Freeze-gelation Method Research Articles

Mg doped ZnO containing silk nanocomposite scaffolds for biofilm prevention during alveolar bone regeneration

Biofilms are created when micro-colonies adhere to a solid surface and produce a strong extracellular matrix which increases the risk of infection and impedes the healing process of bone defects. Although post-operative antibiotics are commonly prescribed to prevent infections, they carry the risk of side effects and antibiotic resistance. Current research explored the potential of magnesium doped zinc oxide incorporated silk fibroin scaffolds to prevent the biofilms formation for alveolar bone regeneration applications. Novel silk fibroin (SF)/hydroxyapatite (HA) scaffolds incorporated with magnesium-doped zinc oxide nanoparticles (Mg–ZnO NPs with 0.5, 1 and 2 % Mg) were fabricated by freeze gelation method. The data suggested that new materials exhibit remarkable antibacterial activity against Staphylococcus aureus. Moreover, these materials are also found to be both biodegradable and biocompatible. The study revealed that scaffolds displayed excellent antibacterial activity that was increased with increasing concentration of Mg in ZnO, with a maximum of 49.39 % was observed for 2 % of Mg doped ZnO. Additionally, biodegradation of the material also increases with the increase in concentration of Mg doping in ZnO. The adequate porosity in the range of 67 %–74.3 % was recorded of new materials substituted with Mg–ZnO, which led to improved cell viability (99.6 %) and uniform deposition of apatite over the surface of scaffolds, making it an excellent candidate for biomedical applications that require antibacterials properties with high cell viability.

Preparation of celecoxib loaded bioactive glass chitosan composite hydrogels: a simple approach for therapeutic delivery of NSAIDs

Arthritis causes inflammatory damage to joints and connective tissues. In the treatment of arthritis, precise and controlled drug delivery to the target site is among the frontline research approaches. In the present research work, celecoxib drug and bioactive glass incorporated chitosan hydrogels were fabricated by the freeze gelation method. Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis/differential scanning calorimetry techniques were used to characterize the hydrogels. Different kinetic models were applied to study the drug release kinetics. The celecoxib release was mainly controlled by a Fickian diffusion process followed by the Higuchi model. Maximum 86.2% drug entrapment was observed in 20 mg drug-loaded hydrogel and its swelling ratio was 115.5% in 28 d. Good hydrophilicity, good drug entrapment efficiency, and moderate drug release patterns of hydrogels can make them suitable for sustained drug release. The cytocompatibility of hydrogels was established by performing an MTT assay on the BHK-21 fibroblast cell line. The promising results have proved that hydrogels can be considered potential material for the slow release of anti-inflammatory drug at the target site in arthritis.

Synthesis, Characterization and Drug Release Study of Novel Guided Tissue Regeneration Membranes Containing Drug Loaded Chitosan Nanoparticles

Periodontitis is an inflammatory disease which can cause the destruction of the supporting tissues of the tooth leading to tooth loss. The guided tissue regeneration is considered as a gold standard for its treatment but the re-infection of surgical site limits its overall success. Objective: To synthesize novel monolayer guided tissue regeneration (GTR) membrane containing drug loaded chitosan nanoparticles and to evaluate the drug release from the synthesized GTR membranes. Methods: The chitosan nanoparticles containing ciprofloxacin were synthesized by the ionotropic gelation method and these synthesized nanoparticles were added into chitosan GTR membrane fabricated by the freeze gelation method. For comparison GTR membrane was prepared as a control by freeze gelation method in which the drug was added directly. The prepared membranes were characterized by the SEM and FTIR. The drug release was measured from the membrane samples in the phosphate buffer saline (PBS) at 1, 3, 5, 7 and 9 days. Results: The GTR membrane containing the ciprofloxacin loaded chitosan nanoparticles showed fast drug release as compared to the membrane in which the ciprofloxacin was added directly. Conclusions: The inclusion of antibiotic loaded chitosan nanoparticles can increase the drug release from GTR membrane.

Design and performance testing of a monolithic nickel-based SiC catalyst for steam methane reforming

Hydrogen is a highly promoted carbon-free energy carrier that has drawn significant attention recently due to its potential to decarbonise energy sector. More than three-quarters of hydrogen is currently produced via steam methane reforming (SMR), and nickel-based catalysts are used in most applications. Structured catalysts have been reported to be able to further improve catalyst performance as they can optimise heat and mass transfer, as well as prevent coke formation with its structural and textural proprieties. Silicon carbide (SiC) has excellent hardness, thermal conductivity, and chemical inertness, therefore is a promising material to develop structured nickel-based monolithic SiC catalysts for SMR. In this work, a structured monolithic catalyst support has been formed by a modified freeze-gelation method, initially starting from SiC powder, and nickel has been distributed to form a monolithic nickel-based catalyst by wet impregnation. The results showed that the catalysts can achieve thermodynamic equilibrium at 600 °C with a gas hourly space velocity (GHSV) of 10,000 h−1, while reaching a high methane conversion of 86% at 800 °C and GHSV value of 20,000 h−1 during the performance tests using low feeding concentration and low pressure. This is the first time SiC catalytic materials have had their performance demonstrated for SMR under realistic operating conditions.

Chitosan-sodium percarbonate-based hydrogels with sustained oxygen release potential stimulated angiogenesis and accelerated wound healing.

The prolonged hypoxic conditions hinder chronic wounds from healing and lead to severe conditions such as delayed re-epithelialization and enhanced risk of infection. Multifunctional wound dressings are highly required to address the challenges of chronic wounds. Herein, we report polyurethane-coated sodium per carbonate-loaded chitosan hydrogel (CSPUO2 ) as a multifunctional dressing. The hydrogels (Control, CSPU, and CSPUO2 ) were prepared by freeze gelation method and the developed hydrogels showed high porosity, good absorption capacity, and adequate biodegradability. The release of oxygen from the CSPUO2 hydrogel was confirmed by the increase in pH and a sustained oxygen release was observed over the period of 21 days, due to polyurethane (CSPU) coating. The CSPUO2 hydrogel exhibited around 2-fold increased angiogenic potential in CAM assay when compared with Control and CSPU dressing. CSPUO2 also showed good level of antibacterial efficacy against E. coli and S. aureus. In a full-thickness rat wound model, CSPUO2 hydrogel considerably accelerated wound healing with exceptional re-epithelialization granulation tissue formation less inflammatory cells and improved skin architecture highlighting the tremendous therapeutic potential of this hydrogel when compared with control and CSPU to treat chronic diabetic and burn wounds.

Freeze-gelated sodium alginate incorporated GO hydrogel membrane fabrication, thermal and mechanical studies

In this study, sodium alginate-graphene oxide (SA-GO) hydrogel membrane was prepared by freeze-gelation method and externally crosslinked with CaCl2. The prepared SA, SA-0.5% GO and SA-1% GO were characterized by FTIR analysis for the bonding interaction of sodium alginate and porosity of SA-GO hydrogels was confirmed by analyzing surface morphology through SEM. A further enhancement in porosity was confirmed by swelling studies due to water absorption. Also, GO incorporated hydrogel membranes showed controlled degradation at pH 7.4 in-vitro. Moreover, TGA analysis showed improved thermal stability of SA hydrogel with increasing concentration of GO. The mechanical studies revealed that SA-1% GO hydrogel membrane exhibit a fracture stress and young modulus of 0.30 MPa and 0.016 MPa respectively.

Chitosan/collagen/Mg, Se, Sr, Zn-substituted calcium phosphate scaffolds for bone tissue engineering applications: A growth factor free approach

According to the biomimetic bone scaffold design paradigm, a scaffold resembling natural bone tissue with molecular, structural and biological compatibility is needed to allow effective regeneration of bone tissue. Continuing our previous studies regarding scaffolds with chitosan matrix containing Mg, Se, Sr, Zn-substituted calcium phosphates (CaPs), the focus of this work was to further improve the properties of these growth factor-free scaffolds. By addition of collagen into the chitosan matrix at weight ratios of 100:0, 75:25, 50:50, 25:75 and 0:100, we aimed to better resemble natural bone tissue. Highly porous composite scaffolds based on chitosan and collagen, with 30 wt% of Mg, Se, Sr, Zn-substituted CaPs, were prepared by the freeze-gelation method. The scaffolds show a highly porous structure, with interconnected pores in the range of 20–350 μm and homogeneously dispersed CaPs. The added collagen further enhanced the stability measured during 28 days in simulated biological conditions. Live/dead and CyQUANT assays confirmed good viability and proliferation of human bone marrow-derived mesenchymal stem/stromal cells, while successful osteogenic differentiation was confirmed by alkaline phosphatase quantification and type I collagen immunocytochemical staining. Results indicated that the addition of collagen into the chitosan matrix containing Mg, Se, Sr, Zn-substituted CaPs improved the physicochemical and biological properties of the scaffolds.

Macroporous silicon-wollastonite scaffold with Sr/Se/Zn/Mg-substituted hydroxyapatite/chitosan hydrogel

The scaffolds, which morphologically and physiologically mimic natural features of the bone, are of a high demand for regenerative medicine. To address this challenge, bioactive porous silicon/wollastonite (SC) scaffold has been developed for potential bone tissue engineering applications. Additive manufacturing through the selective laser melting approach has been exploited to fabricate computer-aided designed scaffolds with a pore size of 400 μm. To increase the biocompatibility and osteogenic properties of SC scaffolds, the hydrogel based on a mixture of four mono-substituted hydroxyapatites (sHAp) and biopolymer chitosan (CHT) has been incorporated into SC by impregnation and freeze-gelation method. The pore size of 400 μm of SC has provided enough space for the impregnation of polymer solution and composite (CHT/sHAp) suspension to form highly porous hydrogel within pores. By the combination of SC and CHT/sHAp, both cell attachment and homogeneous proliferation on SC scaffold as well as mechanical properties of CHT/sHAp hydrogel have been improved.

HPMC crosslinked chitosan/hydroxyapatite scaffolds containing Lemongrass oil for potential bone tissue engineering applications

The chitosan (CS), hydroxypropyl methyl cellulose (HPMC), hydroxyapatite (HAp and Lemon grass oil (LGO) based scaffolds was prepared by freeze gelation method. The composite formation was confirmed by FTIR (Fourier-transform infrared spectroscopy) analysis and surface morphology was evaluated by SEM (Scanning Electron Microscopy) analysis. The mechanical strength, biodegradation, swelling, porosity and antibacterial activity were evaluated on the basis of LGO contents. The scaffold structure was porous and the mechanical strength was enhanced as a function of LGO contents. The scaffold properties analysis revealed the biodegradation nature and swelling behavior of CS-HPMC-HAp-LGO was also affected significantly as a function of LGO contents. The cytotoxicity of CS-HPMC-HAp-LGO was studied against MC3T3-E1 cells and based on cell viability, no toxic sign was observed. The antimicrobial activity was evaluated against S. aureus and CS-HPMC-HAp-LGO scaffolds showed promising activity, which was varied as a function of LGO contents. The findings revealed that the CS-HPMC-HAp-LGO are biocompatible and have potential for bone tissue engineering.

Osteogenic and antibacterial scaffolds of silk fibroin/Ce-doped ZnO for bone tissue engineering

Among the most frequently encountered facial fractures orbital floor fractures are very common. The orbital floor fracture treatment is a challenging task due to critical size defects and intricate anatomy. Tissue engineering is a promising interdisciplinary field; providing alternate bone substitutes that act as bioactive materials to induce bone repair and growth. Nanoceria (cerium oxide nanoparticles) have excellent antibacterial properties by inducing H2O2 due to simultaneous changes in Ce3+ and Ce4+ oxidation states. In the current study, we have made-up various compositions of silk fibroin (SF) scaffolds incorporated with hydroxyapatite (HAp) and Ce-doped ZnO nanoparticles through the freeze gelation method. The composite scaffolds were characterized by using FT-IR and micro-CT techniques while mechanical stability was determined through the mechanical testing machine. The other studies performed were porosity, swelling behavior, degradation, and antibacterial studies. In vitro cell studies, including attachment of cell, the proliferation of the cell, and cytotoxicity were checked by using MC3T3-E1 preosteoblast lines of the cell. Favorable biocompatibility, attachment, and proliferation were observed. The porosity of composite scaffolds was found to be in the range of 50%–66% with an appreciable degradation rate. These novel composite scaffolds present promising candidates for craniofacial defects reconstruction.

Developing sulfur-doped titanium oxide nanoparticles loaded chitosan/cellulose-based proangiogenic dressings for chronic ulcer and burn wounds healing.

Development of biomaterials supporting angiogenesis are highly desired in medical applications. In current work, chitosan and cellulose were cross-linked by using triethyl orthoformate and loaded with sulfur-doped titanium oxide nanoparticles. A readily available and inexpensive titanium oxide was added as a potential proangiogenic agent based on our group findings and other reports on metal oxide nanoparticles activity to stimulate angiogenesis. A simple freeze gelation method led to the development of flexible, foldable, and porous membranes. To investigate the chemical characteristics of the synthesized membranes, Fourier-transform infrared spectroscopy was used. Scanning electron microscopy equipped with energy-dispersive X-ray microanalysis was employed for surface morphological investigations. The cross-linked membranes showed higher degree of swelling capacity compared to the same material with titania-loaded nanoparticles in vitro. The synthesized materials showed higher degree of degradation in H2 O2 as compared to phosphate-buffered saline and lysozyme. Chorioallantoic membrane assay was done to investigate the angiogenic potential. Titanium oxide nanoparticles loaded membranes (CLHTS-5wt%) exhibited the best degree of angiogenesis in comparison to the other tested materials. In CLHTS-5wt% experimental group, a good level of attachment and ingrowth of several blood vessels was observed. Interestingly, the same tested group (CLHTS-5wt%) had shown the increasing trend of cellular metabolic rate of the seeded cells from Day 0 to Day 7 in vitro. These findings were further confirmed by the decline in lactate dehydrogenase enzyme release which was monitored until 72 h, indicating the promising ability of this biomaterial in wound healing applications.

Preparation and characterization of biocomposites based on chitosan and biomimetic hydroxyapatite derived from natural phosphate rocks

Highly porous chitosan/hydroxyapatite (CS/HA) biocomposite scaffolds were prepared using the freeze-gelation method. A starting biomimetic HA powder was synthesized by a wet precipitation method using an abundant natural phosphate (NP) ore as raw material. Then, CS/HA scaffolds with different weight ratios (100/0; 90/10; 80/20; 70/30) have been prepared. The used powders and synthesized scaffolds were characterized by XRF, ICP-MS, FTIR, TG-DSC, XRD, SEM, and cell viability. The results showed that the precipitated raw powder was mainly composed of HA and amorphous calcium phosphate (ACP) with some traces of Mg2+, SiO42−, Sr2+, Na+ and Fe2+ ions which were usually found in such mineral NP precursors. The heat treatment of the raw powder at more than 750 °C leads to the formation of Mg-substituted β-tricalcium phosphate (β-TCMP). Moreover, the culture of human embryonic kidney cells indicated the non-cytotoxicity of the as-prepared powder. On the other hand, the elaborated CS/HA scaffolds exhibited a highly porous structure with well-interconnected pores and homogeneously dispersed HA particles. The measurement of swelling capacity under physiological conditions revealed that the addition of HA to the CS matrix effectively decreased the swelling percentage. The obtained results suggest that the elaborated CS/HA composites may have effective potential as biocompatible scaffolding materials for bone tissue engineering.

In vitro/in vivo evaluation of statistically engineered alginate scaffold reinforced with dual drugs loaded silica nanoparticles for enhanced fungal therapeutics

In the current study, sustained release salicylic acid (SA) and ketoconazole (KCZ) loaded silica nanoparticles (SiO2-NPs) were encapsulated in natural macromolecule-alginate (ALG) based scaffold through freeze gelation method for an effective treatment of commonly prevailed fatal fungal infections. After statistical optimization by central composite rotatable design (CCRD), the optimized scaffold was subjected to comparative in vitro/in vivo antifungal, skin irritation, wound healing, cytotoxicity, and histopathological evaluations. In physico-chemical characterization performed through X-ray diffraction (p-XRD), Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA), an absolute lack of structural interactions was found between drugs and formulation components. The zeta potential and scanning electron microscopy (SEM) revealed spherical, highly porous negatively charged (–23.1) SiO2-NPs having a size distribution of 40–80 nm with successful encapsulation in negatively charged scaffold (-20.2 mV). The entrapment efficiency and drugs release exhibited visible quadratic influence of formulation variables on scaffold. The optimized ALG-scaffold demonstrated comparatively an enhanced in vitro, in vivo antifungal activity, least cytotoxicity and rapid wound healing efficacy in histopathological evaluation by sustained drugs release up to 14-days without any skin irritation effect. The study suggested the potential of alginate scaffold for not only the endurance of drugs loaded SiO2-NPs but also for the simultaneous co-delivery of medicaments fulfilling the need of consistent prolonged availability of drugs for better fungal therapeutics.

An Environmental Friendly Tapioca Starch-Alginate Cultured Scaffold as Biomimetic Muscle Tissue.

Natural porous scaffolds have been studied and developed for decades in biomedical science in order to support cells with a simulated extracellular matrix in natural tissue as an ideal environment. Such three-dimensional scaffolds provide many degrees of freedom to modulate cell activity, such as porosity, pore size, mechanical strength, biodegradability, and biocompatibility. In this study, a porous, three-dimensional material of alginate incorporating tapioca starch was fabricated. A particular freeze-gelation method was applied to homogenously mix starch in the alginate, and the concentration was controllable. This pure natural composite porous scaffold was characterized physically and biologically. The synergistic functions, including biocompatibility, biodegradability, cell adhesion, and cell proliferation, were also investigated. A myogenic differentiation model further verified that the composite porous scaffold provided a suitable environment, supporting the differentiation effect in the myogenic process. The positive results demonstrated that this novel material has the potential to serve as a biomedical or clean meat appliance.

Production of bioactive glass/chitosan scaffolds by freeze-gelation for optimized vancomycin delivery: Effectiveness of glass presence on controlling the drug release kinetics

The major objective of this work was the creation of vancomycin loaded composite scaffolds designed for bone treatment from inexpensive and biocompatible materials such as chitosan. Bioactive glass was chosen as filler due to its outstanding bioactivity and ability for bone regeneration. The scaffolds were prepared using the freeze-gelation method, which was efficient and cost-effective. They included different glass contents (0, 25, and 50 wt %) and symbolized as C, C25, and C50, respectively. The SEM/EDXA, TGA and the FTIR were used to characterize the scaffolds. The degradation properties of the scaffolds were controlled through modifying their glass contents. Furthermore, the kinetics of the released drug was improved as the glass content increased. The final cumulative percentages of released drug from scaffolds C, C25, and C50 reached 52.49, 70.82 and 98.22%, respectively. The Higuchi model proved that the drug was released through a diffusion-controlled mechanism. For neat polymer scaffold, the drug was released in two following stages. In contrast, for composite scaffolds, the release pattern was modulated and differentiated into four stages. That modulation was attributed to glass presence and deposition of apatite layer on their surfaces. Additionally, cell viability was enhanced by the presence of glass. In brief, glass presence was highly effective in controlling degradation properties and improving the drug release kinetics of the scaffolds. Therefore, the scaffolds made of chitosan and bioactive glass could be a good candidate for localized bone treatment.

Freeze gelation 3D printing of rGO-CuCo2S4 nanocomposite for high-performance supercapacitor electrodes

Reduced graphene oxide (rGO)-CuCo2S4 nanocomposites are synthesized by a facile hydrothermal method. Thiourea has been used as a sulfur source for synthesizing CuCo2S4 nanoparticles. The synthesized materials are then dispersed in phenol with the addition of Polyvinylpyrrolidone (PVP), which acts as a binder to form the homogeneous rGO-CuCo2S4 slurry. This as-prepared slurry is then deposited on the graphite paper using 3D printing technique combined with the freeze gelation method to form a rGO - CuCo2S4 electrode. X-ray diffractometry (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and electrochemical techniques have been used to characterize rGO-CuCo2S4 nanocomposite. The nanocomposite has a microporous structure with CuCo2S4 nanoparticles decorated on the rGO sheet surface. Electrochemical studies revealed that the rGO-CuCo2S4 nanocomposite electrode has a high specific capacitance of ca. 1123 F/g at 5 mV/s and excellent capacitance retention. A 91% capacitance remained approximately after 20000 successive cycles at a high current density of 125 A/g are remarkable and it has not been widely reported for a supercapacitor electrode.

Microencapsulation of biosynthesized zinc oxide nanoparticles (ZnO-NPs) using Plumeria leaf extract and kinetic studies in the release of ZnO-NPs from microcapsules

Biosynthesis using plant extract is known as one of the potential techniques to synthesize different zinc oxide nanoparticles (ZnO-NPs) in different size ranges. ZnO-NPs were synthesized using Plumeria leaf extract with laboratory chemical reagent Zn(CH3COO)2 and followed by the micro-encapsulation of biosynthesized ZnO-NPs using chitosan and cellulose with TEOF as a cross-linker employing freeze gelation method. Both neat and encapsulated ZnO-NPs have been characterized by FT-IR, UV spectroscopy, XRD, and SEM techniques. The UV-spectroscopic analysis confirmed the characteristic band of ZnO-NPs at 356.0 nm, and FIIR showed the peaks at 544 cm−1 and 545 cm−1 corresponding to the Zn–O bond. Powder XRD pattern showed the wurtzite structure of ZnO and gave the calculated average crystallite size as of 27.23 nm. In the case of encapsulated ZnO-NPs, the UV–visible spectrum showed two strong absorption peaks at 232.5 nm, 242.5 nm, and a weak peak at 357 nm. A broad peak at 3333 cm−1 in FT-IR spectra is either due to N–H stretching in the amide group of chitosan or hydroxyl group in encapsulated ZnO-NPs. It was observed that chitosan loaded ZnO-NPs had higher entrapment efficiency (81.98%) at 15 mL of plant extract. The kinetic profile in the release of ZnO particles out from encapsulated ZnO-NPs was observed to follow four kinetic paths in 120 min at pH 1.2. The particle release followed the zero-order kinetic in the first 50 min and then followed by Hixson–Crowell kinetic in the next 50 min with two different rate constants, 2.6 × 10−3 min−1 and 13 × 10−3 min−1, before it backs to the zero-order kinetics. This study shows that ZnO nanoparticles can easily be biosynthesized and encapsulated for use in the pharmaceutical industry.

Development of hybrid scaffold: Bioactive glass nanoparticles/chitosan for tissue engineering applications.

Bone tissue engineering is gaining popularity as an alternative method for the treatment of osseous defects. A number of biodegradable polymers have been explored for tissue engineering purposes. A new family of biodegradable polymer/bioactive glass composite materials has been designed to be used in bone regeneration approaches. In this work, a hybrid scaffold of chitosan (CH) and bioactive glass nanoparticles (BGN) was prepared by the freeze-gelation method. This method has been studied by adjusting the concentration of acetic acid; this process can influence the structure properties of the scaffold. In this work, several BGN/CH composites have been prepared by varying the proportion of BGN in the hybrid scaffold (20, 40, 60, and 80%). Brunauer-Emmett-Teller results showed the increased surface area and porosity volume of our composite with decreasing BGN proportion. BGN/CH hybrid scaffold was characterized by using physicochemical techniques. Obtained results showed a macroporous morphology of the scaffold with a pore size of about 200 μm, and a homogeneous distribution of the BGN in the CH matrix. X-ray diffraction study confirmed the amorphous state of the BGN/CH hybrid scaffold. Interaction between CH and BGNs in the composite was confirmed. The in vitro assays showed adequate degradation properties, which is essential for the potential replacement by the new tissue. The in vitro bioactivity studies confirmed the formation of an apatite layer on the surface of the hybrid scaffold, which results in a direct bone bonding of the implant. These results indicate that BGN/CH hybrid scaffold developed is a potential candidate for bone tissue engineering.

Thyroxine impregnated chitosan-based dressings stimulate angiogenesis and support fast wounds healing in rats: Potential clinical candidates

This research paper demonstrates efficacy of chitosan and thyroxine loaded chitosan (CS) dressings for their angiogenic and wound healing potential. The dressings were prepared by freeze gelation method. Thyroxine was loaded by physical adsorption into chitosan membranes. The porosity was analyzed by scanning electron microscopy (SEM) and chemical structures were investigated by Fourier transform infra-red spectroscopy (FTIR). Cell culture studies showed materials were non-toxic and chorioallantoic membranes assay (CAM) confirmed that the thyroxine loaded chitosan stimulated angiogenesis much higher than simple chitosan dressings. In addition, thyroxine loaded dressings showed excellent wound healing potential when tested on full thickness rats wounds. A good epithelialization was obtained along with robust wound closure. Overall, as compared to chitosan, thyroxine containing membranes showed high level of angiogenesis and fast wound healing.

Freeze-gelled alginate/gelatin scaffolds for wound healing applications: An in vitro, in vivo study.

In this study, fabrication of a three-dimensional porous scaffold was performed using freeze gelation method. Recently, fabrication of scaffolds using polymer blends has become common for many tissue engineering applications due to their unique tunable properties. In this work, we fabricated alginate-gelatin porous hydrogels for wound healing application using a new method based on some modifications to the freeze-gelation method. Alginate and gelatin were mixed in three different ratios and the resulting solutions underwent freeze gelation to obtain 3D porous matrices. We analyzed the samples using different characterization tests. The scanning electron microscopy (SEM) results indicated that the freeze gelation method was successful in obtaining porous morphologies for all the fabricated alginate-gelatin samples as previously was seen in single-polymer fabrication using this method. The alginate to gelatin ratio affected swelling, biodegradation, cell culture and mechanical properties of the matrices. The scaffold with the lowest content of gelatin had the highest swelling ratio while biodegradation and cell proliferation and viability were increased with the gelatin content. Regarding the mechanical properties, as the gelatin content increased, the scaffold became more ductile and showed higher tensile strength. The in-vivo results also showed the biocompatibility of the blend scaffold and its positive role in wound healing process in rats. The low-cost procedure used in this study to fabricate the porous alginate-gelatin scaffolds can be adapted and modified to suit different tissue engineering applications.