The Mechanical and Biological Properties of Chitosan Scaffolds for Tissue Regeneration Templates Are Significantly Enhanced by Chitosan from Gongronella butleri

A review of chitosan polysaccharides: Neuropharmacological implications and tissue regeneration

One of the current challenges in targeting neurological disorders is that many therapeutic molecules cannot cross the blood-brain barrier (BBB), which limits the use of natural molecules in nervous tissue regeneration. Thus, the development of new drugs to effectively treat neurological disorders would be a challenge. Natural resources are well known as a source of several therapeutic agents for the treatment of neurologic disorders. Recently, chitosan (CTS) and its derivatives from arthropod exoskeletons, have attracted much attention as a drug delivery system to transport therapeutic substances across the BBB and thanks to other neuroprotective effects including the participation to the CNS regenerations scaffolds to replicate the extracellular matrix and microenvironment of the body. This review will discuss the place of natural resource therapy in targeting neurological disorders. In particular, it will highlight recent understanding and progress in the applications of CTS as drug delivery systems and their therapeutic effects on these disorders through tissue regeneration, as well as the molecular mechanisms by which they exert these effects.

Folate-engineered chitosan nanoparticles: next-generation anticancer nanocarriers

Chitosan nanoparticles (NPs) are well-recognized as promising vehicles for delivering anticancer drugs due to their distinctive characteristics. They have the potential to enclose hydrophobic anticancer molecules, thereby enhancing their solubilities, permeabilities, and bioavailabilities; without the use of surfactant, i.e., through surfactant-free solubilization. This allows for higher drug concentrations at the tumor sites, prevents excessive toxicity imparted by surfactants, and could circumvent drug resistance. Moreover, biomedical engineers and formulation scientists can also fabricate chitosan NPs to slowly release anticancer agents. This keeps the drugs at the tumor site longer, makes therapy more effective, and lowers the frequency of dosing. Notably, some types of cancer cells (fallopian tube, epithelial tumors of the ovary, and primary peritoneum; lung, kidney, ependymal brain, uterus, breast, colon, and malignant pleural mesothelioma) have overexpression of folate receptors (FRs) on their outer surface, which lets folate-drug conjugate-incorporated NPs to target and kill them more effectively. Strikingly, there is evidence suggesting that the excessively produced FR&αgr (isoforms of the FR) stays consistent throughout treatment in ovarian and endometrial cancer, indicating resistance to conventional treatment; and in this regard, folate-anchored chitosan NPs can overcome it and improve the therapeutic outcomes. Interestingly, overly expressed FRs are present only in certain tumor types, which makes them a promising biomarker for predicting the effectiveness of FR-targeted therapy. On the other hand, the folate-modified chitosan NPs can also enhance the oral absorption of medicines, especially anticancer drugs, and pave the way for effective and long-term low-dose oral metronomic scheduling of poorly soluble and permeable drugs. In this review, we talked briefly about the techniques used to create, characterize, and tailor chitosan-based NPs; and delved deeper into the potential applications of folate-engineered chitosan NPs in treating various cancer types.

Chitosan as a tool for tissue engineering and rehabilitation: Recent developments and future perspectives - A review

Chitosan has established itself as a multifunctional and auspicious biomaterial within the domain of tissue engineering, presenting a decade of uninterrupted advancements and novel implementations. This article provides a comprehensive overview of the most recent developments in chitosan-based tissue engineering, focusing on significant progress made in the last ten years. An exploration is conducted of the various techniques utilized in the modification of chitosan and the production of scaffolds, with an analysis of their effects on cellular reactions and tissue regeneration. The investigation focuses on the integration of chitosan with other biomaterials and the addition of bioactive agents to improve their functionalities. Upon careful analysis of the in vitro and in vivo research, it becomes evident that chitosan effectively stimulates cell adhesion, proliferation, and differentiation. Furthermore, we offer valuable perspectives on the dynamic realm of chitosan-based approaches tailored to distinct tissue categories, including nerve, bone, cartilage, and skin. The review concludes with a discussion of prospective developments, with particular attention given to possible directions for additional study, translational implementations, and the utilization of chitosan to tackle existing obstacles in the field of tissue engineering. This extensive examination provides a significant amalgamation of the advancements achieved over the previous decade and directs scholars towards uncharted territories in chitosan-based tissue engineering.

Weaponizing chitosan and its derivatives in the battle against lung cancer

Lung cancer (LC) is a crisis of catastrophic proportions. It is a global problem and urgently requires a solution. The classic chemo drugs are lagging behind as they lack selectivity, where their side effects are spilled all over the body, and these adverse effects would be terribly tragic for LC patients. Therefore, they could make a bad situation worse, inflict damage on normal cells, and inflict pain on patients. Since our confidence in classic drugs is eroding, chitosan can offer a major leap forward in LC therapy. It can provide the backbone and the vehicle that enable chemo drugs to penetrate the hard shell of LC. It could be functionalized in a variety of ways to deliver a deadly payload of toxins to kill the bad guys. It is implemented in formulation of polymeric NPs, lipidic NPs, nanocomposites, multiwalled carbon nanotubes, and phototherapeutic agents. This review is a pretty clear proof of chitosan's utility as a weapon in battling LC. Chitosan-based formulations could work effectively to kill LC cells. If a researcher is looking for a vehicle for medication for LC therapy, chitosan can be an appropriate choice.

Impacts of chitosan and its nanoformulations on the metabolic syndromes: a review

A significant public health issue worldwide is metabolic syndrome, a cluster of metabolic illnesses that comprises insulin resistance, obesity, dyslipidemia, hyperglycemia, and hypertension. The creation of natural treatments and preventions for metabolic syndrome is crucial. Chitosan, along with its nanoformulations, is an oligomer of chitin, the second-most prevalent polymer in nature, which is created via deacetylation. Due to its plentiful biological actions in recent years, chitosan and its nanoformulations have drawn much interest. Recently, the chitosan nanoparticle-based delivery of CRISPR-Cas9 has been applied in treating metabolic syndromes. The benefits of chitosan and its nanoformulations on insulin resistance, obesity, diabetes mellitus, dyslipidemia, hyperglycemia, and hypertension will be outlined in the present review, highlighting potential mechanisms for the avoidance and medication of the metabolic syndromes by chitosan and its nanoformulations.

Chitosan thread in the healing of the cecal wall of rabbits (Oryctolagus cuniculus) submitted to cecorrhaphy

The development and evaluation of synthesis materials are crucial to reducing the morbidity and magnitude of post-enterorrhaphy surgical complications. Despite the possibility of production, chitosan thread has not yet been used in enterorrhaphy, and its effects on intestinal healing have not been evaluated. Therefore, this study aimed to evaluate the effects of chitosan thread on the intestinal wall repair of rabbits submitted to cecorrhaphy. For this, 42 rabbits were allocated into two groups with 21 animals. One group was submitted to cecorrhaphy with chitosan suture thread (CG) and the other with poliglecaprone suture thread (PG). The occurrence of postoperative complications, the intensity of edema, cellular response, formation of granulation tissue, as well as the deposition and maturation of collagen fibers, and the intensity of vascular endothelial growth factor (VEGF-α) expression, were evaluated during the intestinal wall repair process. The evaluations occurred on the 5th, 15th, and 25th postoperative (PO) days. The animals did not develop peritonitis, but adherence was observed in six animals from CG and seven from PG, with no difference between groups. The polymorphonuclear infiltrate showed higher intensity and higher amount of type III collagen fibers in CG on the 15th PO day. In contrast, a lower amount of type I collagen fibers was observed in CG samples on the 25th PO day. Therefore, the chitosan thread used for cecorrhaphy in rabbits results in minimal postoperative complications, presents biocompatibility, and bioactively assists the tissue repair process of the cecal wall, inducing minimal tissue reaction, stimulating the deposition of type III collagen fibers in the proliferative phase, with sustained VEGF-α expression, but with reduced deposition of type I fibers, indicating a delay in collagen maturation.

Marine-derived polysaccharides and their therapeutic potential in wound healing application - A review

Polysaccharides originating from marine sources have been studied as potential material for use in wound dressings because of their desirable characteristics of biocompatibility, biodegradability, and low toxicity. Marine-derived polysaccharides used as wound dressing, provide several benefits such as promoting wound healing by providing a moist environment that facilitates cell migration and proliferation. They can also act as a barrier against external contaminants and provide a protective layer to prevent further damage to the wound. Research studies have shown that marine-derived polysaccharides can be used to develop different types of wound dressings such as hydrogels, films, and fibres. These dressings can be personalised to meet specific requirements based on the type and severity of the wound. For instance, hydrogels can be used for deep wounds to provide a moist environment, while films can be used for superficial wounds to provide a protective barrier. Additionally, these polysaccharides can be modified to improve their properties, such as enhancing their mechanical strength or increasing their ability to release bioactive molecules that can promote wound healing. Overall, marine-derived polysaccharides show great promise for developing effective and safe wound dressings for various wound types.

Research progress on chitin/chitosan-based emulsion delivery systems and their application in lipid digestion regulation

Excessive lipid intake is linked to an elevated risk of health problems. However, reducing lipid contents may influence food structure and flavor. Some alternatives are needed to control the lipid absorption. Emulsions are common carriers for lipids, which can control the hydrolysis and absorption of lipids. Chitin (Ch) and chitosan (CS) are natural polysaccharides with good biodegradability, biocompatibility, and unique cationic properties. They have been reported to be able to delay lipolysis, which can be regarded as one of the most promising agents that regulates lipid digestion (LiD). The application of Ch/CS and their derivatives in emulsions are summarized in this review with a focus on their performances and mechanisms for LiD regulation, aiming to provide theoretical guidance for the development of novel Ch/CS emulsions, and the regulation of LiD. A reasonable design of emulsion interface can provide its resistance to the external environment and then control LiD. The properties of emulsion interface are the key factors affecting LiD. Therefore, systematic study on the relationship between Ch/CS-based emulsion structure and LiD can not only instruct the reasonable design of emulsion interface to accurately regulate LiD, but also provide scientific guidelines for applying Ch/CS in functional food, medicine and other fields.

In Vivo Evaluation of Collagen and Chitosan Scaffold, Associated or Not with Stem Cells, in Bone Repair

Natural polymers are increasingly being used in tissue engineering due to their ability to mimic the extracellular matrix and to act as a scaffold for cell growth, as well as their possible combination with other osteogenic factors, such as mesenchymal stem cells (MSCs) derived from dental pulp, in an attempt to enhance bone regeneration during the healing of a bone defect. Therefore, the aim of this study was to analyze the repair of mandibular defects filled with a new collagen/chitosan scaffold, seeded or not with MSCs derived from dental pulp. Twenty-eight rats were submitted to surgery for creation of a defect in the right mandibular ramus and divided into the following groups: G1 (control group; mandibular defect with clot); G2 (defect filled with dental pulp mesenchymal stem cells-DPSCs); G3 (defect filled with collagen/chitosan scaffold); and G4 (collagen/chitosan scaffold seeded with DPSCs). The analysis of the scaffold microstructure showed a homogenous material with an adequate percentage of porosity. Macroscopic and radiological examination of the defect area after 6 weeks post-surgery revealed the absence of complete repair, as well as absence of signs of infection, which could indicate rejection of the implants. Histomorphometric analysis of the mandibular defect area showed that bone formation occurred in a centripetal fashion, starting from the borders and progressing towards the center of the defect in all groups. Lower bone formation was observed in G1 when compared to the other groups and G2 exhibited greater osteoregenerative capacity, followed by G4 and G3. In conclusion, the scaffold used showed osteoconductivity, no foreign body reaction, malleability and ease of manipulation, but did not obtain promising results for association with DPSCs.

Application of polyvinyl alcohol/chitosan copolymer hydrogels in biomedicine: A review

Hydrogels is a hydrophilic, cross-linked polymer of three-dimensional network structures. The application of hydrogels prepared from a single polymer in the biomedical field has many drawbacks. The functional blend of polyvinyl alcohol and chitosan allows hydrogels to have better and more desirable properties than those produced from a single polymer, which is a good biomaterial for development and design. In this paper, we have reviewed the progress in the application of polyvinyl alcohol/chitosan composite hydrogels in various medical fields, the different cross-linking agents and cross-linking methods, and the research progress in the optimization of composite hydrogels for their subsequent wide range of biomedical applications.

Endophytic fungi mediates production of bioactive secondary metabolites via modulation of genes involved in key metabolic pathways and their contribution in different biotechnological sector

Endophytic fungi stimulate the production of an enormous number of bioactive metabolites in medicinal plants and affect the different steps of biosynthetic pathways of these secondary metabolites. Endophytic fungi possess a number of biosynthetic gene clusters that possess genes for various enzymes, transcription factors, etc., in their genome responsible for the production of secondary metabolites. Additionally, endophytic fungi also modulate the expression of various genes responsible for the synthesis of key enzymes involved in metabolic pathways of such as HMGR, DXR, etc. involved in the production of a large number of phenolic compounds as well as regulate the expression of genes involved in the production of alkaloids and terpenoids in different plants. This review aims to provide a comprehensive overview of gene expression related to endophytes and their impact on metabolic pathways. Additionally, this review will emphasize the studies done to isolate these secondary metabolites from endophytic fungi in large quantities and assess their bioactivity. Due to ease in synthesis of secondary metabolites and their huge application in the medical industry, these bioactive metabolites are now being extracted from strains of these endophytic fungi commercially. Apart from their application in the pharmaceutical industry, most of these metabolites extracted from endophytic fungi also possess plant growth-promoting ability, bioremediation potential, novel bio control agents, sources of anti-oxidants, etc. The review will comprehensively shed a light on the biotechnological application of these fungal metabolites at the industrial level.

Biofabrication of engineered dento-alveolar tissue

Oral health is essential for a good overall health. Dento-alveolar conditions have a high prevalence, ranging from tooth decay periodontitis to alveolar bone resorption. However, oral tissues exhibit a limited regenerative capacity, and full recovery is challenging. Therefore, regenerative therapies for dento-alveolar tissue (e.g., alveolar bone, periodontal membrane, dentin-pulp complex) have gained much attention, and novel approaches have been proposed in recent decades. This review focuses on the cells, biomaterials and the biofabrication methods used to develop therapies for tooth root bioengineering. Examples of the techniques covered are the multitude of additive manufacturing techniques and bioprinting approaches used to create scaffolds or tissue constructs. Furthermore, biomaterials and stem cells utilized during biofabrication will also be described for different target tissues. As these new therapies gradually become a reality in the lab, the translation to the clinic is still minute, with a further need to overcome multiple challenges and broaden the clinical application of these alternatives.

The interplay of cells, polymers, and vascularization in three-dimensional lung models and their applications in COVID-19 research and therapy

Millions of people have been affected ever since the emergence of the corona virus disease of 2019 (COVID-19) outbreak, leading to an urgent need for antiviral drug and vaccine development. Current experimentation on traditional two-dimensional culture (2D) fails to accurately mimic the in vivo microenvironment for the disease, while in vivo animal model testing does not faithfully replicate human COVID-19 infection. Human-based three-dimensional (3D) cell culture models such as spheroids, organoids, and organ-on-a-chip present a promising solution to these challenges. In this report, we review the recent 3D in vitro lung models used in COVID-19 infection and drug screening studies and highlight the most common types of natural and synthetic polymers used to generate 3D lung models.

Tissue Engineering Challenges for Cultivated Meat to Meet the Real Demand of a Global Market

Cultivated meat (CM) technology has the potential to disrupt the food industry-indeed, it is already an inevitable reality. This new technology is an alternative to solve the environmental, health and ethical issues associated with the demand for meat products. The global market longs for biotechnological improvements for the CM production chain. CM, also known as cultured, cell-based, lab-grown, in vitro or clean meat, is obtained through cellular agriculture, which is based on applying tissue engineering principles. In practice, it is first necessary to choose the best cell source and type, and then to furnish the necessary nutrients, growth factors and signalling molecules via cultivation media. This procedure occurs in a controlled environment that provides the surfaces necessary for anchor-dependent cells and offers microcarriers and scaffolds that favour the three-dimensional (3D) organisation of multiple cell types. In this review, we discuss relevant information to CM production, including the cultivation process, cell sources, medium requirements, the main obstacles to CM production (consumer acceptance, scalability, safety and reproducibility), the technological aspects of 3D models (biomaterials, microcarriers and scaffolds) and assembly methods (cell layering, spinning and 3D bioprinting). We also provide an outlook on the global CM market. Our review brings a broad overview of the CM field, providing an update for everyone interested in the topic, which is especially important because CM is a multidisciplinary technology.

Effects of Neutralization on the Physicochemical, Mechanical, and Biological Properties of Ammonium-Hydroxide-Crosslinked Chitosan Scaffolds

It has been reported that chitosan scaffolds, due to their physicochemical properties, stimulate cell proliferation in different tissues of the human body. This study aimed to determine the physicochemical, mechanical, and biological properties of chitosan scaffolds crosslinked with ammonium hydroxide, with different pH values, to better understand cell behavior depending on the pH of the biomaterial. Scaffolds were either neutralized with sodium hydroxide solution, washed with distilled water until reaching a neutral pH, or kept at alkaline pH. Physicochemical characterization included scanning electron microscopy (SEM), elemental composition (EDX), Fourier-transform infrared (FTIR) spectroscopy, Raman spectroscopy, thermogravimetric analysis (TGA), and mechanical testing. In vitro cytotoxicity was assessed via dental-pulp stem cells' (DPSCs') biocompatibility. The results revealed that the neutralized scaffolds exhibited better cell proliferation and morphology. It was concluded that the chitosan scaffolds' high pH (due to residual ammonium hydroxide) decreases DPSCs' cell viability.

Multifunctional role of chitosan in farm animals: a comprehensive review

The deacetylation of chitin results in chitosan, a fibrous-like material. It may be produced in large quantities since the raw material (chitin) is plentiful in nature as a component of crustacean (shrimps and crabs) and insect hard outer skeletons, as well as the cell walls of some fungi. Chitosan is a nontoxic, biodegradable, and biocompatible polygluchitosanamine that contains two essential reactive functional groups, including amino and hydroxyl groups. This unique chemical structure confers chitosan with many biological functions and activities such as antimicrobial, anti-inflammatory, antioxidative, antitumor, immunostimulatory and hypocholesterolemic, when used as a feed additive for farm animals. Studies have indicated the beneficial effects of chitosan on animal health and performance, aside from its safer use as an antibiotic alternative. This review aimed to highlight the effects of chitosan on animal health and performance when used as a promising feed additive.

Crossing Phylums: Butterfly Wing as a Natural Perfusable Three-Dimensional (3D) Bioconstruct for Bone Tissue Engineering

Despite the advent of promising technologies in tissue engineering, finding a biomimetic 3D bio-construct capable of enhancing cell attachment, maintenance, and function is still a challenge in producing tailorable scaffolds for bone regeneration. Here, osteostimulatory effects of the butterfly wings as a naturally porous and non-toxic chitinous scaffold on mesenchymal stromal cells are assessed. The topographical characterization of the butterfly wings implied their ability to mimic bone tissue microenvironment, whereas their regenerative potential was validated after a 14-day cell culture. In vivo analysis showed that the scaffold induced no major inflammatory response in Wistar rats. Topographical features of the bioconstruct upregulated the osteogenic genes, including COL1A1, ALP, BGLAP, SPP1, SP7, and AML3 in differentiated cells compared to the cells cultured in the culture plate. However, butterfly wings were shown to provide a biomimetic microstructure and proper bone regenerative capacity through a unique combination of various structural and material properties. Therefore, this novel platform can be confidently recommended for bone tissue engineering applications.

Kinetics, isotherms and thermodynamics of oil spills removal by novel amphiphilic Chitosan-g-Octanal Schiff base polymer developed by click grafting technique

Kinetic, isothermal and thermodynamic studies for the oil spills removal process have been conducted by Chitosan and novel amphiphilic Chitosan-g-Octanal Schiff base adsorbents developed by click chemistry and evaluated successfully in the removal of heavy crude oil spills. Chitosan was first prepared from wastes of marine shrimp shells, and then Chitosan and Chitosan-g-Octanal Schiff base adsorbents were synthesized and verified their structures, thermal stability and their morphological changes using FT-IR spectroscopy, TGA and SEM. The oil adsorption percentages (%) using heavy crude oil were 96.41% for the Chitosan-g-Octanal Schiff base adsorbent compared to 64.99% for native Chitosan counterpart. High rate of adsorption was observed where 40% of oil adsorbed within 15 min only using the Chitosan-g-Octanal Schiff base adsorbent compared to 90 min for native Chitosan adsorbent. The adsorption process followed the pseudo-second order model, and the equilibrium data were sufficiently fitted with the Langmuir model with a maximum adsorption capacity 30.30 g/g at 25 °C. Thermodynamic parameters computed from Van’t Hoff plot confirmed the process to be endothermic, favorable and spontaneous.

Draft genome of Gongronella butleri reveals the genes contributing to its biodegradation potential

BACKGROUND

Gongronella butleri is a fungus with many industrial applications including the composting of solid biowaste. Kerala Agricultural University, India, has developed a microbial consortium of which GbKAU strain of G. butleri is a major component. Even with great industrial significance, genome of this fungus is not published, and the genes and pathways contributing to the applications are not understood. This study had the objective to demonstrate the solid biowaste decomposing capability of the strain, to sequence and annotate the genome, and to reveal the genes and pathways contributing to its biodegradation potential.

RESULTS

Strain GbKAU of G. butleri isolated and purified from the organic compost was found to produce higher levels of laccase and amylase, compared to Bacillus subtilis which is being widely used in biosolid waste management. Both were shown to be equally efficient in the in vivo composting capabilities. Whole genome sequencing has given ~11 million paired-end good quality reads. De novo assembly using dual-fold approach has yielded 44,639 scaffolds with draft genome size of 29.8 Mb. A total of 11,428 genes were predicted and classified into 359 groups involved in diverse pathways, of which 14 belonged to the enzymes involved in the degradation of macromolecules. Seven previously sequenced strains of the fungus were assembled and annotated. A direct comparison showed that the number of genes present in those strains was comparable to our strain, while all the important biodegrading genes were conserved across the genomes. Gene Ontology analysis had classified the genes according to their molecular function, biological process, and cellular component. A total of 104,718 SSRs were mined and classified to mono- to hexa-nucleotide repeats. The variant analysis in comparison with the closely related genus Cunninghamella has revealed 1156 variants.

CONCLUSIONS

Apart from demonstrating the biodegradation capabilities of the GbKAU strain of G. butleri, the genome of this industrially important fungus was sequenced, de novo assembled, and annotated. GO analysis has classified the genes based on their functions, and the genes involved in biodegradation were revealed. Biodegradation potential, genome features in comparison with other strains, and the functions of the identified genes are discussed.

Drotaverine Hydrochloride Superporous Hydrogel Hybrid System: a Gastroretentive Approach for Sustained Drug Delivery and Enhanced Viscoelasticity

This study aims to prepare drotaverine hydrochloride superporous hydrogel hybrid systems (DSHH systems) to prolong its residence time in the stomach, provide extended release and reduce its frequency of administration. Drotaverine hydrochloride (DRH) is a spasmolytic drug that suffers from brief residence due to intestinal hypermotility during diarrheal episodes associated with gastrointestinal colics resulting in low bioavailability and repeated dosing. Eight DSHH systems were prepared using gas blowing technique. The prepared DSHH systems were evaluated regarding their morphology, incorporation efficiency, density, porosity, swelling ratio, viscoelastic property, erosion percentage and release kinetics. The FH8 formula containing equal proportion of chitosan (3%) /polyvinyl alcohol (3%) as strengthener and crosslinked with tripolyphosphate showed the highest incorporation efficiency (91.83 ± 1.33%), good swelling ratio (28.32 ± 3.15% after 24 h), optimum viscoelastic properties (60.19 ± 3.82 kPa) and sustained release profile (88.03 ± 2.15% after 24 h). A bioequivalence study was done to compare the bioavailability of the candidate formula versus Spasmocure®. Statistical analysis showed significant (P < 0.05) increase in bioavailability 2.7 folds with doubled Tmax (4 h) compared to the marketed product (2 h). These results declared that the superporous hydrogel hybrid systems could be a potential gastroretentive approach for the sustained delivery of drugs with short residence time with enhanced viscoelasticity.

Exploring the Impact of Chitosan Composites as Artificial Organs

Chitosan and its allies have in multiple ways expanded into the medical, food, chemical, and biological industries and is still expanding. With its humble beginnings from marine shell wastes, the deacetylated form of chitin has come a long way in clinical practices. The biomedical applications of chitosan are truly a feather on its cap, with rarer aspects being chitosan’s role in tissue regeneration and artificial organs. Tissue regeneration is a highly advanced and sensitive biomedical application, and the very fact that chitosan is premiering here is an authentication of its ability to deliver. In this review, the various biomedical applications of chitosan are touched on briefly. The synthesis methodologies that are specific for tissue engineering and biomedical applications have been listed. What has been achieved using chitosan and chitosan composites in artificial organ research as well as tissue regeneration has been surveyed and presented. The lack of enthusiasm, as demonstrated by the very few reports online with respect to chitosan composites and artificial organs, is highlighted, and the reasons for this lapse speculated. What more needs be done to expand chitosan and its allies for a better utilization and exploitation to best benefit the construction of artificial organs and building of tissue analogs has been discussed.

Bioactive Chitosan-Based Organometallic Scaffolds for Tissue Engineering and Regeneration

Captivating achievements in developing advanced hybrid biostructures through integrating natural biopolymers with inorganic materials (e.g., metals and metalloids) have paved the way towards the application of bioactive organometallic scaffolds (OMSs) in tissue engineering and regenerative medicine (TERM). Of various biopolymers, chitosan (CS) has been used widely for the development of bioactive OMSs, in large part due to its unique characteristics (e.g., biocompatibility, biodegradability, surface chemistry, and functionalization potential). In integration with inorganic elements, CS has been used to engineer advanced biomimetic matrices to accommodate both embedded cells and drug molecules and serve as scaffolds in TERM. The use of the CS-based OMSs is envisioned to provide a new pragmatic potential in TERM and even in precision medicine. In this review, we aim to elaborate on recent achievements in a variety of CS/metal, CS/metalloid hybrid scaffolds, and discuss their applications in TERM. We also provide comprehensive insights into the formulation, surface modification, characterization, biocompatibility, and cytotoxicity of different types of CS-based OMSs.

Chitosan as a matrix of nanocomposites: A review on nanostructures, processes, properties, and applications

Chitosan is a biopolymer that is natural, biodegradable, and relatively low price. Chitosan has been attracting interest as a matrix of nanocomposites due to new properties for various applications. This study presents a comprehensive overview of common and recent advances using chitosan as a nanocomposite matrix. The focus is to present alternative processes to produce embedded or coated nanoparticles, and the shaping techniques that have been employed (3D printing, electrospinning), as well as the nanocomposites emerging applications in medicine, tissue engineering, wastewater treatment, corrosion inhibition, among others. There are several reviews about single chitosan material and derivatives for diverse applications. However, there is not a study that focuses on chitosan as a nanocomposite matrix, explaining the possibility of nanomaterial additions, the interaction of the attached species, and the applications possibility following the techniques to combine chitosan with nanostructures. Finally, future directions are presented for expanding the applications of chitosan nanocomposites.

Chitosan-poly(vinyl alcohol) intelligent films fortified with anthocyanins isolated from Clitoria ternatea and Carissa carandas for monitoring beverage freshness

Biodegradable chitosan-poly(vinyl alcohol) films containing natural anthocyanin-rich extracts were prepared using solvent casting method and employed as intelligent indicators for monitoring beverages freshness. The surface and cross-sectional scanning electron micrograph indicated a compact structure for the intelligent films, whereas the atomic force micrograph indicated a 16.22 and 20.31 nm increase in surface roughness for Clitoria ternatea and Carissa carandas extract incorporated films, respectively. Moreover, the test films demonstrated enhanced radical scavenging efficacy. The extracts and anthocyanin incorporated films presented excellent colorimetric changes at pH 2 to 8. In addition, the C. ternatea test films showed changes in color for juice stored at 25 °C after 72 h. Photo-degradability results indicated stability of test films stored in dark at 4 °C and 25 °C, whereas leaching study indicated the release of ≤2.0% anthocyanin after 24 h. The cytocompatibilty assay showed that the test and control films were biocompatible with a viability of >80% on HaCat cells. The results demonstrated that the incorporation of anthocyanins-rich extracts into chitosan-poly(vinyl alcohol) did not significantly interfere with the films properties (p > 0.05). The natural anthocyanin incorporated films demonstrated good pH sensing property that could be further explored for monitoring of beverages freshness.

Chitosan hydrogels in 3D printing for biomedical applications

Tissue engineering and regenerative medicine have entered a new stage of development by the recent progress in biology, material sciences, and particularly an emerging additive manufacturing technique, three-dimensional (3D) printing. 3D printing is an advanced biofabrication technique which can generate patient-specific scaffolds with highly complex geometries while hosting cells and bioactive agents to accelerate tissue regeneration. Chitosan hydrogels themselves have been widely used for various biomedical applications due to its abundant availability, structural features and favorable biological properties; however, the 3D printing of chitosan-based hydrogels is still under early exploration. Therefore, 3D printing technologies represent a new avenue to explore the potential application of chitosan as an ink for 3D printing, or as a coating on other 3D printed scaffolds. The combination of chitosan-based hydrogels and 3D printing holds much promise in the development of next generation biomedical implants.

Hemocyanin Modification of Chitosan Scaffolds with Calcium Phosphate Phases Increase the Osteoblast/Osteoclast Activity Ratio-A Co-Culture Study

The ongoing research on biomaterials that support bone regeneration led to the quest for materials or material modifications that can actively influence the activity or balance of bone tissue cells. The bone biocompatibility of porous chitosan scaffolds was modified in the present study by the addition of calcium phosphates or hemocyanin. The first strategy comprised the incorporation of calcium phosphates into chitosan to create a biomimetic chitosan—mineral phase composite. The second strategy comprised dip-coating of chitosan scaffolds with hemocyanin extracted from crayfish hemolymph. The cytocompatibility was assessed in a mono-culture of human bone marrow stromal cells (hBMSCs) and their differentiation to osteoblasts; in a mono-culture of human monocytes (hMs) and their maturation to osteoclasts; and in a co-culture of hBMSC/osteoblasts—hM/osteoclasts. Mineral incorporation caused an increase in scaffold bioactivity, as shown by reduced calcium concentration in the cell culture medium, delayed differentiation of hBMSCs, and reduced osteoclastic maturation of hMs in mono-culture. Dip-coating with hemocyanin led to increased proliferation of hBMSCs and equivalent osteoclast maturation in mono-culture, while in co-culture, both an inhibitory effect of mineral incorporation on osteoblastogenesis and stimulatory effects of hemocyanin were observed. It was concluded that highly bioactive scaffolds (containing mineral phases) restrain osteoblast and osteoclast development, while hemocyanin coating significantly supports osteoblastogenesis. These influences on the osteoblasts/osteoclasts activity ratio may support scaffold-driven bone healing in the future.

Mussel-inspired polydopamine-mediated surface modification of freeze-cast poly (ε-caprolactone) scaffolds for bone tissue engineering applications

There are many methods used to fabricate the scaffolds for tissue regeneration, among which freeze casting has attracted a great deal of attention due to the capability to create a unidirectional structure. In this study, polycaprolactone (PCL) scaffolds were fabricated by freeze-casting technology in order to create porous microstructure with oriented open-pore channels. To induce biomineralization, and to improve hydrophilicity and cell interactions, mussel-inspired polydopamine (PDA) was coated on the surface of the freeze-cast PCL constructs. Then, the synergistic effects of oriented microstructure and deposited layer on efficient reconstruction of injured bone were studied. Microscopic observations demonstrated that, the coated layer did not show any special change in lamellar microstructure of the scaffolds. Water-scaffold interactions were evaluated by contact angle measurements, and they demonstrated strong enhancement in the hydrophilicity of the polymeric scaffolds after PDA coating. Biodegradation ratio and water uptake evaluation confirmed an increase in the measured values after PDA precipitation. The biomineralization of the PDA-coated scaffolds was characterized by field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDX) and X-ray diffraction (XRD). Obtained results confirmed biomineralization of the constructs after a 28-day immersion in a simulated body fluid (SBF) solution. Mechanical analysis demonstrated higher compressive strength after PDA coating. L929 fibroblast cell viability and attachment illustrated that PDA-coated PCL scaffolds are able to support cell adhesion and proliferation. The increased secretion of alkaline phosphatase (ALP) after culturing osteosarcoma cell lines (MG-63) revealed the initial capability of scaffolds to induce bone regeneration. Therefore, the PDA-coated scaffolds introduce a promising approach for bone tissue engineering application.

Structural and biochemical characterization of the exopolysaccharide deacetylase Agd3 required for Aspergillus fumigatus biofilm formation

The exopolysaccharide galactosaminogalactan (GAG) is an important virulence factor of the fungal pathogen Aspergillus fumigatus. Deletion of a gene encoding a putative deacetylase, Agd3, leads to defects in GAG deacetylation, biofilm formation, and virulence. Here, we show that Agd3 deacetylates GAG in a metal-dependent manner, and is the founding member of carbohydrate esterase family CE18. The active site is formed by four catalytic motifs that are essential for activity. The structure of Agd3 includes an elongated substrate-binding cleft formed by a carbohydrate binding module (CBM) that is the founding member of CBM family 87. Agd3 homologues are encoded in previously unidentified putative bacterial exopolysaccharide biosynthetic operons and in other fungal genomes.

Potential of Chitosan and Its Derivatives for Biomedical Applications in the Central Nervous System

It is well known that the central nervous system (CNS) has a limited regenerative capacity and that many therapeutic molecules cannot cross the blood brain barrier (BBB). The use of biomaterials has emerged as an alternative to overcome these limitations. For many years, biomedical applications of chitosan have been studied due to its remarkable biological properties, biocompatibility, and high versatility. Moreover, the interest in this biomaterial for CNS biomedical implementation has increased because of its ability to cross the BBB, mucoadhesiveness, and hydrogel formation capacity. Several chitosan-based biomaterials have been applied with promising results as drug, cell and gene delivery vehicles. Moreover, their capacity to form porous scaffolds and to bear cells and biomolecules has offered a way to achieve neural regeneration. Therefore, this review aims to bring together recent works that highlight the potential of chitosan and its derivatives as adequate biomaterials for applications directed toward the CNS. First, an overview of chitosan and its derivatives is provided with an emphasis on the properties that favor different applications. Second, a compilation of works that employ chitosan-based biomaterials for drug delivery, gene therapy, tissue engineering, and regenerative medicine in the CNS is presented. Finally, the most interesting trends and future perspectives of chitosan and its derivatives applications in the CNS are shown.

HEMA based pH-sensitive semi IPN microgels for oral delivery; a rationale approach for ketoprofen

Objectives: The study aimed to develop safe, effective, and targeted drug delivery system for administration of nonsteroidal anti-inflammatory drugs (NSAIDs) in the form of microgels. We developed pH responsive microgels to overcome the mucosal damage caused by traditional immediate release dosage forms. Colon targeting and controlled release formulations have the potential to improve efficacy and reduce undesirable effects associated with NSAIDs.Methods: The pH sensitive oral hydrogel demonstrates the potential to target the colon. Cellulose acetate phthalate (CAP) and hydroxyethyl methacrylate (HEMA) based microgel particles were produced using a free radical polymerization technique using ammonium persulfate (APS) initiator and methylenebisacrylamide (MBA) as the crosslinking agent. Swelling and in-vitro drug release studies were performed at a range of pH conditions. The produced formulations were characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, scanning electron microscopy (SEM), and X-ray diffraction. Biocompatibility of the microgels was analyzed in cytotoxicity studies.Key findings: The swelling and release rate were negligible at pH 1.2, which confirmed the pH-responsiveness of CAP-co-poly(HEMA). The co-polymeric system prevents the release of ketoprofen sodium in the stomach owing to limited swelling at gastric pH, whilst promoting release at the basic pH observed in the colon. SEM images confirmed porous nature of the microgels that facilitate effective drug diffusion through the polymeric matrix. Cytotoxicity studies revealed biocompatibility of hydrogels.Conclusion: These investigations showed that that the controlled drug release and gastro-protective drug delivery of NSAIDS was achieved using CAP-co-poly(HEMA) microgel particles.

Dual Crosslinked Collagen/Chitosan Film for Potential Biomedical Applications

The application of polymeric biomaterial scaffolds utilizing crosslinking strategy has become an effective approach in these days. In the present study, the development and characterization of collagen-chitosan hydrogel film has been reported on using dual crosslinking agent's, i.e., tannic acid and genipin simultaneously. Incorporation of genipin imparts a greenish-blue color to the polymeric film. The effect of dual crosslinking and their successful interaction within the matrix was evaluated by infrared analysis spectroscopy. The porosity of the film was examined using scanning electron microscopy (SEM). Results of TGA determine the intermediate thermal degradation. Further, the crosslinking phenomenon has found primary impact on the strength of the films. Enzymatic degradation for the films was performed with lysozyme and lipase. The cell adhesion and proliferation was also accomplished using mouse embryonic cell lines wherein the cells cultured on the dual crosslinked film. The thriving utilization of such dual crosslinked polymeric film finds their applications in ophthalmology especially as an implant for temporary injured cornea and skin tissue regeneration.

The Effect of PEGDE Concentration and Temperature on Physicochemical and Biological Properties of Chitosan

Chitosan (CHT) is a polysaccharide with multiple claimed properties and outstanding biocompatibility, generally attributed to the presence of protonable amino groups rendering a cationic natural polymer. However, the effect of changes in CHT structure due to hydration is not considered in its performance. This study compares the effects on biocompatibility after drying at 25 °C and 150 °C scaffolds of chitosan, polyethylene glycol diglycidyl ether (PEGDE) crosslinked CHT (low, medium and high concentration) and glutaraldehyde (GA) crosslinked CHT. PEGDE crosslinked CHT showed a reduction in free amino groups and the amide I/II ratio, which exhaustive drying reduced further. In X-ray diffraction (DRX) analysis, PEGDE crosslinked CHT showed multiple peaks, whereas the crystallinity percentage was reduced with an increase in PEGDE concentration and thermal treatments at 150 °C. In a direct contact cell assay, high osteoblast viability was achieved at low and medium PEDGE concentrations, which was improved when the crosslinked scaffolds were thermally treated at 150 °C. This was attributed to its partial hydrophilicity, low crystallinity and low surface roughness; this in spite of the small reduction in the amount of free amino groups on the surface induced during drying at 150 °C. Furthermore, PEGDE crosslinked CHT scaffolds showed strong vinculin and integrin 1β expression, which render them suitable for bone contact applications.

Mimicked scaffolds based on coated silk woven fabric with gelatin and chitosan for soft tissue defect in oral maxillofacial area

Soft tissue defects in the oral maxillofacial area are critical problems for many patients and, in some cases, patients require an operation coupled with a performance scaffold substitution. In this research, mimicked anatomical scaffolds were constructed using gelatin- and chitosan-coated woven silk fibroin fabric. The morphologies, crystals, and structures were observed and then characterized using scanning electron microscopy, X-ray diffraction, and differential scanning calorimetry, respectively. Physical performance was evaluated from the swelling behavior, mechanical properties, and biodegradation, while the biological performance was tested with fibroblasts and keratinocytes, after which cell proliferation, viability, and histology were evaluated. The results revealed that a coated woven silk fibroin fabric displayed a crystal structure of silk fibroin with amorphous gelatin and chitosan layers. Also, the coated fabrics contained residual water within their structure. The physical performance of the coated woven silk fibroin fabric with gelatin showed suitable swelling behavior and mechanical properties along with acceptable biodegradation for insertion at a defect site. The biological performances including cell proliferation, viability, and histology were suitable for soft tissue reconstruction at the defect sites. Finally, the results demonstrated that mimicked anatomical scaffolds based on a gelatin layer on woven silk fibroin fabric had the functionality that was promising for soft tissue construction in oral maxillofacial defect.

Crosstalk between chitosan and cell signaling pathways

The field of tissue engineering (TE) experiences its most exciting time in the current decade. Recent progresses in TE have made it able to translate into clinical applications. To regenerate damaged tissues, TE uses biomaterial scaffolds to prepare a suitable backbone for tissue regeneration. It is well proven that the cell-biomaterial crosstalk impacts tremendously on cell biological activities such as differentiation, proliferation, migration, and others. Clarification of exact biological effects and mechanisms of a certain material on various cell types promises to have a profound impact on clinical applications of TE. Chitosan (CS) is one of the most commonly used biomaterials with many promising characteristics such as biocompatibility, antibacterial activity, biodegradability, and others. In this review, we discuss crosstalk between CS and various cell types to provide a roadmap for more effective applications of this polymer for future uses in tissue engineering and regenerative medicine.

Degradability of chitosan micro/nanoparticles for pulmonary drug delivery

Chitosan, a natural carbohydrate polymer, has long been investigated for drug delivery and medical applications due to its biodegradability, biocompatibility and low toxicity. The micro/nanoparticulate forms of chitosan are reported to enhance the efficiency of drug delivery with better physicochemical properties including improved solubility and bioavailability. This polymer is known to be biodegradable and biocompatible; however, crosslinked chitosan particles may not be biodegradable. Crosslinkers (e.g., tripolyphosphate and glutaraldehyde) are needed for efficient micro/nanoparticle formation, but it is not clear whether the resultant particles are biodegradable or able to release the encapsulated drug fully. To date, no studies have conclusively demonstrated the complete biodegradation or elimination of chitosan nanoparticles in vivo. Herein we review the synthesis and degradation mechanisms of chitosan micro/nanoparticles frequently used in drug delivery especially in pulmonary drug delivery to understand whether these nanoparticles are biodegradable.

Multi-functional carboxylic acids for chitosan scaffold

In general, CS scaffold is prepared by lyophilizing CS hydrogel which traditionally can be prepared by dissolving CS in acetic acid and crosslinking with dialdehyde. However, this method expresses unpleasant odor and toxicity leading to obstruct the practical applications. Here, the aqueous solution of multi-functional carboxylic acids is considered as the alternative and ordorless solvents to provide dual functions, i.e. (i) protonation of CS for the dissolution, and (ii) providing the preferable structure to give crosslink networks under amide bond through the conjugation reaction. The present work demonstrates the potential use of multi-functional carboxylic acids for preparation of CS scaffold and shows the tunable physicochemical and mechanical properties. The work also extends to the basic studies on biological properties to propose as the potential material for dental tissue engineering.

Investigation of the lubrication properties and synergistic interaction of biocompatible liposome-polymer complexes applicable to artificial joints

Achievement of efficient biolubrication is essential for the design of artificial joints with long lifetimes. This study examines the frictional behaviors and adsorption structures of liposomes and liposome complexes with biocompatible polymers to reveal the underlying lubrication mechanisms between biomimetic bearing surfaces of polyetheretherketone (PEEK) and silicon nitride (Si₃N₄). The liposomes with increasing carbon chain lengths exhibit the remarkable lubrication capabilities that correlate strongly with the structural integrity of small unilamellar vesicles adsorbed on the Si₃N₄ surfaces, while the bilayer structures weaken the stability of vesicles against rupture and cause the increase of friction. The synergistic interaction of liposomes and biocompatible negative-charged polymer leads to the formation of a boundary-lubricating layer with high-density liposome-polymer complex structures that can efficiently improve the lubrication properties of liposomes. Our findings might have implications for future biolubrication investigations on biocompatible liposome-polymer complexes applicable to artificial joints at the specified macroscale conditions.

Aligned microchannel polymer-nanotube composites for peripheral nerve regeneration: Small molecule drug delivery

Peripheral nerve injury accounts for roughly 2.8% of all trauma patients with an annual cost of 7 billion USD in the U.S. alone. Current treatment options rely on surgical intervention with the use of an autograft, despite associated shortcomings. Engineered nerve guidance conduits, stem cell therapies, and transient electrical stimulation have reported to increase speeds of functional recovery. As an alternative to the conduction effects of electrical stimulation, we have designed and optimized a nerve guidance conduit with aligned microchannels for the sustained release of a small molecule drug that promotes nerve impulse conduction. A biodegradable chitosan structure reinforced with drug-loaded halloysite nanotubes (HNT) was formed into a foam-like conduit with interconnected, longitudinally-aligned pores with an average pore size of 59.3 ± 14.2 μm. The aligned composite with HNTs produced anisotropic mechanical behavior with a Young's modulus of 0.33 ± 0.1 MPa, very similar to that of native peripheral nerve. This manuscript reports on the sustained delivery of 4-Aminopyridine (4AP, molecular weight 94.1146 g/mol), a potassium-channel blocker as a growth factor alternative to enhance the rate of nerve regeneration. The conduit formulation released a total of 30 ± 2% of the encapsulated 4AP in the first 7 days. Human Schwann cells showed elevated expression of key proteins such as nerve growth factor, myelin protein zero, and brain derived neurotrophic factor in a 4AP dose dependent manner. Preliminary in vivo studies in a critical-sized sciatic nerve defect in Wistar rats confirmed conduit suturability and strength to withstand ambulatory forces over 4 weeks of their implantation. Histological evaluations suggest conduit biocompatibility and Schwann cell infiltration and organization within the conduit and lumen. These nerve guidance conduits and 4AP sustained delivery may serve as an attractive strategy for nerve repair and regeneration.