R. Di Leonardo a,1, L. Angelani a, D. Dell’Arciprete b, G. Ruocco b, V. Iebba c, S. Schippa c, M. P. Conte c, F. Mecarini d,e, F. De Angelis d,e, and E. Di Fabrizio d,e
-Author Affiliations
aConsiglio Nazionale delle Ricerche-Istituto per i Processi Chimico-Fisici, c/o Università di Roma “Sapienza,” I-00185, Rome, Italy;
bDipartimento di Fisica, Università di Roma “Sapienza,” I-00185, Rome, Italy;
cDipartimento Scienze di Sanità Pubblica, Università di Roma “Sapienza,” I-00185, Rome, Italy;
dNanobioscience Department, Italian Institute of Technology, I-16163, Genova, Italy; and
eBionanotechnology and Engineering for Medicine Laboratory, Università della Magna Graecia, I-88100, Catanzaro, Italy
Edited by Howard C. Berg [*], Harvard University, Cambridge, MA, and approved April 13, 2010 (received for review September 14, 2009)
Abstract
Self-propelling bacteria are a nanotechnology dream. These unicellular organisms are not just capable of living and reproducing, but they can swim very efficiently, sense the environment, and look for food, all packaged in a body measuring a few microns. Before such perfect machines can be artificially assembled, researchers are beginning to explore new ways to harness bacteria as propelling units for microdevices. Proposed strategies require the careful task of aligning and binding bacterial cells on synthetic surfaces in order to have them work cooperatively. Here we show that asymmetric environments can produce a spontaneous and unidirectional rotation of nanofabricated objects immersed in an active bacterial bath. The propulsion mechanism is provided by the self-assembly of motile Escherichia coli cells along the rotor boundaries. Our results highlight the technological implications of active matter’s ability to overcome the restrictions imposed by the second law of thermodynamics on equilibrium passive fluids.
biological motors self-propulsion ratchet effect
Footnotes
1To whom correspondence should be addressed. E-mail:roberto.dileonardo@phys.uniroma1.it.
Author contributions: R.D.L. and L.A. designed research; R.D.L., L.A., D.D.A., G.R., V.I., S.S., M.P.C., F.M., F.D.A., and E.D.F. performed research; and R.D.L. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.0910426107/-/DCSupplemental.
1To whom correspondence should be addressed. E-mail:roberto.dileonardo@phys.uniroma1.it.
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PDF gratuito deste artigo aqui.
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[*] Howard C. Berg, da Universidade Harvard, editor deste artigo, é um dos pesquisadores pioneiros do flagelo bacteriano.
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NOTA INTERESSANTE DESTE BLOGGER:
Não há menção da evolução nesta pesquisa. Por que? Quem foi que disse mesmo que nada em biologia faz sentido a não ser à luz da evolução? Ah, foi o Dobzhansky. Aquele que disse que as evidências se danassem, pois o que vale é a teoria?
Pois é, parece que o mantra dobzhanskyano foi pra lata do lixo da história da ciência aqui nesta pesquisa.
