# Injectable in Situ Cross-linked Oxidized Alginate-Gelatin-Based Hydrogels for Cartilage Tissue Engineering

## TL;DR

This paper introduces an injectable hydrogel system for cartilage tissue engineering with tunable properties and good cell compatibility.

## Contribution

A novel injectable hydrogel system combining covalent and noncovalent cross-linking for cartilage tissue engineering is introduced.

## Key findings

- The hydrogels have tailorable mechanical properties with an effective modulus of 12–20 kPa.
- The system demonstrates suitable injectability with injection forces of 3–5 N.
- The hydrogels support favorable interactions with chondrogenic ATDC5 cells.

## Abstract

The present study
introduces an injectable oxidized alginate-gelatin
hydrogel system for cartilage tissue engineering, employing a combination
of covalent and noncovalent cross-linking mechanisms. Specifically,
the network is formed through Schiff’s Base reactions alongside
enzymatic and ionic cross-linking. The hydrogels were investigated
regarding their mechanical properties, swelling and degradation behavior,
injectability, and cytocompatibility. The results indicated tailorable
mechanical properties with an effective modulus ranging from 12 to
20 kPa, depending on the enzymatic cross-linker concentration, while
demonstrating suitable injectability required for clinical applications
with injection forces in the range of 3–5 N. Moreover, the
syringe-mixing approach of in situ cross-linked hydrogels
showed favorable cell–material interactions with chondrogenic
ATDC5 cells.