Fibroin and Polyvinyl Alcohol Hydrogel Wound Dressing Containing Silk Sericin Prepared Using High-Pressure Carbon Dioxide

The Impact of Green Physical Crosslinking Methods on the Development of Sericin-Based Biohydrogels for Wound Healing

Silk sericin (SS)-based hydrogels show promise for wound healing due to their biocompatibility, moisture regulation, and cell proliferation properties. However, there is still a need to develop green crosslinking methods to obtain non-toxic, absorbent, and mechanically strong SS hydrogels. This study investigated the effects of three green crosslinking methods, annealing treatment (T), exposure to an absolute ethanol vapor atmosphere (V.E), and water vapor (V.A), on the physicochemical and mechanical properties of SS and poly (vinyl alcohol) (PVA) biohydrogels. X-ray diffraction and Fourier-transform infrared spectroscopy were used to determine chemical structures. Thermal properties and morphological changes were studied through thermogravimetric analysis and scanning electron microscopy, respectively. The water absorption capacity, mass loss, sericin release in phosphate-buffered saline (PBS), and compressive strength were also evaluated. The results showed that physical crosslinking methods induced different structural transitions in the biohydrogels, impacting their mechanical properties. In particular, V.A hydrogen presented the highest compressive strength at 80% deformation owing to its compact and porous structure with crystallization and bonding sites. Moreover, both the V.A and T hydrogels exhibited improved absorption capacity, stability, and slow SS release in PBS. These results demonstrate the potential of green physical crosslinking techniques for producing SS/PVA biomaterials for wound healing applications.

Exploring the apoptotic effects of sericin on HCT116 cells through comprehensive nanostring transcriptomics and proteomics analysis

Sericin, a silk protein from Bombyx mori (silkworms), has many applications, including cosmetics, anti-inflammation, and anti-cancer. Sericin complexes with nanoparticles have shown promise for breast cancer cell lines. Apoptosis, a programmed cell death mechanism, stops cancer cell growth. This study found that Sericin urea extract significantly affected HCT116 cell viability (IC50 = 42.00 ± 0.002 µg/mL) and caused apoptosis in over 80% of treated cells. S-FTIR analysis showed significant changes in Sericin-treated cells' macromolecule composition, particularly in the lipid and nucleic acid areas, indicating major cellular modifications. A transcriptomics study found upregulation of the apoptotic signaling genes FASLG, TNFSF10, CASP3, CASP7, CASP8, and CASP10. Early apoptotic proteins also showed that BAD, AKT, CASP9, p53, and CASP8 were significantly upregulated. A proteomics study illuminated Sericin-treated cells' altered protein patterns. Our results show that Sericin activated the extrinsic apoptosis pathway via the caspase cascade (CASP8/10 and CASP3/7) and the death receptor pathway, involving TNFSF10 or FASLG, in HCT116 cells. Upregulation of p53 increases CASP8, which activates CASP3 and causes HCT116 cell death. This multi-omics study illuminates the molecular mechanisms of Sericin-induced apoptosis, sheds light on its potential cancer treatment applications, and helps us understand the complex relationship between silk-derived proteins and cellular processes.

Low-adhesion and low-swelling hydrogel based on alginate and carbonated water to prevent temporary dilation of wound sites

Hydrogel-based wound dressings have been developed for rapid wound healing; however, their adhesive properties have not been adequately investigated. Excessive adhesion to the skin causes wound expansion and pain when hydrogels absorb exudates and swell at wound sites. Herein, we developed a low-adhesion and low-swelling hydrogel dressing using alginate, which is non-adhesive to cells and skin tissue, CaCO3, and carbonated water. The alginate/CaCO3 solution rapidly formed a hydrogel upon the addition of carbonated water, and the CO2 in the hydrogel diffused into the atmosphere, preventing acidification and obtaining a pH value suitable for wound healing. Remarkably, the skin adhesion and swelling of the hydrogel were 11.9- to 16.5-fold and 1.9-fold lower, respectively, than those of clinical low-adhesion hydrogel dressings. In vivo wound-healing tests in mice demonstrated its therapeutic efficacy, and the prepared hydrogel prevented temporary wound dilation during early healing. These results illustrate the importance of controlling skin adhesion and swelling in wound dressings and demonstrate the potential clinical applications of this wound-friendly hydrogel dressing.

Characterization and Evaluation of Silk Sericin-Based Hydrogel: A Promising Biomaterial for Efficient Healing of Acute Wounds

The present study was aimed to prepare the potent silk sericin-based hydrogels in combination with plant extracts (curcumin and banana peel powder) and silver nanoparticles (AgNPs) to accelerate the acute wound healing process. Experimental excision wounds were created in mice by biopsy puncture, and the wound healing potential of silk sericin (2%)-based hydrogel and its combinations with curcumin (2%), banana peel powder (2%), and AgNPs (2%) was estimated by calculating the percent wound contraction, healing time, histology of skin tissues, and different biochemical tests. The results showed that the mice treated with sericin-based hydrogels showed significantly (P < 0.001) high percent wound contraction as compared to negative control, and wounds were healed in 11 days. The histological evaluation also showed that wounds covered with hydrogels were healed more than the uncovered wounds. Furthermore, the results of biochemical tests revealed that the treatment groups showed a significant (P < 0.001) decrease in the serum level of pro-inflammatory cytokines (IL-6). A significant (P < 0.001) increase in anti-inflammatory cytokines (IL-10) and anti-oxidant enzymes was observed in treatment groups. The highest wound healing potential was observed by sericin-based hydrogel containing banana peel powder, leaving behind the commercially available ointment polyfax (positive control). It can be concluded that the silk sericin-based hydrogels in combination with plant extract and AgNPs can be used as natural biomaterials in wound dressing for the rapid healing of acute wounds.

Sericin coated thin polymeric films reduce keratinocyte proliferation via the mTOR pathway and epidermal inflammation through IL17 signaling in psoriasis rat model

Therapeutic treatment forms can play significant roles in resolving psoriatic plaques or promoting wound repair in psoriatic skin. Considering the biocompatibility, mechanical strength, flexibility, and adhesive properties of silk fibroin sheets/films, it is useful to combine them with anti-psoriatic agents and healing stimulants, notably silk sericin. Here, we evaluate the curative properties of sericin-coated thin polymeric films (ScF) fabricated from silk fibroin, using an imiquimod-induced psoriasis rat model. The film biocompatibility and psoriatic wound improvement capacity was assessed. A proteomics study was performed to understand the disease resolving mechanisms. Skin-implantation study exhibited the non-irritation property of ScF films, which alleviate eczema histopathology. Immunohistochemical and gene expression revealed the depletion of β-defensin, caspase-3 and -9, TNF-α, CCL-20, IL-1β, IL-17, TGF-β, and Wnt expressions and S100a14 mRNA level. The proteomics study suggested that ScF diminish keratinocyte proliferation via the mTOR pathway by downregulating mTOR protein, corresponding to the modulation of TNF-α, Wnt, and IL-1β levels, leading to the enhancement of anti-inflammatory environment by IL-17 downregulation. Hematology data demonstrated the safety of using these biomaterials, which provide a potential therapeutic-option for psoriasis treatment due to desirable effects, especially anti-proliferation and anti-inflammation, functioning via the mTOR pathway and control of IL-17 signaling.

Silk fibroin carriers with sustained release capacity for treating neurological diseases

Neurological diseases such as traumatic brain injury, cerebral ischemia, Parkinson's, and Alzheimer's disease usually occur in the central and peripheral nervous system and result in nervous dysfunction, such as cognitive impairment and motor dysfunction. Long-term clinical intervention is necessary for neurological diseases where neural stem cell transplantation has made substantial progress. However, many risks remain for cell therapy, such as puncture bleeding, postoperative infection, low transplantation success rate, and tumor formation. Sustained drug delivery, which aims to maintain the desired steady-state drug concentrations in plasma or local injection sites, is considered as a feasible option to help overcome side effects and improve the therapeutic efficiency of drugs on neurological diseases. Natural polymers such as silk fibroin have excellent biocompatibility, which can be prepared for various end-use material formats, such as microsphere, gel, coating/film, scaffold/conduit, microneedle, and enables the dynamic release of loaded drugs to achieve a desired therapeutic response. Sustained-release drug delivery systems are based on the mechanism of diffusion and degradation by altering the structures of silk fibroin and drugs, factors, and cells, which can induce nerve recovery and restore the function of the nervous system in a slow and persistent manner. Based on these desirable properties of silk fibroin as a carrier with sustained-release capacity, this paper discusses the role of various forms of silk fibroin-based drug delivery materials in treating neurological diseases in recent years.

Physicochemical Properties of Egg-Box-Mediated Hydrogels with Transiently Decreased pH Employing Carbonated Water

Anionic polysaccharides, including low-methoxy (LM) pectin, are extensively used in biomaterial applications owing to their safety, biocompatibility, and feasibility in constructing supramolecular assemblies by forming egg-box structures with divalent cations. Mixing an LM pectin solution with CaCO₃ spontaneously forms a hydrogel. The gelation behavior can be controlled by adding an acidic compound to change the solubility of CaCO₃. CO₂ is used as the acidic agent and can be easily removed after gelation, thereby reducing the acidity of the final hydrogel. However, CO₂ addition has been controlled under varied thermodynamical conditions; therefore, specific CO₂ effects on gelation are not necessarily visualized. To evaluate the CO₂ impact on the final hydrogel, which would be extended to control hydrogel properties further, we utilized carbonated water to supply CO₂ into the gelation mixture without changing its thermodynamic conditions. The addition of the carbonated water accelerated gelation and significantly increased the mechanical strength, promoting cross-linking. However, the CO₂ volatilized into the atmosphere, and the final hydrogel became more alkaline than that without the carbonated water, probably because a considerable amount of the carboxy group was consumed for cross-linking. Moreover, when aerogels were prepared from the hydrogels with carbonated water, they exhibited highly ordered networks of elongated porosity in scanning electron microscopy, proposing an intrinsic structural change by CO₂ in the carbonated water. We also controlled the pH and strength of the final hydrogels by changing the CO₂ amounts in the carbonated water added, thereby validating the significant effect of CO₂ on hydrogel properties and the feasibility of using carbonated water.

Effects of sericin and egg white on the inflammation of damaged skin in mice

Sericin and egg white (EW) have shown the ability to promote wound healing. However, there have been insufficient studies regarding the effects of sericin and EW mixtures on wound healing. This study aimed to investigate the effects of a hybrid sericin and EW solution on wound repair and inflammation-related indicators in mouse skin. In this work, sericin with a low molecular weight was first mixed with homogeneous EW to prepare a hybrid wound dressing. Histology evaluation, the expression of C-reactive protein (CRP) and inflammatory cytokines in mice were tested to determine the effects of this dressing on skin injuries in mice. The results showed that sericin and the hybrid solution of sericin and EW effectively promoted wound healing in mouse skin. The wound recovery rates of mice 12 days after treatment with a medium dose of sericin (0.2 g ml^-1) and the same dosage of sericin with added EW were 1.32 and 1.65 times that of mice treated with phosphate buffer saline as a control, respectively. In addition, the mixture solution was more effective in wound healing than sericin alone. Sericin with EW significantly reduced the expression of CRP and inflammatory cytokines in mice during wound healing. A sericin and EW hybrid solution can effectively shorten the time needed for wound healing and reduce inflammation-related indicators in mice, making it a promising candidate for wound dressing.

Sericin-Based Poly(Vinyl) Alcohol Relieves Plaque and Epidermal Lesions in Psoriasis; a Chance for Dressing Development in a Specific Area

The noncontagious immune-mediated skin disease known as psoriasis is regarded as a chronic skin condition with a 0.09-11.4% global prevalence. The main obstacle to the eradication of the disease continues to be insufficient treatment options. Sericin, a natural biopolymer from Bombyx mori cocoons, can improve skin conditions via its immunomodulatory effect. Many external therapeutic methods are currently used to treat psoriasis, but sericin-based hydrogel is not yet used to treat plaques of eczema. Through the use of an imiquimod rat model, this study sought to identify the physical and chemical characteristics of a silk sericin-based poly(vinyl) alcohol (SS/PVA) hydrogel and assess both its therapeutic and toxic effects on psoriasis. The cytokines, chemokines, and genes involved in the pathogenesis of psoriasis were investigated, focusing on the immuno-pathological relationships. We discovered that the SS/PVA had a stable fabrication and proper release. Additionally, the anti-inflammatory, antioxidant, and anti-apoptotic properties of SS/PVA reduced the severity of psoriasis in both gross and microscopic skin lesions. This was demonstrated by a decrease in the epidermal histopathology score, upregulation of nuclear factor erythroid 2-related factor 2 and interleukin (IL)-10, and a decrease in the expression of tumor necrosis factor (TNF)-α and IL-20. Moreover, the genes S100a7a and S100a14 were downregulated. Additionally, in rats given the SS/PVA treatment, blood urea nitrogen, creatinine, and serum glutamic oxaloacetic transaminase levels were within normal limits. Our findings indicate that SS/PVA is safe and may be potentiated to treat psoriasis in a variety of forms and locations of plaque because of its physical, chemical, and biological characteristics.

Evaluation of Keratin/Bacterial Cellulose Based Scaffolds as Potential Burned Wound Dressing

The study presents the preparation and characterization of new scaffolds based on bacterial cellulose and keratin hydrogel which were seeded with adipose stem cells. The bacterial cellulose was obtained by developing an Acetobacter xylinum culture and was visualized using SEM (scanning electron microscopy) and elementally determined through EDAX (dispersive X-ray analysis) tests. Keratin species (β–keratose and γ-keratose) was extracted by hydrolytic degradation from non-dyed human hair. SEM, EDAX and conductometric titration tests were performed for physical–chemical and morphological evaluation. Cytocompatibility tests performed in vitro confirmed the material non-toxic effect on cells. The scaffolds, with and without stem cells, were grafted on the burned wounds on the rabbit’s dorsal region and the grafts were monitored for 21 days after the application on the wounds. The clinical monitoring of the grafts and the histopathological examination demonstrated the regenerative potential of the bacterial cellulose–keratin scaffolds, under the test conditions.

Optimality of poly-vinyl alcohol/starch/glycerol/citric acid in wound dressing applicable composite films

This work addresses response surface methodology (RSM) design based investigations to obtain optimality of quaternary formulations [variant macromolecular concentrations of starch (St, 5-10 w/w%), polyvinyl alcohol (PVA, 5-10 w/w%), citric acid (CA, 15-40 wt%) and glycerol (Gl, 15-40 wt%)] associated to wound dressing films. Appropriate combinations of the swelling index (SI), weight loss (WL%) during 27 days, tensile strength (TS) and percentage elongation (%E) have been considered during such studies. The optimized composition was achieved through RSM optimization and exhibited very good water absorption (300.5% SI) and flexibility (87.5%E), and acceptable in-vitro degradation (51.4% WL) and TS (5 MPa) values, which are significantly better than reported data. Further, the film constitution indicated amplified antibacterial effectiveness against both Gram-positive (Listeria monocytogenes) and Gram-negative (Escherichia coli) bacteria and enhanced cell growth (145.5%) to thereby infer upon the potential associated with its application as a viable wound dressing film.