A simple and rapid fabrication method for biodegradable drug-encapsulating microrobots using laser micromachining, and characterization thereof

Magnetically manipulated biodegradable microrobots that encapsulate drugs from the outset are produced in a novel, simple way using UV-laser micro-machining. This method enables multiple microrobots to be produced rapidly, without the need for post-drug encapsulation or polymerization by light exposure, which may cause the drug compound to denature. The microrobot consists of poly (dl-lactic-co-glycolic acid) (PLGA), iron (Fe) particles and 5-fluorouracil (5-FU) as biodegradable, magnetic and drug material, respectively. The fabricated microrobots are precisely and remotely controlled in a fluidic environment by external magnetic fields. To prove the feasibility of targeted drug delivery, the drug release is profiled as a function of time, biodegrading in aqueous solution at 37 °C over 6 weeks. The Fe concentration has a significant effect on the biodegradation rate of the microrobots. The amount of drug encapsulated can be controlled by adjusting the concentration of the drug in the PLGA/Fe/5-FU mixture whilst fabricating the microrobots. Approximately 0.013 μg of 5-FU is released from a single PLGA/Fe/5-FU microrobot over a period of 6 weeks. In addition, we have conducted drug testing with human colorectal cancer (HCT116) cells to investigate the effect of drugs released from our microrobots on cancer cells. While no significant reduction in live cell ratio was observed with the controls, it decreased approximately 20% when cells were cultured with the PLGA/Fe/5-FU microrobot for 2 days. It presents that 5-FU was delivered from the microrobot to cancer cells and negatively affected them.