Nanoscale electric polarizability of ultrathin biolayers on insulating substrates by electrostatic force microscopy. Issue 43 (21st October 2015)

• Record Type: Journal Article
• Authors: Dols-Perez, A.; Gramse, G.; Calò, A.; Gomila, G.; Fumagalli, L.
• Is Part Of: Nanoscale. Volume 7:Issue 43(2015)
• Page Start: 18327
• Page End: 18336
• Publication Date: 2015-10-21
• Subjects: Nanoscience -- Periodicals; Nanotechnology -- Periodicals; 620.505
• DOI: 10.1039/c5nr04983k
• Languages: English
• ISSNs: 2040-3364

Abstract

Abstract : We measured and quantified the local electric polarization properties of ultrathin (∼5 nm) biolayers on mm-thick mica substrates. Abstract : We measured and quantified the local electric polarization properties of ultrathin (∼5 nm) biolayers on mm-thick mica substrates. We achieved it by scanning a sharp conductive tip (<10 nm radius) of an electrostatic force microscope over the biolayers and quantifying sub-picoNewton electric polarization forces with a sharp-tip model implemented using finite-element numerical calculations. We obtained relative dielectric constants ε r = 3.3, 2.4 and 1.9 for bacteriorhodopsin, dioleoylphosphatidylcholine (DOPC) and cholesterol layers, chosen as representative of the main cell membrane components, with an error below 10% and a spatial resolution down to ∼50 nm. The ability of using insulating substrates common in biophysics research, such as mica or glass, instead of metallic substrates, offers both a general platform to determine the dielectric properties of biolayers and a wider compatibility with other characterization techniques, such as optical microscopy. This opens up new possibilities for biolayer research at the nanoscale, including nanoscale label-free composition mapping.