Constricted Apertures for Dynamic Trapping and Micro-/Nanoscale Discrimination Based on Recapture Kinetics

Abstract

Sensing via analyte passage through a constricted aperture is a powerful and robust technology which is being utilized broadly, from DNA sequencing to single virus and cell characterization. Micro-and nanoscale structures typically translocate a constricted aperture, or pore, using electrophoretic force. In the present work, we explore the advances in metrology which can be achieved through rapid directional switching of hydrodynamic forces. Interestingly, multipass measurements of microscale and nanoscale structures achieve cell discrimination. We explore this celldiscrimination phenomenon as well as other features of hydrodynamic focusing such as dynamic trapping and discrete interval sensing.

Pressure-Biased Nanopores for Excluded Volume Metrology, Lipid Biomechanics, and Cell-Adhesion Rupturing

“…The attempts to translocate ∼1 μm polystyrene beads through a borosilicate pore of ∼1.3 μm (Figure 1a) were not successful under applied voltage (up to 1000 mV) due to a net electroosmotic flow in the opposite direction of translocation as previously shown by our group. 11 At low salt concentration (0.1X PBS), the counterions in solution screen the surface charge of the nanopore walls (as shown by increased surface concentrations of the cation in Figure 1b) and cause EOF streaming out of the pore at zero pressure. At a low negative pressure (ΔP ≈ −200 Pa), the translocation of polystyrene microspheres was experimentally observed from the cis chamber (i.e., outside the pipet) to the trans chamber (i.e., inside the pipet).…”

“…In addition, the application of pressure decreased the standard deviation of the volume measurement in all experiments. We believe this is caused by particles traveling through the center of the pore more frequently (i.e., via a single trajectory) since (1) the capture volume is constrained to a narrow region directly in front of the pore, 11 and (2) the fluid flow profile within the pore is parabolic with the highest flow velocities occurring in the center of the pore (Figure 2(d,e)).…”

“…The translocation of a mixed population of bacterial cells in a micrometer sized glass pore was carried out under a pressure bias. Unlike previous studies which focused on the mass-dependent recapture of cells, 53 this analysis focuses on the pressure-corrected sizing and deformation-sensing capabilities of glass pores. The two bacterial species (Serratia marcescens and Micrococcus luteus) travel through the microaperture and provide unique current signatures which made them easy to discriminate against.…”

“…5−10 We recently reported micro/nanoscale discrimination and dynamic trapping using pressure in micro/ nanosized pores. 11 However, a detailed analysis of the impact of pressure on event characteristics has not been explored to date. Among the goals of this work is to elucidate the effects of pressure on the recorded signals in terms of current drop amplitude and translocation time and derive methods to obtain physically relevant properties of the translocating species (i.e., excluded volume, deformation or shape changes, and the unbinding of aggregates from each other).…”

“…The use of pressure in nanopore translocations has been explored in the past for slowing down DNA translocation speed, resolving small DNA molecules, creating a DNA trap, and changing event frequency and multipass measurements. − We recently reported micro/nanoscale discrimination and dynamic trapping using pressure in micro/nanosized pores . However, a detailed analysis of the impact of pressure on event characteristics has not been explored to date.…”