A novel, rapid and automated conductometric method to evaluate surfactant-cells interactions by means of critical micellar concentration analysis

- An automated method for conductometric curves determination is proposed.
- The procedure is validated on both surfactants and surfactant-cell mixtures.
- A script for data analysis, developed in the free R environment, is presented.
- The measure times prevent cell physiology changes independent by surfactant action.
- The high resolution leads to inflection points otherwise not detectable.

Conductometry is widely used to determine critical micellar concentration and micellar aggregates surface properties of amphiphiles. Current conductivity experiments of surfactant solutions are typically carried out by manual pipetting, yielding some tens reading points within a couple of hours. In order to study the properties of surfactant-cells interactions, each amphiphile must be tested in different conditions against several types of cells. This calls for complex experimental designs making the application of current methods seriously time consuming, especially because long experiments risk to determine alterations of cells, independently of the surfactant action. In this paper we present a novel, accurate and rapid automated procedure to obtain conductometric curves with several hundreds reading points within tens of minutes. The method was validated with surfactant solutions alone and in combination with Saccharomyces cerevisiae cells. An easy-to use R script, calculates conductometric parameters and their statistical significance with a graphic interface to visualize data and results. The validations showed that indeed the procedure works in the same manner with surfactant alone or in combination with cells, yielding around 1000 reading points within 20 min and with high accuracy, as determined by the regression analysis.

Graphical depiction of the proposed automated method.