Rheological and thermal characteristics of a two phase hydrogel system for potential wound healing applications

Hydrogels fabricated from single polymers have been extensively investigated for wound healing applications. However, in many cases a single polymer cannot meet divergent demands in terms of both properties and performance. In this work, a two phase hydrogel was prepared by physically imbedding a xerogel in the core of a freeze thawed hydrogel. The outer hydrogel was prepared by freeze thawing poly (vinyl alcohol) (PVA) and poly (acrylic acid) (PAA) while the xerogels were prepared by UV polymerisation of 1-vinyl-2-pyrrolidinone (NVP). The rheological results indicated that the two phase hydrogels over a period of 2 weeks formed a strong interface and demonstrated greater physical strength. This suggested that the inner gel containing PVP diffused into the PVA/PAA hydrogel, which in turn increased hydrogen bonding, resulting in the overall increase in the stiffness of the gel. Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) confirmed hydrogen bonding had occurred between the constituents of the two phase hydrogels. Thermal analysis suggested that T _g of each of the samples was above 80 °C, which indicated no impact on the behaviour of the gel at body temperature, but did however, give an indication of the stiffness of the dry polymer.     

Silver coated bioactive glass particles for wound healing applications

Bioactive glass particles (0.42SiO₂–0.15CaO–0.23Na₂O–0.20ZnO) of varying size (<90 μm and 425–850 μm) were synthesized and coated with silver (Ag) to produce Ag coated particles (PAg). These were compared against the uncoated analogous particles (Pcon.). Surface area analysis determined that Ag coating of the glass particles resulted in increased the surface area from 2.90 to 9.12 m²/g (90 μm) and 1.09–7.71 m²/g (425–850 μm). Scanning electron microscopy determined that the Ag coating remained at the surface and there was little diffusion through the bulk. Antibacterial (Escherichia coli—13 mm and Staphylococcus epidermidis—12 mm) and antifungal testing (Candida albicans—7.7 mm) determined that small Ag-coated glass particles exhibited the largest inhibition zones compared to uncoated particles. pH analysis determined an overall higher pH consider in the smaller particles, where after 24 h the large uncoated and Ag coated particles were 8.27 and 8.74 respectively, while the smaller uncoated and Ag coated particles attained pH values of 9.63 and 9.35 respectively.     

Development of novel chitin/nanosilver composite scaffolds for wound dressing applications

Antibiotic resistance of microorganisms is one of the major problems faced in the field of wound care and management resulting in complications like infection and delayed wound healing. Currently a lot of research is focused on developing newer antimicrobials to treat wounds infected with antibiotic resistant microorganisms. Silver has been used as an antimicrobial agent for a long time in the form of metallic silver and silver sulfadiazine ointments. Recently silver nanoparticles have come up as a potent antimicrobial agent and are finding diverse medical applications ranging from silver based dressings to silver coated medical devices. Chitin is a natural biopolymer with properties like biocompatibility and biodegradability. It is widely used as a scaffold for tissue engineering applications. In this work, we developed and characterized novel chitin/nanosilver composite scaffolds for wound healing applications. The antibacterial, blood clotting and cytotoxicity of the prepared composite scaffolds were also studied. These chitin/nanosilver composite scaffolds were found to be bactericidal against S. aureus and E. coli and good blood clotting ability. These results suggested that these chitin/nanosilver composite scaffolds could be used for wound healing applications.     

Physical, antibacterial and antioxidant properties of chitosan films incorporated with thyme oil for potential wound healing applications

Chitosan films incorporated with thyme oil for potential applications of wound dressing were successfully prepared by solvent casting method. The water vapor permeability, oxygen transmission rate, and mechanical properties of the films were determined. Surface and cross-section morphologies and the film thicknesses were determined by Scanning Electron Microscopy (SEM). Fourier transform infrared (FT-IR) spectroscopy was conducted to determine functional group interactions between the chitosan and thyme oil. Thermal behaviors of the films were analyzed by Thermal Gravimetry (TGA) and Differential Scanning Calorimetry (DSC). In addition, the antimicrobial and the antioxidant activities of the films were investigated. The antimicrobial test was carried by agar diffusion method and the growth inhibition effects of the films including different amount of thyme oil were tested on the gram negative microorganisms of Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and a gram positive microorganism of Staphylococcus aureus. The minimum thyme oil concentration in chitosan films showing the antimicrobial activity on all microorganisms used in the study was found as 1.2 % (v/v). In addition, this concentration showed the highest antioxidant activity due to mainly the carvacrol in thyme oil. Water vapor permeability and oxygen transmission rate of the films slightly increased, however, mechanical properties decreased with thyme oil incorporation. The results revealed that the thyme oil has a good potential to be incorporated into chitosan to make antibacterial and permeable films for wound healing applications.     

Development of nanotechnology for advancement and application in wound healing: a review

Wound healing is a series of different dynamic and complex phenomena. Many studies have been carried out based on the type and severity of wounds. However, to recover wounds faster there are no suitable drugs available, which are highly stable, less expensive as well as has no side effects. Nanomaterials have been proven to be the most promising agent for faster wound healing among all the other wound healing materials. This review briefly discusses the recent developments of wound healing by nanotechnology, their applicability and advantages. Nanomaterials have unique physicochemical, optical, and biological properties. Some of them can be directly applied for wound healing or some of them can be incorporated into scaffolds to create hydrogel matrix or nanocomposites, which promote wound healing through their antimicrobial, as well as selective anti‐ and pro‐inflammatory, and proangiogenic properties. Owing to their high surface area to volume ratio, nanomaterials have not only been used for drug delivery vectors but also can affect wound healing by influencing collagen deposition and realignment and provide approaches for skin tissue regeneration.Inspec keywords: skin, wounds, cellular biophysics, drug delivery systems, tissue engineering, hydrogels, nanocomposites, proteins, nanomedicineOther keywords: wound healing materials, nanomaterials, nanotechnology, proangiogenic properties, proinflammatory properties, collagen deposition, drug delivery vectors, skin tissue regeneration     

Nanocarrier-based systems for wound healing

In general, the systems intended for the treatment and recovery of wounds, seek to act as a coating for the damaged area, maintaining an adequate level of humidity, reducing pain, and preventing the invasion and proliferation of microorganisms. Although many of the systems that are currently on the market meet the purposes mentioned above, with the arrival of nanotechnology, it has sought to improve the performance of these coatings. The variety of nano-systems that have been proposed is very extensive, including the use of very different materials (natural or synthetic) ranging from polymers or lipids to systems derived from microorganisms. With the objective of improving the performance of the systems, seeking to combat several of the problems that arise in a wound, especially when it is chronic, these materials have been combined, giving rise to nanocomposites or scaffolds. In recent years, the interest in the development of systems for the treatment of wounds is notable, which is reflected in the increase in publications related to the subject. Therefore, this document presents generalities of systems involving nanocarriers, mentioning some examples of representative systems of each case.     

Development of a novel soft X-ray source for laboratory applications

A new soft X-ray source has been developed and characterized. X-rays are generated by the illumination of a multialkali photocathode with visible light to produce electrons that are accelerated onto a thin metal film anode. The novel feature of the design is that the photocathode and anode are in close proximity so that the X-ray emission is a spatial and temporal replica of the input light signal. Measurements of the X-ray emission brightness, energy spectrum and minimum source size are presented, and some unique applications of the new source are discussed.     

Effect of pore size and cross-linking of a novel collagen-elastin dermal substitute on wound healing

Collagen-elastin (CE) scaffolds are frequently used for dermal replacement in the treatment of full-thickness skin defects such as burn wounds. But little is known about the optimal pore size and level of cross-linking. Different formulations of dermal substitutes with unidirectional pores were tested in porcine full-thickness wounds in combination with autologous split skin mesh grafts (SSG). Effect on wound healing was evaluated both macro- and microscopically. CE scaffolds with a pore size of 80 or 100 μm resulted in good wound healing after one-stage grafting. Application of scaffolds with a larger average pore size (120 μm) resulted in more myofibroblasts and more foreign body giant cells (FBGC). Moderate crosslinking impaired wound healing as it resulted in more wound contraction, more FBGC and increased epidermal thickness compared to no cross-linking. In addition, take rate and redness were negatively affected compared to SSG only. Vascularization and the number of myofibroblasts were not affected by cross-linking. Surprisingly, stability of cross-linked scaffolds was not increased in the wound environment, in contrast to in vitro results. Cross-linking reduced the proliferation of fibroblasts in vitro, which might explain the reduced clinical outcome. The non-cross-linked CE substitute with unidirectional pores allowed one-stage grafting of SSG, resulting in good wound healing. In addition, only a very mild foreign body reaction was observed. Cross-linking of CE scaffolds negatively affected wound healing on several important parameters. The optimal non-cross-linked CE substitute is a promising candidate for future clinical evaluation.     

Development of fibroblast culture in three-dimensional activated carbon fiber-based scaffold for wound healing

This work developed a novel bi-layer wound dressing composed of 3D activated carbon fibers that allows facilitates fibroblast cell growth and migration to a wound site for tissue reconstruction, and the gentamicin is incorporated into a poly(γ-glutamic acid)/gelatin membrane to prevent bacterial infection. In an in vitro, field emission scanning electron microscopy shows that rat skin fibroblasts appeared and spread on the surface of activated carbon fibers, and penetrated the interior and exterior of the 3D activated carbon fiber construct to a depth of roughly 200 μm. An in vivo analysis shows that fibroblast cells containing the proposed 3D scaffold had the potential of a biologically functionalized dressing to accelerate wound closure. Additionally, fibroblasts migrated to the wound site in a bi-layer wound dressing containing fibroblasts, enhancing fibronectin and type I collagen expression, resulting in faster skin regeneration than that achieved with a Tegaderm? hydrocolloid dressing or gauze.     

Preparation of green cellulose diacetate-based antibacterial wound dressings for wound healing

Managing wounds is a growing universal problem and developing effective wound dressings to staunch bleeding and protect wounds from bacterial infections is an increasingly serious challenge. In this work, a remolding electrospinning nanofiber three-dimensional structure wound dressing (CCP) was prepared with superhydrophilicity, high water absorption and absorbing capacity, excellent hemostatic capacity and antibacterial ability, and biocompatibility to promote wound healing. Polyhexamethylene guanidine hydrochloride (PHMG) was grafted to cellulose diacetate (CDA) wound dressing surface through an amide reaction. A water contact angle analysis demonstrated that CCP wound dressing could be beneficial to promote wound exudate management effectively with rapid absorption of water within 0.2 s. In vitro hemo- and cytocompatibility assay showed that a CCP wound dressing had no significant hemotoxicity or cytoxicity. Specifically, CCP wound dressings could be beneficial to accelerate wound hemostasis and further reduce mortality caused by uncontrolled bleeding. Furthermore, CCP wound dressings have an excellent antibacterial ability, which could be beneficial to inhibit wound inflammatory over-reaction and promote normal wound healing. Combined together, the prepared wound dressing in this research effort is expected to have high-potential in clinical applications.     

EPDIM peptide-immobilized porous chitosan beads for enhanced wound healing: Preparation,characterizations and in vitro evaluation

EPDIM peptide is known to regulate cellular activities by interacting with α₃β₁ integrin, which can be contributed to wound healing process. In this study, EPDIM was immobilized onto three-dimensional porous chitosan beads (χtopore) as a scaffold for enhanced wound healing. The significant decrease in contact angle indicates that EPDIM immobilization could lead to the enhanced surface wettability after its immobilization. The immobilized EPDIM was fairly distributed along its surface and the morphology was maintained even after the reaction. The immobilized amount of EPDIM was found to be about 5.68 nmol/mg of χtopore by amino acid analysis. To verify the complete removal of coupling agents after EPDIM immobilization, each coupling agent was quantitatively analyzed by LC-MS. In vitro proliferation rates of both NIH 3T3 and HaCaT showed that EPDIM immobilization onto χtopore could significantly enhance the growth rate of both cells, while the unmodified χtopore did not increase in cell number even after 15 days of culture. Therefore, these results demonstrate that EPDIM peptide-immobilized χtopore can be utilized as an attractive scaffold for enhanced wound healing.     

Electrospun emodin polyvinylpyrrolidone blended nanofibrous membrane: a novel medicated biomaterial for drug delivery and accelerated wound healing

In this work, blended nanofibrous membranes were prepared by an electrospinning technique with polyvinylpyrrolidone (PVP) K90 as the filament-forming polymer, and emodin, an extract of polygonum cuspidate known as a medicinal plant, as the treatment drug. Detailed analysis of the blended nanofibrous membrane by scanning electron microscopy, Differential scanning calorimetry and X-ray diffraction revealed that emodin was well distributed in the ultrafine fibers in the form of amorphous nanosolid dispersions. Results from attenuated total reflectance Fourier transform infrared spectra suggested that the main interactions between PVP and emodin might be mediated through hydrogen bonding. In vitro dissolution tests proved that the blended nanofibrous membrane produced more desired release kinetics of the entrapped drug (emodin) as compared to the pure drug. Furthermore, wound healing test and histological evaluation revealed that the emodin loaded nanofibrous membrane to be more effective as a healing accelerator thereby proving potential strategies to develop composite drug delivery system as well as promising materials for future therapeutic biomedical applications.     

Performance evaluation of novel surface flame self-aspirated porous radiant burners for cooking applications

Porous radiant burners (PRBs) are based on the principle of porous media combustion (PMC) in which both combustion and stabilization of the flame take place towards the end of combustion zone (CZ). It has lot of advantages over conventional free flame burners. The porous matrix has high thermal conductivity and high emissivity. Hence, contributions to conduction, convection and radiation in the PMC are significant. This paper presents experimental results on the thermal and emission performance of newly developed, bi-layered, self-aspirated porous radiant surface flame burners used in cooking applications. It comprises firebrick material in the CZ and steel balls in the preheating zone (PZ). Performance of this burner is compared to that of a conventional cooking burner (CB) within the operating range of 0.5–2 kW. The effect of burner geometry (one is circular and the other one is square in cross section) on the thermal performance and emission using liquefied petroleum gas (LPG) as the fuel is also studied and their thermal performances are compared to the conventional ones. The experimental results have revealed that the thermal efficiencies of circular and square PRBs are much higher than those of the conventional burner. The maximum thermal efficiency of the self-aspirated circular porous radiant burner (SCPRB) is found to be 71.78% at the flow rate (V) of 2.0 m/s with a porosity of 85%, whereas the thermal efficiency obtained from self-aspirated square porous radiant burner (SSPRB) is marginally less than that of SCPRB at the corresponding flow rate and porosity. The emission levels are much lower in these novel PRBs as compared with the conventional burner and these values are well below the World Health Organization (WHO) standard. The NO_x emission values corresponding to the optimum velocity of 2.0 m/s are 87 ppm for CB, and 24 and 27 ppm, respectively, for SCPRB and SSPRB. CO emission values are 32, 33 and 155 ppm for SCPRB, SSPRB and CB, respectively, corresponding to the optimum velocity of flow.     

Antimicrobial and in vitro wound healing properties of novel clay based bionanocomposite films

The present study investigates the development of methyl cellulose (MC)–sodium alginate (SA)–montmorillonite (MMT) clay based bionanocomposite films with interesting wound healing properties. The differential scanning calorimetry analysis of the composite films revealed presence of single glass transition temperature (T_g) confirming the miscible nature of the ternary blended films. The increase in MMT ratio in the composite films reduced the mobility of biopolymer chains (MC/SA) which increased the T_g of the film. Thermogravimetric analysis showed that dispersion of clay (MMT) at nano level significantly delayed the weight loss that correlated with higher thermal stability of the composite films. It was observed that the developed films were able to exhibit antimicrobial activity against four typical pathogenic bacteria found in the presence of wound. The developed films were able to significantly inhibit (10 mg/ml) the growth of Enterococcus faecium and Pseudomonas aeruginosa. In vitro scratch assay indicated potential wound closure activities of MC-2–4 bionanocomposite films at their respective highest subtoxic doses. In conclusion, these ternary bionanocomposite films were found to be promising systems for wound healing applications.     

In situ encapsulation of horseradish peroxidase in electrospun porous silica fibers for potential biosensor applications

Nanoporous silica nanofibers have been employed as a matrix to encapsulate horseradish peroxide enzymes via a simple electrospinning method. A viscous solution of prehydrolyzed tetramethyl orthosilicate, beta-d-glucose, poly(vinyl alcohol), and enzymes were employed as spinning solution to generate porous fibers in the form of nonwoven mats. The silica fiber mats thus produced have a high surface area because of the small diameter (100 to 200 nm) of the fibers as well as the extreme porosity (2 to 4 nm) of individual fibers caused by the glucose template present in them. The high surface area, mechanical flexibility, thermal stability, reusability, and freedom of encapsulating various enzymes make porous silica nanofibers excellent biosensors.     

Sodium carboxymethylation-functionalized chitosan fibers for cutaneous wound healing application

A water absorption biomaterial, sodium carboxymethylation-functionalized chitosan fibers (Na-NOCC fibers) were prepared, applied for cutaneous wound repair, and characterized by FTIR and NMR. The water absorption of Na-NOCC fibers increased significantly with substitution degree rising, from 3.2 to 6.8 g/g, and higher than that of chitosan fibers (2.2 g/g) confirmed by swelling behavior. In the antibacterial action, the high degree of substitution of Na-NOCC fibers exhibited stronger antibacterial activities against E. coli (from 66.54% up to 88.86%). The inhibition of Na-NOCC fibers against S. aureus were above 90%, and more effective than E. coli. The cytotoxicity assay demonstrated that Na-NOCC2 fibers were no obvious cytotoxicity to mouse fibroblasts. Wound healing test and histological examination showed that significantly advanced granulation tissue and capillary formation in the healing-impaired wounds treated with Na-NOCC fibers, as compared to those treated with gauze, which demonstrated that Na- NOCC fibers could promote skin repair and might have great application for wound healing.     

Pluronic lecithin organogel of 5-aminosalicylic acid for wound healing

5-Aminosalicylic acid (5-ASA) is an aminosalicylate anti-inflammatory drug, which is also known as mesalazine or mesalamine. Currently employed in treating inflammatory bowel disease, ulcerative colitis, inflamed anus or rectum, and maintain remission in Crohn's disease. Evidence from the researchers highlighted its significant re-epithelization in allergic asthma, aphthous, and gastric ulcerative conditions. The objective of the study was to formulate the pluronic lecithin organogel (PLO) containing 5-ASA and evaluate its wound-healing ability in a full thickness excision wound rat model. The data obtained from in silico docking studies revealed 5-ASA is having an affinity towards the transforming growth factor-beta (TGF-β) specifically towards beta1. Among various formulations prepared (F1 to F8), F1, and F6 have shown a maximum in vitro drug release with optimum pH and viscosity. From MTT assay it was found that selected PLO formulations showed no toxicity and enhanced cell proliferation in HaCaT cell lines. In vivo wound-healing studies in albino Wistar rats has revealed that PLO accelerates wound closure and reepithelization to the statistically significant level on day 3 (p?相似文献   

Development of porous ceramic bodies for applications in tissue engineering and drug delivery systems

Hydroxyapatite (OHAp) particles with a specific surface area of 9 m²/g were obtained through a thermal treatment at 900 °C followed by deagglomeration by ball milling in ethanol for 20 h. Slurries with a 50-vol.% solids loading were prepared by mixing the particles with water. Organic inclusions with particles sizes from 55 to 750 μm were added and ceramic bodies were consolidated by slip casting. Dense and porous ceramic bodies were obtained with densities as low as 30% and as high as 94% and pore sizes up to 750 μm. The possibility of manufacturing ceramic bodies with porosity gradients designed according to the features of the porous ceramic bodies was studied in order to adapt them to the severe requirements of tissue engineering scaffolds.     

Studies on antimicrobial and wound healing applications of gauze coated with CHX–Ag hybrid NPs

In this study, chlorhexidine (CHX)–silver (Ag) hybrid nanoparticles (NPs) coated gauze was developed, and their bactericidal effect and in vivo wound healing capacities were tested. A new method was developed to synthesise the NPs, wherein Ag nitrate mixed with sodium (Na) metaphosphate and reduced using Na borohydride. Finally, CHX digluconate was added to form the hybrid NPs. To study the antibacterial efficacy of particles, the minimal inhibition concentration and biofilm degradation capacity against Gram‐positive and Gram‐negative bacteria was studied using Escherichia coli and Staphylococcus aureus. The results indicated that the NP inhibited biofilm formation and was bactericidal as well. The gauze was doped with NPs, and its wound healing property was evaluated using mice model. Results indicated that the wound healing process was fastened by using the NPs gauze doped with NPs without the administration of antibiotics.Inspec keywords: nanomedicine, nanoparticles, wounds, silver, cellular biophysics, biomedical materials, nanofabrication, microorganisms, antibacterial activityOther keywords: NPs gauze, antimicrobial wound healing applications, hybrid NPs, chlorhexidine–silver hybrid nanoparticles, CHX, coated gauze, bactericidal effect, minimal inhibition concentration, biofilm degradation capacity, Gram‐negative bacteria, wound healing property, wound healing process, in vivo wound healing capacities, Staphylococcus aureus, Escherichia coli, antibiotics administration, Na borohydride, Ag nitrate mixing, sodium metaphosphate, CHX digluconate, NP inhibited biofilm formation, Ag