Natalia Jaramillo-Quiceno

Silk textile production generates considerable amounts of waste, increasing environmental impact. However, this waste holds significant potential as a sustainable source of regenerated silk fibroin (SF) for biomedical applications. This study investigated the physicochemical properties and cellular compatibility of SF extracted from silk cocoons (SFC) and silk waste (SFW). Both materials demonstrated comparable morphology, thermal stability, and wettability. Structural analysis and amino acid composition revealed that while SFC presented a higher molecular weight, lower polydispersity, and a greater presence of charged amino acid residues (Asp, Arg, Lys, and His), the regeneration process effectively compensates for these variations. Specifically, the transition from random coil to β-sheet during film casting homogenizes the matrix, ensuring that the final biological properties remain comparable. Quantitative metabolic assays confirmed that both SFC and SFW maintain cell viability above 70%, meeting ISO 10993-5 standards for non-cytotoxicity. Furthermore, qualitative cell adhesion studies demonstrated effective fibroblast spreading and attachment to both film surfaces, indicating that the initial molecular variations in the waste source do not compromise the resulting matrix's biological performance. These findings highlight that SFW is a functionally equivalent and sustainable alternative to SFC, suitable for the development of advanced biomaterials.

Feeding a growing population under the pressures of climate change requires solutions that safeguard yields while strengthening agricultural resilience. Integrated Crop Management (ICM)—which combines precise fertilization, efficient water use, and targeted pest control—offers a promising framework. Hydrogels, with their water retention and controlled release properties, can enhance ICM by improving fertilizer efficiency, reducing water loss, and supporting soil health. Despite extensive research, their optimal use in agriculture remains unclear, and limitations continue to restrict large-scale adoption. To address this gap, this study applies the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology alongside bibliometric analysis to examine hydrogel applications in ICM from 2000 to 2024. Ninety Scopus-indexed publications were analyzed across four domains: pesticides, nutritional growth inputs, soil conditioners, and bioactive substances. The results reveal a marked increase in hydrogel structural complexity, greater diversity in characterization methods, ongoing reliance on high-impact pesticides despite advances in bio-based hydrogels, and persistent gaps in assessing environmental impacts and regulatory compliance. These findings underscore the need for stronger collaboration between academia and industry to translate hydrogel research into effective, sustainable agricultural practices under changing climatic conditions.

Fibrous by-products, including defective or double cocoons, are obtained during silk processing. These cocoons primarily contain fibroin and sericin (SS) proteins along with minor amounts of wax and mineral salts. In conventional textile processes, SS is removed in the production of smooth, lustrous silk threads, and is typically discarded. However, SS has garnered attention for its antioxidant, antibacterial, biocompatible, and anticancer properties as well as its excellent moisture absorption, making it a promising polymer for biomedical applications. Owing to its functional groups (carboxyl, amino, and hydroxyl), SS can blend and crosslink with other polymers, thereby improving the mechanical properties of sericin-based materials. This study explored the effects of different SS/polyvinyl alcohol (PVA) ratios on porous scaffolds fabricated via freeze-drying, focusing on the mechanical stability, water absorption, and protein release in phosphate-buffered saline (PBS). The scaffold morphology revealed reduced porosity with higher SS content, while increased PVA content led to material folding and layering. A greater PVA content enhanced water absorption, mechanical properties, and thermal stability, although SS release decreased. These results demonstrate that scaffold properties can be tailored by optimizing the SS/PVA ratio to suit specific biomedical applications.

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.

This study aimed to understand the impact of different concentration routes on the structure and properties of silk sericin (SS) films. Sericin was extracted from defective cocoons (DC), at high temperature and pressure (HTHP) using an autoclave. The obtained aqueous solution was concentrated using three different routes until a final concentration of 2% (w/v) was reached. These routes include freeze-thawing (SS_FT), rotary evaporation (SS_E), and the dissolution of spray-dried SS in distilled water (SS_SD). Films were formed from the three solutions obtained, which were characterized by Fourier transform infrared spectro-metry (ATR-FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC), and their water absorption capacity and non-soluble fraction were evaluated. According to the FTIR and TGA results, the samples concentrated by evaporation or using spray-dried SS exhibited a more amorphous and lighter structural conformation than those found in F-SS_FT. This finding suggests that the use of high temperatures for SS concentration promotes protein degradation and the formation of less ordered structures in SS films. The structural properties of the SS films were confirmed by the water absorption results. In particular, the major presence of crystalline structures in F‑SS_FT seems to limit their affinity for water, favoring the non-soluble fraction in this sample. The marked effect of the concentration method on the structure and properties of SS films highlights the potential of this process in the design of more efficient manufacturing routes for SS-based materials that exhibit a distinctive performance.

The use of fertilizers coated with insoluble organic compounds is a promising approach for enhancing fertilizer efficiency and crop yield. Silk sericin (SS) is a protein with a high potential for the development of materials oriented toward fertilizer coating and soil amendment because of its biodegradability and the fact that it represents an important source of nitrogen for plants. Thus, this study proposes the design and evaluation of a novel SS-based multilayer coating for fertilizer granules. A pan-coating process was applied to form two distinct layers on the granules: an inner layer made of silk sericin/polyvinyl alcohol, SS/PVA (50/50 w/w), which has low solubility and porosity, and an outer hydrogel layer of SS/PVA with carboxymethyl cellulose CMC (SS/CMC/PVA 45/25/30 w/w/w). Scanning electron microscopy (SEM) was employed for the morphological characterization of the coated fertilizer (CF), examining both the cross-section and surface, while SEM with energy-dispersive X-ray spectroscopy (SEM/EDS) was used to analyze the chemical composition of the surface. The ability of the coating to reduce the nutrient-release rate was studied using water- and soil-release tests. Furthermore, its performance was evaluated in in vivo assays using jalapeño bell pepper (Capsicum annum) plants. The results revealed that the structure and composition of the multilayer coating significantly influenced its ability to delay nutrient release in both water and soil. Moreover, the inclusion of SS in the coating potentially contributed to the increased nitrogen content in the soil, thereby improving plant growth rates.

Silk degumming is considered the first point in the preparation of silk-based materials since this process could modify the silk fiber and the properties of its related products. This study evaluated the differences in morphology, secondary structure, amino acid content, thermal stability, and mechanical properties of two types of raw materials, defective cocoons (DC) and silk fibrous waste (SW), degummed by chemical (C) and autoclaving (A) methods. Subsequently, silk fibroin films were prepared by dissolving each type of degummed fibers, and thermal and structural films properties were determined. The findings demonstrated that autoclaving is an efficient alternative to remove silk sericin, as the resulting fibers presented improved structural, thermal, and mechanical properties compared to those obtained by the chemical method. For films preparation, autoclave resulted in a good option, but dissolution parameters need to be adjusted for defective cocoons. Furthermore, similarities between the physicochemical properties of fibers and films from both fibrous wastes suggest that SW is a promising raw material for producing fibrous resources and regenerated silk fibroin materials. Overall, these findings suggest new recycling methods for fibrous waste and by-products generated in the silk textile production process.

Hydrogel-type absorbent materials are currently a technological alternative for improving water retention in the soil and reducing nutrient loss by leaching and evaporation. This study aimed to evaluate the application of a new hydrogel based on silk sericin (SS) as a water retention material in soil. The morphology of the hydrogel was characterized using Scanning Electron Microscopy (SEM), and its impact on moisture retention in sandy loam soil (SLS) under different levels of matric pressure (MP) was evaluated. Additionally, water content data were collected over time for both SLS and SLS with hydrogel (SLS + H), and the data were used to fit predictive models. The results indicate that the hydrogel had a porous morphology that promoted water retention and soil release. Under a MP of 0.3 bar, the use of the hydrogel increased water retention by 44.70% with respect to that of SLS. The predictive models developed were adequately adjusted to the behavior of the moisture data over time and evidenced the incidence of the absorbent material on the dynamics of the moisture content in the soil. Therefore, these models could be useful for facilitating subsequent simulations or for designing automatic soil moisture control systems oriented to smart farming.