A drug release system induced by near infrared laser using alginate microparticles containing melanin

The photothermal effect is used in a new drug release system to control drug delivery in a specific region. Melanin absorbs near-infrared (NIR) light with a high photothermal conversion efficiency, and as a result, an NIR laser can be used to induced drug release from alginate microparticles containing melanin (ALG-Mel microparticles). The temperature of the ALG-Mel microparticle solution at a concentration of 5 mg/mL increased to 38.1 °C from 26.0 °C after irradiation with 808 nm NIR at 1.5 W/cm2 for 5 min, and this increase in temperature was found to be independent of the ALG-Mel microparticle concentration. After the NIR laser irradiation, 5-fluorouracil (5-FU) was released from the ALG-Mel microparticles to 87.4 ± 0.5% of the total loaded drug for 24 h. Without NIR laser irradiation, 5-FU was released from the ALG-Mel microparticles to 60.8 ± 1.5% of the total loaded drug for 24 h. These results indicate that NIR laser irradiation can be used with ALG-Mel microparticles as a drug delivery system for release within a target region.