A chitosan based scaffold with enhanced mechanical and biocompatible performance for biomedical applications

Permeation enhancer decorated nanoparticles for oral delivery of insulin: manipulating the surface density of borneol and PEG for absorption barriers

Oral protein drugs' delivery faces challenges due to multiple absorption barriers for macromolecules. Co-administration with permeation enhancers and encapsulation in nano-carriers are two promising strategies to enhance their oral absorption. Herein, the poly(lactic-co-glycolic acid) nanoparticles (PLGA NPs) are decorated with polyethylene glycol (PEG) and a traditional Chinese medicine-derived permeation enhancer borneol (BO) for oral insulin delivery. Compared with a physical mixture of BO and PEG-decorated PLGA NPs, PLGA-PEG-BO NPs significantly facilitate insulin permeation across intestinal epithelia through various transcytosis pathways. The relationship among the BO surface density, physico-chemical properties and multiple barriers penetration ability is further investigated. Increasing the BO density boosts penetration through the epithelial cell layer but reduces enzyme and mucus barrier penetration. When the surface PEG density is at 90% and BO density is at 10%, the NPs possess the strongest overall ability to overcome both the mucus layer barrier and epithelial cell barrier, as illustrated by the highest permeation efficiency through Caco-2/HT29-MTX cell co-cultural monolayers. In diabetic rodents, PLGA-PEG90%-BO10% NPs exhibit high intestinal safety and a substantial hypoglycemic effect, with insulin availability at 6.22 ± 2.30%, double that of orally delivered insulin PLGA-PEG NPs and far superior to a physical mixture with BO. This study reveals the importance of tailored absorption enhancer decoration for oral protein delivery.

Innovative approaches in lung tissue engineering: the role of exosome-loaded bioscaffolds in regenerative medicine

Lung diseases account for over four million premature deaths every year, and experts predict that this number will increase in the future. The top cause of death globally is diseases which include conditions like lung cancer asthma and COPD. Treating severe acute lung injury is a complex task because lungs struggle to heal themselves in the presence of swelling inflammation and scarring caused by damage, to the lung tissues. Though achieving lung regeneration, in controlled environments is still an ambition; ongoing studies are concentrating on notable progress, in the field of lung tissue engineering and methods for repairing lung damage. This review delves into methods, for regenerating lungs with a focus on exosome carry bioscaffolds and mesenchymal stem cells among others. It talks about how these new techniques can help repair lung tissue and improve lung function in cases of damage. Also noted is the significance of ex vivo lung perfusion (EVLP), for rejuvenating donor lungs and the healing properties of exosomes in supporting lung regeneration.

Recent advances in the development of chitosan/hyaluronic acid-based hybrid materials for skin protection, regeneration, and healing: A review

Biomaterials play vital roles in regenerative medicine, specifically in tissue engineering applications. They promote angiogenesis and facilitate tissue creation and repair. The most difficult aspect of this field is acquiring smart biomaterials that possess qualities and functions that either surpass or are on par with those of synthetic products. The biocompatibility, biodegradability, film-forming capacity, and hydrophilic nature of the non-sulfated glycosaminoglycans (GAGs) (hyaluronic acid (HA) and chitosan (CS)) have attracted significant attention. In addition, CS and HA possess remarkable inherent biological capabilities, such as antimicrobial, antioxidant, and anti-inflammatory properties. This review provides a comprehensive overview of the recent progress made in designing and fabricating CS/HA-based hybrid materials for dermatology applications. Various formulations utilizing CS/HA have been developed, including hydrogels, microspheres, films, foams, membranes, and nanoparticles, based on the fabrication protocol (physical or chemical). Each formulation aims to enhance the materials' remarkable biological properties while also addressing their limited stability in water and mechanical strength. Additionally, this review gave a thorough outline of future suggestions for enhancing the mechanical strength of CS/HA wound dressings, along with methods to include biomolecules to make them more useful in skin biomedicine applications.

Biological activity of lyophilized chitosan scaffolds with inclusion of chitosan and zinc oxide nanoparticles

The constant demand for biocompatible and non-invasive materials for regenerative medicine in accidents and various diseases has driven the development of innovative biomaterials that promote biomedical applications. In this context, using sol-gel and ionotropic gelation methods, zinc oxide nanoparticles (NPs-ZnO) and chitosan nanoparticles (NPs-CS) were synthesized with sizes of 20.0 nm and 11.98 nm, respectively. These nanoparticles were incorporated into chitosan scaffolds through the freeze-drying method, generating a porous morphology with small (<100 μm), medium (100-200 μm), and large (200-450 μm) pore sizes. Moreover, the four formulations showed preliminary bioactivity after hydrolytic degradation, facilitating the formation of a hydroxyapatite (HA) layer on the scaffold surface, as evidenced by the presence of Ca (4%) and P (5.1%) during hydrolytic degradation. The scaffolds exhibited average antibacterial activity of F1 = 92.93%, F2 = 99.90%, F3 = 74.10%, and F4 = 88.72% against four bacterial strains: K. pneumoniae, E. cloacae, S. enterica, and S. aureus. In vivo, evaluation confirmed the biocompatibility of the functionalized scaffolds, where F2 showed accelerated resorption attributed to the NPs-ZnO. At the same time, F3 exhibited controlled degradation with NPs-CS acting as initiation points for degradation. On the other hand, F4 combined NPs-CS and NPs-ZnO, resulting in progressive degradation, reduced inflammation, and an organized extracellular matrix. All the results presented expand the boundaries in tissue engineering and regenerative medicine by highlighting the crucial role of nanoparticles in optimizing scaffold properties.

Multifunctional Casein-Based Wound Dressing Capable of Monitoring and Moderating the Proteolytic Activity of Chronic Wounds

Every 1.2 s, a diabetic foot ulcer is developed, and every 20 s, one amputation is carried out in diabetic patients. Monitoring and controlling protease activity have been considered as a strategy for more efficient management of diabetic and other chronic wounds. This study aimed to develop a casein-based dressing that, by its disappearance, provides information about the activity of proteases and simultaneously harnesses proteolytic activity. Casein films were fabricated by using an aqueous solution, and heat treatment was successfully deployed as a green and clean approach to confer hydrolytic stability. Our results showed that casein-based films' mechanical characteristics, water absorption, and proteolytic stability could be controlled by the length of the heat treatment, which proved to be a useful tool. An increase in the treatment duration from 30 min to 3 h led to toleration of 2.4 times higher stress, 2 times lower water uptake, and 3.4 times higher proteolytic stability at examined conditions. Selected casein-based structures responded to Bacillus sp. bacteria's protease (BSP) and human neutrophil elastase (HNE) as representatives of bacterial and nonbacterial proteases found in the wounds at 10 and 200 ng mL-1 levels, respectively. The hydrolysis was accompanied by a 36% reduction in proteolytic activity measured by using a casein-based universal protease activity assay. The released casein fragments could scavenge 90% of the examined radicals. In-vitro cell culture studies showed that the hydrolysates were not cytotoxic, and the casein-based film had a favorable interaction with fibroblast cells, indicating its potential as a scaffold in the case that proteolytic activity would not be to the extent that causes its rapid disintegration. In general, these findings hold promise for applying the developed casein-based structure for detecting proteolytic activity without the need for any equipment, kits, or expertise and, more importantly, in a highly economical manner. In the case that the proteolytic activity would not be severe, it could also serve as a substrate for cell adhesion and growth; this would aid in the healing process.

Cell-Tissue Interaction: The Biomimetic Approach to Design Tissue Engineered Biomaterials

The advancement achieved in Tissue Engineering is based on a careful and in-depth study of cell-tissue interactions. The choice of a specific biomaterial in Tissue Engineering is fundamental, as it represents an interface for adherent cells in the creation of a microenvironment suitable for cell growth and differentiation. The knowledge of the biochemical and biophysical properties of the extracellular matrix is a useful tool for the optimization of polymeric scaffolds. This review aims to analyse the chemical, physical, and biological parameters on which are possible to act in Tissue Engineering for the optimization of polymeric scaffolds and the most recent progress presented in this field, including the novelty in the modification of the scaffolds' bulk and surface from a chemical and physical point of view to improve cell-biomaterial interaction. Moreover, we underline how understanding the impact of scaffolds on cell fate is of paramount importance for the successful advancement of Tissue Engineering. Finally, we conclude by reporting the future perspectives in this field in continuous development.

Characteristics of Chitosan Films with the Bioactive Substances-Caffeine and Propolis

Chitosan is a natural and biodegradable polymer with promising potential for biomedical applications. This study concerns the production of chitosan-based materials for future use in the medical industry. Bioactive substances-caffeine and ethanolic propolis extract (EEP)-were incorporated into a chitosan matrix to increase the bioactivity of the obtained films and improve their mechanical properties. Acetic and citric acids were used as solvents in the production of the chitosan-based films. The obtained materials were characterized in terms of their antibacterial and antifungal activities, as well as their mechanical properties, including tensile strength and elongation at break. Moreover, the chemical structures and surface morphologies of the films were assessed. The results showed that the solution consisting of chitosan, citric acid, caffeine, and EEP exhibited an excellent antiradical effect. The activity of this solution (99.13%) was comparable to that of the standard antioxidant Trolox (92.82%). In addition, the film obtained from this solution showed good antibacterial activity, mainly against Escherichia coli and Enterococcus faecalis. The results also revealed that the films produced with citric acid exhibited higher activity levels against pathogenic bacteria than the films obtained with acetic acid. The antimicrobial effect of the chitosan-based films could be further enhanced by adding bioactive additives such as caffeine and propolis extract. The mechanical tests showed that the solvents and additives used affected the mechanical properties of the films obtained. The film produced from chitosan and acetic acid was characterized by the highest tensile strength value (46.95 MPa) while the chitosan-based film with citric acid showed the lowest value (2.28 MPa). The addition of caffeine and propolis to the film based on chitosan with acetic acid decreased its tensile strength while in the case of the chitosan-based film with citric acid, an increase in strength was observed. The obtained results suggested that chitosan films with natural bioactive substances can be a promising alternative to the traditional materials used in the medical industry, for example, as including biodegradable wound dressings or probiotic encapsulation materials.

Porous Chitosan Hydrogels Produced by Physical Crosslinking: Physicochemical, Structural, and Cytotoxic Properties

Chitosan hydrogels are biomaterials with excellent potential for biomedical applications. In this study, chitosan hydrogels were prepared at different concentrations and molecular weights by freeze-drying. The chitosan sponges were physically crosslinked using sodium bicarbonate as a crosslinking agent. The X-ray spectroscopy (XPS and XRD diffraction), equilibrium water content, microstructural morphology (confocal microscopy), rheological properties (temperature sweep test), and cytotoxicity of the chitosan hydrogels (MTT assay) were investigated. XPS analysis confirmed that the chitosan hydrogels obtained were physically crosslinked using sodium bicarbonate. The chitosan samples displayed a semi-crystalline nature and a highly porous structure with mean pore size between 115.7 ± 20.5 and 156.3 ± 21.8 µm. In addition, the chitosan hydrogels exhibited high water absorption, showing equilibrium water content values from 23 to 30 times their mass in PBS buffer and high thermal stability from 5 to 60 °C. Also, chitosan hydrogels were non-cytotoxic, obtaining cell viability values ≥ 100% for the HT29 cells. Thus, physically crosslinked chitosan hydrogels can be great candidates as biomaterials for biomedical applications.

Photocurable Thiol-yne Alginate Hydrogels for Regenerative Medicine Purposes

Every year millions of people worldwide undergo surgical interventions, with the occurrence of mild or severe post-treatment consequences meaning that rehabilitation plays a key role in modern medicine. Considering the cases of burns and plastic surgery, the pressing need for new materials that can be used for wound patches or body fillers and are able to sustain tissue regeneration and promote cell adhesion and proliferation is clear. The challenges facing next-generation implant materials also include the need for improved structural properties for cellular organization and morphogenic guidance together with optimal mechanical, rheological, and topographical behavior. Herein, we propose for the first time a sodium alginate hydrogel obtained by a thiol-yne reaction, easily synthesized using carbodiimide chemistry in a two-step reaction. The hydrogels were formed in all cases within a few minutes of light irradiation, showing good self-standing properties under solicitation. The mechanical, rheological, topographical, and swelling properties of the gels were also tested and reported. Lastly, no cytotoxicity was detected among the hydrogels. Soluble extracts in culture media allowed cell proliferation, and no differences between samples were detected in terms of metabolic activity and DNA content. These results suggest the potential use of these cytocompatible hydrogels in tissue engineering and regenerative medicine.

Oriented nanofibrous P(MMD-co-LA)/Deferoxamine nerve scaffold facilitates peripheral nerve regeneration by regulating macrophage phenotype and revascularization

Delayed injured nerve regeneration remains a clinical problem, partly ascribing to the lack of regulation of regenerative microenvironment, topographical cues, and blood nourishment. Functional electrospun conduits have been established as an efficacious strategy to facilitate nerve regeneration by providing structural guidance, regulating the regenerative immune microenvironment, and improving vascular regeneration. However, the synthetic polymers conventionally used to fabricate electrospinning scaffolds, such as poly(L-lactic acid), poly(glycolic acid), and poly(lactic-co-glycolic acid), can cause aseptic inflammation due to acidic degradation products. Therefore, a poly[3(S)-methyl-morpholine-2,5-dione-co-lactic] [P(MMD-co-LA)] containing alanine units with good mechanical properties and reduced acid degradation products, was obtained by melt ring-opening polymerization (ROP). Here, we aimed to explore the effect of oriented nanofiber/Deferoxamine (DFO, a hydrophilic angiogenic drug) scaffold in the rapid construction of a favorable regenerative microenvironment, including cell bridge, polarized vascular system, and immune microenvironment. In vitro studies have shown that the scaffold can sustainably release DFO, which accelerates the migration and tube formation of human umbilical vein endothelial cells (HUVECs), as well as the expression of genes related to angiogenesis. The physical clues provided by the arranged nanofibers can regulate the polarization of macrophages and reduce the expression of inflammatory factors. Furthermore, the in vivo results demonstrated a higher M2 polarization level of the oriented nanofibrous scaffold treatment group with reducedinflammation reaction in the injured nerve. Moreover, the in-situ release of DFO up-regulated the expression of HIF1-α and SDF-1α genes, as well as the expression of HIF1-α's target gene VEGF, further promoting revascularization and enhancing nerve regeneration at the defect site. The obtained results provide essential insights on accelerating the creation of the nerve regeneration microenvironment by combining the physiological processes of nerve regeneration with topographical cues and chemical signal induction.

Rationally engineered chitin deacetylase from Arthrobacter sp. AW19M34-1 with improved catalytic activity toward crystalline chitin

Chitin and its derivatives have anticoagulant, antimicrobial, and antioxidant properties, but the poor solubility of chitin limits its application in different fields. In this study, site-directed mutagenesis was performed to enhance the deacetylation activity of chitin deacetylases CDA from Arthrobacter (ArCE4). The mutant Mut-2-8 with Y172E/E200S/Y201W showed a 2.84- fold and 1.39-fold increase in catalytic efficiency (kcat/Km) for the deacetylation of (GluNAc)₅ and α-chitin, respectively. These results demonstrated that the mutations significantly improved the activation of ArCE4 on crystalline chitin. The molecular docking study confirmed that the enhancement of catalytic efficiency is due to the extra two hydrogen bonds and one acetyl group. In summary, the activity of Mut-2-8 to insoluble chitin was significantly improved by reactional design, which is beneficial to resolve the issues of the expensive cost of the enzymes and low efficiency. Mut-2-8 exhibits potential applications in the chitosan industry.

Preparation, Characterization, and Biological Evaluation of Transparent Thin Carboxymethyl-Chitosan/Oxidized Carboxymethyl Cellulose Films as New Wound Dressings

Full thickness burns in which the damage penetrates deep into the skin layers and reaches underneath the muscle, compel the need for more effective cure. Herein, cross-linked carboxymethyl-chitosan (CM-chitosan) films, prepared by Schiff base association with oxidized carboxymethyl cellulose (OCMC), are investigated regarding the wound healing capacity on full thickness burn injuries in vivo. Transparent thin CM-chitosan/OCMC films are obtained with tensile strength reaching 6.11 MPa, elongation at break above 27%, and water absorption more than 800%, which operates in favor of absorbing excess exudate and monitoring the wound status. Furthermore, the nonadherent CM-chitosan/OCMC films, with satisfactory biodegradability, cell, and tissue compatibility, are readily used to the wound sites and easily removed following therapy on scalded tissue so as to alleviate the suffering from burn. The films efficiently promote epithelial and dermal regeneration compared to the control, achieving 75.9% and 94.4% wound closure, respectively, after 14 and 27 days. More importantly, CM-chitosan/OCMC films accelerate wound healing with natural mechanisms which include controlling inflammatory response, reducing apoptosis, promoting fibroblast cell proliferation, and collagen formation. In conclusion, the CM-chitosan/OCMC films elevate the repair ratio of burn injuries and have great potential for facilitating the healing process on full-thickness exuding wounds.

Sustainable cultivation of Navicula incerta using cellulose-based scaffold incorporated with nanoparticles in air-liquid interface cultivation system

Microalgae cultivation using open cultivation systems requires large area and it is susceptible to contamination as well as weather changes. Meanwhile, the closed systems require large capital investment, and they are susceptible to the build-up of dissolved oxygen. Air-liquid interface culture systems with low water-footprint, but high packing density can be used for microalgae cultivation if low-cost culture scaffolds are available. In this study, cellulose-based scaffolds were synthesized using NaOH/urea aqueous solution as the solvent. Titanium dioxide (TiO₂), silica gel and polyethylene glycol 1000 (PEG 1000) nanoparticles were added into the membrane scaffolds to increase the hydrophilicity of nutrient absorbing to support the growth of microalgae. The membrane scaffolds were characterized by FTIR, SEM, contact angle, porosity and porometry. All three nanoparticles additives showed their ability in reducing the contact angle of membrane scaffolds from 63.4 ± 2.3° to a range of 52.6 ± 1.2° to 38.8 ± 1.5° due to the hydrophilic properties of the nanoparticles. The decreasing in pore size when nanoparticles were added did not affect the porosity of membrane scaffolds. Cellulose membrane scaffold with TiO₂ showed the highest percentage of microalgae Navicula incerta growth rate of 22.1% because of the antibacterial properties of TiO₂ in lowering the risk of cell contamination and enhancing the growth of N. incerta. The results exhibited that cellulose-based scaffold with TiO₂ added could be an effective support in plant cell culture field.

Poly(δ-valerolactone)/Poly(ethylene-co-vinylalcohol)/β-Tri-calcium Phosphate Composite as Scaffolds: Preparation, Properties, and In Vitro Amoxicillin Release

Two poly(δ-valerolactone)/poly(ethylene-co-vinylalcohol)/beta-tricalcium phosphate (PEVAL/PDVAL/β-TCP) composites containing an equal ratio of polymer and filled with 50 and 70 wt% of β-TCP microparticles were prepared by the solvent casting method. Interconnected pores were realized using the salt leached technique, and the porosity of the resulted composites was evaluated by the scanning electron microscopy (SEM) method. The homogeneity of the hybrid materials was investigated by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analysis. The prepared materials' SEM images showed interconnected micropores that respond to the conditions required to allow their uses as scaffolds. The porosity of each scaffold was determined from micro computed tomography (micro-CT) data, and the analysis of the mechanical properties of the prepared materials was studied through the stress-strain compressive test. The proliferation test results used human mesenchymal stem cells (MSCs) to grow and proliferate on the different types of prepared materials, reflecting that the hybrid materials were non-toxic and could be biologically acceptable scaffolds. The antibacterial activity test revealed that incorporation of amoxicillin in the specimens could inhibit the bacterial growth of S. aureus. The in vitro study of the release of amoxicillin from the PEVAL/PDVAL/amoxicillin and PEVAL/PDVAL/β-TCP/amoxicillin drug carrier systems in pH media 7.4, during eight days, gave promising results, and the antibiotic diffusion in these scaffolds obeys the Fickian model.