Fabrication and potential application of a di-functional magnetic system: magnetic hyperthermia therapy and drug delivery

Abstract

A novel di-functional system was synthesized by encapsulation of superparamagnetic Fe₃O₄ and a therapeutic agent 5-fluorouracil (5-Fu) with the thermo-responsive poly(N-isopropylacrylamide) (PNIPAM), which was coated with mesoporous SiO₂ nanoparticles in a mesoporous core–shell structure. The system featured functionalized magnetic Fe₃O₄ and a smart thermo-responsive polymer PNIPAM. In an alternating magnetic field (AMF), the magnetic nanoparticles were heated up to 45 °C, which was the cancer treatment temperature. Therefore, it has potential for hyperthermia treatment. The smart polymer PNIPAM has a lower critical solution temperature (LCST), which is representative of a phase transition behavior. Based on it, the thermo-responsive polymer PNIPAM played a role of an on-off trigger switch in the process of drug releasing. The tests of drug releasing were investigated by UV-visible spectrophotometry at 45 °C and 25 °C. The test results showed that there was little drug released at 25 °C (below the LCST) but drug was mainly released at the temperature of 45 °C (above the LCST). In a word, our studies were mainly about the di-function of the composite: magnetic hyperthermia treatment and drug release. It has potential applications for reducing side effects of cancer treatment and achieving controlled drug release in response to variations of temperature.