Bio-fabrication of stem-cell-incorporated corneal epithelial and stromal equivalents from silk fibroin and gelatin-based biomaterial for canine corneal regeneration.

Corneal grafts are the imperative clinical treatment for canine corneal blindness. To serve the growing demand, this study aimed to generate tissue-engineered canine cornea in part of the corneal epithelium and underlying stroma based on canine limbal epithelial stem cells (cLESCs) seeded silk fibroin/gelatin (SF/G) film and canine corneal stromal stem cells (cCSSCs) seeded SF/G scaffold, respectively. Both cell types were successfully isolated by collagenase I. SF/G corneal films and stromal scaffolds served as the prospective substrates for cLESCs and cCSSCs by promoting cell adhesion, cell viability, and cell proliferation. The results revealed the upregulation of tumor protein P63 (P63) and ATP-binding cassette super-family G member 2 (Abcg2) of cLESCs as well as Keratocan (Kera), Lumican (Lum), aldehyde dehydrogenase 3 family member A1 (Aldh3a1) and Aquaporin 1 (Aqp1) of differentiated keratocytes. Moreover, immunohistochemistry illustrated the positive staining of tumor protein P63 (P63), aldehyde dehydrogenase 3 family member A1 (Aldh3a1), lumican (Lum) and collagen I (Col-I), which are considerable for native cornea. This study manifested a feasible platform to construct tissue-engineered canine cornea for functional grafts and positively contributed to the body of knowledge related to canine corneal stem cells.

Impacts of Blended Bombyx mori Silk Fibroin and Recombinant Spider Silk Fibroin Hydrogels on Cell Growth.

Binary-blended hydrogels fabricated from Bombyx mori silk fibroin (SF) and recombinant spider silk protein eADF4(C16) were developed and investigated concerning gelation and cellular interactions in vitro. With an increasing concentration of eADF4(C16), the gelation time of SF was shortened from typically one week to less than 48 h depending on the blending ratio. The biological tests with primary cells and two cell lines revealed that the cells cannot adhere and preferably formed cell aggregates on eADF4(C16) hydrogels, due to the polyanionic properties of eADF4(C16). Mixing SF in the blends ameliorated the cellular activities, as the proliferation of L929 fibroblasts and SaOS-2 osteoblast-like cells increased with an increase of SF content. The blended SF:eADF4(C16) hydrogels attained the advantages as well as overcame the limitations of each individual material, underlining the utilization of the hydrogels in several biomedical applications.

Comparative Study of Silk Fibroin-Based Hydrogels and Their Potential as Material for 3-Dimensional (3D) Printing.

Three-dimensional (3D) printing is regarded as a critical technology in material engineering for biomedical applications. From a previous report, silk fibroin (SF) has been used as a biomaterial for tissue engineering due to its biocompatibility, biodegradability, non-toxicity and robust mechanical properties which provide a potential as material for 3D-printing. In this study, SF-based hydrogels with different formulations and SF concentrations (1-3%wt) were prepared by natural gelation (SF/self-gelled), sodium tetradecyl sulfate-induced (SF/STS) and dimyristoyl glycerophosphorylglycerol-induced (SF/DMPG). From the results, 2%wt SF-based (2SF) hydrogels showed suitable properties for extrusion, such as storage modulus, shear-thinning behavior and degree of structure recovery. The 4-layer box structure of all 2SF-based hydrogel formulations could be printed without structural collapse. In addition, the mechanical stability of printed structures after three-step post-treatment was investigated. The printed structure of 2SF/STS and 2SF/DMPG hydrogels exhibited high stability with high degree of structure recovery as 70.4% and 53.7%, respectively, compared to 2SF/self-gelled construct as 38.9%. The 2SF/STS and 2SF/DMPG hydrogels showed a great potential to use as material for 3D-printing due to its rheological properties, printability and structure stability.

Crosslinked Silk Fibroin/Gelatin/Hyaluronan Blends as Scaffolds for Cell-Based Tissue Engineering.

3D porous scaffolds fabricated from binary and ternary blends of silk fibroin (SF), gelatin (G), and hyaluronan (HA) and crosslinked by the carbodiimide coupling reaction were developed. Water-stable scaffolds can be obtained after crosslinking, and the SFG and SFGHA samples were stable in cell culture medium up to 10 days. The presence of HA in the scaffolds with appropriate crosslinking conditions greatly enhanced the swellability. The microarchitecture of the freeze-dried scaffolds showed high porosity and interconnectivity. In particular, the pore size was significantly larger with an addition of HA. Biological activities of NIH/3T3 fibroblasts seeded on SFG and SFGHA scaffolds revealed that both scaffolds were able to support cell adhesion and proliferation of a 7-day culture. Furthermore, cell penetration into the scaffolds can be observed due to the interconnected porous structure of the scaffolds and the presence of bioactive materials which could attract the cells and support cell functions. The higher cell number was noticed in the SFGHA samples, possibly due to the HA component and the larger pore size which could improve the microenvironment for fibroblast adhesion, proliferation, and motility. The developed scaffolds from ternary blends showed potential in their application as 3D cell culture substrates in fibroblast-based tissue engineering.

Comprehensive Review of Hybrid Collagen and Silk Fibroin for Cutaneous Wound Healing.

The use of hybridisation strategy in biomaterials technology provides a powerful synergistic effect as a functional matrix. Silk fibroin (SF) has been widely used for drug delivery, and collagen (Col) resembles the extracellular matrix (ECM). This systematic review was performed to scrutinise the outcome of hybrid Col and SF for cutaneous wound healing. This paper reviewed the progress of related research based on in vitro and in vivo studies and the influence of the physicochemical properties of the hybrid in wound healing. The results indicated the positive outcome of hybridising Col and SF for cutaneous wound healing. The hybridisation of these biomaterials exhibits an excellent moisturising property, perfectly interconnected structure, excellent water absorption and retention capacity, an acceptable range of biodegradability, and synergistic effects in cell viability. The in vitro and in vivo studies clearly showed a promising outcome in the acceleration of cutaneous wound healing using an SF and Col hybrid scaffold. The review of this study can be used to design an appropriate hybrid scaffold for cutaneous wound healing. Therefore, this systematic review recapitulated that the hybridisation of Col and SF promoted rapid cutaneous healing through immediate wound closure and reepithelisation, with no sign of adverse events. This paper concludes on the need for further investigations of the hybrid SF and Col in the future to ensure that the hybrid biomaterials are well-suited for human skin.

Localized delivery of curcumin from injectable gelatin/Thai silk fibroin microspheres for anti-inflammatory treatment of osteoarthritis in a rat model.

The previously developed gelatin/silk fibroin microspheres were loaded with curcumin and applied for anti-inflammatory treatment in monosodium iodoacetate (MIA)-induced osteoarthritis (OA) in a rat model. The MIA-induced OA rats received a single intra-articular injection with gelatin or gelatin/silk fibroin (30/70) microspheres encapsulating curcumin. The therapeutic effects of treatment groups [concentration of interleukin-6 (IL-6) in blood serum, radiographic and the histological grading on articular joint] were compared with those of normal saline treated OA and normal rats. The result showed that both microsphere groups reduced the level of IL-6 in serum after 1 week of treatment. The gelatin/silk fibroin (30/70) microspheres encapsulating curcumin delayed the cellular destruction in articular joint and synovial tissue after 8 weeks. The radiographic and histological gradings on articular cartilage lesion and synovial tissue change of rats treated with gelatin/silk fibroin (30/70) microspheres encapsulating curcumin were close to those of the normal rats. It was explained that the slow-degrading gelatin/silk fibroin (30/70) microspheres released curcumin for extended period and showed a prolonged anti-inflammatory effect, compared to the fast-degrading gelatin microspheres. This delivery system of curcumin was suggested to be applied for localized treatment of anti-inflammatory in OA with minimal invasion.

Thai Silk Fibroin/Gelatin Sponges for the Dual Controlled Release of Curcumin and Docosahexaenoic Acid for Anticancer Treatment.

In this study, curcumin and/or docosahexaenoic acid (DHA) were encapsulated in Thai silk fibroin/gelatin (SF/G) sponges, prepared at different blending ratios, aimed to be applied as a controlled release system for localized cancer therapy. The SF/G sponges were fabricated by freeze-drying and glutaraldehyde cross-linking techniques. Physicochemical properties of the SF/G sponges were characterized. Then, curcumin and/or DHA were loaded in the sponges by physical adsorption. The encapsulation efficiency and the in vitro release of curcumin and/or DHA from the sponges were evaluated. SF/G sponges could encapsulate curcumin and/or DHA at high encapsulation efficiency. The highly cross-linked and slowly degrading SF/G (50/50) sponge released curcumin and/or DHA at the slowest rate. The in vitro cytotoxicity of the sponges against noncancer cells (L929 mouse fibroblast) and anticancer of curcumin and/or DHA released from the sponges against cervical cancer cells (CaSki) were tested. All sponges were not toxic to L929 mouse fibroblast. The mixed curcumin­DHA at the ratio of 1:4 had the highest inhibiting effect on the growth of CaSki, comparing with the release of curcumin or DHA alone. SF/G sponges could be a potential carrier for dual release of curcumin and DHA for anticancer effect.

Improvement of Physical and Wound Adhesion Properties of Silk Sericin and Polyvinyl Alcohol Dressing Using Glycerin.

OBJECTIVE: This study aimed to use glycerin to improve physical and wound adhesion properties of a wound dressing made of silk sericin and polyvinyl alcohol (PVA). DESIGN: Glycerin of a natural-derived plasticizer was used to modify the properties of silk sericin/PVA scaffolds. Various concentrations of glycerin were mixed with silk sericin and PVA and then fabricated into the scaffolds by a freeze-drying technique. The control study was performed to examine the properties of the silk sericin/PVA scaffolds with and without glycerin. MAIN OUTCOME MEASURES: Physical, mechanical, wound adhesion properties, the release profile of silk sericin, and in vivo safety of the silk sericin/PVA scaffolds with and without glycerin were investigated. MAIN RESULTS: The silk sericin/PVA scaffolds with glycerin exhibited more homogenous structure, less compressive modulus, higher Young modulus and elongation percentage, and a higher degree of crosslinking compared with the scaffold without glycerin. The silk sericin/PVA scaffold with 2% wt/vol glycerin showed more controlled release of silk sericin than the other scaffolds. The sustained release of silk sericin from the scaffold with glycerin would be advantageous for long-term healing of wounds. The silk sericin/PVA scaffold with 2% (wt/vol) glycerin was less adhesive to the wound compared with the scaffold without glycerin. Furthermore, the implantation of silk sericin/PVA scaffolds with 2% (wt/vol) glycerin did not cause any irritation to the tissue. CONCLUSION: The silk sericin/PVA scaffolds with glycerin were introduced as a biocompatible, more flexible, and less adhesive wound dressing than the scaffold without glycerin.

Cell engineering by the internalization of bioinstructive micelles for enhanced bone regeneration.

AIM: To direct precursor cells toward the osteoblastic lineage, by using an intracellular nanocarrier releasing dexamethasone. MATERIALS & METHODS: Biodegradable gelatin-based micelles entrapped dexamethasone (dex-micelles). Internalization efficiency and biocompatibility of dex-micelles and their potency for in vitro osteogenic differentiation and in vivo bone regeneration were assessed. RESULTS: Dex-micelles were internalized by rat bone marrow mesenchymal stem cells and demonstrated a pH-responsive release profile and an enhancement of 2D and 3D in vitro osteogenic differentiation. In vivo implantation of gelatin scaffolds seeded with rat bone marrow mesenchymal stem cells precultured for 24 h with dex-micelles promoted a significant enhancement of de novo bone formation in a rat ulna defect, in a dose-dependent manner. CONCLUSION: The proposed intracellular delivery system is a powerful tool to promote bone regeneration.

A green salt-leaching technique to produce sericin/PVA/glycerin scaffolds with distinguished characteristics for wound-dressing applications.

Sericin/PVA/glycerin scaffolds could be fabricated using the freeze-drying technique; they showed good physical and biological properties and can be applied as wound dressings. However, freeze-drying is an energy- and time-consuming process with a high associated cost. In this study, an alternative, solvent-free, energy- and time-saving, low-cost salt-leaching technique is introduced as a green technology to produce sericin/PVA/glycerin scaffolds. We found that sericin/PVA/glycerin scaffolds were successfully fabricated without any crosslinking using a salt-leaching technique. The salt-leached sericin/PVA/glycerin scaffolds had a porous structure with pore interconnectivity. The sericin in the salt-leached scaffolds had a crystallinity that was as high as that of the freeze-dried scaffolds. Compared to the freeze-dried scaffolds with the same composition, the salt-leached sericin/PVA/glycerin scaffolds has larger pores, a lower Young's modulus, and faster rates of biodegradation and sericin release. When cultured with L929 mouse fibroblast cells, a higher number of cells were found in the salt-leached scaffolds. Furthermore, the salt-leached scaffolds were less adhesive to the wound, which would reduce pain upon removal. Therefore, salt-leached sericin/PVA/glycerin scaffolds with distinguished characteristics were introduced as another choice of wound dressing, and their production process was simpler, more energy efficient, and saved time and money compared to the freeze-dried scaffolds.

Green synthesis of silk sericin-capped silver nanoparticles and their potent anti-bacterial activity.

In this study, a 'green chemistry' approach was introduced to synthesize silk sericin (SS)-capped silver nanoparticles (AgNPs) under an alkaline condition (pH 11) using SS as a reducing and stabilizing agent instead of toxic chemicals. The SS-capped AgNPs were successfully synthesized at various concentrations of SS and AgNO3, but the yields were different. A higher yield of SS-capped AgNPs was obtained when the concentrations of SS and AgNO3 were increased. The SS-capped AgNPs showed a round shape and uniform size with diameter at around 48 to 117 nm. The Fourier transform infrared (FT-IR) spectroscopy result proved that the carboxylate groups obtained from alkaline degradation of SS would be a reducing agent for the generation of AgNPs while COO- and NH2 + groups stabilized the AgNPs and prevented their precipitation or aggregation. Furthermore, the SS-capped AgNPs showed potent anti-bacterial activity against various gram-positive bacteria (minimal inhibitory concentration (MIC) 0.008 mM) and gram-negative bacteria (MIC ranging from 0.001 to 0.004 mM). Therefore, the SS-capped AgNPs would be a safe candidate for anti-bacterial applications.

The development of injectable gelatin/silk fibroin microspheres for the dual delivery of curcumin and piperine.

The objective of this study was to develop the microspheres from gelatin (G) and silk fibroin (SF) aimed to be applied for the controlled release of curcumin and piperine. The glutaraldehyde-crosslinked G/SF microspheres at various weight blending ratios (100/0, 70/30, 50/50, and 30/70) were successfully fabricated by water in oil emulsion technique. The microspheres prepared from all compositions were in a round shape with homogeneous size distribution both in the dried (194-217 µm) and swollen states (297-367 µm). When subjected in collagenase solution at physiological condition, the G microspheres gradually degraded within 14 days while the blended G/SF microspheres, particularly at 50/50 and 30/70, were not degraded. For the release application, the microspheres were loaded with curcumin and/or piperine. It was found that the microspheres composed of SF tended to entrap curcumin and piperine with the high entrapment and loading efficiencies, possibly due to their hydrophobic interactions. The G/SF microspheres, particularly at the ratios of 50/50 and 30/70, released curcumin and piperine in a sustained manner both for the single and dual release systems. The controlled dual release of curcumin and piperine from the G/SF microspheres would prolong their half-life, provide the optimal concentrations for therapeutic effects at a target site, and improve the bioavailability of curcumin. These novel injectable microspheres dually releasing curcumin and piperine would be introduced for the treatment of diseases without the need of operation.

Clinical potential of a silk sericin-releasing bioactive wound dressing for the treatment of split-thickness skin graft donor sites.

PURPOSE: An ethyl alcohol-precipitated silk sericin/PVA scaffold that controlled the release of silk sericin was previously developed and applied for the treatment of full-thickness wounds in rats and demonstrated efficient healing. In this study, we aimed to further evaluate the clinical potential of this scaffold, hereafter called "silk sericin-releasing wound dressing", for the treatment of split-thickness skin graft donor sites by comparison with the clinically available wound dressing known as "Bactigras®". METHODS: In vitro characterization and in vivo evaluation for safety of the wound dressings were performed. A clinical trial of the wound dressings was conducted according to standard protocols. RESULTS: The sericin released from the wound dressing was not toxic to HaCat human keratinocytes. A peel test indicated that the silk sericin-releasing wound dressing was less adhesive than Bactigras®, potentially reducing trauma and the risk of repeated injury upon removal. There was no evidence of skin irritation upon treatment with either wound dressing. When tested in patients with split-thickness skin graft donor sites, the wounds treated with the silk sericin-releasing wound dressing exhibited complete healing at 12 ± 5.0 days, whereas those treated with Bactigras® were completely healed at 14 ± 5.2 days (p = 1.99 × 10(-4)). In addition, treatment with the silk sericin-releasing wound dressing significantly reduced pain compared with Bactigras® particularly during the first 4 postoperative days (p = 2.70 × 10(-5) on day 1). CONCLUSION: We introduce this novel silk sericin-releasing wound dressing as an alternative treatment for split-thickness skin graft donor sites.

Preliminary characterization of genipin-cross-linked silk sericin/poly(vinyl alcohol) films as two-dimensional wound dressings for the healing of superficial wounds.

The genipin-cross-linked silk sericin/poly(vinyl alcohol) (PVA) films were developed aiming to be applied as two-dimensional wound dressings for the treatment of superficial wounds. The effects of genipin cross-linking concentration on the physical and biological properties of the films were investigated. The genipin-cross-linked silk sericin/PVA films showed the increased surface density, tensile strength, and percentage of elongation, but decreased percentage of light transmission, water vapor transmission rate, and water swelling, compared to the non-cross-linked films. This explained that the cross-linking bonds between genipin and silk sericin would reduce the mobility of molecular chains within the films, resulting in the more rigid molecular structure. Silk sericin was released from the genipin-cross-linked films in a sustained manner. In addition, either L929 mouse fibroblast or HaCat keratinocyte cells showed high percentage of viability when cultured on the silk sericin/PVA films cross-linked with 0.075 and 0.1% w/v genipin. The in vivo safety test performed according to ISO 10993-6 confirmed that the genipin-cross-linked silk sericin/PVA films were safe for the medical usages. The efficacy of the films for the treatment of superficial skin wounds will be further investigated in vivo and clinically. The genipin-cross-linked silk sericin/PVA films would be promising choices of two-dimensional wound dressings for the treatment of superficial wounds.

Development of electrospun beaded fibers from Thai silk fibroin and gelatin for controlled release application.

Thai silk fibroin and gelatin are attractive biomaterials for tissue engineering and controlled release applications due to their biocompatibility, biodegradability, and bioactive properties. The development of electrospun fiber mats from silk fibroin and gelatin were reported previously. However, burst drug release from such fiber mats remained the problem. In this study, the formation of beads on the fibers aiming to be used for the sustained release of drug was of our interest. The beaded fiber mats were fabricated using electrospinning technique by controlling the solution concentration, weight blending ratio of Thai silk fibroin/gelatin blend, and applied voltage. It was found that the optimal conditions including the solution concentration and the weight blending ratio of Thai silk fibroin/gelatin at 8-10% (w/v) and 70/30, respectively, with the applied voltage at 18 kV provided the fibers with homogeneous formation of beads. Then, the beaded fiber mats obtained were crosslinked by the reaction of carbodiimide hydrochloride (EDC)/N-hydroxysuccinimide (NHS). Methylene blue as a model active compound was loaded on the fiber mats. The release test of methylene blue from the beaded fiber mats was carried out in comparison to that of the smooth fiber mats without beads. It was found that the beaded fiber mats could prolong the release of methylene blue, comparing to the smooth fiber mats without beads. This was possibly due to the beaded fiber mats that would absorb and retain higher amount of methylene blue than the fiber mats without beads. Thai silk fibroin/gelatin beaded fiber mats were established as an effective carrier for the controlled release applications.

Physico-chemical properties and efficacy of silk fibroin fabric coated with different waxes as wound dressing.

Silk fibroin (SF) has been widely used as a wound dressing material due to its suitable physical and biological characteristics. In this study, a non-adhesive wound dressing which applies to cover the wound surface as an absorbent pad that would absorb wound fluid while accelerate wound healing was developed. The modification of SF fabrics by wax coating was purposed to prepare the non-adhesive wound dressing that is required in order to minimize pain and risk of repeated injury. SF woven fabrics were coated with different types of waxes including shellac wax, beeswax, or carnauba wax. Physical and mechanical properties of the wax-coated SF fabrics were characterized. It was clearly observed that all waxes could be successfully coated on the SF fabrics, possibly due to the hydrophobic interactions between hydrophobic domains of SF and waxes. The wax coating improved tensile modulus and percentage of elongation of the SF fabrics due to the denser structure and the thicker fibers coated. The in vitro degradation study demonstrated that all wax-coated SF fabrics remained up to 90% of their original weights after 7 weeks of incubation in lysozyme solution under physiological conditions. The wax coating did not affect the degradation behavior of the SF fabrics. A peel test of the wax-coated SF fabrics was carried out in the partial- and full-thickness wounds of porcine skin in comparison to that of the commercial wound dressing. Any wax-coated SF fabrics were less adhesive than the control, as confirmed by less number of cells attached and less adhesive force. This might be that the wax-coated SF fabrics showed the hydrophobic property, allowing the loosely adherence to the hydrophilic wound surface. In addition, the in vivo biocompatibility test of the wax-coated SF fabrics was performed in Sprague-Dawley rats with subcutaneous model. The irritation scores indicated that the carnauba wax-coated SF fabric was not irritant while the shellac wax or beeswax-coated SF fabrics were slightly irritant, comparing with the commercial wound dressing. Therefore, SF fabrics coated with waxes, particularly carnauba wax, would be promising choices of non-adhesive wound dressing.

Accelerated healing of full-thickness wounds by genipin-crosslinked silk sericin/PVA scaffolds.

Silk sericin has recently been studied for its advantageous biological properties, including its ability to promote wound healing. This study developed a delivery system to accelerate the healing of full-thickness wounds. Three-dimensional scaffolds were fabricated from poly(vinyl alcohol) (PVA), glycerin (as a plasticizer) and genipin (as a crosslinking agent), with or without sericin. The physical and biological properties of the genipin-crosslinked sericin/PVA scaffolds were investigated and compared with those of scaffolds without sericin. The genipin-crosslinked sericin/PVA scaffolds exhibited a higher compressive modulus and greater swelling in water than the scaffolds without sericin. Sericin also exhibited controlled release from the scaffolds. The genipin-crosslinked sericin/PVA scaffolds promoted the attachment and proliferation of L929 mouse fibroblasts. After application to full-thickness rat wounds, the wounds treated with genipin-crosslinked sericin/PVA scaffolds showed a significantly greater reduction in wound size, collagen formation and epithelialization compared with the control scaffolds without sericin but lower numbers of macrophages and multinucleated giant cells. These results indicate that the delivery of sericin from the novel genipin-crosslinked scaffolds efficiently healed the wound. Therefore, these genipin-crosslinked sericin/PVA scaffolds represent a promising candidate for the accelerated healing of full-thickness wounds.

Modification of human cancellous bone using Thai silk fibroin and gelatin for enhanced osteoconductive potential.

The modification of human cancellous bone (hBONE) with silk fibroin/gelatin (SF/G) using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC)/N-hydroxysuccini-mide (NHS) crosslinking was established. The SF/G solutions at a weight ratio of 50/50 and the solution concentrations of 1, 2, and 4 wt % were studied. SF/G sub-matrix was formed on the surface and inside pore structure of hBONE. All hBONE scaffolds modified with SF/G showed smaller pore sizes, less porosity, and slightly lower compressive modulus than unmodified hBONE. SF/G sub-matrix was gradually biodegraded in collagenase solution along 4 days. The hBONE scaffolds modified with SF/G, particularly at 2 and 4 wt % solution concentrations, promoted attachment, proliferation, and osteogenic differentiation of bone marrow-derived mesenchymal stem cells (MSC), comparing to the original hBONE. The highest cell number, ALP activity and calcium production were observed for MSC cultured on the hBONE scaffolds modified with 4 wt % SF/G. The mineralization was also remarkably induced in the cases of modified hBONE scaffolds as observed from the deposited calcium phosphate by EDS. The modification of hBONE with SF/G was, therefore, the promising method to enhance the osteoconductive potential of human bone graft for bone tissue engineering.

Development of ethyl alcohol-precipitated silk sericin/polyvinyl alcohol scaffolds for accelerated healing of full-thickness wounds.

Silk sericin has been recently reported for its advantageous biological properties to promote wound healing. In this study, we established that the ethyl alcohol (EtOH) could be used to precipitate sericin and form the stable sericin/polyvinyl alcohol (PVA) scaffolds without the crosslinking. The sericin/PVA scaffolds were fabricated via freeze-drying and subsequently precipitating in various concentrations of EtOH. The EtOH-precipitated sericin/PVA scaffolds showed denser structure, higher compressive modulus, but lower water swelling ability than the non-precipitated scaffolds. Sericin could be released from the EtOH-precipitated sericin/PVA scaffolds in a sustained manner. After cultured with L929 mouse fibroblasts, the 70 vol% EtOH-precipitated sericin/PVA scaffolds showed the highest potential to promote cell proliferation. After applied to the full-thickness wounds of rats, the 70 vol% EtOH-precipitated sericin/PVA scaffolds showed significantly higher percentage of wound size reduction and higher extent of type III collagen formation and epithelialization, compared with the control scaffolds without sericin. The accelerated wound healing by the 70 vol% EtOH-precipitated sericin/PVA scaffolds was possibly due to (1) the bioactivity of sericin itself to promote wound healing, (2) the sustained release of precipitated sericin from the scaffolds, and (3) the activation and recruitment of wound healing-macrophages by sericin to the wounds. This finding suggested that the EtOH-precipitated sericin/PVA scaffolds were more effective for the wound healing, comparing with the EtOH-precipitated PVA scaffolds without sericin.