Nanomotor

[1][2][3][4] While nanoparticles have been utilized by artists for centuries, such as in the famous Lycurgus cup, scientific research into nanotechnology did not come about until recently.

In 1959, Richard Feynman gave a famous talk entitled "There's Plenty of Room at the Bottom" at the American Physical Society's conference hosted at Caltech.

In addition, Brownian motion must be considered because particle-solvent interaction can dramatically impact the ability of a nanomotor to traverse through a liquid.

Now, the more pressing challenge is to overcome issues such as biocompatibility, control on directionality and availability of fuel before nanomotors can be used for theranostic applications within the body.

[8] The two-micron long nanomotors were composed of two segments, platinum and gold, that could catalytically react with diluted hydrogen peroxide in water to produce motion.

Joseph Wang in 2008 was able to dramatically enhance the motion of Au-Pt catalytic nanomotors by incorporating carbon nanotubes into the platinum segment.

[19] These multi-functional nanowires move in different directions depending on the stimulus (e.g. chemical fuel or ultrasonic power) applied.

[19] For example, bimetallic nanomotors have been shown to undergo rheotaxis to move with or against fluid flow by a combination of chemical and acoustic stimuli.

[21] Without the reliance on electrostatic interactions, bubble-induced propulsion enables motor movement in relevant biological fluids, but typically still requires toxic fuels such as hydrogen peroxide.

One in vivo application, however, of microtube motors has been described for the first time by Joseph Wang and Liangfang Zhang using gastric acid as fuel.

[22] Recently titanium dioxide has also been identified as a potential candidate for nanomotors due to their corrosion resistance properties and biocompatibility.

[23] Future research into catalytical nanomotors holds major promise for important cargo-towing applications, ranging from cell sorting microchip devices to directed drug delivery.

Starting and stopping the movement of such motor proteins would involve caging the ATP in molecular structures sensitive to UV light.

For example, in 2020 Stolz et al. showed the cross-over from classical motion to quantum tunneling in a nanomotor made of a rotating molecule driven by the STM's current.