Tough and Elastic α-Tricalcium Phosphate Cement Composites with Degradable PEG-Based Cross-Linker

Abstract

Dual setting cements composed of an in situ forming hydrogel and a reactive mineral phase combine high compressive strength of the cement with sufficient ductility and bending strength of the polymeric network. Previous studies were focused on the modification with non-degradable hydrogels based on 2-hydroxyethyl methacrylate (HEMA). Here, we describe the synthesis of suitable triblock degradable poly(ethylene glycol)-poly(lactide) (PEG-PLLA) cross-linker to improve the resorption capacity of such composites. A study with four different formulations was established. As reference, pure hydroxyapatite (HA) cements and composites with 40 wt% HEMA in the liquid cement phase were produced. Furthermore, HEMA was modified with 10 wt% of PEG-PLLA cross-linker or a test series containing only 25% cross-linker was chosen for composites with a fully degradable polymeric phase. Hence, we developed suitable systems with increased elasticity and 5–6 times higher toughness values in comparison to pure inorganic cement matrix. Furthermore, conversion rate from α-tricalcium phosphate (α-TCP) to HA was still about 90% for all composite formulations, whereas crystal size decreased. Based on this material development and advancement for a dual setting system, we managed to overcome the drawback of brittleness for pure calcium phosphate cements.

Chitosan Effect on Hardening Dynamics of Calcium Phosphate Cement: Low-Field NMR Relaxometry Investigations

“…Its evolution during hardening revealed a consumption of the mobile component and a shift to smaller values, as polymerization progressed. This evolution could be associated with the transformation of components during cement setting due to gelation reactions [ 26 ].…”

Calcium Orthophosphate (CaPO4) Containing Composites for Biomedical Applications: Formulations, Properties, and Applications

“…Unfortunately, self-hardening CaPO 4 formulations with ceramic properties become brittle after setting, while the hardening time may not be suitable for clinical procedures [478]. Therefore, several attempts have been made to transform them into biocomposites to improve their properties, for example, by adding PEG [479,480], polylactide [481], PLGA [482], gelatin [414,[483][484][485][486], osteocalcin/collagen [487], alginic acid [488], chitin [489], chitosan [451,490], fibrin glue [491], silk fibroin [492,493], silanized HPMC [494], CMC [495], PVA fibers with CMC [496] and without CMC [497], CMC/gelatin/fullerenol [498], bioactive glass [499][500][501][502], bioactive glass functionalized with hypoxia conditioned medium [503], calcium silicate [504][505][506], cockle shell powders [507], metals [508], magnetic nanoparticles [509], and so on. Light-curing formulations have also been prepared [510,511].…”