Tracking the Interaction of Drug Molecules with Individual Mesoporous Amorphous Calcium Phosphate/ATP Nanocomposites – An X-ray Spectromicroscopic Study
Adenosine triphosphate (ATP) biomolecules play critial role in biomineralization process at the formation of amorphous calcium phosphate composites (ACPC), and ACPC is an important drug carrier due to its significant advantages in biocompatibility and biodegradability. Hence, studying the behavior of ACPC nano drug carrier is crucial to investigate the structural regulation of biomimetic minerals and calcium phosphate (CaP) based drug delivery system. However, it is difficult to probe the interaction using traditional characterization methods. In this paper XANES analysis together with STXM successfully provide a means to reveal the interaction of ATP and drug molecules with individual mesoporous ACPC. We find that the adenosine and phosphate group of ATP biomolecules coordinate with Ca2+ and play critical roles in the formation of ACPC; drug molecules with -COOH groups are linked to Ca2+ via carboxylic acid groups by primarily electrostatic interaction, and the N-containing ring structures within drug molecules also coordinate with Ca2+.