Biomedical Engineering Reference
In-Depth Information
of.the.algae.exposed.to.the.quantum.dots.suggested.a.potential.environmental.impact.of.
nanoparticles.on.plant.species.
26.7.2 Plant-Derived Solar Cell Devices
The. photosynthesis. machinery. of. plants. responsible. for. nature's. 90-terawatt. solar.
energy.conversion.process.has.long.been.an.admired.target.for.mimicry..With.today's.
expanding.interest.in.solar.energy,.it.has.been.the.dream.of.bionanotechnology.design-
ers. to. replicate. the. photosynthesis. system. to. create. more. eficient. solar. cells.. Despite.
huge.challenges,.there.has.been.progress..Several.reports.have.appeared.that.integrate.
the.PSI.protein.discussed.in.Section.26.2.with.solid-state.electronics.to.produce.biologi-
cal.solar.cells..We.will.mention.only.two.examples,.but.the.work.is.just.beginning.and.
bears.close.watching.
First,.the.group.of.Das.and.co-workers
50
.created.a.hybrid.solid-state.device.containing.
photosystem.I.(PSI).isolated.from.spinach.chloroplasts.as.the.solar.collector..In.this.device,.
the. PSI. protein. was. coated. as. a. thin. layer. on. a. gold. electrode.. Electronic. integration. of.
the. devices. was. achieved. by. self-assembling. the. protein. complex. in. an. oriented. mono-
layer,. stabilizing. and. hydrating. the. complex. with. surfactant. peptides,. and. then. coating.
this.layer.with.a.protective.organic.semiconductor..The.resulting.photovoltaic.cell.resulted.
in.a.respectable.internal.quantum.eficiency.of.almost.12%.
A.more.recent.study.demonstrated.that.the.PSI.protein's.remarkable.functionality.can.
be.accessed.in.wet.or.dry.solid-state.nanoelectronic.devices..Ciesielski.and.co-workers
51
.
showed. that. the. PSI. protein. complex. retains. its. photonic. energy. conversion. function-
ality. after. covalent. attachment. to. the. nanoporous. gold. electrode. surface. (Figure 26.6a)..
Modiication.of.the.gold.surface.with.an.aldehyde.thiol.linker.provides.a.versatile.functional.
O
O
O
N
N
N
S
S
S
400
Au
Planar Electrode
NPGL Electrode
PSI Solution
300
PSI
200
N
N
N
N
100
S
S
Au
0
10
20
30
40
Time (s)
50
60
70
(a)
(b)
FIGURE 26.6
a:. Conjugation. of. PSI. protein. to. porous. gold. surface. can. be. accomplished. by. Schiff-based. formation.. b:.
Photocurrent.of.immobilized.PSI.on.2D.planer.and.3D.nanoporous.gold.photodevice..(Reprinted.from.Ciesielski,.
P.N.,.et.al..
ACS Nano
2(12).2465.(2008)..With.permission.of.the.American.Chemical.Society.)
