Temperature controlled camptothecin release from biodegradable magnetic PLGA microspheres

Abstract Drug loaded magnetic microspheres (MMS) can be magnetically guided to a target area within the body, where the pharmaceutical agent is released passively. For a faster release, the microspheres have to be disintegrated actively, e.g., by an increase of the temperature of the MMS. In the here presented study, poly(lactic-co-glycolic) acid (PLGA) microspheres were prepared. Magnetic nanoparticles with high magnetic heating performance and the drug camptothecin were embedded into the PLGA matrix. Resulting microspheres were characterized by means of dynamic light scattering, scanning electron microscopy, magnetometry, magnetic calorimetry, and UV/Vis spectrophotometry for determination of the drug release as a function of time and temperature. The MMS diameter is about 1.5 µm and the MMS show a content of magnetic material of up to 16 wt% and a drug loading of about 0.5 wt%. The MMS have a specific heating power of 161 W/g MMS , which enables sufficient magnetic heating for enforced drug release from the MMS in tissue concentrations of 2% by mass. Depending on the applied temperatures and the used PLGA type, the loaded drug is released within hours to days and a temperature increase from 37 to 43 °C leads to a significant faster drug release. The principle of magnetically triggered drug release is demonstrated by magnetic hyperthermia induced release of a drug from the MMS.