Ni pci 6251

The bending actuation of the MSDEBA is characterized using a setup consisting of a high voltage power supply (Trek 20/20 C), NI data logger (NI PCI 6251) and a digital camera (Canon D7000). LabVIEW program is used to control the voltage applied to the MSDEBA and the activation duration. Videos of the MSDEBA are taken during the activation and later Tracker software is used to track the motion of the tips of the MSDEBA which is marked by a black dot (Refer to Supplementary Videos 1–3). Using the tracked data point the adjacent tip distance and opposite tip distance are calculated, which are the indication of the opening of the MSDEBA.

Patch-clamp recordings were carried out at room temperature (22 ± 1°C). Ionic currents were recorded by the whole-cell patch-clamp technique with the amplifier VE-2 (Alembic, Canada). Patch pipettes (Corning Kovar Sealing code 7052, WPI) had resistances of 1–1.5 MΩ. Currents were filtered at 5 kHz (23 dB, 8-pole low-pass Bessel filter) and digitized at 30 kHz (NI PCI-6251, National Instruments, Austin, TX, United States). Data were acquired and analyzed with ELPHY software (G. Sadoc, CNRS, Gif/Yvette, France). To measure peak I_Na amplitude and determine current–voltage (I/V curves) and activation-Vm relationships, currents were elicited by test potentials of 0.2 Hz frequency to −100 to +60 mV for 50 msec by increments of 5 or 10 mV from a holding potential of −120 mV. The steady-state inactivation-Vm protocol was established from a holding potential of −120 mV and a 2 s conditioning pre-pulse was applied in 5 or 10 mV increments between −140 and +20 mV, followed by a 50 msec test pulse to −20 mV at 0.2 Hz frequency. Data for the activation-Vm and steady-state availability-Vm relationships of I_Na were fitted to the Boltzmann equation: Y = 1/{1 + exp[-(Vm-V_1/2)/k]}, where Vm is the membrane potential, V_1/2 is the half-activation or half-availability potential, k is the slope factor and Y represents the relative conductance.

For nanopore conductance measurements, a Teflon sample chamber was machined (shown in Fig 1G) with well capacity of 60μl in the front well (nanopore well) and 30μl in the other end (capillary well). Borosilicate capillaries carrying the nanopore at one end were glued on the Teflon chamber using curable silicone glue. Experimental buffer solution (10mM TrisCl, 1mM EDTA and appropriate KCl, pH 8) was carefully filled into the capillary and the wells ensuring no air bubbles at the pore. Stable I-V curves and low-noise open pore current was obtained after about 20 minutes of stabilization. λ DNA (New England Biolabs) translocation using resistive pulse technique was performed at various applied voltages in experimental buffer with 0.5M KCl salt. All ionic current measurements were made with Axopatch 200B (Axon Instruments, USA) amplifier. For all I-V measurements Axopatch amplifier’s internal low pass filter was set to 5 kHz and data was acquired at 5000 samples per second. For DNA translocation measurements low pass filter was set to 10 kHz and data acquisition was done with NI-PCI-6251 (National Instruments) DAQ card at 200 kHz sampling rate. All measurements used custom written LabView (National Instruments) codes for data acquisition and Matlab codes [44 (link)] for data analysis.