# Semi-Interpenetrated Polymeric Networks of Chitosan and Poly(γ-Glutamic Acid) with Potential Biomedical Applications

## TL;DR

This paper explores hydrogels made from chitosan and poly(γ-glutamic acid) that show improved properties for biomedical uses like drug delivery and tissue engineering.

## Contribution

The novelty lies in creating semi-interpenetrating polymer networks of chitosan and γ-PGA with enhanced mechanical and biocompatible properties.

## Key findings

- The hydrogels showed increased mechanical strength and biocompatibility with γ-PGA addition.
- Swelling capacity was highly sensitive to pH and temperature, with SF1 showing the highest swelling ratio at pH 3.6 and 37°C.
- SEM and porosity tests confirmed denser structures with higher γ-PGA content.

## Abstract

Hydrogels are polymeric matrices very similar to living
tissue
due to their elasticity, porosity, and ability to absorb high water
content. They are highly attractive materials for a wide range of
biomedical applications, such as tissue engineering, wound healing,
and drug delivery. In this regard, hydrogels of semi-interpenetrating
polymer networks (semi-IPNs) based on the biopolymers chitosan and
poly­(γ-glutamic acid) (γ-PGA) were prepared as systems
with improved properties compared to hydrogels of individual polymers.
The resulting hydrogels were characterized by Fourier transform infrared
spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric
analysis (TGA), porosity testing, compressive strength, cell viability,
and swelling capacity. FTIR spectra of the semi-IPNs confirmed the
presence of the functional groups of each polymer. SEM images revealed
a porous structure of the hydrogels, which became denser and more
compact with increasing γ-PGA content. This behavior was corroborated
by the porosity test, which decreased with the formation of the γ-PGA-reinforced
network. The swelling capacity study of the hydrogels demonstrated
their sensitivity to pH and temperature. For the semi-IPN hydrogels,
SF1 had the highest swelling ratio (20.55) at pH 3.6 and T = 37 °C. The formation of the semi-IPNs brought about improvements
in mechanical properties compared to the chitosan hydrogel. The presence
of γ-PGA contributed to improved biocompatibility of the materials,
especially in formulations with 0.025 and 0.05 g of this biopolymer.
These results suggest that the obtained chitosan/γ-PGA semi-interpenetrating
networks may be promising materials with great potential for use in
biomedical applications.