Synthesis, characterization and property testing of Hydrogels composed of Sodium-AMPS and modified water-soluble starch for use as wound dressings

Abstract

This research focuses on the synthesis, characterization, and property evaluation of hydrogels composed of 2-acrylamido-2-methylpropane sulfonic acid sodium salt (Na-AMPS) and modified water-soluble starch for potential use as wound dressings. Dialdehyde-soluble starch (DAS) was synthesized by oxidizing soluble starch with periodate. The optimal oxidation time, resulting in the highest aldehyde content of 94.2%, was found to be 24 hours. The structure of DAS was confirmed through proton nuclear magnetic resonance spectroscopy and Fourier transform infrared spectroscopy analysis. Afterwards, hydrogels based on Na-AMPS were prepared, characterized, and their properties tested. They were prepared with different concentrations of soluble starch or DAS (0, 1 2 and 3 %w/v of Na-AMPS) and trimethylolpropane ethoxylate triacrylate (0.5, 0.10, 0.15 and 0.2%mol of Na-AMPS) was used as a crosslinker. Fourier transform infrared spectroscopy and scanning electron microscope (SEM) analysis were used to confirm the successful hydrogel synthesis and examine the surface morphology. SEM analysis revealed oval granules on the surface of soluble starch/P(Na-AMPS) hydrogels and a fibrillary morphology with a high surface area for DAS/P(Na-AMPS) hydrogels. The gel fractions of soluble starch/P(Na-AMPS) hydrogels exhibited more than 97.5%, while those of DAS/P(Na-AMPS) hydrogels were more than 90.8%. These percentage gel fractions indicate the high effectiveness of photopolymerization. The water transport properties of the hydrogel were investigated. DAS/P(Na-AMPS) hydrogels exhibited superior swelling capacity (up to 56,600%) due to the presence of hydrophilic aldehyde groups. All hydrogels exhibited slow water evaporation rates, demonstrating a gradual decrease in percentage water retention over time. Moreover, the water vapor transmission rates of all synthesized hydrogels (ranging from 1077 to 1632 g/m2·day) indicate their potential for use as wound dressings. Increasing DAS content resulted in decreased stress and Young’s modulus but increased percentage strain compared to soluble starch/P(Na-AMPS) hydrogels. An increase in TMPETA concentrations leads to higher water retention due to increased crosslinking density but results in decreased swelling capacity. All results indicate that the synthesized hydrogel exhibits a range of desirable properties. These include high swelling capacity for efficient absorption, good adherence, and transparency. Additionally, they demonstrate good flexibility and conformability, facilitating easy application and removal. Furthermore, they exhibit high fluid and gas permeability, attributed to a high-water vapor transmission rate and slow water evaporation, which is effective for moisture management. In conclusion, the synthesized hydrogel is non-toxic and biocompatible, as evidenced by its high cell viability. Thus, the hydrogels synthesized in this research possess the necessary properties to potentially serve as wound dressings.