Jump to main content
Jump to site search

Issue 16, 2016
Previous Article Next Article

The importance of correcting for variable probe–sample interactions in AFM-IR spectroscopy: AFM-IR of dried bacteria on a polyurethane film

Author affiliations

Abstract

AFM-IR is a combined atomic force microscopy–infrared spectroscopy method that shows promise for nanoscale chemical characterization of biological–materials interactions. In an effort to apply this method to quantitatively probe mechanisms of microbiologically induced polyurethane degradation, we have investigated monolayer clusters of ∼200 nm thick Pseudomonas protegens Pf-5 bacteria (Pf) on a 300 nm thick polyether–polyurethane (PU) film. Here, the impact of the different biological and polymer mechanical properties on the thermomechanical AFM-IR detection mechanism was first assessed without the additional complication of polymer degradation. AFM-IR spectra of Pf and PU were compared with FTIR and showed good agreement. Local AFM-IR spectra of Pf on PU (Pf–PU) exhibited bands from both constituents, showing that AFM-IR is sensitive to chemical composition both at and below the surface. One distinct difference in local AFM-IR spectra on Pf–PU was an anomalous ∼4× increase in IR peak intensities for the probe in contact with Pf versus PU. This was attributed to differences in probe–sample interactions. In particular, significantly higher cantilever damping was observed for probe contact with PU, with a ∼10× smaller Q factor. AFM-IR chemical mapping at single wavelengths was also affected. We demonstrate ratioing of mapping data for chemical analysis as a simple method to cancel the extreme effects of the variable probe–sample interactions.

Graphical abstract: The importance of correcting for variable probe–sample interactions in AFM-IR spectroscopy: AFM-IR of dried bacteria on a polyurethane film

Back to tab navigation

Supplementary files

Publication details

The article was received on 22 Apr 2016, accepted on 05 Jul 2016 and first published on 12 Jul 2016


Article type: Communication
DOI: 10.1039/C6AN00940A
Citation: Analyst, 2016,141, 4848-4854
  •   Request permissions

    The importance of correcting for variable probe–sample interactions in AFM-IR spectroscopy: AFM-IR of dried bacteria on a polyurethane film

    D. E. Barlow, J. C. Biffinger, A. L. Cockrell-Zugell, M. Lo, K. Kjoller, D. Cook, W. K. Lee, P. E. Pehrsson, W. J. Crookes-Goodson, C. Hung, L. J. Nadeau and J. N. Russell, Analyst, 2016, 141, 4848
    DOI: 10.1039/C6AN00940A

Search articles by author

Spotlight

Advertisements