A microfluidic platform facilitates high-throughput mechanical testing of single molecules

“A, B Schematic and representative photograph of the microfluidic platform used in fluid loading on a chip (FLO-Chip). C (i) Schematic, and (ii) Differential Interference Contrast (DIC) image of beads anchored to the coverslip via a single dsDNA tether. Application of flow causes ~2.6μm displacement of the bead center as the result of the drag force applied on the bead. Scale bars, 2 μm. D (i) Schematic of the direction of in-plane and off-plane stretching force (F) applied on a tether bead under flow. Application of F leads to transverse fluctuation of the tethered bead. (ii) Calibration of F with respect to the inlet perfusion rate (Q) in the 1500 μm and 2500 μm wide microchannel. Transverse fluctuation of n = 33 beads in the 2500 µm wide channel and n = 23 beads in the 1500 µm wide channel were monitored over three independent experiments under different flow rates. Error bars represent standard deviation. The calibration line (red dash line) indicated a linear relationship between drag force and perfusion rate with slope of ~1.4 ± 0.2 pN s mm⁻¹. Error bars represent standard deviation. (iii) Force-extension examination of single tethers under varying F. The tether length (l) was well described according to the worm-like chain model (solid red line, persistence length = 56 ± 8 nm, contour length = 1.8 ± 0.1 µm). Black arrowheads denote flow direction. Scale bars are 2 μm. Source data are provided as a Source Data file.” Reproduced under a Creative Commons Attribution 4.0 International License from Akbari, E., Shahhosseini, M., Robbins, A. et al. Low cost and massively parallel force spectroscopy with fluid loading on a chip. Nat Commun 13, 6800 (2022).