A New Generation of Electrospun Fibers Containing Bioactive Glass Particles for Wound Healing

Green Electrospun Poly(vinyl alcohol)/Gelatin-Based Nanofibrous Membrane by Incorporating 45S5 Bioglass Nanoparticles and Urea for Wound Dressing Applications: Characterization and In Vitro and In Vivo Evaluations

This study reports the fabrication and characterization of poly(vinyl alcohol) (PVA) and gelatin (Gel)-based nanofiber membranes cross-linked with citric acid (CA) by a green electrospinning method in which nano 45S5 bioglass (BG) and urea were incorporated. Various combinations of PVA, gelatin, and BG were prepared, and nanofiber membranes with average fiber diameters between 238 and 595 nm were fabricated. Morphological, chemical, and mechanical properties, porosity, swelling, water retention, and water vapor transmission rate of the fabricated membranes were evaluated. PVA:Gel (90:10), 15% CA, and 3% BG were determined as the optimum blend for nanofiber membrane fabrication via electrospinning. The membrane obtained using this blend was further functionalized with 10% w/w polymer urea coating by the electrospray method following the cross-linking. In vitro biocompatibility tests revealed that the fabricated membranes were all biocompatible except for the one that functionalized with urea. In vivo macroscopic and histopathological analysis results of PVA/Gel/BG and PVA/Gel/BG/Urea treated wounds indicated increased collagenization and vascularization and had an anti-inflammatory effect. Furthermore, careful examination of the in vivo macroscopic results of the PVA/Gel/BG/Urea membrane indicated its potential to decrease uneven scar formation. In conclusion, developed PVA/Gel/BG and PVA/Gel/BG/Urea electrospun membranes with multifunctional and biomimetic features may have the potential to be used as beneficial wound dressings.

Tailorable mechanical and degradation properties of KCl-reticulated and BDDE-crosslinked PCL/chitosan/κ-carrageenan electrospun fibers for biomedical applications: Effect of the crosslinking-reticulation synergy

The development of intricated and interconnected porous mats is desired for many applications in biomedicine and other relevant fields. The mats that comprise the use of natural, bioactive, and biodegradable polymers are the focus of current research activities. In the present work, crosslinked fibers with improved characteristics were produced by incorporating 1,4-butanediol diglycidyl ether (BDDE) into a polymer formulation containing polycaprolactone (PCL), chitosan (CS), and κappa-carrageenan (κ-C). A slight variation of formic acid (FA)/acetic acid (AA) ratio used as a solvent system, significantly affected the characteristics of the produced fiber mats. Both polysaccharides and BDDE played a major role in tailoring mechanical properties when fibrous scaffolds were reticulated under KCl-mediated basic conditions for determined periods of time at 50 °C. In vitro biological assessment of the electrospun fiber mats revealed proliferation of MC3T3-E1 cells when incubated for 1 and 7 days. After staining the cells with 4',6-diamidino-2-phenylindole (DAPI)/rhodamine phalloidin an autofluorescence response was observed by fluorescence microscopy in the scaffold manufactured using a solvent with higher FA/AA ratio due to the formation of microfibers. The results demonstrated the potential of the BDDE-crosslinked PCL/CS/κ-C electrospun fibers as promising materials for biomedical applications that may include soft and bone tissue regeneration.

Incorporation of Magnesium and Zinc Metallic Particles in PLGA Bi-layered Membranes with Sequential Ion Release for Guided Bone Regeneration

Guided bone regeneration (GBR) membranes are commonly used for periodontal tissue regeneration. Due to the complications of existing GBR membranes, the design of bioactive membranes is still relevant. GBR membranes with an asymmetric structure can accommodate the functional requirements of different interfacial tissues. Here, poly(lactic acid-glycolic acid) (PLGA) was selected as the matrix for preparing a bi-layered membrane with both dense and porous structure. The dense layer for blocking soft tissues was incorporated with zinc (Zn) particles, while the porous layer for promoting bone regeneration was co-incorporated with magnesium (Mg) and Zn particles. Mg/Zn-embedded PLGA membranes exhibited 166% higher mechanical strength in comparison with pure PLGA membranes and showed suitable degradation properties with a sequential ion release behavior of Mg²⁺ first and continuously Zn²⁺. More importantly, the release of Zn²⁺ from bi-layered PLGA endowed GBR membranes with excellent antibacterial activity (antibacterial rate > 69.3%) as well as good cytocompatibility with MC3T3-E1 (mouse calvaria pre-osteoblastic cells) and HGF-1 (human gingival fibroblast cells). Thus, the asymmetric bi-layered PLGA membranes embedded with Mg and Zn particles provide a simple and effective strategy to not only reinforce the PLGA membrane but also endow membranes with osteogenic and antibacterial activity due to the continuous ion release profile, which serves as a promising candidate for use in GBR therapy.

Electrospun Nanomaterials Based on Cellulose and Its Derivatives for Cell Cultures: Recent Developments and Challenges

The development of electrospun nanofibers based on cellulose and its derivatives is an inalienable task of modern materials science branches related to biomedical engineering. The considerable compatibility with multiple cell lines and capability to form unaligned nanofibrous frameworks help reproduce the properties of natural extracellular matrix and ensure scaffold applications as cell carriers promoting substantial cell adhesion, growth, and proliferation. In this paper, we are focusing on the structural features of cellulose itself and electrospun cellulosic fibers, including fiber diameter, spacing, and alignment responsible for facilitated cell capture. The study emphasizes the role of the most frequently discussed cellulose derivatives (cellulose acetate, carboxymethylcellulose, hydroxypropyl cellulose, etc.) and composites in scaffolding and cell culturing. The key issues of the electrospinning technique in scaffold design and insufficient micromechanics assessment are discussed. Based on recent studies aiming at the fabrication of artificial 2D and 3D nanofiber matrices, the current research provides the applicability assessment of the scaffolds toward osteoblasts (hFOB line), fibroblastic (NIH/3T3, HDF, HFF-1, L929 lines), endothelial (HUVEC line), and several other cell types. Furthermore, a critical aspect of cell adhesion through the adsorption of proteins on the surfaces is touched upon.

Modified Sol–Gel Synthesis of Mesoporous Borate Bioactive Glasses for Potential Use in Wound Healing

In this study, we successfully utilized nitrate precursors for the synthesis of silver (Ag)-doped borate-based mesoporous bioactive glass (MBGs) based on the 1393B3 glass formulation in the presence of a polymeric substrate (polyvinyl alcohol (PVA)) as a stabilizer of boric acid. The X-ray diffraction (XRD) analysis confirmed the glassy state of all the MBGs. The incorporation of 7.5 mol% Ag into the glass composition led to a decrease in the glass transition temperature (T_g). Improvements in the particle size, zeta potential, surface roughness, and surface area values were observed in the Ag-doped MBGs. The MBGs (1 mg/mL) had no adverse effect on the viability of fibroblasts. In addition, Ag-doped MBGs exhibited potent antibacterial activity against gram-positive and gram-negative species. In summary, a modified sol–gel method was confirmed for producing the Ag-doped 1393B3 glasses, and the primary in vitro outcomes hold promise for conducting in vivo studies for managing burns.

Cell loaded hydrogel containing Ag-doped bioactive glass-ceramic nanoparticles as skin substitute: Antibacterial properties, immune response, and scarless cutaneous wound regeneration

An ideal tissue-engineered dermal substitute should possess angiogenesis potential to promote wound healing, antibacterial activity to relieve the bacterial burden on skin, as well as sufficient porosity for air and moisture exchange. In light of this, a glass-ceramic (GC) has been incorporated into chitosan and gelatin electrospun nanofibers (240-360 nm), which MEFs were loaded on it for healing acceleration. The GC was doped with silver to improve the antibacterial activity. The bioactive nanofibrous scaffolds demonstrated antibacterial and superior antibiofilm activities against Gram-negative and Gram-positive bacteria. The nanofibrous scaffolds were biocompatible, hemocompatible, and promoted cell attachment and proliferation. Nanofibrous skin substitutes with or without Ag-doped GC nanoparticles did not induce an inflammatory response and attenuated LPS-induced interleukin-6 release by dendritic cells. The rate of biodegradation of the nanocomposite was similar to the rate of skin regeneration under in vivo conditions. Histopathological evaluation of full-thickness excisional wounds in BALB/c mice treated with mouse embryonic fibroblasts-loaded nanofibrous scaffolds showed enhanced angiogenesis, and collagen synthesis as well as regeneration of the sebaceous glands and hair follicles in vivo.

In vitroandin vivostudy of magnesium containing bioactive glass nanoparticles modified gelatin scaffolds for bone repair

Magnesium containing bioactive glass nanoparticles modified gelatin scaffolds (MBGNs/Gel scaffolds) have shown recently the potential for bone regeneration due to its good biocompatibility, bioresorbability and bioactivity. Nevertheless, its use is limited by its complicated manufacturing process and a relatively expensive price. In this study, MBGNs were prepared by sol-gel process. The MBGNs/Gel was synthesized by a simple immersion method. SEM, transmission electron microscopy and dynamic light scattering analysis showed that the particles had spherical morphology with mean particle size of 100 nm. The MBGNs/Gel scaffolds were observed by SEM. The scaffolds showed connected pore structure with pore size ranging from 100 to 300 μm. SEM images with high magnification showed the existence of MBGNs on the surface of micro-pores. The ion release results revealed the release of Mg, Ca and Si elements from the MBGNs. MTT assay and cytotoxicity studies indicated that, the scaffolds provide a suitable ion related micro-environment for cell attachment and spreading. The Reverse Transcription-Polymerase Chain Reaction (RT-PCR) results showed the scaffolds could promote the osteogenesis of MC3T3-E1. Thein vivostudy also showed higher amount of new bone and trabecular bone which indicated excellent bone induction and conduction property of modified scaffolds. So, the developed MBGNs/Gel scaffolds are a potential candidate for bone regeneration applications.

Bioactive glass-based fibrous wound dressings

Since the discovery of silicate bioactive glass (BG) by Larry Hench in 1969, different classes of BGs have been researched over decades mainly for bone regeneration. More recently, validating the beneficial influence of BGs with tailored compositions on angiogenesis, immunogenicity and bacterial infection, the applicability of BGs has been extended to soft tissue repair and wound healing. Particularly, fibrous wound dressings comprising BG particle reinforced polymer nanofibers and cotton-candy-like BG fibers have been proven to be successful for wound healing applications. Such fibrous dressing materials imitate the physical structure of skin’s extracellular matrix and release biologically active ions e.g. regenerative, pro-angiogenic and antibacterial ions, e.g. borate, copper, zinc, etc., that can provoke cellular activities to regenerate the lost skin tissue and to induce new vessels formation, while keeping an anti-infection environment. In the current review, we discuss different BG fibrous materials meant for wound healing applications and cover the relevant literature in the past decade. The production methods for BG-containing fibers are explained and as fibrous wound dressing materials, their wound healing and bactericidal mechanisms, depending on the ions they release, are discussed. The present gaps in this research area are highlighted and new strategies to address them are suggested.

Mesoporous Silica Nanoparticles and Mesoporous Bioactive Glasses for Wound Management: From Skin Regeneration to Cancer Therapy

Exploring new therapies for managing skin wounds is under progress and, in this regard, mesoporous silica nanoparticles (MSNs) and mesoporous bioactive glasses (MBGs) offer great opportunities in treating acute, chronic, and malignant wounds. In general, therapeutic effectiveness of both MSNs and MBGs in different formulations (fine powder, fibers, composites etc.) has been proved over all the four stages of normal wound healing including hemostasis, inflammation, proliferation, and remodeling. The main merits of these porous substances can be summarized as their excellent biocompatibility and the ability of loading and delivering a wide range of both hydrophobic and hydrophilic bioactive molecules and chemicals. In addition, doping with inorganic elements (e.g., Cu, Ga, and Ta) into MSNs and MBGs structure is a feasible and practical approach to prepare customized materials for improved skin regeneration. Nowadays, MSNs and MBGs could be utilized in the concept of targeted therapy of skin malignancies (e.g., melanoma) by grafting of specific ligands. Since potential effects of various parameters including the chemical composition, particle size/morphology, textural properties, and surface chemistry should be comprehensively determined via cellular in vitro and in vivo assays, it seems still too early to draw a conclusion on ultimate efficacy of MSNs and MBGs in skin regeneration. In this regard, there are some concerns over the final fate of MSNs and MBGs in the wound site plus optimal dosages for achieving the best outcomes that deserve careful investigation in the future.

Hemostatic and Tissue Regeneration Performance of Novel Electrospun Chitosan-Based Materials

The application of chitosan (Ch) as a promising biopolymer with hemostatic properties and high biocompatibility is limited due to its prolonged degradation time, which, in turn, slows the repair process. In the present research, we aimed to develop new technologies to reduce the biodegradation time of Ch-based materials for hemostatic application. This study was undertaken to assess the biocompatibility and hemostatic and tissue-regeneration performance of Ch-PEO-copolymer prepared by electrospinning technique. Chitosan electrospinning membranes (ChEsM) were made from Ch and polyethylene oxide (PEO) powders for rich high-porous material with sufficient hemostatic parameters. The structure, porosity, density, antibacterial properties, in vitro degradation and biocompatibility of ChEsM were evaluated and compared to the conventional Ch sponge (ChSp). In addition, the hemostatic and bioactive performance of both materials were examined in vivo, using the liver-bleeding model in rats. A penetrating punch biopsy of the left liver lobe was performed to simulate bleeding from a non-compressible irregular wound. Appropriately shaped ChSp or ChEsM were applied to tissue lesions. Electrospinning allows us to produce high-porous membranes with relevant ChSp degradation and swelling properties. Both materials demonstrated high biocompatibility and hemostatic effectiveness in vitro. However, the antibacterial properties of ChEsM were not as good when compared to the ChSp. In vivo studies confirmed superior ChEsM biocompatibility and sufficient hemostatic performance, with tight interplay with host cells and tissues. The in vivo model showed a higher biodegradation rate of ChEsM and advanced liver repair.