eng Science and Education Publishing Nanoscience and Nanotechnology Research 2372-4676 2017-05-09 4 3 98 105 10.12691/nnr-4-3-3 NNR2017433 article Sherif S. Z. Hindi shindig@kau.edu.sa 1 Department of Arid Land Agriculture, Faculty of Meteorology, Environment and Arid Land Agriculture, King Abdullaziz University, P.O. Box 80208, Jeddah 21589, Saudi Arabia A molecular machine is a group of molecular components that are able to produce quasi-mechanical movements when exposed to specific stimuli. There are three broad divisions of the molecular machines, namely natural or biological, synthetic, and natural-synthetic hybrid machines. Biological motors convert chemical energy to produce linear or rotary motion as well as controlling many biological functions. Examples of the linear motions are proteins, muscle contraction, intracellular transport, signal transduction, ATP synthase, membrane translocation proteins and the flagella motor. The rotary motor example of biological molecular machines is the synthesis and hydrolysis of ATP. Synthetic molecular machine includes motors, propellers, switches, shuttles, tweezers, sensors, logic gates. Natural-synthetic hybrid systems are mechanical motor such as those inspired from DNA-based structures. http://pubs.sciepub.com/nnr/4/3/3/nnr-4-3-3.pdf molecular machines rotors propeller switches shuttle tweezers valves