# Tailoring the Properties of Marine-Based Alginate Hydrogels: A Comparison of Enzymatic (HRP) and Visible-Light (SPS/Ruth)-Induced Gelation

## TL;DR

This study explores how to modify and crosslink alginate hydrogels using enzymatic and light-based methods, enhancing their properties for tissue engineering applications.

## Contribution

The paper introduces optimized enzymatic and visible-light crosslinking methods for phenol-functionalized alginate hydrogels, enabling improved mechanical properties.

## Key findings

- Phenol groups were successfully introduced to sodium alginate using EDC/NHS/MES and tyramine.
- Optimal enzymatic crosslinking conditions were identified as 1 mM H2O2 and 10 U/mL HRP.
- The crosslinked hydrogels showed significantly increased viscosity and mechanical strength suitable for tissue engineering.

## Abstract

Alginate is a natural polysaccharide extracted from brown algae and is commonly used as a biomaterial scaffold in tissue engineering. In this study, we performed phenol functionalization of sodium alginate based on chemical modification methods using 1-ethyl-(3-dimethylaminopropyl)carbodiimide/N-hydroxybutanediimide/2-(N-morpholino) ethanesulfonic acid (EDC/NHS/MES) and tyramine. The presence of phenol groups was confirmed by spectrophotometry and Fourier Transform Infrared. We successfully prepared hydrogels using a horseradish peroxidase/hydrogen peroxide (HRP/H2O2) enzymatic system as well as an sodium persulfate (SPS)/ruthenium light-crosslinking system. Optimization identified 1 mM ruthenium and 4 mM SPS as the most effective photo crosslinking conditions. At the same time, 1 mM H2O2 and 10 U/mL HRP are considered optimal conditions for the enzyme-linked reaction. Rheological measurements monitored the gelation process, revealing that the viscosity, storage modulus, and loss modulus of the material increased by at least one hundredfold after crosslinking. Thixotropy results demonstrated excellent recovery of the material. Texture analysis indicated that the crosslinked material possessed notable strength and toughness, highlighting its potential applications in tissue engineering after 3D bioprinting.