Methylcellulose-Encapsulated Magnesium-Substituted Biphasic Calcium Phosphate Granules for Local Drug Delivery in...

Bone tissue restoration requires biomaterials, which combine osteoinductivity and the capability to prevent surgical site infections. Magnesium-substituted biphasic calcium phosphate (Mg-BCP) represents a promising solution, as magnesium substitution increases the biodegradation rate of calcium phosphate ceramics and provides inherent antibacterial properties. This study aimed to achieve wet precipitation synthesis of magnesium-substituted (1-10 mol%) biphasic calcium phosphate and to evaluate its drug delivery potential and antibacterial performance. Porous Mg-BCP granules were fabricated via the gelation of Mg-BCP suspension in sodium alginate followed by polymer removal. Drug delivery potential was evaluated using methylene blue as a model compound, with methylcellulose encapsulation implemented to ensure prolonged release. Magnesium content directly ruled the phase composition: low concentrations (1%) favored hydroxyapatite phase prevalence, while higher concentrations led to the β-tricalcium phosphate formation. Further assessment of drug delivery potential revealed that direct drug loading resulted in burst release, whereas methylcellulose encapsulation successfully enabled prolonged drug delivery. Mg-5BCP formulation demonstrated significant antimicrobial activity with growth inhibition of 17.7 ± 4.1% against C. albicans, 20.8 ± 7.0% against E. faecalis, and 12.9 ± 7.5% against E. coli. Therefore, Mg-5BCP-methylcellulose composite granules present a versatile platform for antibacterial drug delivery for bone tissue engineering applications.