, nutrient cycling and spiraling in freshwaters, nutrient cycling between aquatic and terrestrial systems, habitat for other organisms, and serving as indicators of ecosystem health. About 20% of mayfly species worldwide might have a threatened conservation status due to influences from pollution, invasive alien species, habitat loss and degradation, and climate change. Even mitigation of negative influences has benefits and tradeoffs, as, in several cases, sustainable energy production negatively impacts mayflies.

The function of histone acetylation in cervical cancer development

Cervical cancer is the fourth most common female cancer in the world. It is well known that cervical cancer is closely related to high-risk human papillomavirus (HPV) infection. However, epigenetics has increasingly been recognized for its role in tumorigenesis. Epigenetics refers to changes in gene expression levels based on non-gene sequence changes, primarily through transcription or translation of genes regulation, thus affecting its function and characteristics. Typical post-translational modifications (PTMs) include acetylation, propionylation, butyrylation, malonylation and succinylation, among which the acetylation modification of lysine sites has been studied more clearly so far. The acetylation modification of lysine residues in proteins is involved in many aspects of cellular life activities, including carbon metabolism, transcriptional regulation, amino acid metabolism and so on. In this review, we summarize the latest discoveries on cervical cancer development arising from the aspect of acetylation, especially histone acetylation.

Anti-proliferative effect of chitosan nanoparticles (extracted from crayfish Procambarus clarkii, Crustacea: Cambaridae) against MDA-MB-231 and SK-BR-3 human breast cancer cell lines

Actually, the most common cancer in women is the breast cancer which is the second most widespread cancer overall. In 2018, there were over two million new cases of women breast cancer. Particularly, we tried to extract chitosan from crayfish Procambarus clarkii, Crustacea: Cambaridae, by N-deacetylation of chitin. The chemical structure of chitosan was characterized by Fourier transform infrared (FT-IR) spectroscopy. Also DDA was calculated from FT-IR and ultraviolet spectrophotometry data. Chitosan nanoparticles were prepared using a ball-milling technique. The as-prepared chitosan nanoparticles were characterized by transmission electron microscopy, dynamic light scattering as well as zeta potential. The cytotoxicity of chitosan and its nanoparticles (50 and 100 μg/mL) against human breast cancer (SK BR3 and MDA-MB-231 cell lines) was evaluated. MTT assay asserts the significant inhibitory action of both chitosan and its nanoparticles on the proliferation of human breast cancer cells in vitro. Chitosan nanoparticles had more anti-proliferative effects on MDA-MB-231 and SK-BR-3 cell lines than its corresponding chitosan. Although, chitosan nanoparticles, that has higher DDA, had a higher cytotoxic activity against human breast cancer MDA-MB-231 and SK-BR-3 cell lines in vitro. Eventually, chitosan and its nanoparticles can be considered as a promising natural compounds in human breast cancer treatment.