Dados do Trabalho

Título/Title/Titulo

Crosslinked electrospun membranes based on SPIMA for tissue engineering applications.

Introdução/Introduction/Introdución

Introduction
In tissue engineering and regenerative medicine fields, the mimicking of the extracellular matrix (ECM) is being widely studied to improve the cell adhesion, proliferation and differentiation. Among the techniques used to reproduce the EMC’s morphology, electrospinning has been intensively employed to obtain nanofibrous structures from polymeric solutions, emulsions, suspensions or molten polymers. Soy protein isolate (SPI) electrospun mats have been studied for different biomedical applications, such as wound dressing, tissue engineering, and drug delivery systems, among others. However, the high water solubility of electrospun proteins limits their use; therefore, several strategies to tailor the SPI stability, such as chain crosslinking or blending have been explored.

Objetivos - Metodologia - Resultados - Discussão dos Resultados/Objectives - Methodology - Results - Discussion of Results/Objetivos - Metodología - Resultados - Discusión de los resultados

Objectives
To increase the water stability of electrospun SPI nanofibrous mats by photocrosslinking of functionalized SPI (SPIMA) chains.

Methodology
SPIMA was synthesized in 2 steps. Initially, an alkaline pretreatment was carried out by adding a 1.6 M potassium hydroxide solution to a 14% w/w SPI aqueous solution, then stirred during 1.5 h at 70°C. Then a predetermined amount of methacrylic anhydride (Sigma Aldrich) was added into the previous solution and reacted during 2 h at 70°C under magnetic stirring. The mixture was neutralized and dialyzed in distilled water during 3 days at room temperature, and then freeze-dried for 72 h. The degree of methacrylation was determined by Habeeb’s test, in which the variation in the absorption band of amino groups at 340 nm was measured.
The solution for electrospinning was obtained by dissolving 3% w/v photoinitiator and 1% w/v SPIMA in 10 M acetic acid. Protein solution was electrospun using a Yflow equipment, and a 0.6 kV/cm electric field. The ambient temperature was maintained at 21°C and the humidity at 40%. Crosslinking was performed using UV light at different exposure times (0, 2.5, 5, and 10 min) and the mats named S1, S2, S3, and S4, respectively.
Electrospun matrices were observed using a scanning electron microscope (JSM-6460 /LV, JEOL Inc.).

Results and Discussion
SPIMA was successfully synthesized with a methacrylation degree of 55%.SEM micrographs showed a fibrous morphology for all the membranes. S1 sample displayed a defectless fibrous structure with an average diameter of 219 nm. On the other hand, the fibers of crosslinked samples lost the perfect round shape and exhibited an increase in fiber diameter with the exposition time (284, 299, and 308 nm for S2, S3, and S4 samples, respectively). This morphological change can be due to the fact that UV-crosslinking procedure was carried out by immersing samples in ethanol.

Considerações Finais/Final considerations/Consideraciones finales

Conclusion
The SPIMA electrospun mats were obtained by electrospinning. The optimization of electrospinning parameters allowed handling the morphology and diameter of fibers. The crosslinking process affected the morphology of fibers, but it was necessary to improve the mats stability in water. Moreover, additional tests are being carried out to further characterize the membranes, and to determine whether the process was able to reduce protein solubility.

Palavras-chave/Key words/Palabras clave

Soy Protein Isolate
Protein Functionalization
Crosslinking
Electrospinning
Tissue Engineering