Open AccessOptimizing 1-μs-Resolution Single-Molecule Force Spectroscopy on a Commercial Atomic Force Microscope
Author(s) -
Devin T. Edwards,
Jaevyn K. Faulk,
Aric W. Sanders,
Matthew S. Bull,
Robert Walder,
Marc-André LeBlanc,
Marcelo C. Sousa,
Thomas T. Perkins
Publication year - 2015
Publication title -
nano letters
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 4.853
H-Index - 488
eISSN - 1530-6992
pISSN - 1530-6984
DOI - 10.1021/acs.nanolett.5b03166
Subject(s) - cantilever , force spectroscopy , atomic force microscopy , materials science , nanotechnology , folding (dsp implementation) , resolution (logic) , surface micromachining , spectroscopy , optoelectronics , fabrication , physics , computer science , composite material , medicine , alternative medicine , engineering , pathology , quantum mechanics , artificial intelligence , electrical engineering
Atomic force microscopy (AFM)-based single-molecule force spectroscopy (SMFS) is widely used to mechanically measure the folding and unfolding of proteins. However, the temporal resolution of a standard commercial cantilever is 50-1000 μs, masking rapid transitions and short-lived intermediates. Recently, SMFS with 0.7-μs temporal resolution was achieved using an ultrashort (L = 9 μm) cantilever on a custom-built, high-speed AFM. By micromachining such cantilevers with a focused ion beam, we optimized them for SMFS rather than tapping-mode imaging. To enhance usability and throughput, we detected the modified cantilevers on a commercial AFM retrofitted with a detection laser system featuring a 3-μm circular spot size. Moreover, individual cantilevers were reused over multiple days. The improved capabilities of the modified cantilevers for SMFS were showcased by unfolding a polyprotein, a popular biophysical assay. Specifically, these cantilevers maintained a 1-μs response time while eliminating cantilever ringing (Q ≅ 0.5). We therefore expect such cantilevers, along with the instrumentational improvements to detect them on a commercial AFM, to accelerate high-precision AFM-based SMFS studies.