Nanorobots for Targeted Delivery in Deep Biological Tissues

Participating Researchers
Current members: Dr. Meng Zhang, Dr. Haoying Wang

In our previous research, we developed a variety of micro-/nano-sized propulsion units. The size range expands three orders-of-magnitude and the propulsion mechanisms are designed to match the rheology of biological media. For example, to propel in viscoelastic media, the fluidic drag is highly dependent on the size of the device [ref 1]. When the characteristic size of the structure or device is comparable or smaller than the pore size of the biopolymer network, the device only exhibits viscous drag, and can "slip" unhindered through the porous network.

We developed the world's smallest nanorobot that can penetrate real biological tissues [ref 2]. The nanopropellers mimic the corkscrew propulsion of bacteria and have a spherical head and a helical tail (Fig. 1) with a diameter of ~500 nm, which perfectly matches the nano-sized pores of the targeted biological tissue — the vitreous humor of the eye. The propellers exhibit a finite magnetic moment in the diametric direction and when actuated under a rotating magnetic field, the rotation is coupled to translation due to its helical shape. Our experimental results show that a swarm of nanopropellers can be controlled to navigate over centimeter distance in the eye and reach the targeted region (optic disc) of ~6 mm in diameter on the retina (Fig. 1). One key research question is whether the active nanoparticles can be wirelessly guided to penetrate solid tumor tissues and more efficiently deliver cancer drugs.

1) Qiu, T. et al. (2014): IEEE International Conference on Robotics and Automation (ICRA), 3801-3806
2) Wu, Z. et al. (2018) : Sci. Adv. 2018, 4, eaat4388
3) Yu, T. et al. (2020): Microchannels with self-pumping walls, ACS Nano, 14, 13673

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