Efficient and controlled nanoscale propulsion in harsh environments requires careful design and manufacturing of nanomachines, which can harvest and translate the propelling forces with high spatial and time resolution. Here we report a new class of artificial nanomachine, named magneto-acoustic hybrid nanomotor, which displays efficient propulsion in the presence of either magnetic or acoustic fields without adding any chemical fuel. These fuel-free hybrid nanomotors, which comprise a magnetic helical structure and a concave nanorod end, are synthesized using a template-assisted electrochemical deposition process followed by segment-selective chemical etching. Dynamic switching of the propulsion mode with reversal of the movement direction and digital speed regulation are demonstrated on a single nanovehicle. These hybrid nanomotors exhibit a diverse biomimetic collective behavior, including stable aggregation, swarm motion, and swarm vortex, triggered in response to different field inputs. Such adaptive hybrid operation and controlled collective behavior hold considerable promise for designing smart nanovehicles that autonomously reconfigure their operation mode according to their mission or in response to changes in their surrounding environment or in their own performance, thus holding considerable promise for diverse practical biomedical applications of fuel-free nanomachines.
An effective and rapid bacterial killing nanotechnology strategy based on lysozyme-modified fuel-free nanomotors is demonstrated. The efficient antibacterial property of lysozyme, associated with the cleavage of glycosidic bonds of peptidoglycans present in the bacteria cell wall, has been combined with ultrasound (US)-propelled porous gold nanowire (p-AuNW) motors as biocompatible dynamic bacteria nanofighters. Coupling the antibacterial activity of the enzyme with the rapid movement of these p-AuNWs, along with the corresponding fluid dynamics, promotes enzyme-bacteria interactions and prevents surface aggregation of dead bacteria, resulting in a greatly enhanced bacteria-killing capability. The large active surface area of these nanoporous motors offers a significantly higher enzyme loading capacity compared to nonporous AuNWs, which results in a higher antimicrobial activity against Gram-positive and Gram-negative bacteria. Detailed characterization studies and control experiments provide useful insights into the underlying factors controlling the antibacterial performance of the new dynamic bacteria nanofighters. Rapid and effective killing of the Gram-positive Micrococcus lysodeikticus bacteria (69-84% within 1-5 min) is demonstrated.
Electrochromic (EC) properties of tungsten trioxide (WO 3 ) was improved with preparing hybrids of tungsten trioxide−titanium dioxide (WO 3 −TiO 2 ) and tungsten trioxide−poly(3,4-ethylenedioxythiophene) (WO 3 −PEDOT) by a rotating capacitively coupled radio frequency (rf 13.56 MHz) plasma reactor. Energy-dispersive X-ray spectroscopy mapping results indicated that TiO 2 and PEDOT were coated homogeneously onto the surface of the WO 3 powders. Thin films of hybrid powders have been prepared by the physical vapor deposition method of the electron beam evaporation technique. Redox potentials, optical contrast at 700 nm, and durability during 2000 cycles of EC devices were investigated, comparatively. Hybrids of WO 3 indicated excellent coloration efficiency (cm 2 C −1 ) and switching speed values compared with untreated WO 3 . The coloration efficiency values were found to be 85.88 and 41.61 cm 2 C −1 of WO 3 −TiO 2 and WO 3 −PEDOT, respectively. The switching speed of WO 3 (13.3 s, from bleached state to colored state) increased to 1.4 s for WO 3 −TiO 2 .
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