Biocompatible and Thermoresistant Hydrogels Based on Collagen and Chitosan.

Pablo Sánchez-Cid,Victor Perez-Puyana,José Fernando Rubio-Valle,Alberto Romero,Mohammed Rafii-El-Idrissi Benhnia,Mohammed Rafii-El-Idrissi Benhnia,Mohammed Rafii-El-Idrissi Benhnia,Francisco J Ostos,Francisco J Ostos,Francisco J Ostos,Mercedes Jiménez-Rosado

doi:10.3390/polym14020272

Abstract

Hydrogels are considered good biomaterials for soft tissue regeneration. In this sense, collagen is the most used raw material to develop hydrogels, due to its high biocompatibility. However, its low mechanical resistance, thermal stability and pH instability have generated the need to look for alternatives to its use. In this sense, the combination of collagen with another raw material (i.e., polysaccharides) can improve the final properties of hydrogels. For this reason, the main objective of this work was the development of hydrogels based on collagen and chitosan. The mechanical, thermal and microstructural properties of the hydrogels formed with different ratios of collagen/chitosan (100/0, 75/25, 50/50, 25/75 and 0/100) were evaluated after being processed by two variants of a protocol consisting in two stages: a pH change towards pH 7 and a temperature drop towards 4 °C. The main results showed that depending on the protocol, the physicochemical and microstructural properties of the hybrid hydrogels were similar to the unitary system depending on the stage carried out in first place, obtaining FTIR peaks with similar intensity or a more porous structure when chitosan was first gelled, instead of collagen. As a conclusion, the synergy between collagen and chitosan improved the properties of the hydrogels, showing good thermomechanical properties and cell viability to be used as potential biomaterials for Tissue Engineering.

Highlights

Hydrogels are polymeric networks capable of absorbing up to thousands of times their dry weight of water without dissolving or losing their structural integrity [1]
The combination of collagen and chitosan in binary hydrogels improved the characteristics of unitary systems
Systems with the thermal stability of chitosan were achieved without compromising the biocompatibility of collagen at a neutral pH, which facilitates their integration as scaffolds for Regenerative Medicine

Summary

Introduction

Hydrogels are polymeric networks capable of absorbing up to thousands of times their dry weight of water without dissolving or losing their structural integrity [1]. Hydrogels can be physical or chemical depending on the crosslinking carried out In this way, physical hydrogels have non-permanent physical bonds, such as Van der Waals interactions or hydrogen bonds, while chemical hydrogels are composed of covalent bonds, which are stronger [3]. Physical hydrogels have non-permanent physical bonds, such as Van der Waals interactions or hydrogen bonds, while chemical hydrogels are composed of covalent bonds, which are stronger [3] For this reason, physical hydrogels are less stable, being dependent on external stimuli such as ionic strength, solvents, pH or temperature; while chemical ones tend to have greater mechanical resistance, being less dependent on external stimuli. Perez-Puyana et al studied the influence of the cooling parameters (i.e., temperature and time) on the collagen-based hydrogel properties [7]

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