Probing structural changes in single enveloped virus particles using nano-infrared spectroscopic imaging
(A) Nano-FTIR spectra of influenza virus particles at neutral pH (green) and at pH 5 (red). Topography and hyperspectral images of a virus particle at pH 7. Topography, and spectra obtained at two different points on the particle (A and B) (a). Near-field amplitude, A2 (b and d) and phase φ2 (c and e) images at frequencies 1400 and 1225 cm-1 sliced from hyperspectral data. Scale bar 100 nm.