Department: NanoEngineering
Faculty Advisor(s): Joseph Wang
Award(s): Best Literature Review Award

Primary Student
Name: Wei Gao
Email: w1gao@ucsd.edu
Phone: 858-534-2926
Grad Year: 2014

Locomotion of nanoscale objects through a fluid environment currently represents one of the major challenges of nanotechnology due to the limitations of the low Reynolds numbers. The advanced artificial nanomachines can serve as an ideal platform for diverse biomedical applications such as targeted drug delivery and biomaterials isolation. Here highly efficient tubular microrockets are synthesized rapidly and inexpensively using an electrochemical growth of bilayer polymer (e.g. PANI, PPy, PEDOT)/metal microtubes within the conically-shaped pores of a polycarbonate template. These oxygen bubble propelled Pt based microrockets are only 8 μm long, can operate in very low levels of the hydrogen peroxide fuel (down to 0.2%) and achieve a consistently remarkable high speed of 1400 body lengths/s in physiological temperature (the speed record of all artificial nanomotors). These tubular microrockets have been succefully used for diverse biomaterials (e.g. cancer cells, DNA, protein and bacteria) isolation from fuel enhanced biological environments. For example, lectin modified PANI/Pt microrockets are used for selective bacteria (E. Coli) isolation from food, clinical and environmental samples. These multifunctional microtube rockets combine the selective capture of E. coli with the uptake of polymeric drug-carrier particles to provide an attractive motion-based theranostics strategy. Triggered release of the captured bacteria is also demonstrated by movement through a low-pH glycine-based dissociation solution. As a great expansion of such template prepared bilayer microrockets, newly developed hydrogen bubble propelled zinc based microrockets display effective autonomous motion in extreme acidic environments such as human stomach, without any additional chemical fuel such as hydrogen peroxide. The observed speed−pH dependence of such microrocket holds great promise for sensitive pH measurements in extreme acidic environments. The new microrockets display an ultrafast propulsion (as high as 100 body lengths/s) along with attractive capabilities including guided movement and directed cargo transport. Such acid-driven microtubular rockets offer considerable potential in extreme environments (e.g. human stomach and silicon wet-etching baths) for diverse biomedical and industrial applications.

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