Engineered self-assembling monolayers for label free detection of influenza nucleoprotein

Integratingnanotechnologyintouseabledevicesre- quires a combination of bottom up and top down methodolo- gy.Oftenthe techniquestomeasureandcontrol thesedifferent components are entirely different, so methods that can analyse the nanoscale component in situ are of increasing importance. Here we describe a strategy that employs a self-assembling monolayer of engineered protein chimeras to display an array of oriented antibodies (IgG) on a microelectronic device for the label free detection of influenza nucleoprotein. The struc- tural and functional properties of the bio-interface were characterised by a range of physical techniques including sur- face plasmon resonance,quartz-crystal microbalance and neu- tron reflectometry. This combination of methods reveals a 13.5 nm thick engineered-monolayer that (i) self-assembles on gold surfaces, (ii) captures IgG with high affinity in a defined orientation and (iii) specifically recognises the influ- enza A nucleoprotein. Furthermore we also show that this non-covalent self-assembled structure can render the dissoci- ation of bound IgG irreversible by chemical crosslinking in situ without affecting the IgG function. The methods can thus