Silk sericin is a natural polymer produced by silkworm Bombyx mori; which has the function of covering the fibroin filaments so that they remain linked together as well as maintaining the structural integrity of the cocoon. Despite its properties and benefits, sericin is currently discarded during textile production as it is considered a side product of silk cocoons during the degumming process. Among the most important biological properties of sericin are good oxygen permeability, moisture-regulating capacity, resistance to UV radiation, ability to promotes cell growth, biocompatibility and mitogenic effect. All these characteristics make sericin a promising polymer to be used in biomedical applications, especially in tissue engineering and regenerative medicine. Some studies report that sericin favors the biological nature of keratinocytes and fibroblasts, potentializing it as a biomaterial for the repair of epithelial tissue, mainly utilized as wound dressing. Given the importance that sericin can have in the field of bioengineering, and that its use can favor the sericulture agroindustry, this manuscript reviews recent studies of this protein for its application in tissue engineering, specifically for cutaneous regeneration.

The use of silk proteins sericin (SS) and fibroin (SF) has been increased for biomedical applications. In order to improve their behavior inside of biological environment, silk biomaterials must be treated after their manufacturing by means of diverse methods. These include ethanol post-treatments to increase their crystallinity, mechanical properties and water stability. In this study, the effect of ethanol post-treatments on the properties of silk protein materials was evaluated. Defective cocoons and silk fibrous waste (SW) were used to obtain silk sericin sponges (S-SS) and silk fibroin films (F-SF), respectively. Two ethanol treatments were evaluated in SS and SF: immersion (I) and solvent vapor annealing (SVA). Morphological modifications induced by ethanol post-treatments were studied by scanning electron microscopy (SEM). Conformational structure of the samples was analyzed by attenuated total reflectance–Fourier-transform infrared spectroscopy (ATR–FTIR), and the thermal properties were evaluated by differential scanning calorimetry (DSC) measurements. SEM images revealed that ethanol process induces changes in treated F-SF and S-SS, the material surfaces are more roughness, and these effects were more pronounced in samples treated by I than that subjected to SVA. As a result of the ethanol treatments, the ATR–FTIR and DSC results showed an increment in relative content of β-sheet structures in both silk protein materials. The results suggest that ethanol post-treatments induce conformational transitions and morphological modifications in S-SS and F-SF that should be considered to select the post-treatment conditions according to the biomedical application requirements.

Protein-based biomaterials are excellent candidates for biomedical applications since they have similar properties to the extracellular matrix. Recently, the use of sericin (SS), a protein present in the silk cocoon, can be used as biomaterial. To improve their properties, SS biomaterials must be subject to treatments after their manufacturing. Ethanol post-treatments by immersion and solvent vapor, are used for increasing their crystallinity, mechanical and water stability. In this work, the effect of ethanol post-treatment on the properties of SS scaffolds elaborated by the lyophilization technique was evaluated. Four post-treatments were carried out on the samples: immersed in absolute ethanol for 5 min (SS/EtOH 5 min) and for 1 h (SS/EtOH 1 h); and exposition in a saturated ethanol vapor environment for 1 h (SS/VapEtOH 1 h) and for 24 h (SS/VapEtOH 24 h). The scaffolds were characterized by X-ray diffraction (XRD) and Fourier‑transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), water absorption, degradation in a phosphate-buffered saline solution, sericin release from the scaffolds, and the cytotoxicity test. The ATR-FTIR results showed an increment in the relative content of β-sheet structures and an increment in the crystallinity. SEM images revealed that the post-treatment process induces changes in treated materials to present morphological changes. The treatment materials were more water-stable. The excipients of the SS scaffolds evaluated in human epithelial fibroblasts do not generate an acute cytotoxic effect. The results suggest that ethanol post-treatments induce conformational transitions and morphological changes, which should be considered for selecting the post-treatment conditions according to developing materials for wound regeneration.

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.

Biodegradable bioplastics have emerged as a promising sustainable alternative to minimize the environmental impact of traditional plastics. Nevertheless, many of them degrade slowly under natural or industrial conditions, raising concerns about their practical biodegradability. This fact is related to the high-order structure of the polymer backbones, i.e., high molar mass and high crystallinity. Research efforts are being devoted to the development of technologies capable of reducing the length of polymer segments by accelerated chain scission, which could help improve biodegradation rates upon disposal of bioplastic products. The objective of this review is to examine the current state of the art of abiotic degradation techniques, physically driven by temperature, mechanical stress, UV/gamma/microwave irradiation, or plasma or dielectric barrier discharge, and chemically induced by ozone, water, or acidic/basic solutions, with the aim of enhancing the subsequent biodegradation of bioplastics in controlled valorization scenarios such as composting and anaerobic digestors. Particular attention is given to pretreatment degradation technologies that modify surface properties to enhance microbial adhesion and enzymatic activity. Technologies such as ozonation and plasma-driven treatments increase surface hydrophilicity and introduce functional groups with oxygen bonds, facilitating subsequent microbial colonization and biodegradation. Irradiation-based techniques directly alter the chemical bonds at the polymer surface, promoting the formation of free radicals, chain scission, and crosslinking, thereby modifying the polymer structure. Pretreatments involving immersion in aqueous solutions may induce solution sorption and diffusion, together with hydrolytic chain breakage in bulk, with a relevant contribution to the ulterior biodegradation performance. By promoting abiotic degradation and increasing the accessibility of biopolymers to microbial systems, these pretreatment strategies can offer effective tools to enhance biodegradation and, therefore, the end-of-life management of bioplastics, supporting the transition toward sustainable cradle-to-cradle pathways within a biocircular economy.