Graphene oxide, graphdyine oxide, and blackphosphorus coated micromotors integrating "three engines" for motion control using different stimuli such as chemical fuel, light, and magnetic fields are described. Micromotors can be massproduced by wrapping gold-sputtered polystyrene microspheres with the 2D nanomaterials, followed by simultaneous assembly of Pt or MnO 2 nanoparticles (NPs) as bubble (catalytic)-engines, Fe 2 O 3 NPs as magnetic engines, and quantum dots (QDs) as light engines. The design and composition of micromotors are key to get the desired propulsion performance. In bubble-magnetic and bubble-light mode, a built-in acceleration system allows micromotor speed to be increased up to 3.0 and 1.5 times after application of the magnetic field or light irradiation, respectively. In the bubble-magnetic-light mode, such speed increase can be combined in a single unit for on-demand braking and accelerating systems. Fluid dynamics simulations illustrate that such adaptative behavior and improved propulsion efficiency is produced by a better distribution of the fuel and thus energy propelling the micromotor by activation of the magnetic and/or light engines. The new micromotors described here, which combine multiple engines with functional nanomaterials, hold considerable promise to develop novel nanovehicles with adaptative behavior to perform complex tasks in lab-on-a-chips or dynamic micropatterning applications.
Graphene oxide/PtNPs/Fe2O3 “dual‐propelled” catalytic and fuel‐free rotary actuated magnetic Janus micromotors modified with the lanbiotic Nisin are used for highly selective capture/inactivation of gram‐positive bacteria units and biofilms. Specific interaction of Nisin with the Lipid II unit of Staphylococcus Aureus bacteria in connection with the enhanced micromotor movement and generated fluid flow result in a 2‐fold increase of the capture/killing ability (both in bubble and magnetic propulsion modes) as compared with free peptide and static counterparts. The high stability of Nisin along with the high towing force of the micromotors allow for efficient operation in untreated raw media (tap water, juice and serum) and even in blood and in flowing blood in magnetic mode. The high selectivity of the approach is illustrated by the dramatically lower interaction with gram‐negative bacteria (Escherichia Coli). The double‐propulsion (catalytic or fuel‐free magnetic) mode of the micromotors and the high biocompatibility holds considerable promise to design micromotors with tailored lanbiotics that can response to the changes that make the bacteria resistant in a myriad of clinical, environmental remediation or food safety applications.
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