TOWARDS TRANSFORMATIVE HEALTHCARE APPLICATIONS: BIOMIMETIC HYDROXYAPATITE SYSTEMS FOR CONTROLLED DRUG DELIVERY

Recently, there has been a growing interest in multifunctional materials, therefore we developed a system that combines biocompatibility, gradient changing and antibacterial properties. We aim to combine these properties in the development of a biomimetic system based on hydroxyapatite (Ca₁₀ (PO₄)₆ (OH)₂, HA) by incorporating silver nanoparticles (Ag NPs) into HA matrices, leveraging their antimicrobial effects, while also exploring their role as drug release triggers (absorb infrared (IR) light of 808-960 nm, convert to heat energy to induce localized heating and cause a structure leak for drug release) to unmodified HA which cannot be activated by IR in significant amounts. Limited diffusion aggregation is used to form HA (enhanced with glycine or produced with different outer electrolytes) by diffusing calcium phosphates through Na₂HPO₄-agar. The composite was then packed with tetracycline and deposition of polyelectrolytes (PE). The combination of polydiallyldimethylammonium chloride (PDADMAC) and heparin forms a robust PE. Infrared light (808 nm, 1.4 mW/cm²) was utilized as energy source for non-invasive and on-demand drug release. Physical and chemical characterization of HA was carried out. Glycine did not affect the p-factor of the resulting rings, which is equal to ca. 1.00. NIR increased release rates 2.1-fold (k = 39.21 compared to 18.22). High glycine concentrations reduces HA crystallinity (94 to 30%), a 12.5% increased drug loading capacity, increases solubility (5× control). NIR reduced the Korsmeyer-Peppas release exponent (n) from 0.42 (Fickian) to 0.11 (PE-coated HA-Ag), confirming photothermal disruption of diffusion barriers due to the presence of silver nanoparticle peaks in the composition.