The single cell-electrode interaction is relevant to fundamental biological processes involving cell adhesion, cell fusion, cell activity, and membrane response to environmental stress. Our focus is on single-celled marine microalgae as the globally important primary producers, drivers of essential biogeochemical cycles and present the basis of the aquatic food web. Selected algal cell specie possesses only cell membrane, pronounced motility and tolerates a wide range of salinity. It will be shown changes of algal cell nanomechanical properties and adhesion dynamics during their growth using complementary surface methods and mathematical modelling. AFM measurements reveal that nanomechanical properties change during cell growth, and this is reflected in the interfacial adhesion dynamics. AFM results show that: (i) cells are larger in exponential than in the stationary phase, which is in an agreement with the amperometrically determined larger amount of interfacial displaced charge and (ii) cells in the exponential phase are stiffer and more hydrophobic than those in the stationary phase, which suggests molecular modification of cell envelope during aging. Results obtained with the reaction kinetics model of the three-step process (1) indicate that adhesion and spreading at the charged interface is slower when cells are in exponential phase, which may be attributed to larger volume and stiffer and more hydrophobic cellular material. In the future, cell mechanical properties could be considered as a marker for environmental stress in order to better understand algal behaviour at the aquatic interfaces.

(1) Ivošević DeNardis N, Pečar Ilić J, Ružić I, Pletikapić G. Electrochimica Acta. 2015, 176 (743–754). Available from:doi:10.1016/j.electacta.2015.07.068.

Financing: This work was supported by the Croatian Ministry of Science, Education and Sports through the projects (i) 098-0982934-2744, (ii) Croatia–France bilateral programme Cogito (0411B014), and (iii) Grants provided by the French Centre National de la Recherche