Influence of bacterial nanocellulose surface modification on calcium phosphates precipitation for bone tissue engineering

Abstract

Bacterial nanocellulose (BNC) is a nano fibrillar polymer, which is biostable and non-resorbable when inside the human body. It has excellent biocompatibility and a microstructure with high mechanical strength, and if processed correctly, can mimic the extra-cellular matrix architecture. BNC, modified with bone-like minerals such as calcium phosphates, can improve cell adhesion and promote the formation of new bone tissues. As a result of the need for three-dimensional (3D) porous scaffolds for bone tissue regeneration, this study evaluated the effect of calcium phosphate mineralization process on BNC and (2,2,6,6-Tetramethylpiperidin-1-yl)oxyl (TEMPO)-oxidized BNC scaffolds, to understand the influence of hydroxyl or carboxylate groups on the nucleation and growth of apatite crystals. The results showed 3D scaffolds with controlled microporosity, between 50 and 350 µm, and interconnected pores. The porous morphology of the TEMPO-oxidized BNC scaffolds varied significantly with the oxidation time and only remained preserved after 60 min of the TEMPO-mediated oxidation. BNC and TEMPO-oxidized BNC scaffolds were used to compare two different mineralization treatments. The growth of homogeneously distributed microcrystals was observed in the unmodified BNC scaffolds, whereas heterogeneously distributed microcrystals were observed in the TEMPO-oxidized BNC scaffolds because of the oxidation treatment which affected the continuity of the surface by fracturing some fibers. Also, in vitro cell studies revealed good cellular adhesion and high cell viability in the modified and unmodified BNC scaffolds. Most of the modifications seemed adequate for cellular adhesion.