Molecular machine



A molecular machine has been defined as a discrete number of molecular components that have been designed to perform mechanical-like movements (output) in response to specific stimuli (input).[1] It is often applied more generally to molecules that simply mimic functions at the macroscopic level. The term is also common in molecular assembler. Molecular machines can be divided into two broad categories: synthetic and biological.

Synthetic molecular machines

A wide variety of rather simple molecular machines have been synthesized by catenanes.

Molecular motors

Molecular motors are molecules that are capable of unidirectional rotation motion powered by external energy input. A number of molecular machines have been synthesized, powered by light or reaction with other molecules.

Molecular propeller

A molecular propeller is a molecule that can propel fluids when rotated, due to its special shape that is designed in analogy to macroscopic propellers. It has several molecular-scale blades attached at a certain pitch angle around the circumference of a nanoscale shaft.

Molecular switch

A molecular switch is a molecule that can be reversibly shifted between two or more stable states. The molecules may be shifted between the states in response to changes in e.g. pH, light, temperature, an electrical current, microenvironment, or the presence of a ligand.

Molecular shuttle

A molecular shuttle in molecule capable of shuttling molecules or ions from one location to another. A common molecular shuttle consists of a rotaxane where the macrocycle can move between two sites or stations along the dumbbell backbone.

Molecular tweezers

DNA machines.

Molecular sensor

A molecular sensor is a molecule that interacts with an analyte to produce a detectable change.[2] Molecular sensors combine molecular recognition with some form of reporter so the presence of the guest can be observed.

Molecular logic gate

A molecular logic gate is a molecule that performs a logical operation on one or more logic inputs and produces a single logic output. Unlike a molecular sensor the molecular logic gate will only output when a particular combination of inputs are presents.

Biological molecular machines

The most complex molecular machines are found in within cells. These include dynein that produces the axonemal beating of cilia and flagella. These proteins are far more complex than any molecular machines that have yet been artificially constructed.

Theoretical molecular machines

The construction of more complex molecular machines is an active area of theoretical research. A number of molecules, such as molecular assembler.

See also

  • Molecular machinery

References

  1. ^ Ballardini R, Balzani V, Credi A, Gandolfi MT, Venturi M. (2001). "Artificial Molecular-Level Machines: Which Energy To Make Them Work?". Acc. Chem. Res. 34 (6): 445-455. doi:10.1021/ar000170g.
  2. ^ Cavalcanti A, Shirinzadeh B, Freitas Jr RA, Hogg T. (2008). "Nanorobot architecture for medical target identification". Nanotechnology 19 (1): 015103(15pp). doi:10.1088/0957-4484/19/01/015103.
 
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