Novel Superparamagnetic Microdevices Based on Magnetized PLGA/PLA Microparticles Obtained by Supercritical Fluid Emulsion and Coating by Carboxybetaine-Functionalized Chitosan Allowing the Tuneable Release of Therapeutics

Microcarriers showed a mean size of 800 ± 60 nm with an encapsulation efficiency of up to 90%. The inversion of surface charge, after the f-chi coating, suggested the presence of a uniform functionalized surface available for further chemical linkage. The external chitosan layer had a thickness of 200 ± 50 nm. An excellent MAG dispersion was confirmed within the biopolymer matrix that was shown to be responsive to external magnetic field; indeed, Fluo was released over 3 or 5 days from PLGA or f-chi-PLGA microdevices into phosphate-buffered saline medium at 37°C, whereas remote on-off controlled release was achieved when an alternating magnetic field was applied.