A Molecular propeller is a

molecule A molecule is a group of two or more atoms that are held together by Force, attractive forces known as chemical bonds; depending on context, the term may or may not include ions that satisfy this criterion. In quantum physics, organic chemi ...

that can propel fluids when rotated, due to its special shape that is designed in analogy to macroscopic

propellers A propeller (often called a screw if on a ship or an airscrew if on an aircraft) is a device with a rotating hub and radiating blades that are set at a pitch to form a helical spiral which, when rotated, exerts linear thrust upon a working flu ...

: it has several molecular-scale

blade A blade is the Sharpness (cutting), sharp, cutting portion of a tool, weapon, or machine, specifically designed to puncture, chop, slice, or scrape surfaces or materials. Blades are typically made from materials that are harder than those they a ...

s attached at a certain pitch angle around the circumference of a shaft, aligned along the rotational axis. The molecular propellers designed in the group of Prof. Petr Král from the

University of Illinois at Chicago The University of Illinois Chicago (UIC) is a public research university in Chicago, Illinois, United States. Its campus is in the Near West Side community area, adjacent to the Chicago Loop. The second campus established under the Universi ...

have their blades formed by planar

aromatic In organic chemistry, aromaticity is a chemical property describing the way in which a conjugated system, conjugated ring of unsaturated bonds, lone pairs, or empty orbitals exhibits a stabilization stronger than would be expected from conjugati ...

molecules and the shaft is a

carbon nanotube A carbon nanotube (CNT) is a tube made of carbon with a diameter in the nanometre range ( nanoscale). They are one of the allotropes of carbon. Two broad classes of carbon nanotubes are recognized: * ''Single-walled carbon nanotubes'' (''S ...

Molecular dynamics Molecular dynamics (MD) is a computer simulation method for analyzing the Motion (physics), physical movements of atoms and molecules. The atoms and molecules are allowed to interact for a fixed period of time, giving a view of the dynamics ( ...

simulations show that these propellers can serve as efficient pumps in the bulk and at the surfaces of liquids. Their pumping efficiency depends on the chemistry of the interface between the blades and the liquid. For example, if the blades are

hydrophobic In chemistry, hydrophobicity is the chemical property of a molecule (called a hydrophobe) that is seemingly repelled from a mass of water. In contrast, hydrophiles are attracted to water. Hydrophobic molecules tend to be nonpolar and, thu ...

, water molecules do not bind to them, and the propellers can pump them well. If the blades are

hydrophilic A hydrophile is a molecule or other molecular entity that is attracted to water molecules and tends to be dissolved by water.Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon'' Oxford: Clarendon Press. In contrast, hydrophobes are n ...

, water molecules form

hydrogen bonds In chemistry, a hydrogen bond (H-bond) is a specific type of molecular interaction that exhibits partial covalent character and cannot be described as a purely electrostatic force. It occurs when a hydrogen (H) atom, covalently bonded to a mo ...

with the atoms in the polar blades. This can largely block the flow of other water molecules around the blades and significantly slow down their pumping.

Driving

Molecular propellers can be rotated by

molecular motors Molecular motors are natural (biological) or artificial molecular machines that are the essential agents of movement in living organisms. In general terms, a motor is a device that consumes energy in one form and converts it into motion or mech ...

that can be driven by chemical, biological, optical and electrical means, or various ratchet-like mechanisms. Nature realizes most biological activities with a large number of highly sophisticated molecular motors, such as

myosin Myosins () are a Protein family, family of motor proteins (though most often protein complexes) best known for their roles in muscle contraction and in a wide range of other motility processes in eukaryotes. They are adenosine triphosphate, ATP- ...

, kinesin, and

ATP synthase ATP synthase is an enzyme that catalyzes the formation of the energy storage molecule adenosine triphosphate (ATP) using adenosine diphosphate (ADP) and inorganic phosphate (Pi). ATP synthase is a molecular machine. The overall reaction catalyzed ...

. For example, rotary

attached to protein-based tails called

flagella A flagellum (; : flagella) (Latin for 'whip' or 'scourge') is a hair-like appendage that protrudes from certain plant and animal sperm cells, from fungal spores ( zoospores), and from a wide range of microorganisms to provide motility. Many pr ...

can propel bacteria.

Applications

In a similar way, the assembly of a molecular propeller and a molecular motor can form a nanoscale machine that can pump fluids or perform locomotion. Future applications of these nanosystems range from novel analytical tools in physics and chemistry,

drug delivery Drug delivery involves various methods and technologies designed to transport pharmaceutical compounds to their target sites helping therapeutic effect. It involves principles related to drug preparation, route of administration, site-specif ...

and

gene therapy Gene therapy is Health technology, medical technology that aims to produce a therapeutic effect through the manipulation of gene expression or through altering the biological properties of living cells. The first attempt at modifying human DNA ...

in biology and medicine, advanced nanofluidic

lab-on-a-chip A lab-on-a-chip (LOC) is a device that integrates one or several laboratory functions on a single integrated circuit (commonly called a "chip") of only millimeters to a few square centimeters to achieve automation and high-throughput screening. ...

techniques, to tiny

robots" \n\n\n\n\n\n\nrobots.txt is the filename used for implementing the Robots Exclusion Protocol, a standard used by websites to indicate to visiting web crawlers and other web robots which portions of the website they are allowed to visit.\n\nThe sta ...

performing various activities at the nanoscale or microscale.

References

{{reflist

External links

University of Illinois at Chicago press releaseTechnology & Science highlight in CBC news
Molecular machines

Driving

Applications

See also

References

External links