Bioactive composite scaffolds of carboxymethyl chitosan-silk fibroin containing chitosan nanoparticles for sustained release of ascorbic acid

Effect of Specific Surface Area and Hydrophobicity of Electrospun Nanofibers on the Sustained Release Performance of Diclofenac Sodium

Nanofibers produced by electrospinning are suitable options for slow-release materials. Diclofenac sodium (DS) is a nonsteroidal anti-inflammatory medication with a brief half-life that can serve as an effective sustained-release agent. This paper presents a novel method for producing DS-sustained release nanofibers by electrostatic spinning processes. During the preparation, the slow-release capabilities of biodegradable materials poly(lactic acid) (PLA) and polycaprolactone (PCL) are investigated. A composite drug-carrying scaffold is prepared to enhance the sustained-release performance. The sustained release ability is affected by the specific surface area of the nanofibers and the hydrophobicity of the polymer. The findings indicate that the composite nanofiber with a PLA/PCL ratio of 1:1 demonstrates the most effective sustained-release performance. The release rate is mostly influenced by the hydrophobicity of the polymer at this point. Sustained-release kinetic simulations were performed and revealed that the release of nanofibers follows a first-order release paradigm. This work presents a straightforward approach for creating a sustained-release formulation of DS.

Nitric oxide-releasing thiolated starch nanoparticles embedded in gelatin sponges for wound dressing applications

This study introduces a novel wound dressing by combining nitric oxide-releasing thiolated starch nanoparticles (NO-TS NPs) with gelatin. First, starch was thiolated (TS), and then its nanoparticles were prepared (TS NPs). Subsequently, NPs were covalently bonded to sodium nitrite to obtain NO-releasing TS NPs (NO-TS-NPs) that were incorporated into gelatin sponges at various concentrations. The resulting spherical TS NPs had a mean size of 85.42 ± 5.23 nm, which rose to 100.73 ± 7.41 nm after bonding with sodium nitrite. FTIR spectroscopy confirmed S-nitrosation on the NO-TS NPs' surface, and morphology analysis showed well-interconnected pores in all sponges. With higher NO-TS NPs content, pore size, porosity, and water uptake increased, while compressive modulus and strength decreased. Composites exhibited antibacterial activity, particularly against E. coli, with enhanced efficacy at higher NPs' concentrations. In vitro release studies demonstrated Fickian diffusion, with faster NO release in sponges containing more NPs. The released NO amounts were non-toxic to fibroblasts, but samples with fewer NO-TS NPs exhibited superior cellular density, cell attachment, and collagen secretion. Considering the results, including favorable mechanical strength, release behavior, antibacterial and cellular properties, gelatin sponges loaded with 2 mg/mL of NO-TS NPs can be suitable for wound dressing applications.

The Protective Effect of N-acetylcysteine against Liposome and Chitosan-Induced Cytotoxicity

AIM

N-acetylcysteine (NAC) as an antioxidant used to moderate liposome and chitosan-Induced cell cytotoxicity at their high concentrations.

METHODS

liposome and chitosan were prepared and characterized. The cytotoxicity effect of liposome with NAC-loaded liposome (liposome-NAC) and chitosan solution with chitosan solution containing NAC (chitosan-NAC) on the A549 cell line was compared.

RESULTS

Particle size, zeta potential, and NAC drug release for liposome were 125.9 ± 8 nm, -34.7 ± 2.1 mv, and 51.1% ±3%, respectively. SEM (Scanning electron microscope) and TEM (Transmission electron microscope) indicated spherical shape of liposome. Encapsulation efficiency of liposome-NAC was 12% ±0.98%. Particle size and zeta potential for chitosan solution were 361 ± 11.3 nm and 10.8 ± 1.52 mv. Stability storage study indicated good stability of chitosan and liposome. Cell viability of liposome-NAC and chitosan-NAC significantly was higher than liposome and chitosan at all four concentrations.

CONCLUSION

NAC has a protective effect against liposome and chitosan-induced cell toxicity.

Electrospun Silk Fibroin/kappa-Carrageenan Hybrid Nanofibers with Enhanced Osteogenic Properties for Bone Regeneration Applications

In this study, a novel nanofibrous hybrid scaffold based on silk fibroin (SF) and different weight ratios of kappa-carrageenan (k-CG) (1, 3, and 5 mg of k-CG in 1 mL of 12 wt% SF solution) was prepared using electrospinning and genipin (GP) as a crosslinker. The presence of k-CG in SF nanofibers was analyzed and confirmed using Fourier transform infrared spectroscopy (FTIR). In addition, X-ray diffraction (XRD) analysis confirmed that GP could cause SF conformation to shift from random coils or α-helices to β-sheets and thereby facilitate a more crystalline and stable structure. The ultimate tensile strength (UTS) and Young's modulus of the SF mats were enhanced after crosslinking with GP from 3.91 ± 0.2 MPa to 8.50 ± 0.3 MPa and from 9.17 ± 0.3 MPa to 31.2 ± 1.2 MP, respectively. Notably, while the mean fiber diameter, wettability, and biodegradation rate of the SF nanofibers increased with increasing k-CG content, a decreasing effect was determined in terms of UTS and Young's modulus. Additionally, better cell viability and proliferation were observed on hybrid scaffolds with the highest k-CG content. Osteogenic differentiation was determined from alkaline phosphatase (ALP) activity and Alizarin Red staining and expression of osteogenic marker genes. To this end, we noticed that k-CG enhanced ALP activity, calcium deposition, and expression of osteogenic genes on the hybrid scaffolds. Overall, hybridization of SF and k-CG can introduce a promising scaffold for bone regeneration; however, more biological evaluations are required.

Chitosan/Silk Fibroin Materials for Biomedical Applications-A Review

This review provides a report on recent advances in the field of chitosan (CTS) and silk fibroin (SF) biopolymer blends as new biomaterials. Chitosan and silk fibroin are widely used to obtain biomaterials. However, the materials based on the blends of these two biopolymers have not been summarized in a review paper yet. As these materials can attract both academic and industrial attention, we propose this review paper to showcase the latest achievements in this area. In this review, the latest literature regarding the preparation and properties of chitosan and silk fibroin and their blends has been reviewed.

Carboxymethyl carrageenan immobilized on 3D-printed polycaprolactone scaffold for the adsorption of calcium phosphate/strontium phosphate adapted to bone regeneration

Three dimensional (3D) substrates based on natural and synthetic polymers enhance the osteogenic and mechanical properties of the bone tissue engineering scaffolds. Here, a novel bioactive composite scaffolds from polycaprolactone /kappa-carrageenan were developed for bone regeneration applications. 3D PCL scaffolds were fabricated by 3D printing method followed by coating with carboxymethyl kappa-carrageenan. This organic film was used to create calcium and strontium phosphate layers via a modified alternate soaking process in CaCl ₂ /SrCl ₂ and Na₂HPO₄ solutions in which calcium ions were replaced by strontium, with different amounts of strontium in the solutions. Various characterization techniques were executed to analyze the effects of strontium ion on the scaffold properties. The morphological results demonstrated the highly porous with interconnected pores and uniform pore sizes scaffolds. It was indicated that the highest crystallinity and compressive strength were obtained when 100% CaCl₂ was replaced by SrCl₂ in the solution (P-C-Sr). Incorporation of Sr onto the structure increased the degradation rate of the scaffolds. Mesenchymal stem cells (MSCs) culture on the scaffolds showed that Sr effectively improved attachment and viability of the MSCs and accelerated osteogenic differentiation as revealed by Alkaline phosphatase activity, calcium content and Real Time-Reverse transcription polymerase chain reaction assays.

Nanocomposite sponges for enhancing intestinal residence time following oral administration

In this work, nanocomposites that combine mucopenetrating and mucoadhesive properties in a single system are proposed as innovative strategy to increase drug residence time in the intestine following oral administration. To this aim, novel mucoadhesive chitosan (CH) sponges loaded with mucopenetrating nanoemulsions (NE) were developed via freeze-casting technique. The NE mucopenetration ability was determined studying the surface affinity and thermodynamic binding of the nanosystem with mucins. The ability of nanoparticles to penetrate across a preformed mucins layer was validated by 3D-time laps Confocal Laser Scanning Microscopy imaging. Microscopy observations (Scanning Electron Microscopy and Optical Microscopy) showed that NE participated in the structure of the sponge affecting its stability and in vitro release kinetics. When incubated with HCT 116 and Caco-2 cell lines, the NE proved to be cytocompatible over a wide concentration range. Finally, the in vivo biodistribution of the nanocomposite was evaluated after oral gavage in healthy mice. The intestinal retention of NE was highly enhanced when loaded in the sponge compared to the NE suspension. Overall, our results demonstrated that the developed nanocomposite sponge is a promising system for sustained drug intestinal delivery.

The effect of Allium cepa extract on the chitosan/PLGA scaffolds bioactivity

Allium cepa extracts (AC) allow the fabrication of a biomaterial that, together with chitosan and PLGA, could be osteoconductive and promote a better and faster regeneration of bone tissue, with biocompatibility and biomineralization properties. In this work, scaffolds were developed by the thermally induced phase separation (TIPS) technique. An in vitro bioactivity analysis was performed using simulated body fluid (SBF). Scanning electron microscopy (SEM), energy dispersion spectroscopy, and infrared spectroscopy were used for the scaffolds characterization. The results showed a structure with a pore size distribution between 50 and 100 μm, which allowed the uniform formation of biological apatite crystals on the surface of the scaffolds. The chitosan/policaprolactone/Allium cepa scaffold (ChPAC) showed the most promising results with a ratio of P/Ca between 1.6 and 1.7, a value very close to that of hydroxyapatite.

Bilayer Cylindrical Conduit Consisting of Electrospun Polycaprolactone Nanofibers and DSC Cross-Linked Sodium Alginate Hydrogel to Bridge Peripheral Nerve Gaps

Herein, a bilayer cylindrical conduit (P-CA) is presented consisting of electrospun polycaprolactone (PCL) nanofibers and sodium alginate hydrogel covalently cross-linked with N,N'-disuccinimidyl carbonate (DSC). The bilayer P-CA conduit is developed by combining the electrospinning and outer-inner layer methods. Using DSC, as a covalent crosslinker, increases the degradation time of the sodium alginate hydrogel up to 2 months. The swelling ratio of the hydrogel is also 503% during the first 8 h. The DSC cross-linked sodium alginate in the inner layer of the conduit promotes the adhesion and proliferation of nerve cells, while the electrospun PCL nanofibers in the outer layer provide maximum tensile strength of the conduit during surgery. P-CA conduit promotes the migration of Schwann cells along the axon in a rat model based on functional and histological evidences. In conclusion, P-CA conduit will be a promising construct for repairing sciatic nerves in a rat model.

Chitosan Derivatives and Their Application in Biomedicine

Chitosan is a product of the deacetylation of chitin, which is widely found in nature. Chitosan is insoluble in water and most organic solvents, which seriously limits both its application scope and applicable fields. However, chitosan contains active functional groups that are liable to chemical reactions; thus, chitosan derivatives can be obtained through the chemical modification of chitosan. The modification of chitosan has been an important aspect of chitosan research, showing a better solubility, pH-sensitive targeting, an increased number of delivery systems, etc. This review summarizes the modification of chitosan by acylation, carboxylation, alkylation, and quaternization in order to improve the water solubility, pH sensitivity, and the targeting of chitosan derivatives. The applications of chitosan derivatives in the antibacterial, sustained slowly release, targeting, and delivery system fields are also described. Chitosan derivatives will have a large impact and show potential in biomedicine for the development of drugs in future.