Cytocompatibility of Bilayer Scaffolds Electrospun from Chitosan/Alginate-Chitin Nanowhiskers

Methyl Gallate and Amoxicillin-Loaded Electrospun Poly(vinyl alcohol)/Chitosan Mats: Impact of Acetic Acid on Their Anti-Staphylococcus aureus Activity

Methyl gallate (MG), a natural phenolic compound, exhibits in vitro synergistic activity with amoxicillin (Amox) against methicillin-resistant Staphylococcus aureus (MRSA), a global health concern. This study developed electrospun nanofibers incorporating MG and Amox into a poly(vinyl alcohol) (PVA)/chitosan (CS) blend to target both methicillin-susceptible S. aureus (MSSA) and MRSA. The formulation was optimized, and the impact of acetic acid on antibacterial activity was evaluated using agar disc diffusion. The final formulation was fabricated and characterized using SEM, FTIR, DSC, swelling, and release behavior analyses to understand its antibacterial efficacy. Results revealed that acetic acid eliminated antibacterial activity, but MG (64 mg/mL) and Amox (2.5 mg/mL) were successfully incorporated into a PVA/CS solution prepared with deionized water. The resulting nanofiber mats featured nanoscale fibers (126 ± 45 nm) with and micron-oval beads. Despite the in vitro synergism, the MG/Amox/PVA/CS mats showed no significant improvement over MG or Amox alone against MRSA, likely due to their physicochemical properties. FTIR and DSC results confirmed molecular interactions between the active compounds and the polymer matrix, which may cause a minimal swelling and low drug release at 24 h. This study offers insights into the potential of MG/Amox-loaded nanofibers for anti-MRSA material development.

Electrospinning of methacrylated alginate for tissue engineering applications

Photo-crosslinkable methacrylated alginate derivatives (M-ALGs) were synthesized via modification of sodium alginate with glycidyl methacrylate. Needle (capillary) and needleless electrospinning techniques were employed to produce their nonwoven fiber mats. Spinning parameters such as applied voltage, solution composition, and flow rate were optimized to form uniform bead-free fibers with an average diameter of about 150 nm. The needleless technique allowed successful electrospinning of M-ALG solutions with wider ranges of viscosities and surface tensions owing to its higher applicable voltage (∼65 kV) compared to that of the needle technique (∼30 kV). Photo-crosslinking of the fibers via UV irradiation allowed the fiber mats to remain insoluble in physiological media while maintaining their mechanical properties. Cultivation of multipotent mesenchymal stem cells (MSCs) with the cross-linked fiber mats in a modified Eagle medium (α-MEM) showed the growth of spherical colonies, indicating the sufficient cytocompatibility of the fiber mats with MSCs.

Electrospun Composites of Chitosan with Cerium Oxide Nanoparticles for Wound Healing Applications: Characterization and Biocompatibility Evaluation In Vitro and In Vivo

Cerium oxide nanoparticles (CeONPs), as part of tissue regeneration matrices, can protect cells from reactive oxygen species and oxidative stress. In addition, they can influence the properties of the scaffold, including its electrospinnability and mechanical strength. In this work, we prepared electrospun fiber mats from a chitosan and polyethylene oxide blend (CS-PEO) with the addition of ceria nanoparticles (CS-PEO-CeONP). The addition of CeONPs resulted in a smaller fiber diameter and higher swelling compared to CS-PEO fiber mats. CeONP-modified fiber mats also had a higher Young's modulus due to the reinforcing effect of the nanoparticles. Both mats had comparable adhesion and cytocompatibility to mesenchymal stem cells, which had a more rounded morphology on CS-PEO-CeONP compared to elongated cells on the CS-PEO mats. Biocompatibility in an in vivo rat model showed no acute toxicity, no septic or allergic inflammation, and no rough scar tissue formation. The degradation of both mats passed the stage of matrix swelling. CS-PEO-CeONP showed significantly slower biodegradation, with most of the matrix remaining in the tissue after 90 days. The reactive inflammation was aseptic in nature with the involvement of multinucleated foreign-body type giant cells and was significantly reduced by day 90. CeONPs induced the formation of the implant's connective tissue capsule. Thus, the introduction of CeONPs influenced the physicochemical properties and biological activity of CS-PEO nanofiber mats.

A systematic review on green and natural polymeric nanofibers for biomedical applications

Electrospinning is the simplest technique to produce ultrathin nanofibers, which enables the use of nanotechnology in various applications. Nanofibrous materials produced through electrospinning have garnered significant attention in biomedical applications due to their unique properties and versatile potential. In recent years, there has been a growing emphasis on incorporating sustainability principles into material design and production. However, electrospun nanofibers, owing to their reliance on solvents associated with significant drawbacks like toxicity, flammability, and disposal challenges, frequently fall short of meeting environmentally friendly standards. Due to the limited solvent choices and heightened concerns for safety and hygiene in modern living, it becomes imperative to carefully assess the implications of employing electrospun nanofibers in diverse applications and consumer products. This systematic review aims to comprehensively assess the current state of research and development in the field of "green and natural" electrospun polymer nanofibers as well as more fascinating and eco-friendly commercial techniques, solvent preferences, and other green routes that respect social and legal restrictions tailored for biomedical applications. We explore the utilization of biocompatible and biodegradable polymers sourced from renewable feedstocks, eco-friendly processing techniques, and the evaluation of environmental impacts. Our review highlights the potential of green and natural electrospun nanofibers to address sustainability concerns while meeting the demanding requirements of various biomedical applications, including tissue engineering, drug delivery, wound healing, and diagnostic platforms. We analyze the advantages, challenges, and future prospects of these materials, offering insights into the evolving landscape of environmentally responsible nanofiber technology in the biomedical field.

Bilayer scaffolds/membranes for bone tissue engineering applications: A systematic review

OBJECTIVE

This systematic review evaluates the purpose, materials, physio-mechanical, and biological effects of bilayer scaffolds/membranes used for bone tissue engineering applications.

METHODS

A comprehensive electronic search of English-language literature from 2012 to October 2022 was conducted in PubMed, Scopus, ScienceDirect, and Google Scholar online databases according to the PRISMA 2020 guidelines. The quality of animal studies was evaluated through the SYRCLE's risk of bias tool.

RESULTS

A total of 77 studies were sought for retrieval, and 39 studies met the inclusion criteria. According to the synthesis results, most bilayers had a dense barrier layer that prevented connective tissue penetration and a loose osteogenic layer that supported cell migration and osteogenesis. PLGA, PCL, and chitosan were the most common polymers in the barrier layers, while the most utilized polymers in osteogenic layers were PLGA and gelatin. Electrospinning and solvent casting were the most common fabrication methods to design the bilayer structures. Many studies reported higher biological results for bilayers compared to their single layers. Also, fabricated bilayers' in vitro osteogenesis and in vivo new bone formation were significantly superior or at least comparable to the frequently used commercial membranes.

CONCLUSION

1) Bilayers with two distinct layers and different materials, porosities, mechanical properties, and biological behavior can significantly improve heterogeneous bone regeneration; 2) the addition of ceramics and/or drugs to the osteogenic layer enhances the osteogenic properties of the bilayers; 3) fabrication method and pore size of the layers play an important role in determining the mechanical and biological behavior of them.

Focusing on papain release in the intestine: The effects of Chitinous materials on alginate microsphere properties

Exogenous enzymes, accompanied by a function of assisting digestion, can be employed in therapeutic application which supplement the daily diet for the patients suffering from gastrointestinal diseases. To prevent the degradation of the enzymes in gastric fluid, papain was encapsulated into alginate microspheres with the external wrap of chitin nanocrystals. The protective effect of the assembled alginate microspheres (PAM‐ChNC) on papain was studied and compared with traditional chitosan‐coated alginate microspheres (PAM‐Ch). Scanning electron microscopy results showed that ChNC could form a dense structure on the surface of alginate microspheres. The swelling rate of PAM‐ChNC was lower than that of PAM‐Ch at pH 1.2. The effect of papain (encapsulated in microspheres) on the digestion of myofibrillar protein gels (MP) was investigated by in vitro digestion. The results showed that the degree of hydrolysis of MP + PAM‐ChNC was significantly higher than that of MP+ PAM‐Ch, indicating that PAM‐ChNC was expected to become a controlled release system for oral exogenous enzymes that assist digestion.

Chitosan Composites with Bacterial Cellulose Nanofibers Doped with Nanosized Cerium Oxide: Characterization and Cytocompatibility Evaluation

In this work, new composite films were prepared by incorporating the disintegrated bacterial cellulose (BCd) nanofibers and cerium oxide nanoparticles into chitosan (CS) matrices. The influence of the amount of nanofillers on the structure and properties of the polymer composites and the specific features of the intermolecular interactions in the materials were determined. An increase in film stiffness was observed as a result of reinforcing the CS matrix with BCd nanofibers: the Young’s modulus increased from 4.55 to 6.3 GPa with the introduction of 5% BCd. A further increase in Young’s modulus of 6.7 GPa and a significant increase in film strength (22% increase in yield stress compared to the CS film) were observed when the BCd concentration was increased to 20%. The amount of nanosized ceria affected the structure of the composite, followed by a change in the hydrophilic properties and texture of the composite films. Increasing the amount of nanoceria to 8% significantly improved the biocompatibility of the films and their adhesion to the culture of mesenchymal stem cells. The obtained nanocomposite films combine a number of favorable properties (good mechanical strength in dry and swollen states, improved biocompatibility in relation to the culture of mesenchymal stem cells), which allows us to recommend them for use as a matrix material for the culture of mesenchymal stem cells and wound dressings.

Docosahexaenoic acid-loaded chitosan/alginate membrane reduces biofilm formation by P. aeruginosa and promotes MSC-mediated burn wound healing

Aims: Chitosan, like docosahexaenoic acid (DHA) and mesenchymal stem cells (MSCs), is used in medicine as a wound healing accelerator. Thus, in this study, chitosan-alginate (CA) membranes containing DHA and MSCs were produced, and their antibacterial and antibiofilm activities against burn infections caused by Pseudomonas aeruginosa were investigated.Methods: Physicochemical properties were assessed by SEM, Fourier transform infrared (FTIR), and X-ray diffraction (XRD). Porosity, cytocompatibility, and antibacterial and antibiofilm activities were evaluated both in vitro and in vivo. The viability and apoptosis of MSCs were studied using flow cytometry. Wound healing effects were analyzed based on histopathological features, the wound contraction rate (WCR) ratio, and bacterial clearance.Results: The CA membranes showed antibiofilm activity both in vivo and in vitro, accompanied by reduced lasI and rhlI expressions and pyocyanin production. The membranes were highly porous and biocompatible and showed favorable physicochemical properties. Docosahexaenoic acid incorporation to CA membranes improved their antibacterial and antibiofilm activities, as well as MSCs' viability by reducing crystallinity and increasing porosity (p = .008). Treatment with CA-DHA-MSC accelerated burn wound healing (with complete healing being observed after 14 days, WCR = 85%) and augmented antibacterial and antibiofilm activities in vivo compared to CA-DHA and CA-MSC. The CA-DHA-MSC group delivered a significantly higher WCR and lower inflammation than the CA-MSC group (p = .0001).Conclusion: In combination with DHA-loaded CA membranes, MSCs reduced the healing time of burn wounds, offering a viable option for designing effective wound dressings.

Patches as Polymeric Systems for Improved Delivery of Topical Corticosteroids: Advances and Future Perspectives

Mucoadhesive polymer patches are a promising alternative for prolonged and controlled delivery of topical corticosteroids (CS) to improve their biopharmaceutical properties (mainly increasing local bioavailability and reducing systemic toxicity). The main biopharmaceutical advantages of patches compared to traditional oral dosage forms are their excellent bioadhesive properties and their increased drug residence time, modified and unidirectional drug release, improved local bioavailability and safety profile, additional pain receptor protection, and patient friendliness. This review describes the main approaches that can be used for the pharmaceutical R&D of oromucosal patches with improved physicochemical, mechanical, and pharmacological properties. The review mainly focuses on ways to increase the bioadhesion of oromucosal patches and to modify drug release, as well as ways to improve local bioavailability and safety by developing unidirectional -release poly-layer patches. Various techniques for obtaining patches and their influence on the structure and properties of the resulting dosage forms are also presented.

pH-Sensitive Drug Delivery System Based on Chitin Nanowhiskers-Sodium Alginate Polyelectrolyte Complex

Polyelectrolyte complexes (PECs), based on partially deacetylated chitin nanowhiskers (CNWs) and anionic polysaccharides, are characterized by their variability of properties (particle size, ζ-potential, and pH-sensitivity) depending on the preparation conditions, thereby allowing the development of polymeric nanoplatforms with a sustained release profile for active pharmaceutical substances. This study is focused on the development of hydrogels based on PECs of CNWs and sodium alginate (ALG) for potential vaginal administration that provide controlled pH-dependent antibiotic release in an acidic vaginal environment, as well as prolonged pharmacological action due to both the sustained drug release profile and the mucoadhesive properties of the polysaccharides. The desired hydrogels were formed as a result of both electrostatic interactions between CNWs and ALG (PEC formation), and the subsequent molecular entanglement of ALG chains, and the formation of additional hydrogen bonds. Metronidazole (MET) delivery systems with the desired properties were obtained at pH 5.5 and an CNW:ALG ratio of 1:2. The MET-CNW-ALG microparticles in the hydrogel composition had an apparent hydrodynamic diameter of approximately 1.7 µm and a ζ-potential of -43 mV. In vitro release studies showed a prolonged pH-sensitive drug release from the designed hydrogels; 37 and 67% of MET were released within 24 h at pH 7.4 and pH 4.5, respectively. The introduction of CNWs into the MET-ALG system not only prolonged the drug release, but also increased the mucoadhesive properties by about 1.3 times. Thus, novel CNW-ALG hydrogels are promising carriers for pH sensitive drug delivery carriers.

A Water-Soluble Epoxy-Based Green Crosslinking System for Stabilizing PVA Nanofibers

With the ever-growing concern about environmental conservation, green production and water-based nanofibers have attracted more and more interest from both academic and industrial fields; nevertheless, the stabilization process of water-based nanofibers is primarily relying on the application of organic solvent-based crosslinking agents. In this work, we develop a green approach to fabricate water-resistant polyvinyl alcohol (PVA) nanofibers by using a water-based epoxy compound, N¹, N⁶-bis(oxiran-2-ylmethyl) hexane-1,6-diamine (EH), as the crosslinker. This EH/sodium carbonate/sodium bicarbonate (CBS) solution system can break down large aggregates of PVA molecules into small ones and promote the uniform distribution of EH in the solution, resulting in the improved stability of crosslinked PVA nanofibers. We firstly report that the uniform dispersion of crosslinking agents in the electrospinning solution plays a vital role in improving the stability of spinning solutions and the water resistance of crosslinked PVA nanofibers by comparing crosslinking performances between water-based epoxy and conventional water-based blocked isocyanate (BI). This work could open up a novel strategy and green approach for the stabilization of water-based nanofibers.

An Up‐to‐Date Review on Alginate Nanoparticles and Nanofibers for Biomedical and Pharmaceutical Applications

Alginate is a naturally occurring polysaccharide commonly derived from brown algae cell walls which possesses unique features that make it extremely promising for several biomedical and pharmaceutical purposes. Alginate biomaterials are indeed nowadays gaining increasing interest in drug delivery and tissue engineering applications owing to their intrinsic biocompatibility, non‐toxicity, versatility, low cost, and ease of functionalization. Specifically, alginate‐based nanostructures show enhanced capabilities with respect to alginate bulk materials in the targeted delivery of drugs and chemotherapies, as well as in helping tissue reparation and regeneration. Hence, it is not surprising that the number of scientific reports related to this topic have rapidly grown in the last decade. With these premises, the present review aims to provide a comprehensive state‐of‐the‐art of the most recent advances in the preparation of alginate‐based nanoparticles and electrospun nanofibers for drug delivery, cancer therapy, and tissue engineering purposes. After a short introduction concerning the general properties and uses of alginate and the concept of nanotechnology, the recent literature is then critically presented to highlight the main advantages of alginate‐based nanostructures. Finally, the current limitations and the future perspectives and objectives are discussed in detail.

Encapsulation of Plant Biocontrol Bacteria with Alginate as a Main Polymer Material

One of the most favored trends in modern agriculture is biological control. However, many reports show that survival of biocontrol bacteria is poor in host plants. Providing biocontrol agents with protection by encapsulation within external coatings has therefore become a popular idea. Various techniques, including extrusion, spray drying, and emulsion, have been introduced for encapsulation of biocontrol bacteria. One commonly used biopolymer for this type of microencapsulation is alginate, a biopolymer extracted from seaweed. Recent progress has resulted in the production of alginate-based microcapsules that meet key bacterial encapsulation requirements, including biocompatibility, biodegradability, and support of long-term survival and function. However, more studies are needed regarding the effect of encapsulation on protective bacteria and their targeted release in organic crop production systems. Most importantly, the efficacy of alginate use for the encapsulation of biocontrol bacteria in pest and disease management requires further verification. Achieving a new formulation based on biodegradable polymers can have significant effects on increasing the quantity and quality of agricultural products.

Thermal Properties and Structural Features of Multilayer Films Based on Chitosan and Anionic Polysaccharides

This study investigates the thermal and structural properties of multilayer composites based on chitosan (CS) and polyanions with different functionalities, including sodium sulfoethyl cellulose (SEC), sodium alginate (ALG), and sodium hyaluronate (HA). Unlike polyelectrolyte complexes (PECs) obtained by polymer mixing, the formation of a PEC layer by a process of layer-by-layer deposition of oppositely charged polymers is accompanied by the transformation of the CS polymorphic state, and this affects the relaxation and thermal properties of the resulting multilayer composite. X-ray diffraction analysis showed that the formation of the PEC layer in the CS/SEC multilayer film is accompanied by crystallization of the CS chains and the formation of a predominantly anhydrous CS modification. Thermogravimetric analysis of the CS/SEC film registers a high-temperature peak associated with the thermal decomposition of crystalline CS in the PEC composition. According to the dynamic mechanical analysis, the CS/SEC composite was characterized by a single glass transition temperature, indicating a strong interaction between the layers when using SEC (a strong acid salt) as the counterion to CS. For multilayer composites with weak polyacid salts (ALG and HA), the crystallization of CS in the PEC layer is weaker, as reflected in the thermal degradation of these films. A high-temperature peak is recorded in the thermal decomposition of CS/HA and is absent in the case of CS/ALG. Dynamic mechanical analysis of the CS/ALG composite showed two glass transition temperatures close to those of the original polymers, indicating weak PEC formation. The CS/HA composite showed an intermediate response. Thus, the effect of the PEC layer on the properties of the poly-layer composites decreases in the order CS/SEC > CS/HA > CS/ALG.