Carriers based on poly-3-hydroxyalkanoates containing nanomagnetite to trigger hormone release.

Poly-3-hydroxybutyrate (P(3HB)) and poly-3-hydroxybutyrate-co-3-hydroxyhexanoate (P(3HB-co-3HHx)) are biocompatible and bioabsorbable biopolymers produced by different bacteria with potential for drug delivery in thermo-responsive magnetic microcarriers. Microparticles of P(3HB) and P(3HB-co-3HHx), with 5.85% mol of 3HHx, produced by Burkholderia sacchari, containing nanomagnetite (nM) and lipophilic hormone were prepared by simple emulsion (oil/water) technique leading to progesterone (Pg) encapsulation efficiency higher than 70% and magnetite loads of 3.1 and 2.3% (w/w) for P(3HB)/nM/Pg and P(3HB-co-3HHx)/nM/Pg, respectively. These formulations were characterized by Infrared spectroscopy, X-ray diffraction, Thermal gravimetric analysis and Electron microscopy (TEM, SEM) techniques. The P(3HB)/nM/Pg and P(3HB-co-3HHx)/nM/Pg microparticles presented spherical geometry with wrinkled surfaces and average size between 2 and 40 μm for 90% of the microparticles. The release profiles of the P(3HB)/nM/Pg and P(3HB-co-3HHx)/nM/Pg formulations showed a hormone release trigger (6.9 and 11.1%, respectively) effect induced by oscillating external magnetic field (0.2 T), after 72 h. Progesterone release in non-magnetic tests with P(3HB-co-3HHx)/nM/Pg revealed a slight increment (5.6%) in relation to P(3HB)/nM/Pg. The experimental release of the P(3HB)/nM/Pg and P(3HB-co-3HHx)/nM/Pg samples presented a good agreement with Higuchi model. The 3HHx comonomer content improves the hormone release of the P(3HB-co-3HHx)/nM/Pg formulation with potential for application to synchronize the estrous cycle.