# Macroporous Alginate–PEG Hybrid Double Network Cryogels: Tuning Mechanics, Porosity, and Long-Term Growth Factor Release via Polymer Concentration, Ice Nucleation, and Sulfation

## TL;DR

Researchers developed a new type of biocompatible hydrogel scaffold with improved strength and porosity for tissue engineering.

## Contribution

A hybrid double-network cryogel with tunable mechanics and long-term growth factor release is introduced.

## Key findings

- Optimized cryogels showed highly interconnected macroporous architecture.
- Improved compressive strength and elasticity were achieved.
- The scaffolds maintained cytocompatibility for tissue engineering.

## Abstract

Cryogels are macroporous hydrogel scaffolds with promising
applications
in tissue engineering; however, conventional systems often suffer
from inadequate mechanical strength, limited porosity, and biocompatibility
concerns due to the use of free radical initiators and organic solvents.
In this study, we report the engineering of a hybrid double-network
(HDN) cryogel scaffold composed of alginate and poly­(ethylene glycol)
(PEG), designed for tissue engineering applications. The scaffolds
were fabricated via simultaneous cross-linking of alginate and PEG
networks at subzero temperatures using a solvent-free and initiator-free
biocompatible approach. We systematically investigated the influence
of polymer concentration, ice nucleating agents, and sulfation of
alginate on the resulting cryogel structure, porosity, and mechanical
properties. The optimized HDN cryogels exhibited a highly interconnected
macroporous architecture, improved compressive strength, and enhanced
elasticity while maintaining cytocompatibility. These findings highlight
the potential of HDN cryogels as robust and biocompatible scaffolds
for soft tissue engineering and regenerative medicine applications.