Topographical, chemical, and mechanical analysis of a single collagen fiber, showing amide I absorption. Image courtesy of EPFL, Switzerland.
AFM-infrared chemical maps and spectra of Josephin proteins before incubation at 37 deg C. (a) AFM height image. Infrared absorption map at (b) 1700 cm-1 (amide I), (c) 1655 cm-1 (amide I), (d) 1300 cm-1 (amide III). Scale bar, 2mm. (e) Infrared spectra. (f) Average oligomeric infrared spectrum and secondary-structure deconvolution of amide I band Image courtesy of F.S. Ruggeri et al. DOI: 10.1038/ncomms8831
Distribution of triglycerides in stratum corneum
The stratum corneum is the outermost layer of skin and is composed of corneocytes, a dense network of protein, and intercellular lipids. Above:AFM-IR used to map the distribution of the intercellular lipids of the stratum corneum by imaging the absorption band at 1732 cm-1 in comparison to the amide I absorption band at 1650 cm-1.
Chemical analysis of hair
Light harvesting complex II
Light-harvesting complex II. (a) Surface topography, (b) mechanical stiffness map and (c) IR absorption pattern of the lipoprotein multibilayer, recorded simultaneously on a 1x1 µm area of the sample, the thickness of which was approximately 1.2 µm. Data contributing to the IR-absorption map were acquired at a wavenumber of 1650 cm-1. Scan resolution: X = 512 points, Y = 256 points; scan rate: 0.4 Hz, 8 co-averages.
Resonance enhanced AFM-IR was used to collect topographical and AFM-IR images at 1660 cm-1 of Halobacterium salinarium membranes. IR spectra identifies the α-helix structure of the membrane protein by the position of the amide I absorption band.
AFM imaging, AFM-IR imaging, and Resonance Enhanced AFM-IR spectroscopy of a monolayer island film of a PEG methyl ether thiol on gold.
IR spectra of locally heat treated polyhydroxybutyrate (PHB) reveal variations in crystalline/amorphous content (C-O-C stretches, 1270 cm-1)
AFM-IR spectra reveal variations in the mineral/protein concentration from the interior to the exterior of an osteon.
AFM-IR is used to study phase separation in active pharmaceutical ingredients and passive carrier materials in drug dispersions. Above:The AFM topography image (left) shows phase separation of polyvinylpyrrolidone (PVP) domains in a dextran matrix which are readily identified by the AFM-IR spectra (right).
Chemical analysis of wood using AFM-IR provides high spatial resolution chemical information of wood composites, preservation treatments, and transgenic wood for biofuels. Above: An AFM topography image (left) of a sectioned wood sample and AFM-IR spectra (right) show variation in the lignin and cellulose ratio between the cell wall and middle lamellae.
Subcellular chemical imaging
Local absorption spectra of a cancer cell where subtle shifts in amide I and II bands (1648, 1536 cm-1) are noted along with its lipid/triglyceride contents (1732 cm-1)
Surface topography (left) of internal structure of streptomyces bacteria. Image of the lipid vesicle distribution via the triglyceride absorption band (center). AFM-IR spectra of the bacteria (blue) and vesicles (black), identifying carbonyl ester bands in both spectra points (right). Scan size: 20 µm x 10 µm. Deniset-Besseau, et al, Chem. Lett., 5 (4) 654–658 (2014)
Nano-mechanical property mapping
Nano-mechanical property mapping
Three color mechanical map of wood cells: This composite image was made by overlaying the LCR amplitudes collected at three different contact resonances: (a) 340 kHz, (b) 352 kHz, and (c) 859 kHz. These resonances were selected to highlight the varying ratios of the lignin and cellulose which compose the sample. Image courtesy of Lee et. al., Nanotechnology 2012, 23, 055709.