Resonant Mie Scattering (RMieS) correction of infrared spectra from highly scattering biological samples

Abstract

Infrared spectra of single biological cells often exhibit the ‘dispersion artefact’ observed as a sharp decrease in intensity on the high wavenumber side of absorption bands, in particular the Amide I band at ∼1655 cm⁻¹, causing a downward shift of the true peak position. The presence of this effect makes any biochemical interpretation of the spectra unreliable. Recent theory has shed light on the origins of the ‘dispersion artefact’ which has been attributed to resonant Mie scattering (RMieS). In this paper a preliminary algorithm for correcting RMieS is presented and evaluated using simulated data. Results show that the ‘dispersion artefact’ appears to be removed; however, the correction is not perfect. An iterative approach was subsequently implemented whereby the reference spectrum is improved after each iteration, resulting in a more accurate correction. Consequently the corrected spectra become increasingly more representative of the pure absorbance spectra. Using this correction method reliable peak positions can be obtained.