RESUMEN

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.

RESUMEN

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.

RESUMEN

Resumen Introducción: Colombia produce actualmente seda natural. Durante la transformación de esta a hilos, se retira y descarta la sericina, una proteína que recubre las fibras y que presenta diferentes propiedades que pueden ser aprovechadas industrialmente. Objetivo: Caracterizar la sericina obtenida a partir de hilos de seda colombiana y secada por aspersión. Materiales y métodos: La sericina fue extraída usando agua caliente en autoclave y posteriormente secada por aspersión. La muestra en polvo obtenida se caracterizó mediante pruebas morfológicas (SEM), determinación del punto isoeléctrico, contenido de proteína, actividad antimicrobiana, solubilidad, actividad acuosa (aw) y color. Resultados: Los resultados obtenidos por SEM mostraron que se logró remover la mayor parte de sericina presente en los hilos, y que cuando esta se seca adquiere una forma esférica, con superficie rugosa, cóncava y colapsada. Se encontró que la muestra tiene un contenido de proteína y un punto isoeléctrico de 99,50% y 4,07 respectivamente, y no presenta propiedades antimicrobianas frente a los microorganismos estudiados. La solubilidad aumenta con la temperatura, alcanzando un 44,11% ± 5,75 a 90 °C. El aw fue de 0,287 y su color muestra una tendencia al blanco (coordenadas CIELAB: L: 89,55 ± 0,20, a*: +0,44 ± 0,04 y b*: +5,16 ± 0,30). Conclusiones: Los resultados muestran que es posible extraer sericina desde hilos de seda usando autoclave, con altos porcentajes de rendimiento. Se observa que la muestra es susceptible de ser secada por aspersión, mostrando características que pueden ser estudiadas con mayor profundidad para evaluar la viabilidad de utilizarla en el desarrollo de diferentes productos.

Abstract Introduction: During Colombian silk transformation to obtain threads, a protein called sericin is removed and discarded. Nevertheless, due to its properties, it should be industrially recovered and used. Objective: Characterize the sericin obtained, through spray drying, from Colombian silk threads. Materials and methods: The sericin was extracted using hot water in autoclave and later spray-dried. Obtained solution was dehydrated in dry spray equipment. The obtained powdered sample was characterized by morphological tests (SEM), isoelectric point and protein content, antimicrobial activity, solubility, aqueous activity (aw) and color. Results: The results obtained by SEM showed that the degumming process extracted the most of sericin from the threads. In addition, it was seen that dehydrated samples have a spherical shape, with a rough, concave and collapsed surface. The protein content and the isoelectric point of sericin were 99.5 % and 4.07, respectively. No antimicrobial properties were observed against the microorganisms studied. The solubility of the protein increased with temperature (44.11 % ± 5.75 at 90 °C), its aw was 0.287, and its color showed a white trend whose CIELAB coordinates are L: 89.55 ± 0.20, a*: +0.44 ± 0.04 and b*: +5.16 ± 0.30. Conclusions: The results show that it is possible to extract sericin from silk threads using autoclave, with high percentages of yield. Additionally, it was observed that the sample is susceptible to be dehydrated by spray drying, showing characteristics that can be studied in greater depth to evaluate the viability of using this protein in the development of different products.

Resumo Introdução: Colômbia produz atualmente seda natural. Durante a transformação desta aos fios, retira-se e descarta-se a sericina, uma proteína que recobre as fibras e que apresenta diferentes propriedades que podem ser aproveitadas industrialmente. Objetivo: Caracterizar a sericina obtida a partir de fios de seda colombianos e secagem por aspersão. Materiais e métodos: A sericina foi extraída usando água quente no autoclave e posteriormente desidratada com secagem por aspersão. A amostra em pó obtida caracterizou-se mediante provas morfológicas (SEM), determinação do ponto isoelétrico, contido de proteína, atividade antimicrobiana, solubilidade, atividade aquosa (aw) e cor. Resultados: Os resultados obtidos pelo SEM amostram que conseguiu-se remover a maior parte da sericina presente nos fios, e quando esta se seca adquire uma forma esférica, com superfície rugosa, côncava e colapsada. Encontrou-se que a amostra tem um contido de proteína e um ponto isoeléctrico de 99,50% e 4,07 respetivamente, e não apresenta propriedades antimicrobianas frente aos microrganismos estudados. A solubilidade aumenta com a temperatura, atingindo um 44,11% ± 5,75 a 90 °C. O aw foi de 0,287 e sua cor mostra uma tendência ao branco (coordenadas CIELAB: L: 89,55 ± 0,20, a*: +0,44 ± 0,04 y b*: +5,16 ± 0,30). Conclusões: Os resultados mostram que é possível extrair sericina desde fios de seda usando autoclave, com altos percentagens de rendimento. Observa-se que a amostra é suscetível de ser desidratada com secagem por aspersão, mostrando características que podem ser estudadas com maior profundidade para avaliar a viabilidade de utilizarla no desenvolvimento de diferentes produtos.