Drug release, cell adhesion and wound healing evaluations of electrospun carboxymethyl chitosan/polyethylene oxide nanofibres containing phenytoin sodium and vitamin C

Polysaccharide base electrospun nanofibrous scaffolds for cartilage tissue engineering: Challenges and opportunities

Polysaccharides, known as naturally abundant macromolecular materials which can be easily modified chemically, have always attracted scientists' interest due to their outstanding properties in tissue engineering. Moreover, their intrinsic similarity to cartilage ECM components, biocompatibility, and non-harsh processing conditions make polysaccharides an excellent option for cartilage tissue engineering. Imitating the natural ECM structure to form a fibrous scaffold at the nanometer scale in order to recreate the optimal environment for cartilage regeneration has always been attractive for researchers in the past few years. However, there are some challenges for polysaccharides electrospun nanofibers preparation, such as poor solubility (Alginate, cellulose, chitin), high viscosity (alginate, chitosan, and Hyaluronic acid), high surface tension, etc. Several methods are reported in the literature for facing polysaccharide electrospinning issues, such as using carrier polymers, modification of polysaccharides, and using different solvent systems. In this review, considering the importance of polysaccharide-based electrospun nanofibers in cartilage tissue engineering applications, the main achievements in the past few years, and challenges for their electrospinning process are discussed. After careful investigation of reported studies in the last few years, alginate, chitosan, hyaluronic acid, chondroitin sulfate, and cellulose were chosen as the main polysaccharide base electrospun nanofibers used for cartilage regeneration.

Exogenous and endogenous nitric oxide eluting polylactic acid-based nanofibrous scaffolds for enhancing angiogenesis of diabetic wounds

Delayed wound healing is a major complication that diabetic patients suffer from due to high microbial infection susceptibility, high diabetic wound alkalinity, a low lymphangiogenesis rate, and a high inflammation rate, resulting in severe gangrene. Hence, this study aims to develop a multifunctional adhesive nanofibrous patch to promote the wound healing process. Phenytoin, sildenafil citrate, and/or nitric oxide-eluting nanoparticles were incorporated separately within the polylactic acid nanofibrous layer. Polylactic acid was fabricated in the form of highly porous nanofibrous matrices that resemble the natural structure of skin tissues in order to act as scaffolds that help cell migration and proliferation. A polylactic acid nanofibrous layer incorporating phenytoin was designed to stimulate fibroblast proliferation and inhibit inflammation. Another polylactic acid nanofibrous layer was loaded either with nitric oxide-eluting nanoparticles or sildenafil as a pro-angiogenic layer that can supply tissues with nitric oxide gas either exogenously or endogenously, respectively. The developed nanofibrous layers were in-vitro evaluated through different physicochemical, mechanical, and biological approaches. Finally, the efficiency of the prepared single multilayered patch was tested using an in-vivo alloxan-induced diabetic rats' model, which proved that the patches were able to release the incorporated cargos in a controlled manner, enhancing the wound healing process.

"Review of strategic methods for encapsulating essential oils into chitosan nanosystems and their applications"

Essential oils (EOs) are hydrophobic, concentrated extracts of botanical origin containing diverse bioactive molecules that have been used for their biomedical properties. On the other hand, the volatility, toxicity, and hydrophobicity limited their use in their pure form. Therefore, nano-encapsulation of EOs in a biodegradable polymeric platform showed a solution. Chitosan (CS) is a biodegradable polymer that has been intensively used for EOs encapsulation. Various approaches such as homogenization, probe sonication, electrospinning, and 3D printing have been utilized to integrate EOs in CS polymer. Different CS-based platforms were investigated for EOs encapsulation such as nanoparticles (NPs), nanofibers, films, nanoemulsions, 3D printed composites, and hydrogels. Biological applications of encapsulating EOs in CS include antioxidant, antimicrobial, and anticancer functions. This review explores the principles for nanoencapsulation strategies, and the available technologies are also reviewed, in addition to an in-depth overview of the current research and application of nano-encapsulated EOs.

Evolving Trends in Nanofibers for Topical Delivery of Therapeutics in Skin Disorders

Nanotechnology has yielded nanostructure-based drug delivery approaches, among which nanofibers have been explored and researched for the potential topical delivery of therapeutics. Nanofibers are filaments or thread-like structures in the nanometer size range that are fabricated using various polymers, such as natural or synthetic polymers or their combination. The size or diameter of the nanofibers depends upon the polymers, the techniques of preparation, and the design specification. The four major processing techniques, phase separation, self-assembly, template synthesis, and electrospinning, are most commonly used for the fabrication of nanofibers. Nanofibers have a unique structure that needs a multimethod approach to study their morphology and characterization parameters. They are gaining attention as drug delivery carriers, and the substantially vast surface area of the skin makes it a potentially promising strategy for topical drug products for various skin disorders such as psoriasis, skin cancers, skin wounds, bacterial and fungal infections, etc. However, the large-scale production of nanofibers with desired properties remains challenging, as the widely used electrospinning processes have certain limitations, such as poor yield, use of high voltage, and difficulty in achieving in situ nanofiber deposition on various substrates. This review highlights the insights into fabrication strategies, applications, recent clinical trials, and patents of nanofibers for different skin disorders in detail. Additionally, it discusses case studies of its effective utilization in the treatment of various skin disorders for a better understanding for readers.

Synthesis and characterization of natural fibers reinforced alginate hydrogel fibers loaded with diclofenac sodium for wound dressings

Hydrogels which become increasingly important in the biomedical field are composed of a three-dimensional hydrophilic network. Pure hydrogels are usually weak and brittle; therefore, reinforcements are assimilated into the hydrogel structure to improve the mechanical strength of the hydrogels. However, even if mechanical properties are enhanced, drapability remains an issue. In that regard, natural fiber-reinforced composite hydrogel fibers for wound dressing application are investigated in this study. Kapok and hemp fibers were used as reinforcement to improve the strength of hydrogel fibers. The properties of the prepared composite hydrogel fibers were studied with Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and differential scanning calorimeter (DSC). The effect of alginate concentration and fiber weight percent on the mechanical characteristics and water absorbency was studied. Diclofenac sodium drug was loaded in the hydrogel fibers and investigated the drug release as well as antibacterial characteristics. Both fibers' reinforcement enhanced the strength of the alginate hydrogel fiber, but hemp reinforcement showed better mechanical properties. Kapok reinforcement resulted in a maximum tensile strength of 174 cN (1.24 % elongation) and 432 % exudate absorbency, while hemp reinforcement resulted in 185 cN (1.48 % elongation) and 435 % exudate absorbency. Statistical analysis revealed significant effects of sodium alginate concentration on tensile strength (p-value 0.042) and exudate absorbency (p-value 0.020) and of reinforcement (wt%) on exudate absorbency (p-value 0.043). Therefore, these composite hydrogel fibers with improved mechanical properties are capable of drug release and exhibit antibacterial effectiveness, making them a promising option for use as wound dressings.

Design, development, in-vitro and in-vivo evaluation of polylactic acid-based multifunctional nanofibrous patches for efficient healing of diabetic wounds

Impaired healing of diabetic ulcers is one of the major complications of diabetic patients due to high susceptibility to microbial infections, impaired lymphianogenesis, edema, and consequently impairing proper healing. This could even lead to much worse complications that include severe gangrene, trauma and finally limb amputation. Therefore, this study aims to develop a multilayered durable nanofibrous wound patch loaded with three promising drugs (phenytoin, sildenafil citrate and simvastatin) each in a separate layer to target a different wound healing phase. Polylactic acid was used for the preparation of the nanofibrous matrix of the wound patch, where each drug was incorporated in a separate layer during the preparation process. Drugs release profiles were studied over 3 weeks. Results showed that both phenytoin and simvastatin were released within 14 days while sildenafil continued till 21 days. Both physicochemical and mechanical characteristics of the patches were fully assessed as well as their biodegradability, swellability, breathability and porosity. Results showed that incorporation of drugs preserved the physicochemical and mechanical properties as well as porosity of the developed nanofibers. In addition, patches were evaluated for their biocompatibility and cell adhesion capability before being tested through in-vivo diabetic wound rat model induced by alloxan for three weeks. In vivo results showed that the patches were successful in inducing proper wound healing in diabetic rat model with overcoming the above-mentioned obstacles within 3 weeks. This was confirmed through assessing wound closure as well as from histopathological studies that showed complete healing with proper cell regeneration and arrangement without forming scars.

Preparation and characterization of a hydroxypropyl methylcellulose based wafer for simultaneous delivery of phenytoin and insulin as wound dressing material

In this study, a novel wafer based on Hydroxypropyl methylcellulose (HPMC) was prepared as a wound dressing for the simultaneous delivery of phenytoin (PT) and insulin; evaluation of the cutaneous wound repair property was performed too. Due to its low water solubility, PT was encapsulated in polymeric micelles (PM) by the film hydration method at different polymer/drug ratios and characterized in terms of particle size (PS), polydispersity index (PdI), zeta potential (ZP), drug loading (DL) %, entrapment efficiency (EE) %, and drug release. Then, the optimized PT loaded PM (PT-PM) was embedded in the wafers prepared from the HPMC polymer, alone or in combination with Carbopol 940 (CB) and xanthan gum (XG). This wafer also contained a fixed amount of insulin (PT-PM-Insulin-wafer). The obtained wafers were evaluated in terms of morphology, water uptake ability, porosity, bioadhesion and hardness features. Finally, the efficacy of the PT-PM-Insulin-wafer was assessed in full-thickness excision wound models. The optimized PT-PM showed the PS of 84.05 ± 1.80 nm, PdI of 0.28 ± 0.22, ZP of -3.38 ± 0.26 mV, DL of 15.63 ± 0.01%, EE of 92.66 ± 0.08%, and the release efficiency of 59.95 ± 0.03%. The results obtained from the XRD studies of PT-PM also demonstrated the transition of the crystalline nature of the PT to the amorphous form, while FTIR studies showed some intermolecular interaction of PT and the Soluplus® copolymer chain. It was also found that the incorporation of XG into HPMC wafers influenced the microstructure, thus increasing the porosity, water uptake ability and bioadhesion. Compared with other groups, the PT-PM-Insulin-wafer group showed the enhancement of wound closure through increasing collagen deposition and re-epithelialization. The present study, therefore, revealed that the PT-PM-Insulin-wafer group might have very promising applications for wound healing.

Reviewing Chitin/Chitosan Nanofibers and Associated Nanocomposites and Their Attained Medical Milestones

Chitin/chitosan research is an expanding field with wide scope within polymer research. This topic is highly inviting as chitin/chitosan's are natural biopolymers that can be recovered from food waste and hold high potentials for medical applications. This review gives a brief overview of the chitin/chitosan based nanomaterials, their preparation methods and their biomedical applications. Chitin nanofibers and Chitosan nanofibers have been reviewed, their fabrication methods presented and their biomedical applications summarized. The chitin/chitosan based nanocomposites have also been discussed. Chitin and chitosan nanofibers and their binary and ternary composites are represented by scattered superficial reports. Delving deep into synergistic approaches, bringing up novel chitin/chitosan nanocomposites, could help diligently deliver medical expectations. This review highlights such lacunae and further lapses in chitin related inputs towards medical applications. The grey areas and future outlook for aligning chitin/chitosan nanofiber research are outlined as research directions for the future.

Arthrospira platensis transglutaminase derived antioxidant peptide-packed electrospun chitosan/ poly (vinyl alcohol) nanofibrous mat accelerates wound healing, in vitro, via inducing mouse embryonic fibroblast proliferation

In this present study, we have carried out the antioxidant function of transglutaminase (TG) identified from Arthrospira platensis (Ap) transcriptome. The antioxidant peptide ML11 (MLRSIGIPARL) has been predicted from the transglutaminase core domain and the peptide's free radical scavenging potential was evaluated and it shows that it functions on a dose dependent manner. The ML11 peptide cell toxicity was analysed in the human blood leucocytes which resulted no cytotoxic activity in any of the cell population. Moreover, the nanofibre mat encapsulated with antioxidant peptide ML11 was prepared by electrospinning technique. The antioxidant peptide ML11 encapsulated mat showed increase in fibre diameter compared to the chitosan polyvinyl alcohol blended mat. The change in the crystalline behaviour of both chitosan and polyvinyl alcohol polymer to the amorphous nature was determined by X-ray diffraction at the broad band between 20 and 30° (2θ°). FTIR revealed the functional groups which present in the polymer as well as the interaction between their components of chitosan (CS) and polyvinyl alcohol (PVA). The fibre retains the antioxidant activity due to the peptide encapsulated by scavenging the intracellular ROS that was confirmed by flowcytometry and fluorescence microscopy. The ML11 peptide encapsulated mat showed no cytotoxicity in the NIH-3T3 mouse embryonic fibroblast cells. Also, ML11 peptide encapsulated fibre showed potential wound healing activity in NIH-3T3 cells. Taken altogether, the study indicates that the wound healing potential of the ML11 peptide encapsulated nano fibre mat may be used as biopharmaceutical drug.

Fabrication of sliver nanoparticles/polyvinyl alcohol/gelatin ternary nanofiber mats for wound healing application

PURPOSE

In this study, we aimed to determine the regenerative and antimicrobial impact of the electrospun nanofiber mats, with/without silver nanoparticles (AgNPs), on full-thickness skin wounds in rabbits.

METHODS

Polyvinyl alcohol was combined with gelatin to provide biocompatible electrospun binary nanofiber mats. AgNPs were added to the polyvinyl alcohol/gelatin mixture to obtain ternary nanofiber-AgNPs mats. Binary and ternary nanofiber mats were characterized by scanning electron microscopy before being applied as wound dressings in vivo. Subsequently, wound healing was evaluated.

RESULTS

Both nanofiber/nanofiber-AgNPs mats improved the microscopic quality of the healed skin, albeit without obvious acceleration of the healing rate. As well, both types of nanofiber mats were able to combat microbial invasion into the wound bed.

CONCLUSIONS

Both binary polyvinyl alcohol/gelatin and ternary polyvinyl alcohol/gelatin/AgNPs nanofiber mats developed in the present study depicted similar regenerative and antimicrobial potential when applied as full-thickness wound dressing. However, in comparison to the binary nanofiber mats, no obvious synergistic effect was observed after loading nanofibers with AgNPs.

Wound dressing from polyvinyl alcohol/chitosan electrospun fiber membrane loaded with OH-CATH30 nanoparticles

Novel nanomaterials have been developed for antimicrobial and wound healing applications. Here, we report the preparation of a polyvinyl alcohol/chitosan (PVA/CS) nanofiber with carboxymethyl chitosan nanoparticles (CMCS-OH30 NPs) encapsulating the antibacterial peptide OH-CATH30 (OH-30). The PVA/CS nanofibers containing OH-30 NPs (NP-30-NFs) obtained via electrospinning could achieve a secondary embedded OH-30. The effect of NP-30-NFs on the release of OH-30 was investigated through high-performance liquid chromatography. The antibacterial activities of NP-30-NFs against Escherichia coli and Staphylococcus aureus were studied by bacterial plate counting. NP-30-NFs containing different concentrations of NPs were applied to mouse skin wounds to determine their effectiveness in promoting wound healing. Results showed that NP-30-NFs exhibited antibacterial properties and promoted skin wound healing.

Dendritic Effects of Injectable Biodegradable Thermogels on Pharmacotherapy of Inflammatory Glaucoma-Associated Degradation of Extracellular Matrix

The development of advanced drug delivery systems with extensively sustained release and multiple functions is highly imperative for effective attenuation of the degradation of ocular extracellular matrix that is associated with inflammatory glaucoma. Here, the generation of amine-terminated polyamidoamine dendrimers in an injectable biodegradable thermogel is demonstrated to be important for achieving prolonged drug release profiles and potent anti-inflammatory effects. Among various generations (Gx, x = 0, 1, 3, 5), third-generation G3 is proved as the most effective material for optimizing the synergistic effects of gelatin and poly(N-isopropylacrylamide) and generating a thermogel with the highest biodegradation resistance, the best drug encapsulation/extended-release performance, and the best ability to reduce the elevated expression of inflammatory molecules. A pharmacotherapy based on intracameral injection of thermogels coloaded with pilocarpine and ascorbic acid results in effective alleviation of progressive glaucoma owing to the anti-inflammatory activity and long-acting drug release (above a therapeutic level of 10 µg mL^-1 over 80 days) of thermogels, which simultaneously suppress inflammation and stimulate regeneration of stromal collagen and retinal laminin. These findings on the dendritic effects of rationally designed injectable biomaterials with potent anti-inflammatory effects and controlled drug release demonstrate great promise of their use for pharmacological treatment of progressive glaucoma.

Synthesis, Bioapplications, and Toxicity Evaluation of Chitosan-Based Nanoparticles

The development of advanced nanomaterials and technologies is essential in biomedical engineering to improve the quality of life. Chitosan-based nanomaterials are on the forefront and attract wide interest due to their versatile physicochemical characteristics such as biodegradability, biocompatibility, and non-toxicity, which play a promising role in biological applications. Chitosan and its derivatives are employed in several applications including pharmaceuticals and biomedical engineering. This article presents a comprehensive overview of recent advances in chitosan derivatives and nanoparticle synthesis, as well as emerging applications in medicine, tissue engineering, drug delivery, gene therapy, and cancer therapy. In addition to the applications, we critically review the main concerns and mitigation strategies related to chitosan bactericidal properties, toxicity/safety using tissue cultures and animal models, and also their potential environmental impact. At the end of this review, we also provide some of future directions and conclusions that are important for expanding the field of biomedical applications of the chitosan nanoparticles.

The impact of topical phenytoin loaded nanostructured lipid carriers in diabetic foot ulceration

OBJECTIVE

The aim of this study is to develop, and characterize nanostructured lipid carriers (NLCs) of phenytoin (PHT) in order to improve its entrapment efficiency and sustained release to improve the healing process.

METHODS

Twenty-seven patients with neuropathic diabetic foot ulceration (DFU) were enrolled in this study. Patients were comparable regarding size, grading of ulcer and control of diabetes with no major deformity. All patients were managed by weekly sharp debridement if indicated and offloaded with cast shoes. They were equally divided into three groups: PHT-NLC-hydrogel (0.5%w/v), phenytoin hydrogel (0.5%w/v) and blank hydrogel groups. Changes in wound area were monitored over 2 months.

RESULTS

Baseline wound area of PHT-NLC, PHT and blank hydrogels were 5.50 ± 3.66, 3.94 ± 1.86 and 5.36 ± 2.14 cm², respectively. Ulcers treated with PHT-NLC hydrogel showed smaller wound area compared to control groups (ρ < 0.05). The overall reduction in ulcer size were 95.82 ± 2.22% for PHT-NLC-hydrogel in comparison to 47.10 ± 4.23% and -34.91 ± 28.33% for PHT and blank-hydrogel (ρ < 0.001), respectively.

CONCLUSION

PHT-NLC hydrogel speeds up the healing process of the DFU without adverse effects when compared to the positive and negative control hydrogels. Moreover, the study can open a window for topical application of NLCs loaded with PHT in the treatment of numerous dermatological disorders that resist conventional treatment.

KEY MESSAGE

The delivery of drug molecules and their localization into the skin is the main purpose of the topical dosage forms. In this manuscript, the impact of topical phenytoin loaded nanostructured lipid carrier in improving wound healing in patients with neuropathic diabetic foot ulceration was investigated. Phenytoin loaded nanostructured lipid carrier dressing was found to be more effective than phenytoin hydrogel at the same concentration in healing of neuropathic diabetic foot ulcer.

Hyaluronic acid and chitosan-based nanosystems: a new dressing generation for wound care

INTRODUCTION

The main goal in the management of chronic wounds is the development of multifunctional dressings able to promote a rapid recovery of skin structure and function, improving patient compliance.

AREAS COVERED

This review discusses the use of nanosystems, based on hyaluronic acid and chitosan or their derivatives for the local treatment of chronic wounds. The bioactive properties of both polysaccharides will be described, as well as the results obtained in the last decade by the in vitro and in vivo evaluation of the wound healing properties of nanosystems based on such polymers.

EXPERT OPINION

In the last decades, there has been a progressive change in the local treatments of chronic wounds: traditional inert dressings have been replaced by more effective bioactive ones, based on biopolymers taking part in wound healing and able to release the loaded active agents in a controlled way. With the advance of nanotechnologies, the scenario has further changed: nanosystems, characterized by a large area-to-volume ratio, show an improved interaction with the biological substrates, amplifying the activity of the constituent biopolymers. In the coming years, a deeper insight into wound healing mechanisms and the development of new techniques for nanosystem manufacturing will results in the design of new scaffolds with improved performance.

Naturally-derived electrospun wound dressings for target delivery of bio-active agents

Electrospun nanofibers are known as the advanced means for wound dressing. They have represented remarkable potency to encapsulate and deliver biomolecules promoting the wound healing process. Compared to synthetic polymers, naturally derived polymers (NDP) are more qualified candidates for fabrication of biomedical electrospun scaffolds. Not only nanofibers of NDP illustrate higher biocompatibility and biodegradability rates, but also they mimic the native extracellular matrix more closely, which leads to the wound closure acceleration by enhancing tissue regeneration. Aside, incorporation of bioactive molecules and therapeutic agents into the nanofibers can generate innovative bioactive wound dressings with significantly improved healing potentials. This paper starts with a brief discussion on the steps and factors influencing the wound healing process. Then, the recent applications of electrospun nanofibers as wound dressing with healing accelerating properties are reviewed. Further, the various healing agents and alternative strategies for modification and functionalization of bioactive naturally-derived electrospun nanofibers are discussed.

Cellulose acetate/poly(vinyl alcohol) hybrid fibrous mat containing tetracycline hydrochloride and phenytoin sodium: Morphology, drug release, antibacterial, and cell culture studies

The objective of this study was to introduce an electrospun hybrid fibrous mat (a dual-fiber drug delivery system) based on cellulose acetate and poly(vinyl alcohol) containing tetracycline hydrochloride and phenytoin sodium, respectively. Characterization of samples was carried by morphology, drug release, cell cytotoxicity, adhesion, antibacterial property, and wettability investigations. The results showed a uniform shape and a narrow diameter distribution of fibers (between 160 ± 20 nm) for fabricated cellulose acetate/poly(vinyl alcohol) hybrid fibrous mat. The tetracycline hydrochloride release from cellulose acetate significantly decreased due to gel formation of poly(vinyl alcohol) in aqueous media. The best fit for drug release kinetic of hybrid sample was Higuchi model. Sample with tetracycline hydrochloride and phenytoin sodium drugs showed improved cell growth, viability, and antibacterial activity against Escherichia coli (~89%) and Staphylococcus aureus (~98%) in comparison with sample without drugs. The hydrophilic property of cellulose acetate/poly(vinyl alcohol) fibrous sample containing the drugs was also remarkable (~45°). To consider the obtained results, the presented hybrid fibrous mat shows a high potent for biomedical applications.

Development of gelatin/ascorbic acid cryogels for potential use in corneal stromal tissue engineering

To offer an ideal hospitable environment for corneal keratocyte growth, the carrier materials can be functionalized with incorporation of signaling molecules to regulate cell biological events. This study reports, for the first time, the development of gelatin/ascorbic acid (AA) cryogels for keratocyte carriers in vitro and in vivo. The cryogel samples were fabricated by blending of gelatin with varying amounts of AA (0-300 mg) and carbodiimide cross-linking via cryogelation technique. Hydrophilic AA content in the carriers was found to significantly affect cross-linking degree and pore dimension of cryogels, thereby dictating their mechanical and biological stability and AA release profile. The cryogel carriers with low-to-moderate AA loadings were well tolerated by rabbit keratocyte cultures and anterior segment eye tissues, demonstrating good ocular biocompatibility. Although higher incorporated AA level contributed to enhanced metabolic activity and biosynthetic capacity of keratocytes grown on cryogel matrices, the presence of excessive amounts of AA molecules could lead to toxic effect and limit cell proliferation and matrix production. The cytoprotective activity against oxidative stress was shown to be strongly dependent on AA release, which further determined cell culture performance and tissue reconstruction efficiency. With the optimum AA content in carrier materials, intrastromally implanted cell/cryogel constructs exhibited better capability to enhance tissue matrix regeneration and transparency maintenance as well as to mitigate corneal damage in an alkali burn-induced animal model. It is concluded that understanding of antioxidant molecule-mediated structure-property-function interrelationships in gelatin/AA cryogels is critical to designing carrier materials for potential use in corneal stromal tissue engineering.

STATEMENT OF SIGNIFICANCE

Multifunctional cryogel material can offer an ideal hospitable environment for cell-mediated tissue reconstruction. To our knowledge, this is the first report describing the use of gelatin/ascorbic acid (AA) cryogels as keratocyte carriers for corneal stromal tissue engineering. The AA loading during cryogel fabrication is found to have a significant effect on cross-linking degree and pore dimension, mechanical and biological stability, ocular biocompatibility, cell culture performance, and cytoprotective activity, giving comprehensive insight into fine-tuning the structure-property-function interrelationships of keratocyte carrier material. Using an alkali burn-induced animal model, we present evidence that with the optimum AA loading into cryogel materials, intrastromally implanted cell/carrier constructs exhibited better capability to enhance tissue matrix regeneration and transparency maintenance as well as to mitigate corneal damage.

Biodegradable hydrogel-based biomaterials with high absorbent properties for non-adherent wound dressing

Dressing materials involve conventional gauzes and modern materials such as hydrogels and foam-based biomaterials. Although the choice of dressing material depends on the type of wound, a dressing material is expected to be non-cytotoxic. Additionally, moist dressing is considered appropriate to accelerate epithelialisation, while dry dressing may cause tissue damage during removal. An ideal dressing material is expected to provide a moist environment and degrade and release the drug for faster wound healing. Thus, we have designed a hydrogel-based biodegradable dressing material to provide the moist environment with no cytotoxic effect in vitro. The design of the hydrogel involved alginate-collagen reinforced with whisker cellulose derived from cotton. The hydrogel was prepared via amide linkage in the presence of 1-ethyl-(dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysulfosuccinimide (NHS), followed by divalent cationic cross-linking of alginate and hydrogen bonding with cellulose. The high water retention capability of the hydrogel enables a moist environment to be maintained in the wounded area. The constituents of the hydrogel provided a microenvironment that was suitable for cell proliferation in the vicinity of the hydrogel but inhibited cell attachment on it. The MTT assay results indicated a higher fibroblast proliferation and viability in the presence of the hydrogel.

Preparation, structural characterisation and release study of novel hybrid microspheres entrapping nanoselenium, produced by green synthesis

The main goal of this study was to synthesise and characterise different formulations based on alginate and alginate/chitosan microspheres containing nanoselenium (nano-Se) for controlled delivery applications. Nanosize elemental selenium was produced by using probiotic yogurt bacteria (Lactobacillus casei) in a fermentation procedure. The structural and morphological characterisation of the microspheres was performed by Fourier transform infrared (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis. FTIR and XRD pattern indicated that was an effective cross-linking of selenium nanoparticles within the polymeric matrix in both cases. The SEM images reveal that selenium nanoparticles are mainly exposed on the surface of alginate, in contrast to porous structure of alginate/chitosan/nano-Se, interconnected in a regular network. This architecture type has a considerable importance in the delivery process, as demonstrated by differential pulse voltammetry. Selenium release from both matrices is pH sensitive. Moreover, chitosan blended with alginate minimise the release of encapsulated selenium, in simulated gastric fluid, and prolong the duration of release in intestinal fluid. The overall effect is the enhancement of total percentage release concomitant with the longer duration of action. The authors' formulation based on alginate/chitosan is a convenient matrix to be used for selenium delivery in duodenum, caecum and colon.

Multifunctional and biomimetic fish collagen/bioactive glass nanofibers: fabrication, antibacterial activity and inducing skin regeneration in vitro and in vivo

The development of skin wound dressings with excellent properties has always been an important challenge in the field of biomedicine. In this study, biomimetic electrospun fish collagen/bioactive glass (Col/BG) nanofibers were prepared. Their structure, tensile strength, antibacterial activity and biological effects on human keratinocytes, human dermal fibroblasts and human vascular endothelial cells were investigated. Furthermore, the Sprague Dawley rat skin defect model was used to validate their effect on wound healing. The results showed that compared with pure fish collagen nanofibers, the tensile strength of the Col/BG nanofibers increased to 21.87±0.21 Mpa, with a certain degree of antibacterial activity against Staphylococcus aureus. It was also found that the Col/BG nanofibers promoted the adhesion, proliferation and migration of human keratinocytes. Col/BG nanofibers induced the secretion of type one collagen and vascular endothelial growth factor by human dermal fibroblasts, which further stimulated the proliferation of human vascular endothelial cells. Animal experimentation indicated that the Col/BG nanofibers could accelerate rat skin wound healing. This study developed a type of multifunctional and biomimetic fish Col/BG nanofibers, which had the ability to induce skin regeneration with adequate tensile strength and antibacterial activity. The Col/BG nanofibers are also easily available and inexpensive, providing the possibility for using as a functional skin wound dressing.

Single-Dose Electrospun Nanoparticles-in-Nanofibers Wound Dressings with Enhanced Epithelialization, Collagen Deposition, and Granulation Properties

Phenytoin (Ph), an antiepileptic drug, was reported to exhibit high wound healing activity. However, its limited solubility, bioavailability, and inefficient distribution during topical administration limit its use. Therefore, this study aims to develop new single-dose electrospun nanoparticles-in-nanofibers (NPs-in-NFs) wound dressings that allow a well-controlled release of Ph. These NPs-in-NFs systems are based on enhanced chitosan (CS)/poly(ethylene oxide) (PEO) electrospun nanofibers (NFs) incorporating optimized Ph-loaded nanocarriers. First, a study was conducted to investigate Ph loading efficiency into polymeric nanocarriers of different types; pluronic nanomicelles and poly(lactic-co-glycolic) acids nanoparticles (PLGA NPs). The drug release profile from the nanocarriers was further optimized via lecithin coating. Second, different electrospinning parameters were manipulated to fabricate beads-free homogeneous NFs with optimized polymer ratios. Plain and Ph-loaded nanocarriers were characterized using Fourier transform infrared (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), dynamic light scattering (DLS), and scanning electron microscopy (SEM). Both entrapment efficiency of Ph (EE%) and its release profile in phosphate buffer saline (PBS; pH 5.5), simulating the wound environment, were studied. Biodegradability, swelling, vapor permeability, and porosity of the developed Ph-loaded NPs-in-NFs wound dressings were investigated. Morphology of the NPs-in-NFs was also studied using SEM and confocal laser microscopy (CLSM). Besides, the release profiles of Ph from the optimized NPs-in-NFs were assessed. The newly developed wound dressings were evaluated in vitro for their cytotoxicity using human fibroblasts and in vivo using a wound healing mice model. Nanocarriers with particle size ranging from 100 to 180 nm were successfully prepared. All nanocarriers attained a high drug entrapment efficiency exceeding 94% and showed promising sustained release profiles compared to free Ph. Results also demonstrated that NFs incorporating the optimized lecithin-coated Ph-loaded PLGA NPs could be the most promising candidate for efficient wound healing. These NPs-in-NFs systems conferred a well-controlled and sustained release of Ph over 9 days. Moreover, they showed the best re-epithelization and healing quality during the in vivo study with minimal inflammatory and necrotic cells formation.

Reactive electrospinning of composite nanofibers of carboxymethyl chitosan cross-linked by alginate dialdehyde with the aid of polyethylene oxide

We have prepared carboxymethyl chitosan-alginate dialdehyde (CMCS-ADA) nanofibers via a reactive electrospinning process with the aid of polyethylene oxide (PEO). The presence of PEO delayed the gelation of CMCS and ADA, thus providing ease of use to adjust the mixing of CMCS-PEO and ADA-PEO blended solution. The mixed solution can be adjusted to come out from the needle before the gel formation or when the gel was just about to form. Defect-free CMCS-ADA-PEO nanofibers with average diameters ranging from 100nm to 900nm were obtained using water as a solvent. The in situ cross-linked CMCS-ADA nanofibers were then obtained following the extraction of water-soluble PEO. After immersion in phosphate-buffered saline (PBS) at a pH of 7.4 for up to 15days, the as-spun CMCS-ADA-PEO composite nanofibers maintained structural integrity, confirming the success of the crosslinking. The PEO-extracted CMCS-ADA nanofibers promoted the adhesion, proliferation and alkaline phosphatase activity of bone marrow stromal cells.

A novel tetrandrine-loaded chitosan microsphere: characterization and in vivo evaluation

In this study, novel tetrandrine-loaded chitosan microspheres were prepared by the emulsion cross-linking method. The systems were then characterized for physicochemical properties and in vitro drug release. In addition, the pharmacokinetics and tissue distribution of microspheres were further verified in animal models. Particle-size distribution indicated that the size of microspheres was within the range of 7–15 μm, with a median diameter of 12.4 μm. The drug loading and entrapment efficiency of the formulation were 34.6%±12.5% and 87.3%±9.7% (mean ± SD), respectively. In vitro release showed a typical sustained and long-term drug release behavior. The Higuchi equation was the model that fit best with release data. Maintaining a relatively constant plasma concentration in the long-term drug treatment is an outstanding pharmacokinetic advantage of tetrandrine microspheres in vivo. Moreover, compared with tetrandrine solution, tetrandrine microspheres produced a lower drug concentration in the heart, liver, and kidneys. This indicated that the microspheres used in this study were preferable for targeting lung tissue versus other tissues. No damage to the tissues of the lung was found in histopathological examination.