# Development of a Biodegradable Patch Based on Polysaccharides

## TL;DR

Scientists created a biodegradable patch from natural materials that can release drugs through the skin and respond to pH changes.

## Contribution

A novel biocompatible and pH-responsive hydrogel patch was developed using gellan gum, chitosan, and agar–agar crosslinked with glutaraldehyde.

## Key findings

- The patch showed high swelling ratios at different pH levels, indicating pH responsiveness.
- Mechanical tests confirmed flexibility and strength suitable for skin application.
- Methylene blue release reached 78% at 40°C, demonstrating controlled drug release.

## Abstract

Transdermal hydrogel films were fabricated from gellan gum, chitosan, and agar–agar, employing glutaraldehyde as a covalent crosslinker. The obtained formulation exhibited structural stability, pH-sensitive swelling, and high biocompatibility without the participation of metal ions. FTIR spectra showed the emergence of a characteristic imine (C=N) vibration near 1630 cm−1, confirming covalent network formation through Schiff-base reactions. SEM imaging revealed a homogeneous porous architecture (45–120 μm) that enhances moisture absorption and molecular diffusion. The swelling ratio reached 410 ± 12% at pH 9.18 and 275 ± 9% at pH 4.01, evidencing pronounced pH responsiveness. Mechanical strength measured 0.82 ± 0.03 MPa with elongation of 42 ± 2%, ensuring flexibility for skin application. The temperature-controlled release of methylene blue achieved 78 ± 4% at 40 °C after 24 h, consistent with diffusion-limited transport. This gellan–chitosan–agar hydrogel network crosslinked with glutaraldehyde represents a stable, pH-responsive, and biocompatible platform suitable for wound care and transdermal drug delivery.