Chronopotentiometry

Chronopotentiometry is useful for investigation of electroporation phenomenon of bilayer lipid membranes. The measurements are provided in current-clamp conditions. This technique allows to obtain only simple pore in the membrane. The pore has size about few nanometers - size similar to the membrane thickness. The pores are stable or irregular oscillating.
Application of chronopotentiometric measurements
 
  • studies of membrane electroporation phenomenon
  • studies of membrane transport processes
  • studies of basic properties of membranes as capacitance and resistance
    • Hardware

    The program controls the KSP measurement system with following modules:

     DPTG-461 - programmable potentiostat-galvanostat
    ADC-1204 - analog-to-digital convereter
    DAC-1201 - digital-to-analog convereter
    TIMER-49 - programmable timer

     Measurements are made in a four-electrode arrangement.

    Features of the program
     
  • saving of data and printing of the report
  • writting of data as a text file for using in worksheets and graphic programs
  • selection 2-, 3- or 4-electrode system
  • setting up to 10 methods (sets of measurement parameters and experiment descriptions)
  • readout of data directly from the graph
  • readout of curve slope directly from the graph
  • zoom of the graph

    • Main window of the "Chronopotentiometry" program.

     The curve shows electroporation of the bilayer lipid membrane made from egg yolk lecithin. The begin increasing of the potential is for the membrane without pores. Membrane voltage increased with speed dependent on current intensity, membrane capacitance and membrane resistance. When voltage attains to the breakdown voltage value the membrane resistance rapidly decreases causing decreasing of volatge on the membrane. Size of the pore irregular oscillates and membrane potential changes. There is an irreversible breakdown of the membrane. The generated pore is fullfilled by the electrolyte. Disconnecting of the current flowing causes closing of the pore and recovering of uniform structure of the membrane in time of seconds to minutes.

    Used files

    CHRONPOT.EXE - main program file
    CHRONPOT.INI - configuration file
    CHRONPOT.HLP - help file

     DPTG.DLL - driver for the potentiostat/galvanostat module
    ADC.DLL - driver for the analog-to-digital converter module
    DAC.DLL - driver for the digital-to-analog converter module
    TIMER.DLL - driver for the programmable timer module

     *.CPT - files with measurement data

     The files CHRONPOT.EXE, CHRONPOT.INI, CHRONPOT.HLP are contained in the file CHRONPOT.ZIP.
    The *.DLL files you must download separately.

    Selected papers
     
  • S. Kalinowski and Z. Figaszewski, A four-electrode potentiostat-galvanostat for studies of bilayer lipid membranes, Meas. Sci. Technol., 6 (1995) 1050-1056.
  • S. Kalinowski, G. Ibron, K. Bryl and Z. Figaszewski, Chronopotentiometric studies of electroporation of bilayer lipid membranes, Biochim. Biophys. Acta, in press (1998).