Poly(d,l-lactide-co-glycolide)/hydroxyapatite core–shell nanospheres. Part 3: Properties of hydroxyapatite nano-rods and investigation of a distribution of the drug within the composite

A step-by-step analysis of the formation and the drug loading of the poly(d,l-lactide-co-glycolide)/hydroxyapatite (PLGA/HAp) composite was carried out in a perspective of the following parameters: the structure, the morphology and the adsorption/desorption properties of the composite's bioceramic part. The authors demonstrated the importance of the material's capacity to form a fine dispersion of solid HAp particles, as an initial step, for the further loading of the drug and for the formation of the core–shell structures. The nanometer-sized rods of HAp have the capacity of ensuring a rapid adsorption and a controlled desorption of the drug from their surface, and they can act as a nucleating site for the formation of polymeric cores. Each component of this material was labeled with fluorescence dye, which enabled an insight into the distribution of the components in the core–shells that were obtained as the final outcome. Such an analysis showed a high level of uniformity among the cores enclosed within polymeric shells. From a practical perspective, the labeling of each component of the composite can be regarded as an additional functionality of the material: labeling can enable us to monitor its action during the healing process. This ability to be easily detected is expected to enhance the procedure for the controlled delivery of antibiotics after their local implantation of carriers loaded with the antibiotic and to provide more careful control over this process.

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► Ultrasound de-agglomerated HAp rods and activated their surface for drug adsorption.
► It allowed gradual drug release during 10 days confirming drug/HAp interactions.
► HAp/drug particles were coated by PLGA which preserved their size and structure.
► Labeling revealed uniform distribution of components within PLGA/HAp/drug.
► Labeled PLGA/HAp/drug obtained additional functionality important for its application.