Biological Applications

Biological Nanoanalysis with PiFM / DNA Origami – Topography and PiFM / Collagen Single Molecules – Topography and PiFM / Collagen Substructure – Topography and PiFM / Collagen Substructure – Topography and PiFM / Icosahedron Protein Cage / Skin Sample

PiFM

E-coli Bacteria on Mica Substrate

E-coli bacteria is imaged via amide I band (1660 cm-1). While the topography cannot show the fimbriae due to the extreme height difference, PiFM image highlights all the parts of bacteria that are exhibiting amide I band, including fimbriae. The lower right image overlays the PiFM map of mica (acquired at 1030 cm-1) and the distribution of amide I band (acquired at 1660 cm-1) onto the 3D topography. Note that the amide I image shows details that are hard to glean from the topography.

DNA Origami – Topography and PiFM

DNA origami molecules (~3 nm in height) deposited onto mica are imaged via both topography and Photo-induced Force Microscopy (PiFM.) PiFM of the origami clearly displays the amide I vibrational mode at 1720 cm-1, in stark contrast to the 1000 cm-1 signal from the underlying mica substrate.

Collagen Single Molecules – Topography and PiFM

Triple helix collagen molecules (~1 nm in diameter) deposited onto mica are imaged via AFM topography and PiFM by using the amide I vibrational mode at 1668 cm-1.

Collagen Substructure – Topography and PiFM

3D Topography (left) and Amide I signal (1668 cm-1) overlaid on 3D topography (right.)

Collagen Substructure – Topography and PiFM

PiFM spectra at points 2 through 10 shows local variations of Amide I (1668 cm-1, circled with red) and Amide II (1550 cm-1, circled with black) strengths at different collagen positions. Thermal drift of the sample during sequential spectra acquisition renders some uncertainty to precise locations.

Icosahedron Protein Cage

Topography, PiFM spectra and 3D model of a single protein cage. Topography (red) overlaid on PiFM (green) in image (above right-middle.)

Skin Sample

Topography and PiFM of a skin sample.

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