On resistance switching and oscillations in tubulin microtubule droplets

Tubulin is a key protein of the cytoskeleton, forming networks of microtubules (MTs). These networks are vital for many aspects of a cell, including intra-cellular transport. It has been suggested by others that this network could be responsible for sub-cellular information processing, which naturally raises the question of whether such a system could be exploited for more artificial constructs. In this endeavour, this paper studies the electrical properties of Taxol-stabilised MT ensembles.

Electrical experiments were conducted on samples containing MTs. Measurements were made using iridium-coated needle electrodes on a droplet. Cyclic voltammetry was performed, by sweeping through a DC voltage range of [-1.2,+1.2] V. AC measurements were also taken, between 1 kHZ and 10 MHz, and with a DC bias. Separately, pulse train stimulation were conducted, with an amplitude of 0.5 V and duration of 1 ms.

Cyclic voltammetry experiments reveal that the MT droplets act as electrical switches, under the experimental conditions. This is partly revealed in a substantial hysteresis. The stimulation of a MT droplet with a positive fast-impulse resulted in oscillation of the droplet's resistance, not observed in control experiments. Taxol-stabilised MT samples proved to be mem-resistive/mem-inductive, therefore the history of their electrical characterisation is able to change their response and behaviour. If the history of electrical stimuli is the same, so is the response. These findings pave a way towards future designs of MT-based sensing and computing devices, including data storage featuring liquid states.