Recent Advances in Water Desalination through Biotechnology and Nanotechnology - Bionanotechnology: Global Prospects - page 379

19.3.6 Asymmetry-Driven Ion Pumps
As.with.nanotechnology,.biology.has.also.provided.clues.to.developing.advanced.water.
desalination.systems.by.following.the.ideas.of.ion.transport.in.biological.ion.channels.and.
ion.pumps. 55 .While.existential.proof.for.the.working.of.these.systems.has.been.around.in.
living.organisms.for.a.long.time,.implementing.technologies.for.practical.systems.has.con-
tinued.to.be.a.challenge.due.to.several.gaps.in.engineering.these.systems,.and.due.to.a.lack.
of. mechanistic. understanding. of. how. to. manipulate. ion. transport. in. artiicial. systems..
However,.some.recent.studies.have.shown.promise.in.advancing.the.state.of.knowledge.
toward.both.the.science.and.technology.of.these.bioinspired.systems. 36,55-58 .In.particular,.
mimicking. ion. channel. gating. behavior. for. transport. and. control. of. ions. has. generated.
signiicant. interest,.leading. to.the.development. of.luidic. transistors 37 .and.conical. nano-
pores.for.ion.pumps.for.the.potassium.ion 59 .(Figure 19.10)..One.advantage.of.bioinspired.
FIGURE 19.10
(A).Schematic.and.SEM.image.showing.the.development.of.a.device.being.used.as.a.luidic.transistor.allow-
ing.electrostatic.control.of.ions..(From.Karnik,.R.,.et.al.,. Nano Letters ,.5(5),.943-948,.2005..(with.permission.)).(B).
Schematic.depicting.formation.of.a.conical.nanopore.by.electrochemical.etching.at.potential. U .with.current. I ,.
leading.to.data.that.show.pumping.of.the.potassium.ions.against.a.concentration.gradient.as.a.function.of.pore.
diameter.on.the.narrow.side.of.the.conical.nanopore..(From.Siwy,.Z.,.and.Fulinski,.A.,. Physical Review Letters ,.
89(19),.19803-1-19803-4,.2002..With.permission.)