Dressing with epigallocatechin gallate nanoparticles for wound regeneration.

Several reagents have been studied to overcome the problems encountered with antiseptic use, such as moderate cutaneous wound cytotoxicity and skin thinning. We successfully prepared a gelatin/chitosan/epigallocatechin gallate nanoparticle incorporated in a poly(γ-glutamic acid)/gelatin hydrogel, which comprised activated carbon fibers with gentamicin, to fabricate a sandwiched dressing to enhance wound regeneration. The inner layer of activated carbon fibers with gentamicin was designed to prevent bacterial infection, and the outer layer of gelatin/chitosan/epigallocatechin gallate nanoparticles incorporated in a poly(γ-glutamic acid)/gelatin hydrogel was designed to prevent inflammation and facilitate reepithelialization. An in vitro study demonstrated that the dressing effectively inhibited target microorganisms, and scanning electron microscope and confocal laser scanning microscope indicated that the nanoparticles were homogeneously dispersed and migrated into the hydrogel. The in vivo study reported that the sandwiched dressing, comprising the poly(γ-glutamic acid)/gelatin hydrogel, was easy to remove from the wound and facilitated wound tissue regeneration and accelerated healing process.

Silver-based wound dressings reduce bacterial burden and promote wound healing.

Various types of wound dressings have been designed for different purposes and functions. Controlling bacterial burden in a wound during the early phase is important for successful wound repair. Once bacterial burden is under control, the active promotion of wound healing is another important factor for efficient wound healing. This study investigated the potential of three silver-containing dressings, namely KoCarbonAg(®) , Aquacel(®) Ag and Acticoat 7, in reducing bacterial survival and promoting wound healing. The ability of these dressings to block the entry of bacteria from external environment and retain intrinsic bacteria was studied in vitro. In addition, the study used a rat model to compare the healing efficiencies of the three dressings and investigate the quantity of collagen synthesis in vivo. In vitro results indicated that the silver-containing dressings prevented bacterial growth in wounds by blocking the entry of external bacteria and by retaining the bacteria in the dressing. In vivo study indicated that reduction in bacterial burden accelerated wound healing. Wounds treated by the silver-containing dressings showed better healing than those treated with gauze. Moreover, KoCarbonAg(®) further accelerated wound healing by promoting collagen synthesis and arrangement.

Evaluation of various silver-containing dressing on infected excision wound healing study.

Silver-containing dressings have been widely used for controlling wound infection. However, the relationship between different concentrations of silver in dressings and their antimicrobial activities and wound-healing efficacies remains unclear. In the present study, we (in cooperation with Bio-medical Carbon Technology) investigated various silver-containing activated carbon fibers to understand the effects of different silver concentrations on the efficacies of a silver containing dressing. Our results indicated that various silver-containing activated carbon fibers exhibited good antibacterial effects and biocompatibility in terms of cell viability and that silver concentration showed a minor influence on cell growth. The infected excision wound model indicated that compared to silver-containing activated carbon fiber and other commercial silver-containing dressings assisted wound healing by promoting granulation and collagen deposition. Meanwhile, the silver ion can only be restrained in epidermis by intact skin. During application on the wound area, a temporary increase of serum silver can be detected, but this elevated serum silver level decreased to a subtle level after the removal of silver-containing activated carbon fiber.

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.

Evaluation of silver-containing activated carbon fiber for wound healing study: In vitro and in vivo.

Silver has antiseptic properties, anti-inflammatory properties, and is a broad-spectrum antibiotic for multidrug-resistant strains of bacteria. The commercially available product, Silverlon®, is a silver-plated three-dimensional polyamide fabric with a high silver concentration of 546 mg/100 cm(2). Thus, fibroblast cell growth is affected when exposed to the Silverlon® treated cell medium. Our study produced an activated carbon fiber wound dressing that incorporated various silver concentrations (in cooperation of Bio-Medical Carbon Technology) to examine antimicrobial properties and determine fibroblast cell viability upon exposure to the silver impregnated dressing material as compared to other commercially available products such as calcium alginate dressing, Sorbalgon®, and silver-polyamide fabric dressing, Silverlon®. The silver impregnated activated carbon fiber dressing induced less damage to fibroblast cells compared to the effect produced by Silverlon® and exhibited similar antibacterial abilities in vitro. An in vivo analysis showed that various silver concentrations impregnated activated carbon fiber dressings promoted tissue reconstruction for wound healing in rats with Pseudomonas aeruginosa infected wounds.

Growth of carbon nanofibers on carbon fabric with Ni nanocatalyst prepared using pulse electrodeposition.

The pulse electrodeposition (PED) technique was utilized to deposit nanosized (≤10 nm) Ni catalysts on carbon fabric (CF). Via an in situ potential profile, the PED technique can control the Ni catalyst loading, which is an important parameter for the growth of carbon nanofibers (CNFs) on CF. The preparation of CNF-coated CF (carpet-like CF) was carried out in a thermal chemical vapor deposition system with an optimum loading of Ni catalysts deposited in the PED pulse range from 20 to 320 cycles. CNFs grown at 813 K using different pulse cycles had a narrow diameter distribution, around 15 ± 5 nm to 29 ± 7 nm; they have a hydrophobic surface, like lotus leaves. Transmission electron microscopy images confirmed the graphene structural transformation of CNFs with the growth temperature. Solid wire CNFs were initially grown at 813 K with graphene edges exposed on the external surface. At elevated growth temperatures (1073 and 1173 K), bamboo-like CNFs were obtained, with herringbone structures and intersectional hollow cores.