Chitosan Scaffolds With Tunable Structure and Properties for Pulp Regeneration

Objectives: Chitosan-based scaffolds are widely used in pulp regeneration because of their excellent biodegradability and biocompatibility. However, the poor mechanical properties and non-adjusted porous structures of these scaffolds hinder their broad utility. In the present study, a novel cross-linking method was developed to tune the elastic modulus (E) and porosity (P) of chitosan scaffolds based on the ionic strength-dependent solubility of chitosan.
Methods: In briefly, chitosan-acetic acid solution was prepared and frozen at -20 °C in the mold. The frozen sample was immersed in a saturated NaCl solution at −20 °C and then scaffold-I was formed in a saturated NaCl solution at room temperature. Scaffold-I was compressed at different ratios (R) and then crosslinked by tripolyphosphate with different concentration (C_TPP) to fabricate scaffold-II. The structures and physico-mechanical properties of scaffolds was characterized. The cytotoxicity of the scaffolds was evaluated using extracts and L929 fibroblast cells. Proliferation and adhesion of human dental pulp cells (hDPCs) on scaffolds was further studied.
Results: The results showed that both the structures and properties of scaffolds was affected by the R. The porosity of scaffolds decreases from 93.5% to 81.7% with increasing R from 1 to 8 and shape of pore is changed form circle to slim with increasing R. Furthermore, E increases with increasing R and could increase from 0.06 MPa (R = 1) to 3.2 MPa (R = 8). However, the properties of scaffolds was hardly affected by C_TPP. All the scaffolds demonstrated cytocompatibility for fibroblast cells. The number of hDPCs adhering to the scaffolds increases as the compressive ratio increases.

Conclusions: The structures and properties of porous chitosan/TPP scaffolds could be tuned by the crosslinking under compression and they would affect the biological properties and could be used in pulp regeneration in the future.