Abstract
Abstract Magnetic microspheres (MMS) used for magnetic drug targeting consist of magnetic nanoparticles (MNP) and a pharmaceutical agent embedded in a polymeric matrix material. The application of MNP for drug targeting enables guiding the MMS to a target area, imaging the position of the MMS with magnetic particle imaging, and finally inducing drug release. As latter takes place by degradation of the MMS or diffusion through the matrix, an increase in temperature, e.g. through magnetic hyperthermia, leads to an accelerated drug release. Here, MMS consisting of poly(lactic-coglycolic) acid (PLGA) with different monomer ratios were prepared by an oil-in-water emulsion evaporation method. The model drug Camptothecin (CPT) and magnetic multicore nanoparticles (MCNP) with a high specific heating rate were embedded into the microspheres. We obtained MMS in the preferred size range of 1 to 2 μm with a concentration of MCNP of 16wt%, a drug load of about 0.5wt% and an excellent heating performance of 161 W/gMMS. Investigations of the drug release behaviour showed an accelerated drug release when increasing the temperature from 20 °C to 37 °C or 43 °C by using a water bath. In addition, an increase in drug release of about 50% through magnetic heating of the MMS up to 44 °C compared to 37 °C was observed. By this, a magnetic hyperthermia induced CPT release from PLGA MMS is demonstrated for the very first time.
Highlights
The treatment of tumours with chemotherapy leads to severe side effects due to the systemic distribution of the anti-cancer drug and the resulting damage to healthy tissue
scanning electron microscopy (SEM) images of the Magnetic microspheres (MMS) showed a perfectly round morphology for all microspheres loaded with CPT and multicore nanoparticles (MCNP)
The mean size of the MMS was in the desired range with values of 1.3 to 1.8 μm measured with the mastersizer
Summary
The treatment of tumours with chemotherapy leads to severe side effects due to the systemic distribution of the anti-cancer drug and the resulting damage to healthy tissue. Microspheres (MS) in the size range from 1 to 5 μm are used as such carriers whereby natural polymers (e.g. proteins or polysaccharides) or synthetic ones (e.g. poly(ethylene glycol)) can be used [2]. To guide the drug carriers to their target area inside the human body, embedding magnetic nanoparticles (MNP) into the MS is an advantageous tool. Since drugs are released out of the polymeric matrix by either degradation or diffusion, an increase in temperature can accelerate this process [9]. Those additional features can’t be offered by other targeting strategies like antibody targeting [6]
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