Fig. 5. Selective and multiplexed single virus detection. (A) Conductance vs.
time curve recorded from a silicon nanowire device after introduction of
influenza A virus solution; the device had a high surface coverage of antiadenovirus
group III antibody. (B) Conductance vs. time data recorded from a
silicon nanowire device modified with an intermediate density of antiinfluenza
type A antibody. Initially, a solution of paramyxovirus (50 virons per
l) was delivered to the device, and at the point indicated by black arrow the
solution was changed to one containing influenza A (50 virons per l). (C)
Conductance vs. time data recorded simultaneously from two silicon nanowires
elements; one nanowire (nanowire 1) was modified with anti-influenza
type A antibody (blue data), and the other (nanowire 2) was modified with
anti-adenovirus group III antibody (red data). Black arrows 1–4 correspond to
the introduction of adenovirus, influenza A, pure buffer, and a 1:1 mixture of
adenovirus and influenza A, where the virus concentrations were 50 viral
particles perl in phosphate buffer (10M, pH 6.0). Small red and blue arrows
in B and C highlight conductance changes corresponding to diffusion of viral
particles past the nanowire and not specific binding.