Alginate and pDADMAC hydrogel for 3D bioprinting purposes: characterization and cytotoxicity assessment

Details

Supervisors

Dupont-Gillain, Christine C. ; des Rieux, Anne

Faculty

Faculté des bioingénieurs

Degree label

Master [120] : bioingénieur en chimie et bioindustries, à finalité spécialisée

Abstract

Biomaterial science is witnessing a surge in demand for new tissue engineering techniques. Functionalized hydrogels, which consist in hydrophilic crosslinked polymer networks, are a promising class of cell carrier material. However, conventional hydrogels have limitations in terms of cell integration and biodegradability. To overcome these challenges, hydrogels based on Polyelectrolyte complexes (PECs) have attracted attention. PECs are formed by assembling oppositely-charged polyions, offering advantages such as aqueous formation, room temperature crosslinking, and responsiveness to environmental changes. These characteristics make PEC hydrogels desirable as cell carriers in biomedical applications. This study focuses on characterizing a hydrogel formed by PECs of alginate and poly(diallyldimethylammonium chloride) (pDADMAC). The aim of this work is to assess its potential for use in bioprinting applications. The structural and chemical properties of the obtained hydrogel are evaluated using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The mechanical properties are assessed through rheological testing, while a comprehensive investigation of cell viability is conducted by measuring the bioluminescence of cells transduced with a luciferase expression gene. These analyses provide valuable insights into the suitability of the PEC hydrogel for bioprinting purposes. Some results are encouraging for future applications of the material. Firstly, initial observations indicate a physically stable gel with an ideal water content for tissue engineering applications. Moreover, rheological tests demonstrate good stability and show a shear-thinning and thixotropic behaviour, which is favourable for processing and printing. However, these conclusions are tempered by challenging interpretation of results due to limited understanding of the molecular structure of the formed complexes. Additionally, in the current state of the experiments, poor control over complex formation hinders significant modification of the hydrogel structure to overcome these problems. Other findings indicate that more work is needed to make these materials suitable for biomedical applications. For instance, XPS revealed significant surface heterogeneity of the material, and all samples exhibited high cytotoxicity. This latter issue is currently explained by a significant release of free pDADMAC, which is harmful to cells. This has been demonstrated using a colorimetric titration based on the aggregation of gold nanoparticles. The present work highlighted the excellent properties of these hydrogels as material for bioprinting while revealing the need for further work to reach an acceptable biocompatibility.