Magnetic Field Guided Chemotaxis of iMushbots for Targeted Anticancer Therapeutics

We report controlled migrations of an intelligent and biocompatible "iMushbot" composed of Agaricus bisporus, mushroom microcapsules coated with magnetite nanoparticles. The otherwise randomly moving microbot could meticulously direct itself toward and away from the acid- and alkali-rich regions with the help of acid, acidic catalase, and alkali stimuli, emulating the chemotaxis of microorganisms. Although the catalytic decomposition of peroxide-fuel in alkali engendered the directed alkali taxis toward higher pH region, decomposition of peroxide fuel by the acidic catalase activity led to directed acid taxis toward the lower pH region. The presence of magnetite nanoparticles not only helped in improving the "activity" of the motor through the heterogeneous catalytic decomposition of the peroxide fuel but also provided a remote magnetic control on the chemotaxis. The mesoporous iMushbots having negative zeta-potential could easily be loaded with the cationic anticancer drugs, which were magnetically guided toward the cancerous cells to cause apoptosis. The iMushbots exhibited higher degree of drug retaining capacity inside alkaline pH and showed facile drug release preferentially in the lower pH environments. The experiments show the potential of the iMushbots in retaining and transporting drugs in alkaline medium such as human blood and releasing them in acidic medium such as the cancerous tissues for cell apoptosis.