Apatite/Chitosan Composites Formed by Cold Sintering for Drug Delivery and Bone Tissue Engineering Applications

Abstract

In the biomedical field, nanocrystalline hydroxyapatite is still one of the most attractive candidates as a bone substitute material due to its analogies with native bone mineral features regarding chemical composition, bioactivity and osteoconductivity. Ion substitution and low crystallinity are also fundamental characteristics of bone apatite, making it metastable, bioresorbable and reactive. In the present work, biomimetic apatite and apatite/chitosan composites were produced by dissolution–precipitation synthesis, using mussel shells as a calcium biogenic source. With an eye on possible bone reconstruction and drug delivery applications, apatite/chitosan composites were loaded with strontium ranelate, an antiosteoporotic drug. Due to the metastability and temperature sensitivity of the produced composites, sintering could be carried out by conventional methods, and therefore, cold sintering was selected for the densification of the materials. The composites were consolidated up to ~90% relative density by applying a uniaxial pressure up to 1.5 GPa at room temperature for 10 min. Both the synthesised powders and cold-sintered samples were characterised from a physical and chemical point of view to demonstrate the effective production of biomimetic apatite/chitosan composites from mussel shells and exclude possible structural changes after sintering. Preliminary in vitro tests were also performed, which revealed a sustained release of strontium ranelate for about 19 days and no cytotoxicity towards human osteoblastic-like cells (MG63) exposed up to 72 h to the drug-containing composite extract.

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

“…Since the organic-mineral interface in bones is predominantly polysaccharides [805], various biocomposites of CaPO 4 and polysaccharides, such as alginates [413,609,610,612,715,[806][807][808][809], as well as chitosan [426,450,468,490,519,556,[631][632][633][634][635][636][637][638][639][640][641][642][643][644]678,696,702,[810][811][812][813][814][815][816][817][818][819][820][821] and chitin [416,489,[822][823]…”

Polysaccharide Hydroxyapatite (Nano)composites and Their Biomedical Applications: An Overview of Recent Years

“…Preliminary in vitro tests indicated sustained release of strontium ranelate for approximately 19 days and no cytotoxicity in human osteoblast-like cells (MG63) exposed for up to 72 h to the compound extract containing the drug. 176 …”

“…Both the synthesized powders and the cold sintered samples resulted in biomimetic apatite@chitosan composites. Preliminary in vitro tests indicated sustained release of strontium ranelate for approximately 19 days and no cytotoxicity in human osteoblast-like cells (MG63) exposed for up to 72 h to the compound extract containing the drug …”