# Glycerol-Enhanced Gum Karaya Hydrogel Films with a Sandwich-like Structure Enriched with Octenidine for Antibacterial Action against Multidrug-Resistant Bacteria

## TL;DR

This paper introduces a new hydrogel film with antibacterial properties for treating infected wounds and preventing bacterial resistance.

## Contribution

A novel glycerol-enhanced hydrogel with a sandwich-like structure and controlled OCT release for combating multidrug-resistant bacteria.

## Key findings

- Hydrogel films with glycerol show a sandwich-like structure and improved mechanical stability.
- OCT in the hydrogel provides prolonged antibacterial activity against multidrug-resistant bacteria.
- Hydrogel properties like pore size and stability are significantly influenced by glycerol concentration.

## Abstract

This study explores the innovative approach in the development
of freeze-dried hydrogel films, leveraging the unique properties of
gum Karaya (GK), poly­(vinyl alcohol) (PVA), poly­(ethylene glycol)
(PEG), and glycerol with a coating of octenidine dihydrochloride (OCT).
These innovative hydrogel films exhibit at a certain glycerol concentration
a sandwich-like structure, achieved through a tailored freeze-drying
process, which enhances transparency and mechanical stability. OCT
provides superior antibacterial performance, effectively combating
multidrug-resistant bacteria with a controlled and gradual release
mechanism, surpassing conventional OCT solutions that require frequent
reapplication for infected wound treatment without the creation of
bacterial resistance. Advanced environmental scanning electron microscopy
(A-ESEM) reveals the complex microstructure of the hydrogel, highlighting
the dense surface layer and interconnected porous bulk. Variations
in glycerol concentrations proved to significantly impact hydrogels’
properties. Increasing the glycerol concentration decreases the pore
size (around 4.5 μm) while enhancing the polymer network density
and flexibility. However, low concentration increases the pore size
(7.8–15.6 μm), impacting enhanced swelling behavior and
hydrolytic stability. OCT’s rapid antibacterial action, releasing
over 30% within the first hour and maintaining prolonged activity
for up to 2 weeks, emphasizes the material’s potential for
diverse applications. Hydrogels’ remarkable transparency, porosity,
structural stability, and antibacterial efficacy against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli strains suggest promising uses as
transparent dressings, biomedical devices, and infection-resistant
surfaces.