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

Area of Science:

• Biomaterials science
• Biomedical engineering
• Materials science

Background:

• Nanocrystalline hydroxyapatite is a promising bone substitute due to its similarity to bone mineral.
• Bone apatite's metastability, bioresorbability, and reactivity are influenced by ion substitution and low crystallinity.
• Mussel shells offer a sustainable calcium source for biogenic apatite synthesis.

Purpose of the Study:

• To synthesize biomimetic apatite and apatite/chitosan composites using mussel shells.
• To investigate cold sintering as a method for densifying these temperature-sensitive composites.
• To evaluate the potential of these composites for bone reconstruction and drug delivery, specifically loading with strontium ranelate.

Main Methods:

• Dissolution-precipitation synthesis using mussel shells as a calcium source.
• Incorporation of strontium ranelate into apatite/chitosan composites.
• Cold sintering under uniaxial pressure (up to 1.5 GPa) at room temperature for densification.
• Physical and chemical characterization of powders and sintered samples.
• In vitro drug release and cytotoxicity assays using human osteoblastic-like cells (MG63).

Main Results:

• Successful synthesis of biomimetic apatite/chitosan composites from mussel shells.
• Cold sintering achieved approximately 90% relative density without significant structural changes.
• Sustained release of strontium ranelate from the composites over approximately 19 days.
• No cytotoxicity observed for human osteoblastic-like cells exposed to drug-loaded composite extracts for up to 72 hours.

Conclusions:

• Mussel shells can be effectively utilized to produce biomimetic apatite/chitosan composites.
• Cold sintering is a viable technique for densifying these temperature-sensitive materials for biomedical applications.
• The developed composites demonstrate potential for bone reconstruction and sustained drug delivery of antiosteoporotic agents.