title: Multimodal chemo-magnetic control of self-propelling microbots.
abstract: We report a controlled migration of an iron nanoparticle (FeNP) coated polymer micromotor. The otherwise diffusive motion of the motor was meticulously directed through an in situ pH-gradient and an external magnetic field. The self-propulsion owing to the asymmetric catalytic decomposition of peroxide fuel was directed through a pH gradient imposed across the motor-surface, while the magnetic field induced an external control on the movement and the speed of the motor. Interestingly, the sole influence of the pH gradient could move the motor as high as ∼25 body lengths per second, which was further magnified by the external assistance from the magnetic field. Applying a magnetic field against the pH directed motion helped in the quantitative experimental estimation of the force-field required to arrest the chemotactic migration. The influence of the coupled internal and external fields could halt, steer or reverse the direction the motor inside a microchannel, rotate the motor around a target, and deliver the motor to a cluster of cells. This study showcases a multimodal chemical-magnetic field regulated migration of micro-machines for sensing, transport, and delivery inside a fluidic environment.
authors: Centre for Nanotechnology, Indian Institute of Technology Guwahati, Guwahati - 781039, India. dipban@iitg.ernet.in.
authors: Amit Kumar
authors: AK
authors: Singh
authors: Krishna Kanti
authors: KK
authors: Dey
authors: Arun
authors: A
authors: Chattopadhyay
authors: Tapas Kumar
authors: TK
authors: Mandal
authors: Dipankar
authors: D
authors: Bandyopadhyay
mesh_terms: D001672:Biocompatible Materials; D015374:Biosensing Techniques; D002384:Catalysis; D002633:Chemotaxis; D016503:Drug Delivery Systems; D006861:Hydrogen Peroxide / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000737:chemistry*; D060526:Magnetic Fields; D008280:Magnetics; D053768:Metal Nanoparticles / Q000737:chemistry*; D055616:Microtechnology / Q000379:methods*; D009038:Motion; D036103:Nanotechnology / Q000379:methods; D011108:Polymers / Q000737:chemistry; D012371:Robotics / Q000295:instrumentation*
chemical_list: D001672:Biocompatible Materials; D011108:Polymers; D006861:Hydrogen Peroxide; D007501:Iron