Chitosan-hyaluronan/nano chondroitin sulfate ternary composite sponges for medical use

Sulfated polysaccharide as biomimetic biopolymers for tissue engineering scaffolds fabrication: Challenges and opportunities

Sulfated polysaccharides play important roles in tissue engineering applications because of their high growth factor preservation ability and their native-like biological features. There are different sulfated polysaccharides based on different repeating units in the carbohydrate backbone, the position of the sulfate group, and the sulfation degree of the polysaccharide. These led to various sulfated polymers with different negative charge densities and resultant structure-property relationships. Since numerous reports are presented related to sulfated polysaccharide applications in tissue engineering, it is crucial to review the role of effective physicochemical and biological parameters in their usage; as well as their structure-property relationships. Within this review, we focused on the effect of naturally occurring and synthetic sulfated polysaccharides in tissue engineering applications reported in the last years, highlighting the challenges of the scaffold fabrication process, the position, and the degree of sulfate on biomedical activity. Additionally, we discussed their use in numerous in vitro and in vivo model systems.

Regeneration of critical-sized grade II furcation using a novel injectable melatonin-loaded scaffold

BACKGROUND

Periodontal regenerative therapy using bone-substituting materials has gained favorable clinical significance in enhancing osseous regeneration. These materials should be biocompatible, osteogenic, malleable, and biodegradable. This study assessed the periodontal regenerative capacity of a novel biodegradable bioactive hydrogel template of organic-inorganic composite loaded with melatonin.

MATERIALS AND METHODS

A melatonin-loaded alginate-chitosan/beta-tricalcium phosphate composite hydrogel was successfully prepared and characterized. Thirty-six critical-sized bilateral class II furcation defects were created in six Mongrel dogs, and were randomly divided and allocated to three cohorts; sham, unloaded composite, and melatonin-loaded. Periodontal regenerative capacity was evaluated via histologic and histomorphometric analysis.

RESULTS

Melatonin-treated group showed accelerated bone formation and advanced maturity, with a significant twofold increase in newly formed inter-radicular bone compared with the unloaded composite. The short-term regenerative efficacy was evident 4 weeks postoperatively as a significant increase in cementum length concurrent with reduction of entrapped epithelium. After 8 weeks, the scaffold produced a quality of newly synthesized bone similar to normal compact bone, with potent periodontal ligament attachment.

CONCLUSIONS

Melatonin-loaded hydrogel template accelerated formation and enhanced quality of newly formed bone, allowing complete periodontal regeneration. Furthermore, the scaffold prevented overgrowth and entrapment of epithelial cells in furcation defects.

Extracellular matrix component-derived nanoparticles for drug delivery and tissue engineering

The extracellular matrix (ECM) consists of a complex combination of proteins, proteoglycans, and other biomolecules. ECM-based materials have been demonstrated to have high biocompatibility and bioactivity, which may be harnessed for drug delivery and tissue engineering applications. Herein, nanoparticles incorporating ECM-based materials and their applications in drug delivery and tissue engineering are reviewed. Proteins such as gelatin, collagen, and fibrin as well as glycosaminoglycans including hyaluronic acid, chondroitin sulfate, and heparin have been employed for cancer therapeutic delivery, gene delivery, and wound healing and regenerative medicine. Strategies for modifying and functionalizing these materials with synthetic and natural polymers or to enable stimuli-responsive degradation and drug release have increased the efficacy of these materials and nano-systems. The incorporation and modification of ECM-based materials may be used to drive drug targeting and increase tissue-specific cell differentiation more effectively.

Human beta defensin-2 loaded PLGA nanoparticles impregnated in collagen-chitosan composite scaffold for the management of diabetic wounds

Diabetic wound (DW) is the most devastating complication resulting in significant mortality and morbidity in diabetic patients. The standard treatment of DW care fails to address the prerequisites of treating DW owing to its multifactorial pathophysiology. Henceforth, developing a single treatment strategy to handle all the loopholes may effectively manage DW. The objective of the current study was to formulate Human beta defensin-2 (HBD-2) loaded Poly (lactic-co-glycolic acid) (PLGA) nanoparticle impregnated in collagen/chitosan (COL-CS) composite scaffolds for the accelerated healing of DW. Upon investigation, the developed biodegradable crosslinked scaffold possesses low matrix degradation, optimum porosity, and sustained drug release than the non-crosslinked scaffold. In vitro studies revealed that the HBD-2 COL-CS scaffold was biocompatible and accelerated cell migration and angiogenesis. The HBD-2 COL-CS scaffold showed significant antimicrobial activity in S. aureus, E. coli, and P. aeruginosa. The in vivo studies revealed that the HBD-2 COL-CS treated group accelerated healing compared to those in COL-CS and control groups. The ELISA results indicated a significant decrease in MMP-9, TNF-α, MPO, NAG, and NO with an increase in IL-10 in HBD-2 COL-CS treated group. The accelerated healing in HBD-2 COL-CS treated group might be due to the synergistic effects of PLGA (collagen synthesis and deposition and positive angiogenic effect), HBD-2 (anti-inflammatory, antibacterial, positive angiogenic effect, cell proliferation, and migration), COL (established wound healer and stabilizer) and CS (antibacterial, controlled drug release).

Recent Advances in Silver Nanoparticles Containing Nanofibers for Chronic Wound Management

Infections are the primary cause of death from burns and diabetic wounds. The clinical difficulty of treating wound infections with conventional antibiotics has progressively increased and reached a critical level, necessitating a paradigm change for enhanced chronic wound care. The most prevalent bacterium linked with these infections is Staphylococcus aureus, and the advent of community-associated methicillin-resistant Staphylococcus aureus has posed a substantial therapeutic challenge. Most existing wound dressings are ineffective and suffer from constraints such as insufficient antibacterial activity, toxicity, failure to supply enough moisture to the wound, and poor mechanical performance. Using ineffective wound dressings might prolong the healing process of a wound. To meet this requirement, nanoscale scaffolds with their desirable qualities, which include the potential to distribute bioactive agents, a large surface area, enhanced mechanical capabilities, the ability to imitate the extracellular matrix (ECM), and high porosity, have attracted considerable interest. The incorporation of nanoparticles into nanofiber scaffolds constitutes a novel approach to “nanoparticle dressing” that has acquired significant popularity for wound healing. Due to their remarkable antibacterial capabilities, silver nanoparticles are attractive materials for wound healing. This review focuses on the therapeutic applications of nanofiber wound dressings containing Ag-NPs and their potential to revolutionize wound healing.

A Concise Review of Extraction and Characterization of Chondroitin Sulphate from Fish and Fish Wastes for Pharmacological Application

Chondroitin sulphate (CS) is one of the most predominant glycosaminoglycans (GAGs) available in the extracellular matrix of tissues. It has many health benefits, including relief from osteoarthritis, antiviral properties, tissue engineering applications, and use in skin care, which have increased its commercial demand in recent years. The quest for CS sources exponentially increased due to several shortcomings of porcine, bovine, and other animal sources. Fish and fish wastes (i.e., fins, scales, skeleton, bone, and cartilage) are suitable sources of CS as they are low cost, easy to handle, and readily available. However, the lack of a standard isolation and characterization technique makes CS production challenging, particularly concerning the yield of pure GAGs. Many studies imply that enzyme-based extraction is more effective than chemical extraction. Critical evaluation of the existing extraction, isolation, and characterization techniques is crucial for establishing an optimized protocol of CS production from fish sources. The current techniques depend on tissue hydrolysis, protein removal, and purification. Therefore, this study critically evaluated and discussed the extraction, isolation, and characterization methods of CS from fish or fish wastes. Biosynthesis and pharmacological applications of CS were also critically reviewed and discussed. Our assessment suggests that CS could be a potential drug candidate; however, clinical studies should be conducted to warrant its effectiveness.

Preparation and Characterization of a Novel Mucoadhesive Carvedilol Nanosponge: A Promising Platform for Buccal Anti-Hypertensive Delivery

Carvedilol (CRV) is a non-selective third generation beta-blocker used to treat hypertension, congestive heart failure and angina pectoris. Oral administration of CRV showed poor bioavailability (25%), which might be ascribed to its extensive first-pass metabolism. Buccal delivery is known to boost drugs bioavailability. The aim of this study is to investigate the efficacy of bilosomes-based mucoadhesive carvedilol nanosponge for enhancing the oral bioavailability of CRV. The bilosomes were prepared, optimized and characterized for particle size, surface morphology, encapsulation efficiency and ex-vivo permeation studies. Then, the optimized formula was incorporated into a carboxymethyl cellulose/hydroxypropyl cellulose (CMC/HPC) composite mixture to obtain buccal nanosponge enriched with CRV bilosomes. The optimized bilosome formula (BLS9), showing minimum vesicle size, maximum entrapment, and highest cumulative in vitro release, exhibited a spherical shape with 217.2 nm in diameter, 87.13% entrapment efficiency, and sustained drug release for up to 24 h. In addition, ex-vivo drug permeation across sheep buccal mucosa revealed enhanced drug permeation with bilosomal formulations, compared to aqueous drug suspension. Consecutively, BLS9 was incorporated in a CMC/HPC gel and lyophilized for 24 h to obtain bilosomal nanosponge to enhance CRV buccal delivery. Morphological analysis of the prepared nanosponge revealed improved swelling with a porosity of 67.58%. The in vivo assessment of rats indicated that CRV-loaded nanosponge efficiently enhanced systolic/diastolic blood pressure, decreased elevated oxidative stress, improved lipid profile and exhibited a potent cardio-protective effect. Collectively, bilosomal nanosponge might represent a plausible nanovehicle for buccal delivery of CRV for effective management of hypertension.

Nanomaterials for application in wound Healing: current state-of-the-art and future perspectives

Nanoparticles are the gateway to the new era in drug delivery of biocompatible agents. Several products have emerged from nanomaterials in quest of developing practical wound healing dressings that are nonantigenic, antishear stress, and gas-exchange permeable. Numerous studies have isolated and characterised various wound healing nanomaterials and nanoproducts. The electrospinning of natural and synthetic materials produces fine products that can be mixed with other wound healing medications and herbs. Various produced nanomaterials are highly influential in wound healing experimental models and can be used commercially as well. This article reviewed the current state-of-the-art and briefly specified the future concerns regarding the different systems of nanomaterials in wound healing (i.e., inorganic nanomaterials, organic and hybrid nanomaterials, and nanofibers). This review may be a comprehensive guidance to help health care professionals identify the proper wound healing materials to avoid the usual wound complications.

Injectable eggshell-derived hydroxyapatite-incorporated fibroin-alginate composite hydrogel for bone tissue engineering

Tissue engineering is a promising approach to repair and regenerate damaged or lost tissues or organs. In dental aspect, reconstruction of the resorbed alveolar bone after tooth extraction plays an important role in the success of dental substitution, especially in dental implant treatment. The hydroxyapatite (HA)-incorporated fibroin-alginate composite injectable hydrogel was fabricated to be used as scaffold for bone regeneration. HA was synthesized from eggshell biowaste. Fibroin was extracted from Bombyx mori cocoon. The synthesized HA, fibroin and alginate hydrogel were characterized. HA-incorporated fibroin-alginate hydrogel had decreased pore size and porosity compared with pure alginate hydrogel. Thermal analysis showed that hydrogel had a degradation peak of approximately 250 °C. Hydrogel could absorb water, with a swelling ratio of around 300% at 24 h. Hydrogel was degraded as time passed and almost completely degraded at day 7. Its compressive Young's modulus was approximately 0.04 ± 0.02 N/mm² to 0.10 ± 0.02 N/mm². Primary cytotoxicity test indicated non-toxic potential of the fabricated hydrogel. Increased ALP activity was observed in MC3T3-E1 cultured in HA-incorporated fibroin-alginate hydrogel. Results suggested the potential use of injectable HA fibroin-alginate hydrogel as dental scaffolding material. Further studies including in vivo examinations are needed prior to its clinical application.

Novel fabrication of dual nanoparticle loaded-co-polymeric dressing for effective healing efficiency in wound care after fracture surgery

In the present study, curcumin loaded chitosan/poly ethylene glycol nanomaterial (CUR loaded CH/PEG/AgNPs) was fabricated and characterized for wound healing efficiency after fracture surgery. The interaction of functional groups and crystal nature were recorded under FTIR and XRD spectrometer and reveals that the stabilization and purity of NPs was mediated by OH/NH₂ groups in chitosan. FESEM showed the presence of spherical and well dispersed particles. The average size of the particle was 13.48 nm. The CUR loaded CH/PEG/AgNPs showed higher swelling capacity (495.6 g/g) in phosphate buffer saline compared to water (140.2 g/g). The drug loading efficiency was higher in CUR loaded CH/PEG/AgNPs compared to CH/PEG films as recorded by the absorbance peak at 460 nm corresponds to curcumin in the composite. A dose dependent cytotoxicity of CUR loaded CH/PEG/AgNPs was noticed on Vero cells. The viability of Vero cells was increased to 96.5% at 100 μg/mL. A remarkable change in Vero cells such as condensed nuclei and membrane blabbing was noticed in cells treated with CUR loaded CH/PEG/AgNPs. A greater inhibition of Staphylococcus aureus and Escherichia coli was noticed at 24 h and 48 h treated with CUR loaded CH/PEG/AgNPs. A greater healing effect by increasing the wound contraction (98% on day 12) was observed with CUR loaded CH/PEG/AgNPs compared to control. Histopathological examination demonstrated that CUR loaded CH/PEG/AgNPs showed complete tissue regeneration in wound excised rats. The results of this study conclude that CUR loaded CH/PEG/AgNPs could be promising candidate to prevent microbial infections in wound, healing wound rapidly and inhibit the proliferation of apoptotic cells. Thus, CUR loaded CH/PEG/AgNPs could be a potential therapeutic agent with broad spectrum applications in the future. HighlightsA new approach was used to develop curcumin-loaded chitosan/poly(ethylene glycol)/AgNPs.The CUR-loaded CH/PEG/AgNPs were confirmed to be crystals by XRD analysis.The prepared CH/PEG/AgNPs were spherical and averaged 13.48 nm in size.The growth of S. aureus and E. coli were inhibited mostly by CH/PEG/AgNPs treatment.CUR loaded CH/PEG/AgNPs showed complete tissue regeneration in wound excised mice.

Electrospun Nanofibers/Nanofibrous Scaffolds Loaded with Silver Nanoparticles as Effective Antibacterial Wound Dressing Materials

The treatment of wounds is expensive and challenging. Most of the available wound dressings are not effective and suffer from limitations such as poor antimicrobial activity, toxicity, inability to provide suitable moisture to the wound and poor mechanical performance. The use of inappropriate wound dressings can result in a delayed wound healing process. Nanosize range scaffolds have triggered great attention because of their attractive properties, which include their capability to deliver bioactive agents, high surface area, improved mechanical properties, mimic the extracellular matrix (ECM), and high porosity. Nanofibrous materials can be further encapsulated/loaded with metal-based nanoparticles to enhance their therapeutic outcomes in wound healing applications. The widely studied metal-based nanoparticles, silver nanoparticles exhibit good properties such as outstanding antibacterial activity, display antioxidant, and anti-inflammatory properties, support cell growth, making it an essential bioactive agent in wound dressings. This review article reports the biological (in vivo and in vitro) and mechanical outcomes of nanofibrous scaffolds loaded with silver nanoparticles on wound healing.

Hyaluronic Acid-Based Scaffolds as Potential Bioactive Wound Dressings

The negative factors that result in delayed and prolonged wound healing process include microbial pathogens, excess wound exudates, underlying conditions, smoking, obesity, etc. Most of the currently used wound dressings demonstrate an inadequate capacity to treat wounds resulting from the factors mentioned above. The commonly used wound dressings include hydrogels, films, hydrocolloids, foams, fibers, sponges, dermal patches, bandages, etc. These wound dressings can be loaded with various types of bioactive agents (e.g., antibiotics, nanoparticles, anti-inflammatory drugs, etc.) to improve their therapeutic outcomes. Biopolymers offer interesting properties suitable for the design of wound dressings. This review article will be based on hyaluronic-acid-based scaffolds loaded with therapeutic agents for the treatment of wounds.

Chitosan/alginate/hyaluronic acid polyelectrolyte composite sponges crosslinked with genipin for wound dressing application

Wound dressing composed of polyelectrolyte complexes (PECs), based on chitosan/alginate/hyaluronic acid (CS/ALG/HYA) crosslinked by genipin, was prepared by freeze-dried molding. Genipin as excellent natural biological crosslinker was chose for high biocompatibility and improving mechanical properties of materials. The CS/ALG/HYA sponges (CAHSs) were characterized by FTIR, XRD, DSC and SEM. Porosity, swelling behavior and mechanical properties and in vitro degradation of CAHSs were investigated. The cytotoxicity assay was carried out on HUVEC cells in vitro and the result proves the good biocompatibility of CAHSs. Hemolysis tests indicated that the prepared CAHSs were non-hemolytic material (hemolysis ratio < 5%, no cytotoxicity). PT and aPPT coagulation tests demonstrated that CAHS2 and CAHS3 could both activate the extrinsic and intrinsic coagulation pathway and thus accelerated blood coagulation. Further, in a rat full-thickness wounds model, the CAHS2 sponge significantly facilitates wound closure compared to other groups. CAHSs exhibited adjustable physical, mechanical and biological properties. Thus, the chitosan-based polyelectrolyte composite sponges exhibit great potential as promising wound dressings.

Acellular fish skin enhances wound healing by promoting angiogenesis and collagen deposition

Acellular matrix is a type of promising biomaterial for wound healing promotion. Although acellular bovine and porcine tissues have proven effective, religious restrictions and risks of disease transmission remain barriers to their clinical use. Acellular fish skin (AFS), given its similarity to human skin structure and without the aforementioned disadvantages, is thus seen as an attractive alternative. This study aims to fabricate AFS from the skin of black carp (Mylopharyngodon piceus), evaluate its physical and mechanical properties and assess its impact on wound healing. The results showed that AFS has a highly porous structure, along with high levels of hydrophilicity, water-absorption property and permeability. Furthermore, physical characterization showed the high tensile strength of AFS in dry and wet states, and high stitch tear resistance, indicating great potential in clinical applications. Cell Counting Kit-8 was used to test the viability of L929 cells when culturing in the extracts of AFS. Compared with the control group, there is no significant difference in optical density value when culturing in the extracts of AFS at days 1, 3 and 7 (*p> 0.05).In vivowound healing evaluation then highlighted its promotion of angiogenesis and collagen synthesis, its function in anti-inflammation and acceleration in wound healing. Therefore, this study suggests that AFS has potential as a promising alternative to mammal-derived or traditional wound dressing.

Chitosan and Cellulose-Based Hydrogels for Wound Management

Wound management remains a challenge worldwide, although there are several developed wound dressing materials for the management of acute and chronic wounds. The wound dressings that are currently used include hydrogels, films, wafers, nanofibers, foams, topical formulations, transdermal patches, sponges, and bandages. Hydrogels exhibit unique features which make them suitable wound dressings such as providing a moist environment for wound healing, exhibiting high moisture content, or creating a barrier against bacterial infections, and are suitable for the management of exuding and granulating wounds. Biopolymers have been utilized for their development due to their non-toxic, biodegradable, and biocompatible properties. Hydrogels have been prepared from biopolymers such as cellulose and chitosan by crosslinking with selected synthetic polymers resulting in improved mechanical, biological, and physicochemical properties. They were useful by accelerating wound re-epithelialization and also mimic skin structure, inducing skin regeneration. Loading antibacterial agents into them prevented bacterial invasion of wounds. This review article is focused on hydrogels formulated from two biopolymers-chitosan and cellulose-for improved wound management.

Magnetic thermally sensitive interpenetrating polymer network (IPN) nanogels: IPN-pNIPAm@Fe2O3-SiO2

In this paper, iron oxide-silica@poly(acrylamide-co-N,N-diethylacrylamide)/poly(N,N-diethylacrylamide) interpenetrating polymer network (IPN-pNIPAm@Fe₂O₃-SiO₂) nanogels, possessing both magnetic and thermo-sensitive properties were successfully prepared. The preparation approach involved two steps, consisting of nanoparticle self-assembly and in situ polymerization with monomers. The structural combination of interpenetrating polymer networks (IPNs) with the Fe₂O₃-SiO₂ nanoparticles led to a synergistic property enhancement of both IPNs and nanoparticles, which could increase the mechanical strength of hydrogels and decrease the aggregation of nanoparticles. The synergistic effect was induced by the compatibility of these two individual components. Furthermore, the swelling and shrinking behaviors of the IPN-pNIPAm@Fe₂O₃-SiO₂ nanogels revealed the reversible thermo-responsive properties of IPN nanogels. This fabrication approach for IPN-pNIPAm@Fe₂O₃-SiO₂ nanogels can provide a facile route for manufacturing smart nanocomposites with stability in aqueous solution and reversible swelling/deswelling stimuli-responsive properties to achieve multifunctional tasks in clinical therapy.

In this paper, iron oxide-silica@poly(acrylamide-co-N,N-diethylacrylamide)/poly(N,N-diethylacrylamide) interpenetrating polymer network (IPN-pNIPAm@Fe₂O₃-SiO₂) nanogels, possessing both magnetic and thermo-sensitive properties were successfully prepared.

Synthesis and characterization of poly(vinyl alcohol)/chondroitin sulfate composite hydrogels containing strontium-doped hydroxyapatite as promising biomaterials

Novel poly(vinyl alcohol)/chondroitin sulfate (PVA/CS) composite hydrogels containing hydroxyapatite (HA) or Sr-doped HA (HASr) particles were synthesized by a freeze/thaw method and characterized aiming towards biomedical applications. HA and HASr were synthesized by a wet-precipitation method and added to the composite hydrogels in fractions up to 15 wt%. Physical-chemical characterizations of particles and hydrogels included scanning electron microscopy, energy-dispersive spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, thermogravimetry, porosity, compressive strength/elastic modulus, swelling degree, and cell viability. Particles were irregular in shape and appeared to have narrow size variation. The thermal behavior of composite hydrogels was altered compared to the control (bare) hydrogel. All hydrogels exhibited high porosity. HA/HASr particles reduced total porosity without reducing pore size. The mechanical strength was improved as the fraction of HA or HASr was increased. HASr particles led to a faster water uptake but did not interfere with the total hydrogel swelling capacity. In cell viability essay, increased cell growth (above 120%) was observed in all groups including the control hydrogel, suggesting a bioactive effect. In conclusion, PVA/CS hydrogels containing HA or HASr particles were successfully synthesized and showed promising morphological, mechanical, and swelling properties, which are particularly required for scaffolding.

Polymer-Based Materials Loaded with Curcumin for Wound Healing Applications

Some of the currently used wound dressings have interesting features such as excellent porosity, good water-absorbing capacity, moderate water vapor transmission rate, high drug loading efficiency, and good capability to provide a moist environment, but they are limited in terms of antimicrobial properties. Their inability to protect the wound from microbial invasion results in wound exposure to microbial infections, resulting in a delayed wound healing process. Furthermore, some wound dressings are loaded with synthetic antibiotics that can cause adverse side effects on the patients. Natural-based compounds exhibit unique features such as good biocompatibility, reduced toxicity, etc. Curcumin, one such natural-based compound, has demonstrated several biological activities such as anticancer, antibacterial and antioxidant properties. Its good antibacterial and antioxidant activity make it beneficial for the treatment of wounds. Several researchers have developed different types of polymer-based wound dressings which were loaded with curcumin. These wound dressings displayed excellent features such as good biocompatibility, induction of skin regeneration, accelerated wound healing processes and excellent antioxidant and antibacterial activity. This review will be focused on the in vitro and in vivo therapeutic outcomes of wound dressings loaded with curcumin.

Chitosan-modified hyaluronic acid-based nanosized drug carriers

Fabrication possibilities, detailed size and structural characterization of biodegradable chitosan (Chit) polysaccharide-modified hyaluronic acid (HyA)-based colloidal carriers are demonstrated. The negatively charged and highly hydrophilic HyA polymer chains have been ionically modified by positively charged pure Chit and crosslinked Chit macromolecules at various Chit/HyA weight ratios, which resulted in the formation of carrier nanoparticles (NPs) having three different nanostructures depending on the polymer concentrations. Electrostatically-compensated Chit/HyA polymer coils with loose colloidal structure, tripolyphosphate (TPP)-crosslinked Chit-TPP/HyA NPs having interpenetrating polymer network and well-defined Chit-TPP_core-HyA_shell NPs with diameters of 100-300 nm were also prepared and were loaded with tocopherol (TCP) and cholecalciferol (D3) having Vitamin E and D activity, respectively. By using rheological, particle charge titration and conductivity studies we first confirmed that the expected 1:1 Chit/HyA monomer molar ratio is strongly influenced by the pH of the polymer solutions as well as the deacetylation degree of Chit which are crucial factors for the solubility, purity and the quality of the commercially available biocompatible Chit in aqueous medium. Encapsulation studies revealed that D3 could be better incorporated in every system, especially in Chit-TPP/HyA NPs, while for TCP the simple Chit/HyA polymer coils were the most promising carriers.

Potential of Natural Biomaterials in Nano-scale Drug Delivery

BACKGROUND

The usage of natural biomaterials or naturally derived materials intended for interface with biological systems has steadily increased in response to the high demand of amenable materials, which are suitable for purpose, biocompatible and biodegradable. There are many naturally derived polymers which overlap in terms of purpose as biomaterials but are equally diverse in their applications.

METHODS

This review examines the applications of the following naturally derived polymers; hyaluronic acid, silk fibroin, chitosan, collagen and tamarind polysaccharide (TSP); further focusing on the biomedical applications of each as well as emphasising on individual novel applications.

RESULTS

Each of the polymers was found to demonstrate a wide variety of successful biomedical applications fabricated as wound dressings, scaffolds, matrices, films, sponges, implants or hydrogels to suit the therapeutic need. Interestingly, blending and amelioration of polymer structures were the two selection strategies to modify the functionality of the polymers to suit the purpose. Further, these polymers have shown promise to deliver small molecule drugs, proteins and genes as nano-scale delivery systems.

CONCLUSION

The review highlights the range of applications of the aforementioned polymers as biomaterials. Hyaluronic acid, silk fibroin, chitosan, collagen and TSP have been successfully utilised as biomaterials in the subfields of implant enhancement, wound management, drug delivery, tissue engineering and nanotechnology. Whilst there are a number of associated advantages (i.e. biodegradability, biocompatibility, non-toxic, nonantigenic as well as amenability) the selected disadvantages of each individual polymer provide significant scope for their further exploration and overcoming challenges like feasibility of mass production at a relatively low cost.

Three Dimensional Printing Bilayer Membrane Scaffold Promotes Wound Healing

Full-thickness skin wounds are common and could be a heavy physical and economic burden. With the development of three dimensional (3D) printing technology, skin-like constructs have been fabricated for skin wound healing and regeneration. Although the 3D printed skin has great potential and enormous advantages before vascular networks can be well-constructed, living cells are not recommended for 3D skin printing for in vivo applications. Herein, we designed and printed a bilayer membrane (BLM) scaffold consisting of an outer poly (lactic-co-glycolic acid) (PLGA) membrane and a lower alginate hydrogel layer, which respectively mimicked the skin epidermis and dermis. The multi-porous alginate hydrogel of the BLM scaffolds promoted cell adhesion and proliferation in vitro, while the PLGA membrane prevented bacterial invasion and maintained the moisture content of the hydrogel. Skin regeneration using the bilayer scaffold was compared with that of PLGA, alginate hydrogel and the untreated defect in vivo. Tissue samples were analyzed using histopathological and immunohistochemical staining of CD31. In addition, mRNA expression levels of collagen markers [collagen type 1 alpha 1 (COL1a1) and collagen type 3 alpha 1 (COL3a1)] and inflammatory markers [interleukin-1β (IL-1β), as well as tumor necrosis factor (TNF-α)] were measured. Conclusively, the application of BLM scaffold resulted in highest levels of best skin regeneration by increasing neovascularization and boosting collagen I/III deposition. Taken together, the 3D-printed BLM scaffolds can promote wound healing, and are highly suitable for a wide range of applications as wound dressings or skin substitutes.

Enhanced chondrogenic differentiation of human mesenchymal stem cells in silk fibroin/chitosan/glycosaminoglycan scaffolds under dynamic culture condition

Cartilage tissue damage and diseases are the most common clinical situation that occurs because of aging and injury, thereby causing pain and loss of mobility. The inability of cartilage tissue to self-repair is instrumental in developing tissue engineered substitutes. To this effect, the present study aims to engineer cartilage construct by culturing umbilical cord blood-derived human mesenchymal stem cells (hMSCs) on novel 3D porous scaffolds developed from natural biopolymers, silk fibroin (SF) and chitosan (CS), with addition of cartilage matrix components, glucosamine (Gl) and chondroitin sulfate (Ch). The presence of Gl and Ch is expected to enhance cartilage regeneration. The developed SF/CS-Gl-Ch scaffolds possess desired pore size in the range 56.55-168.15 μm, 88-92% porosity, 44.7-46.8̊ contact angle, controlled swelling and biodegradability. Upon culturing under dynamic condition in a spinner flask bioreactor, the scaffold supported hMSCs attachment, proliferation, and further promoted chondrogenic differentiation. Cartilage-specific matrix and gene (Collagen II, Sox9 and aggrecan) expression analyses by histology, immunophenotype, immunofluorescence and quantitative PCR studies showed superiority of cell-scaffold construct generated in dynamic culture towards cartilage tissue generation as compared to cell aggregates formed by pellet culture. This study demonstrates the potentiality of SF/CS-Gl-Ch porous scaffold for the development of tissue construct for cartilage regeneration under dynamic culture condition.

Preparation of a novel asymmetric wettable chitosan-based sponge and its role in promoting chronic wound healing

Cutaneous chronic wounds are characterized by an impaired wound healing which may lead to infection. To surmount this problem, a novel quaternary ammonium chitosan nanoparticles (TMC NPs)/chitosan (CS)composite sponge with asymmetric wettability surfaces was successfully prepared. The optimum concentrations of TMC NPs and CS were 0.2 mg/mL and 2.0%, respectively. The incorporated TMC NPs could improve the antibacterial activity of the CS sponge. Asymmetric modification enables the CS sponge to have hydrophobic outer surface and hydrophilic inner surface. The hydrophobic surface of the sponge shows waterproof and anti-adhesion contaminant properties, whereas the hydrophilic surface preserves water-absorbing capability and efficiently inhibits the growth of bacteria. More importantly, in vivo chronic wound healing model evaluation reveals that TMC NPs/CS composite sponge promotes the wound healing and accelerates re-epithelialization and angiogenesis. And in vivo anti-infection test shows the TMC NPs/CS composite sponge could effectively prevent wound infection. These findings demonstrate that TMC NPs/CS composite sponge is a promising dressing material for chronic wounds.

Chitosan hydrogel scaffold reinforced with twisted poly(l lactic acid) aligned microfibrous bundle to mimic tendon extracellular matrix

Regeneration of tendon requires construct that provides necessary structural support closely mimicking the native architecture. To recreate this complex architecture a construct made of heat-treated, twisted poly(L lactic acid) (PLLA) microfibers coated with chitosan gel and surrounded by PLLA micro-fibrous layer was developed. The developed construct characterized using SEM showed the macroporous nature of gel coating around four distinct PLLA twisted fibrous bundle and a thin fiber layer surrounding the construct. FTIR analysis confirmed the presence of PLLA and chitosan construct. Mechanical strength increased with increasing number of strips. Protein adsorption was significantly low on the construct with outer covering that could retard cell adhesion to the outer layer. The developed construct showed good cell attachment and proliferation of tenocytes. These results indicate that the construct would find application for tendon tissue engineering.

Integrating 3D-printed PHBV/Calcium sulfate hemihydrate scaffold and chitosan hydrogel for enhanced osteogenic property

We developed the 3D-printed poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/calcium sulfate hemihydrate (PHBV/CaSH) scaffolds by using fused deposition modelling (FDM) technique and then coated the scaffolds with chitosan (CS) acetic acid solution. After drying and neutralization, CS hydrogel was formed on the surface of the scaffolds. The resultant PHBV/CaSH/CS scaffolds could promote the adhesion and proliferation of rat bone marrow stromal cells (rBMSCs) and enhance the osteogenesis of rBMSCs by up-regulating the expression level of osteogenic genes compared to the PHBV and PHBV/CaSH scaffolds. In vivo studies further demonstrated the PHBV/CaSH/CS scaffolds could effectively promote new bone formation. Therefore, integrating 3D-printed PHBV/CaSH scaffold and CS hrydogel represents a novel strategy to promote osteogensis property, showing full potential for bone defects repair.

Preparation, Characterization and Wound Healing Effects of New Membranes Based on Chitosan, Hyaluronic Acid and Arginine Derivatives

New membranes based on chitosan and chitosan-hyaluronic acid containing new arginine derivatives with thiazolidine-4-one scaffold have been prepared using the ionic cross-linking method. The presence of the arginine derivatives with thiazolidine-4-one scaffold into the polymer matrix was proved by Fourier-transform infrared spectroscopy (FT-IR). The scanning electron microscopy (SEM) revealed a micro-porous structure that is an important characteristic for the treatment of burns, favoring the exudate absorption, the rate of colonization, the cell structure, and the angiogenesis process. The developed polymeric membranes also showed good swelling degree, improved hydrophilicity, and biocompatibility in terms of surface free energy components, which supports their application for tissue regeneration. Moreover, the chitosan-arginine derivatives (CS-6h, CS-6i) and chitosan-hyaluronic acid-arginine derivative (CS-HA-6h) membranes showed good healing effects on the burn wound model induced to rats. For these membranes a complete reepithelialization was observed after 15 days of the experiment, which supports a faster healing process.

Application of tetracycline hydrochloride loaded-fungal chitosan and Aloe vera extract based composite sponges for wound dressing

Chitosan composite material has been used as an efficient drug carrier for potential drug delivery systems in specific cases of wound dressing management. In the present study, 0.5 g/L of the antibiotic tetracycline hydrochloride (TCH) was loaded into 1% fungal chitosan (FCS) incorporated with 0.2% of Aloe vera extract (AVE). Two types of sponges were prepared, with and without AVE, such as FCS-AVE-TCH and FCS-TCH, respectively. They were characterized by UV–Visible spectrophotometer, attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), and scanning electron microscopy (SEM). A constant amount of cumulative TCH release was observed from FCS-AVE-TCH composite sponges at the phosphate buffer saline (pH 7.4), they exhibited good antibacterial activity against both Gram-positive and Gram-negative bacteria. Furthermore, the Vero cells (African green monkey kidney cell line) treated by the composites showed augmented cell viability, which suggests that it could be used as a cost-effective, potential wound dressing material.

Laminated chitosan-based composite sponges for transmucosal delivery of novel protamine-decorated tripterine phytosomes: Ex-vivo mucopenetration and in-vivo pharmacokinetic assessments

In the current study, laminated chitosan (CS):hydroxypropyl methylcellulose (HPMC) composite sponges were exploited as solid matrices for buccal delivery of tripterine phytosomes functionalized with novel mucopenetrating protamine layer (PRT-TRI-PHY). Tripterine (TRI) is a herbal drug widely investigated as a potential anticancer candidate against various types of cancers. However, clinical use of TRI is handicapped by its low oral bioavailability. To surmount TRI pharmaceutical obstacles, TRI phytosomes (TRI-PHY) were prepared using solvent evaporation technique then coated with a protamine layer via electrostatic assembly process. The developed PRT-TRI-PHY showed a nano-metric size of 250 nm and positive zeta potential (+21.6 mV). Sponges loaded with PRT-TRI-PHY demonstrated a sustained release profile with superior mucoadhesion characteristics compared with the counterparts loaded with uncoated TRI-PHY. The ex-vivo permeation study via chicken pouch mucosa revealed that sponges loaded with PRT-TRI-PHY demonstrated 2.3-folds higher flux value compared with sponges loaded with uncoated TRI-PHY. Additionally, in-vivo pharmacokinetic study in healthy rabbits revealed the significantly higher bioavailability of PRT-TRI-PHY compared with TRI-PHY with relative bioavailability of 244%. Conclusively, mucoadhesive CS-HPMC sponges loaded with a novel mucopenetrating nanocarrier, PRT-TRI-PHY, could significantly improve the absorption of tripterine via buccal mucosa which would be of prime importance for its clinical utility.

Antibacterial activity against Staphylococcus aureus of chitosan/chondroitin sulfate nanocomplex aerogels alone and enriched with erythromycin and elephant garlic (Allium ampeloprasum L. var. ampeloprasum) extract

The antibacterial activity against Staphylococcus aureus of aerogels fabricated from colloidal suspensions of chitosan/chondroitin sulfate nanocomplexes is analyzed. Upon freeze-drying the colloidal suspensions, the aerogels presented a porous structure made of microsheets and microfibers. The aerogels could, in addition, be loaded with antimicrobial agents. Loaded with the antibiotic erythromycin, the aerogels showed crystalline deposits, affecting the topography of the samples as well as their mechanical properties, showing a decrease on the apparent Young’s modulus and hardness at 40% deformation. Loaded with elephant garlic (Allium ampeloprasum L. var. ampeloprasum) extract, the aerogels showed texturization of the microsheets and microfibers, and the higher relative mass allowed an increase on the apparent Young’s modulus and hardness at 40% deformation with respect to pristine aerogels. Unloaded aerogels showed activity against Staphylococcus aureus, including a methicillin-resistant strain. The release of erythromycin from the aerogels to an agar environment is governed by equilibrium forces with the polysaccharides, which allow modulating the load of antibiotic and its concomitant diffusion from the material. The diffusion of the active components of the elephant garlic extract did not show a dependence on the polysaccharide content, revealing a week interaction. The elephant garlic extract resulted active against the methicillin-resistant Staphylococcus aureus strain, while resistance was found for the antibiotic, revealing the therapeutic potential of the natural extract. The antimicrobial aerogels may be used for several therapeutic purposes, such as healing of infected chronic wounds.

Healing of skin wounds using a new cocoon scaffold loaded with platelet-rich or platelet-poor plasma

The cocoons of the silkwormBombyx moriare widely used as biofunctional materials.