Sericin Film Research Articles

Effect of storage and drying temperature on the gelation behavior and structural characteristics of sericin

Owing to unique properties, including the wound healing effect, sericin gel and films have attracted significant attention in the biomedical and cosmetic fields. The structural characteristics and properties of sericin gels and films are especially important owing to their effect on the performance of sericin in biomedical and cosmetic applications. In the present study, the effect of temperature on the gelation behavior, gel disruption, and sol–gel transition of sericin was examined using rheometry. In addition, the effect of the drying temperature on the structural characteristics of the sericin film was determined via Fourier transform infrared (FTIR) spectroscopy. The strength of the sericin gel increased and the gelation process was prolonged with decreasing storage temperatures. FTIR and differential scanning calorimetry (DSC) results also revealed that the crystallinity and the thermal decomposition temperature of the sericin film increased with decreasing drying temperature. The sericin gels were disrupted at a storage time of 40min when they were stored at temperatures higher than 50°C, and the corresponding gel strength decreased with increasing temperature. Furthermore, the thermo-reversible nature of gel–sol transition of sericin was confirmed by rheological and FTIR measurements.

Structure and properties of silk sericin obtained from different silkworm varieties

【Recently, many researchers have studied silk sericin because of its high water retention, good wound healing, good cyto-compatibility, and blood-glucose- and cholesterol-lowering effects. Although sericin film can be used in wound dressing and cosmetic packs, its poor mechanical properties have prevented its use in industrial fields. In the present study, sericin was obtained from different silkworm varieties, and the effect of silkworm variety on the structure and properties of sericin was examined. Except for a small difference in serine content, no significant difference in sericin was noted among the silkworm varieties. In addition, silkworm variety almost had no effect on solution viscosity, implying that it does not influence the molecular weight of sericin. Mechanical properties of sericin film were strongly affected by silkworm variety. Wonwon 126 showed the best mechanical properties, while N74 and Geumgwangju displayed the worst properties.】

Effects of solvent on the solution properties, structural characteristics and properties of silk sericin

Sericin films have attracted much attention from researchers in biomedical and cosmetic fields because of its unique properties, including good cytocompatibility and its promotion of wound healing. However, poor mechanical properties of sericin films have restricted its application in these fields. In this study, a new solvent, formic acid, was used to fabricate sericin solutions and films. The effects of formic acid on the structural characteristics and mechanical properties of the sericin solutions and films were examined and compared with water. The sericin/formic acid solution showed fewer aggregated sericin molecules, resulting in a lower turbidity than that of the sericin/water solution. In addition, the gelation of the sericin solution was retarded in formic acid compared to that of water. Sericin films cast from the formic acid solution exhibited a much higher crystallinity index than that produced from water. The tensile strength and elongation of the sericin films cast from the formic acid solution were more than double that of the sericin films cast from water. It is expected that the more stable sericin solution and high-crystallinity sericin films, which have significantly improved mechanical properties, produced by using formic acid as the solvent could be utilized in biomedical and cosmetic applications.

Novel cross‐linked sericin films: Characterization and properties

ABSTRACTIn the present study, an attempt has been made to convert sericin into film form and further make it insoluble by forming sericin–aluminum metal complex using alum salt, which may lead to some extent of cross‐linking. After complex formation sericin becomes insoluble in warm water as well as thermal stability and tensile strength improves significantly with increasing alum content. Metal complexed sericin films show good antimicrobial property and both the pure and alum modified sericin (AM‐Sericin) films show a very good oil barrier property. But after complex formation moisture content and swelling percentage of sericin film decreases quite significantly with increasing aluminum concentration. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41400.

Mineralization and Biocompatibility of Antheraea pernyi (A. pernyi) Silk Sericin Film for Potential Bone Tissue Engineering

This study aimed to investigate the mineralization of Antheraea pernyi (A. pernyi) silk sericin. Mineralization of A. pernyi sericin was performed by alternative soaking in calcium and phosphate. The inhibition of precipitation of calcium carbonate and von Kossa staining on A. pernyi sericin were tested, and the corresponding results prove that A. pernyi sericin has Ca binding activity. Scanning electron microscope (SEM) observation shows that spherical crystals could be nucleated on the A. pernyi sericin film. These crystals were confirmed to be hydroxyapatite according to FT-IR and XRD spectra, indicating that A. pernyi sericin is capable of mineralization. In addition, cell adhesion and growth activity assay demonstrate that A. pernyi sericin shows excellent biocompatibility for the growth of MG-63 cells.

Preparation and characterization of silk sericin/glycerol/graphene oxide nanocomposite film

Sericin (SS) is a protein that is secreted by silkworms, but it is usually discarded during the degumming process. To obtain and make use of the sericin, we prepared sericin/glycerol/graphene oxide nanocomposite film. The inherent brittleness of pure sericin film was improved by the addition of glycerol (Glc) as a plasticizer. To compensate for the reduced stiffness, we added graphene oxide (GO) into the SS/Glc film. At concentrations of up to 0.8 wt% relative to SS, GO dispersed evenly in the SS matrix without any agglomeration. The maximum tensile strength (9.5±0.7 MPa) and Young’s modulus (414.4±23.2 MPa) were obtained when the GO content was 0.8 wt% relative to SS. The elongation of SS/Glc/GO nanocomposite film also increased by approximately 40 % compared to SS/Glc film. The strong interfacial interaction between the SS and the GO was responsible for the increased stiffness. The increased elongation was due to the reduced crystallinity of the sericin matrix in the presence of GO.

The Effect of Extraction Conditions and Film Side on the Molecular Conformation of Silk Sericin Film

In this study, silk sericin films were prepared using different extraction methods, and the molecular conformation of sericin was examined using Fourier-transform infrared spectroscopy with attenuated total reflection geometry. Additionally, the effect of the film side (air-facing side or plate-facing side) on the molecular conformation of the sericin films was investigated. Interestingly, the molecular conformation of the sericin film depended on the film side. The molecular conformation of air-facing side of the sericin film was significantly influenced by extraction solution and time. The <TEX>${\beta}$</TEX>-sheet crystallization and the crystallinity index of the sericin film markedly increased with an increase in the extraction time in hot water. The order of the crystallinity indices for the sericin films obtained with different extraction solutions was as follows: citric acid solution > urea solution >> hot water. In contrast, no remarkable differences were observed in the molecular conformation of the plate-facing side of the sericin film after extraction in hot water for different time periods. Urea and citric acid solution extractions showed remarkably higher crystallinity indices for sericin than those obtained after hot water extraction. However, no significant differences were observed in the crystallinity index of sericin between urea and citric acid solution extraction in plate-facing side of the film.

Hydroxyapatite/sericin composite film prepared through mineralization of flexible ethanol-treated sericin film with simulated body fluids

Abstract A flexible ethanol-treated sericin film was prepared and used to form a hydroxyapatite/sericin composite film by mineralizing it with simulated body fluids solution. The hydroxyapatite mineral deposited on the surface of the ethanol-treated sericin film was characterized by Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, Energy Dispersive X-Ray Spectroscopy, and X-ray diffraction analysis. Results indicated that the quantity of deposited minerals increased with increasing mineralization time and showed a three-dimensional structure. This structure was determined to be calcium-deficient carbonate apatite with poor crystallinity and growth in the direction of the c -axis similar to natural bone mineral. The mechanical properties of the hydroxyapatite/sericin composite film decreased with increasing mineralization time. XTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) tests showed that the hydroxyapatite/sericin composite film promoted cell viability, which is beneficial for its application in bone tissue engineering.

The Influence of Gamma Irradiation and Ethylene Oxide Treatment on the Physical Properties of Silk Sericin Film

The Influence of Gamma Irradiation and Ethylene Oxide Treatment on the Physical Properties of Silk Sericin Film

A Novel Silk Sericin/Poly (Vinyl Alcohol) Composite Film Crosslinked with Genipin: Fabrication and Characterization for Tissue Engineering Applications

Silk sericin, a gumming protein from silk cocoons, has been a considerable natural protein-based biopolymer for fabrication of desired constructs for potential tissue engineering applications. This study investigated the formulation of a novel biopolymeric silk sericin/poly (vinyl alcohol) film with genipin as crosslinking agent and its physical properties. Silk sericin itself forms a fragile material, adding other polymers such as poly (vinyl alcohol) and glycerin, a plasticizer, resulting in a strong and flexible matrix. The results indicated that at higher concentration of genipin (0.1% w/v), the percentages of crosslinking in sericin/poly (vinyl alcohol) films was significantly higher. The matrices also exhibited higher tensile modulus value and higher elasticity at higher genipin concentration which can be inferred to higher integrity of the structure compared to matrices with genipin at low concentration (0.01% w/v). On the other hand, the reverse patterns were found in percentages of light transmission and the releasing profile of sericin from the composite films. Adding genipin into the matrices resulted in a lower percentage of light transmission indicated the increase in opacity. The releasing profile of sericin from the films showed that high genipin concentrations reduced the peak of protein released and trended to provide the sustain-released profile of protein. These findings indicated that silk sericin film can be formed and the concentrations of crosslinking agents really affect its physical properties.

The characterization of protein release from sericin film in the presence of an enzyme: Towards fibroblast growth factor-2 delivery

Aqueous preparations of silk protein (sericin) films were prepared to evaluate their biodegradation properties. In the absence of trypsin, sericin film swelled rapidly, kept its shape, and remained unaltered for 28 days or longer due to form β-sheet structures. In the presence of trypsin, sericin film gradually degraded; since the rate depended on the concentration of trypsin, the films likely underwent enzymatic hydrolysis. Sericin film incorporating the model protein drug fluorescein isothiocyanate–albumin (FA) also gradually degraded in the presence of trypsin and resulted in the sustained release of FA for 2 weeks or longer; in contrast, FA release was quite slow in the absence of trypsin. It is expected that sericin film has potential as a biodegradable and drug-releasing carrier. To evaluate the practical applicability of sericin film for the repair of defective tissues, fibroblast growth factor-2 (FGF-2) was incorporated into sericin films and the films were implanted on skull defects in rats. Whereas FGF-2 release was suppressed in the absence of trypsin in vitro, it appears that FGF-2, immobilized by ionic interactions between sericin and FGF-2, can be sustained-released in vivo from films incorporating 2500 or 250 ng of FGF-2 to support the growth of tissue around wounds.

Enhancing Effect of Glycerol on the Tensile Properties of Bombyx mori Cocoon Sericin Films

An environmental physical method described herein was developed to improve the tensile properties of Bombyx mori cocoon sericin films, by using the plasticizer of glycerol, which has a nontoxic effect compared with other chemical crosslinkers. The changes in the tensile characteristics and the structure of glycerolated (0–40 wt% of glycerol) sericin films were investigated. Sericin films, both in dry and wet states, showed enhanced tensile properties, which might be regulated by the addition of different concentrations of glycerol. The introduction of glycerol results in the higher amorphous structure in sericin films as evidenced by analysis of attenuated total reflection Fourier transform infrared (ATR-FTIR) spectra, thermogravimetry (TGA) and differential scanning calorimetry (DSC) curves. Scanning Electron Microscopy (SEM) observation revealed that glycerol was homogeneously blended with sericin molecules when its content was 10 wt%, while a small amount of redundant glycerol emerged on the surface of sericin films when its content was increased to 20 wt% or higher. Our results suggest that the introduction of glycerol is a novel nontoxic strategy which can improve the mechanical features of sericin-based materials and subsequently promote the feasibility of its application in tissue engineering.

Sustained-release of protein from biodegradable sericin film, gel and sponge

A silk protein, sericin, contains 18 kinds of amino acids, mostly polar side chains forming a complex of three principal polypeptides. The major polypeptides exhibit hydrophobic characteristics by forming a β-sheet structure in a hydrate state. As a drug-releasing biomaterial made by an aqueous process without using any cross linker, sericin is expected to form various hydrophobic dosage forms. However, its dosage form, with respect to the molecular weight and concentration of sericin, and its biodegradation behavior has not been studied in detail. In this study, the film, gel and sponge of sericin were prepared and examined to determine the release properties of the charged protein, fluorescein isothiocyanate–albumin (FA). The film and gel, as solid and semisolid forms, respectively, were also evaluated for their biodegradation behavior. For in vitro release, FA was sustained-released from these preparations. The concentration and dosage form markedly affected FA release. For in vivo biodegradation, the sericin preparations implanted subcutaneously in rats gradually decreased in size and weight. Histological examination indicated no marked inflammation at the site. As for in vivo release, FA remained for 3–6 weeks or more in rats. These findings suggest that sericin is suitable for use as a drug-releasing biomaterial.

Effect of Thai Silk Sericin and its Extraction Methods on L929 Mouse Fibroblast Cell Viability

Sericin, one of the two main proteins of silk cocoon besides fibroin, has been wildly used as ingredient in cosmetic products and nutrition supplements; however there are considerable controversial reports on its toxicity to cells and its advantages. This work aimed to investigate cell biocompatibility of sericin both in the systems of blended silk fibroin/sericin and pure sericin films using L929 mouse fibroblasts. The effect of concentration of commercial heat extracted sericin on cell viability was first investigated in the system of silk fibroin/sericin (F/S) films using 2 types of silk fibroin, Bombyx mori Nangnoi Srisaket 1 and Bombyx mori Jul 1/1. For both types of silk fibroin, it was found the lower cell number attached and proliferated on the blended F/S films at all sericin concentrations, compared to that on glass and pure fibroin. However, proliferation rate of cells cultured on the blended F/S films was similar to that of cells cultured on glass and pure fibroin films, as confirmed by population doubling time (PDT). Cytotoxicity of sericin extracted from 4 different methods including heat, acid, alkali and urea treatments was further studied in this work in the system of pure sericin films. It could be seen that acid and urea extracted sericin films showed high percentage of cell attachment at 92% and 88%, respectively. However, number of cells proliferated on all sericin films after 48 h culture was not significantly different. This indicated that L929 cells had different proliferation rate when cultured on different types of sericin films. Among 4 extraction methods, the PDT of cells proliferated on urea extracted sericin film was lowest (27 h) and also lower than that of the blended F/S films. This study suggested that sericin extracted by urea treatment could enhance proliferation rate of L929 mouse fibroblasts.

Sericin Film: Influence of Concentration on its Physical Properties

Sericin Film: Influence of Concentration on its Physical Properties

Preparation of Gel Film fromBombyx moriSilk Sericin and Its Characterization as a Wound Dressing

Sericin is a highly hydrophilic protein family acting as the glue in Bombyx mori silk. In order to apply sericin as a wound dressing, a novel sericin film named gel film was prepared by a simple process without using any chemical modifications: sericin solution was gelled with ethanol into a sheet shape and then dried. Infrared analysis revealed that the sericin gel film contained water-stable beta-sheet networks formed in the gelation step. This structural feature rendered the gel film morphologically stable against swelling and gave it good handling properties in the wet state. The sericin gel film rapidly absorbed water, equilibrating at a water content of about 80%, and exhibited elastic deformation up to a strain of about 25% in the wet state. A culture of mouse fibroblasts on the gel film indicated that it had low cell adhesion properties and no cytotoxicity. These characteristics of sericin gel film suggest its potential as a wound dressing.

화학 개질된 실크세리신 필름의 특성

Polar amino groups of the waste SS(silk-sericin) were modified by two isocyanate compounds of MOI(2-(methacryloyloxy)ethyl isocyanate) and AOI (2-(acryloyloxy)ethyl isocyanate). When the MOISS (MOI-modified silk sericin) or AOISS(AOI-modified silk sericin) was pressed hot, vinyl groups in the MOI or AOI were polymerized and then the flexible and transparent films were obtained. Tensile moduli and strengths of the MOISS films were significantly improved as the MOI contents increased. By the addition of the isocyanate compounds, silk sericin films exhibited lower solubility to the distilled water(80℃ ) and also lower swell ratio to the distilled water(room temperature). In the effect of tensile properties and restraining the water swelling, MOI was better than AOI. BOD(biochemical oxygen demand)/TOD(theoretical oxygen demand) of the pure sericin film was almost 100% perfect level after 10 days immersion into the activated sludge. With increasing isocyanate content reacted with polar amino groups, BOD/TOD decreased. When more than 50 mol% of polar amino groups remained unreacted, sericin films could retain more biodegradability. Comparing with MOI from the viewpoint of biodegradability, AOI was more effective.

Development of a novel sericin film suitable for wound dressing application

Development of a novel sericin film suitable for wound dressing application

Preparation of Sericin Film and its Cytocompatibility

Bombyx mori Sericin films were prepared with PEG-DE as cross linking agent. The main physical properties, structure characteristics, cytotoxicity and cell proliferation of sericin films were measured and analyzed. The result showed that sericin films prepared by cast method containing 30-40% of PEG-DE, showed good mechanical properties. PEG-DE caused the changes of the condensed structure of sericin films. The films prepared from sericin extracted both from silk-gland and cocoon shell showed good cytocompatibility. Silk sericin films with PEG-DE had no obvious cytotoxicity to cells.

Preparation of Waste Sericin Films Modified by Isocyanate Compounds and Tensile Properties and Biodegradability

Preparation of Waste Sericin Films Modified by Isocyanate Compounds and Tensile Properties and Biodegradability