  The manipulation of biological substrates is becoming more popular route
towards generating novel computing devices. Physarum polycephalum is used as a
model organism in biocomputing because it can create `wires' for use in hybrid
circuits; programmable growth by manipulation through external stimuli and the
ability withstanding a current and its tolerance to hybridisation with a
variety of nano/microparticles. Lettuce seedlings have also had previous
interest invested in them for generating plant wires, although currently there
is little information as to their suitability for such applications. In this
study both P. polycephalum and Lettuce seedlings were hybridised with gold
nanoparticles - functionalised and unfunctionalised - to explore their uptake,
toxicological effects and, crucially, any alterations in electrical properties
they bestow upon the organisms. Using various microscopy techniques it was
shown that P. polycephalum and lettuce seedlings are able to internalize
nanoparticles and assemble them in vivo, however some toxicological effects
were observed. The electrical resistance of both lettuce seedlings and P.
polycephalum was found to decrease, the most significant reduction being with
lettuce seedlings whose resistance reduced from 3MOhms to 0.5MOhms. We conclude
that gold is a suitable nanomaterial for biohybridisation specifically in
creating conductive pathways for more efficient biological wires in
self-growing hybrid circuitry.
