The performance of an orthosilicic acid-releasing silica gel fiber fleece in wound healing

Utilizing Robust Design to Optimize Composite Bioadhesive for Promoting Dermal Wound Repair

Catechol-modified bioadhesives generate hydrogen peroxide (H2O2) during the process of curing. A robust design experiment was utilized to tune the H2O2 release profile and adhesive performance of a catechol-modified polyethylene glycol (PEG) containing silica particles (SiP). An L9 orthogonal array was used to determine the relative contributions of four factors (the PEG architecture, PEG concentration, phosphate-buffered saline (PBS) concentration, and SiP concentration) at three factor levels to the performance of the composite adhesive. The PEG architecture and SiP wt% contributed the most to the variation in the results associated with the H2O2 release profile, as both factors affected the crosslinking of the adhesive matrix and SiP actively degraded the H2O2. The predicted values from this robust design experiment were used to select the adhesive formulations that released 40-80 µM of H2O2 and evaluate their ability to promote wound healing in a full-thickness murine dermal wound model. The treatment with the composite adhesive drastically increased the rate of the wound healing when compared to the untreated controls, while minimizing the epidermal hyperplasia. The release of H2O2 from the catechol and soluble silica from the SiP contributed to the recruitment of keratinocytes to the wound site and effectively promoted the wound healing.

Centella asiatica extract-SiO2 nanocomposite: More than a drug-delivery system for skin protection from oxidative damage

An innovative nanotechnology-based approach was used for the preparation of Centella asiatica (C. asiatica) extract-SiO2 nanocomposites, specifically tailored for skin protection from oxidative damage. Different amounts of C. asiatica glycolic extract (1.0, 3.0, 5.0, and 10.0 wt %) and fumed silica were used to prepare the nanocomposites by means of ball milling method. The influence of both composition of the starting mixture and milling time on the final products was evaluated by different techniques such as X-ray powder diffraction, scanning electron microscopy, infrared spectroscopy, thermogravimetric analysis, and nitrogen sorption analysis. Results confirmed the integrity of the natural extract after the milling process, and its successful loading in the silica matrix. No cytotoxicity was observed for the obtained nanocomposites, which showed high in-vitro ability to scavenge 2,2-diphenyl-1-picrylhydrazyl and to protect human keratinocytes from damages induced with hydrogen peroxide.

Silicon-Based Scaffold for Wound Healing Skin Regeneration Applications: A Concise Review

Silicon has made its breakthrough in various industries, including clinical and biomedical applications. Silicon-based biomaterials that were fabricated into various types of scaffolds may attract interest due to their highly favorable properties covering their excellent biocompatibility, high surface area, mechanical strength, and selectivity depending on their application including film, hydrogel, nanoparticles, and so on. Silicon-based materials have also shown exciting results involving cell culture, cell growth, as well as tissue engineering. In this article, a simple review compromising the evaluation of silicon's unique properties has been discussed and followed by the application of the silicone-based product in future perspectives in biomedical fields. The review goals are to widen and inspire broader interest in silicone-based materials in wound healing research.

Sol-Gel-Derived Fibers Based on Amorphous α-Hydroxy-Carboxylate-Modified Titanium(IV) Oxide as a 3-Dimensional Scaffold

The development of novel fibrous biomaterials and further processing of medical devices is still challenging. For instance, titanium(IV) oxide is a well-established biocompatible material, and the synthesis of TiO_x particles and coatings via the sol-gel process has frequently been published. However, synthesis protocols of sol-gel-derived TiO_x fibers are hardly known. In this publication, the authors present a synthesis and fabrication of purely sol-gel-derived TiO_x fiber fleeces starting from the liquid sol-gel precursor titanium ethylate (TEOT). Here, the α-hydroxy-carboxylic acid lactic acid (LA) was used as a chelating ligand to reduce the reactivity towards hydrolysis of TEOT enabling a spinnable sol. The resulting fibers were processed into a non-woven fleece, characterized with FTIR, ¹³C-MAS-NMR, XRD, and screened with regard to their stability in physiological solution. They revealed an unexpected dependency between the LA content and the dissolution behavior. Finally, in vitro cell culture experiments proved their potential suitability as an open-mesh structured scaffold material, even for challenging applications such as therapeutic medicinal products (ATMPs).

Electrospun Nanofibers for Manipulating the Soft Tissue Regeneration

Soft tissue damage is a common clinical problem that affects the lives of a large number of patients all over the world. It is of great importance to develop functional...

Evaluation of pro-angiogenic properties of an inorganic silica gel fibre fleece

Hard-to-heal wounds represent an increasing health and economic burden on society. At present, therapy options for hard-to-heal wounds are often unsatisfactory, and the development of more effective wound treatments is urgently needed. We have shown that orthosilicic acid-releasing silica fibre fleece (SIFIB), via its pronounced anti-inflammatory properties, exhibited a significantly enhanced effect on wound closure kinetics in a porcine wound model in vivo. In this present study, we have examined in vitro the impact of the pro-angiogenic potential of SIFIB. Using an in vitro angiogenesis assay we describe for the first time how an inorganic biodegradable silica-based material significantly improved endothelial microvessel-like structure formation. We further demonstrate that the molecular mechanism of this pro-angiogenic activity of SIFIB is based on a significantly increased and tumour necrosis factor (TNF)α-dependent VEGF protein expression. In conclusion, due to its positive effects on angiogenesis, our results further indicate that decomposition products of silica-based biodegradable inorganic materials might represent very relevant therapeutic components of modern wound dressings for the treatment of hard-to-heal wounds.

Fabrication of ciprofloxacin-loaded chitosan/polyethylene oxide/silica nanofibers for wound dressing application: In vitro and in vivo evaluations

Silica plays an effective role in collagen creation; hence, the degradation products of silica-based materials accelerate wound healing. In this regard, chitosan/polyethylene oxide/silica hybrid nanofibers were prepared by the combining the sol-gel method with electrospinning technique to accelerate the wound healing process. Ciprofloxacin, as an antibacterial drug, was then added to the electrospinning mixture. The nanofibers were characterized by SEM, EDX, X-ray mapping, TEM, TGA, FTIR, and XRD analysis. The degradation, swelling ratio, and release of ciprofloxacin were investigated in PBS. The prepared nanofiber could absorb water, maintain its morphological integrity during the degradation process, and gradually release ciprofloxacin. The nanofibers revealed an efficient antibacterial activity against Escherichia coli and Staphylococcus aureus. Cell viability assays showed that the nanofibers had no cytotoxicity against L929 mouse fibroblast and HFFF2 human foreskin fibroblast cell lines. The potential of the chitosan/polyethylene oxide/silica/ciprofloxacin nanofiber for healing full-thickness wound was assessed by applying the scaffold in the dorsal cutaneous wounds of the Balb/C mice. The white blood cell counts of the animals indicated the nanofiber-treated mice compared with the untreated ones had less infection and inflammation. According to the histopathologic data, the prepared nanofiber accelerated and enhanced tissue regeneration by increasing fibroblast cells and angiogenesis as well as decreasing the inflammation phase. The findings suggest that the prepared antibacterial scaffold with drug delivery properties could be an appropriate candidate for many medical and hygienic applications, especially as a bio-compatible and bio-degradable wound dressing.

Controlling the Release of Hydrogen Peroxide from Catechol-Based Adhesive Using Silica Nanoparticle

Catechol-based bioadhesives generate hydrogen peroxide (H₂O₂) as a byproduct during the curing process. H₂O₂ can have both beneficial and deleterious effects on biological systems depending on its concentration. To control the amount of H₂O₂ released from catechol-containing polyethylene glycol-based adhesive (PEG-DA), adhesive was formulated with silica nanoparticles (SiNP) prepared with increased porosity and acid treatment to increase Si-OH surface content. These SiNP demonstrated increased surface area, which promoted interaction with catechol and resulted in increased cure rate, bulk mechanical properties and adhesive properties of PEG-DA. Most importantly, SiNP demonstrated a 50% reduction in the released H₂O₂ while improving the cell viability and proliferation of three primary cell types, including rat dermal fibroblasts, human epidermal keratinocytes, and human tenocytes. Additionally, SiNP degraded into soluble Si, which also contributed to increased cell proliferation. Incorporation of porous and acid-treated SiNP can be a useful approach to simultaneously modulate the concentration of H₂O₂ while increasing the adhesive performance of catechol-based adhesives.

Close-loop dynamic nanohybrids on collagen-ark with in situ gelling transformation capability for biomimetic stage-specific diabetic wound healing

A self-regulated dynamic nanohybrid that can sensitively respond to hyperglycemic microenvironment is developed. The nanohybrid with a core/shell structure is produced through a single-step microfluidics nanoprecipitation method, where drugs-loaded porous silicon (PSi) nanoparticles are encapsulated by H₂O₂ responsive polymeric matrix.

Novel drug delivery systems for natural extracts: The case study of Vitis Vinifera extract-SiO2 nanocomposites

Ball Milling technique has been used to prepare for the first time Vitis Vinifera extract-silica nanocomposites (VV-SiO₂ NCs), which combine the pharmacological effects of the extract with the effectiveness of silica as drug delivery system and active component in the treatment of wound healing. Different contents (1.0, 9.0 and 33.0 wt%) of Vitis Vinifera ethanolic extract were loaded into the silica matrix by grinding the extract with fumed silica using a planetary mill apparatus. The effect of the starting mixture composition and milling time on the final products was examined. The efficiency of the milling process was studied by X-ray Powder Diffraction, Nuclear Magnetic Resonance, and Infrared Spectroscopy, indicating that the natural extract was not affected by the increasing of the milling time. The successful loading of the extract was demonstrated by Nitrogen adsorption/desorption measurements, which showed a decrease in the SSA and pore volume of the silica with the increasing of the extract amount. Morphology of the nanocomposites, investigated by Scanning Electron Microscopy, showed an increased agglomeration in the nanocomposites with the increment of the VV extract amount. Studies on the total phenol quantification and antioxidant activity of the natural extract before and after incorporation in the silica matrix were also carried out. The obtained results indicate that the milling process does not alter the VV extract components, which result to be embedded in the silica matrix. An increase of the antioxidant activity with the increment of the extract amount in the nanocomposites, up to values comparable to the pure VV extract, was also observed.

A conducive bioceramic/polymer composite biomaterial for diabetic wound healing

Diabetic wound is a common complication of diabetes. Biomaterials offer great promise in inducing tissue regeneration for chronic wound healing. Herein, we reported a conducive Poly (caprolactone) (PCL)/gelatin nanofibrous composite scaffold containing silicate-based bioceramic particles (Nagelschmidtite, NAGEL, Ca₇P₂Si₂O₁₆) for diabetic wound healing. NAGEL bioceramic particles were well distributed in the inner of PCL/gelatin nanofibers via co-electrospinning process and the Si ions maintained a sustained release from the composite scaffolds during the degradation process. The nanofibrous scaffolds significantly promoted the adhesion, proliferation and migration of human umbilical vein endothelial cells (HUVECs) and human keratinocytes (HaCaTs) in vitro. The in vivo study demonstrated that the scaffolds distinctly induced the angiogenesis, collagen deposition and re-epithelialization in the wound sites of diabetic mice model, as well as inhibited inflammation reaction. The mechanism for nanofibrous composite scaffolds accelerating diabetic wound healing is related to the activation of epithelial to mesenchymal transition (EMT) and endothelial to mesenchymal transition (EndMT) pathway in vivo and in vitro. Our results suggest that the released Si ions and nanofibrous structure of scaffolds have a synergetic effect on the improved efficiency of diabetic wound healing, paving the way to design functional biomaterials for tissue engineering and wound healing applications.

STATEMENT OF SIGNIFICANCE

In order to stimulate tissue regeneration for chronic wound healing, a new kind of conducive nanofibrous composite scaffold containing silicate-based bioceramic particles (Nagelschmidtite, NAGEL, Ca₇P₂Si₂O₁₆) were prepared via co-electrospinning process. Biological assessments revealed that the NAGEL bioceramic particles could active epithelial to mesenchymal transition (EMT) and endothelial to mesenchymal transition (EndMT) pathway in vitro and in vivo. The new composite scaffold had potential as functional biomaterials for tissue engineering and wound healing applications. The strategy of introducing controllable amount of therapeutic ions instead of loading expensive drugs/growth factors on nanofibrous composite scaffold provides new options for bioactive biomaterials.

Silica nanoparticles as sources of silicic acid favoring wound healing in vitro

There is good evidence that certain silicon-containing materials promote would healing and their common feature is the delivery of orthosilicic acid (Si(OH)₄) either directly or following metabolism. In this respect, amorphous silica nanoparticles (NP), which dissolve in aqueous environments releasing up to 2mM orthosilicic acid, may be appropriate 'slow release' vehicles for bioactive silicon. Here we studied the impact of silica NP suspensions (primary particles∼10nm) in undersaturated conditions (below 2mM Si) with differing degrees of surface charge and dissolution rate on human dermal fibroblasts (CCD-25SK cells) viability, proliferation and migration in a cellular wound model. Silica was shown to be non-toxic for all forms and concentrations tested and whilst the anticipated stimulatory effect of orthosilicic acid was observed, the silica NPs also stimulated fibroblast proliferation and migration. In particular, the amine-functionalized particles promoted wound closure more rapidly than soluble orthosilicic acid alone. We suggest that this effect is related to easy cellular internalization of these particles followed by their intracellular dissolution releasing silicic acid at a faster rate than its direct uptake from the medium. Our findings indicate that amorphous silica-based NPs may favour the delivery and release of bioactive silicic acid to cells, promoting wound healing.

Electrospinning of Bioactive Wound-Healing Nets

The availability of appropriate dressings for treatment of wounds, in particular chronic wounds, is a task that still awaits better solutions than provided by currently applied materials. The method of electrospinning enables the fabrication of novel materials for wound dressings due to the high surface area and porosity of the electrospun meshes and the possibility to include bioactive ingredients. Recent results show that the incorporation of biologically active inorganic polyphosphate microparticles and microspheres and synergistically acting retinoids into electrospun polymer fibers yields biocompatible and antibacterial mats for potential dressings with improved wound-healing properties. The underlying principles and the mechanism of these new approaches in the therapy wounds, in particular wounds showing impaired healing, as well as for further applications in skin regeneration/repair, are summarized.

Pigmentation Effect of Rice Bran Extracted Minerals Comprising Soluble Silicic Acids

Our investigation focused on identifying melanogenesis effect of soluble minerals in rice bran ash extract (RBE) which include orthosilicic acid (OSA). Melanocytes were apparently normal in terms of morphology. It was, however, shown that they were stressed a little in the RBE and OSA added media in aspect of LDH activity. Melanin synthesis and intracellular tyrosinase activity were increased by treatment of RBE which is similar to that of OSA. The Western blotting results showed that TRP-1, tyrosinase, and MITF expression levels were 2-3 times higher in the OSA and RBE groups compared to the control group which promoted melanin synthesis through CREB phosphorylation. Moreover, histology and immunohistochemistry were shown to have similar result to that of protein expression. As a result, minerals which comprise orthosilicic acid has the potential to promote melanogenesis and both RBE and OSA have similar cell viability, protein expression, and immunostaining results, suggesting that RBE comprises specific minerals which promote melanin synthesis through increasing of MITF and CREB phosphorylation. Therefore, RBE could be used as a novel therapeutic approach to combat melanin deficiency related diseases by stimulating melanocytes via its soluble Si and mineral components.

Bioactive glasses beyond bone and teeth: emerging applications in contact with soft tissues

The applications of bioactive glasses (BGs) have to a great extent been related to the replacement, regeneration and repair of hard tissues, such as bone and teeth, and there is an extensive bibliography documenting the role of BGs as bone replacement materials and in bone tissue engineering applications. Interestingly, many of the biochemical reactions arising from the contact of BGs with bodily fluids, in particular the local increase in concentration of various ions at the glass-tissue interface, are also relevant to mechanisms involved in soft tissue regeneration. An increasing number of studies report on the application of BGs in contact with soft tissues, aiming at exploiting the well-known bioactive properties of BGs in soft tissue regeneration and wound healing. This review focuses on research, sometimes involving preliminary in vitro studies but also in vivo evidence, that demonstrates the suitability of BGs in contact with tissues outside the skeletal system, which includes studies investigating vascularization, wound healing and cardiac, lung, nerve, gastrointestinal, urinary tract and laryngeal tissue repair using BGs in various forms of particulates, fibers and nanoparticles with and without polymer components. Potentially active mechanisms of interaction of BGs and soft tissues based on the surface bioreactivity of BGs and on biomechanical stimuli affecting the soft tissue-BG collagenous bonding are discussed based on results in the literature.

Incorporation of silica particles into decellularized tissue biomaterial and its effect on macrophage activation

Secretion of signaling molecules by macrophages is induced by silica particles deposited onto decellularized tissue derived biomaterials.