title: Nanopropulsion by biocatalytic self-assembly.
abstract: A number of organisms and organelles are capable of self-propulsion at the micro- and nanoscales. Production of simple man-made mimics of biological transportation systems may prove relevant to achieving movement in artificial cells and nano/micronscale robotics that may be of biological and nanotechnological importance. We demonstrate the propulsion of particles based on catalytically controlled molecular self-assembly and fiber formation at the particle surface. Specifically, phosphatase enzymes (acting as the engine) are conjugated to a quantum dot (the vehicle), and are subsequently exposed to micellar aggregates (fuel) that upon biocatalytic dephosphorylation undergo fibrillar self-assembly, which in turn causes propulsion. The motion of individual enzyme/quantum dot conjugates is followed directly using fluorescence microscopy. While overall movement remains random, the enzyme-conjugates exhibit significantly faster transport in the presence of the fiber forming system, compared to controls without fuel, a non-self-assembling substrate, or a substrate which assembles into spherical, rather than fibrous structures upon enzymatic dephosphorylation. When increasing the concentration of the fiber-forming fuel, the speed of the conjugates increases compared to non-self-assembling substrate, although directionality remains random.
authors.affiliation: Department of Chemical and Process Engineering, University of Strathclyde , 75 Montrose Street, Glasgow G11XJ, United Kingdom.
authors.forename: Joy
authors.initials: J
authors.lastname: Leckie
authors.forename: Alexander
authors.initials: A
authors.lastname: Hope
authors.forename: Meghan
authors.initials: M
authors.lastname: Hughes
authors.forename: Sisir
authors.initials: S
authors.lastname: Debnath
authors.forename: Scott
authors.initials: S
authors.lastname: Fleming
authors.forename: Alastair W
authors.initials: AW
authors.lastname: Wark
authors.forename: Rein V
authors.initials: RV
authors.lastname: Ulijn
authors.forename: Mark D
authors.initials: MD
authors.lastname: Haw
mesh_terms: D000469:Alkaline Phosphatase / Q000737:chemistry / Q000378:metabolism; D055162:Biocatalysis; D032701:Biomimetics / Q000379:methods*; D004926:Escherichia coli / Q000201:enzymology; D005449:Fluorenes / Q000737:chemistry; D008958:Models, Molecular; D020409:Molecular Motor Proteins / Q000378:metabolism*; D036103:Nanotechnology / Q000379:methods*; D010455:Peptides / Q000737:chemistry; D055503:Protein Multimerization; D017433:Protein Structure, Secondary; D045663:Quantum Dots / Q000737:chemistry
chemical_list: C496789:9-fluorenylmethoxycarbonyl; D005449:Fluorenes; D020409:Molecular Motor Proteins; D010455:Peptides; D000469:Alkaline Phosphatase
keywords: aromatic peptide amphiphiles; biocatalysis; nanopropulsion; self-assembly; single particle tracking