Real-time, label-free monitoring of cell viability based on cell adhesion measurements with an atomic force microscope

Abstract

BackgroundThe adhesion of cells to an oscillating cantilever sensitively influences the oscillation amplitude at a given frequency. Even early stages of cytotoxicity cause a change in the viscosity of the cell membrane and morphology, both affecting their adhesion to the cantilever. We present a generally applicable method for real-time, label free monitoring and fast-screening technique to assess early stages of cytotoxicity recorded in terms of loss of cell adhesion.ResultsWe present data taken from gold nanoparticles of different sizes and surface coatings as well as some reference substances like ethanol, cadmium chloride, and staurosporine. Measurements were recorded with two different cell lines, HeLa and MCF7 cells. The results obtained from gold nanoparticles confirm earlier findings and attest the easiness and effectiveness of the method.ConclusionsThe reported method allows to easily adapt virtually every AFM to screen and assess toxicity of compounds in terms of cell adhesion with little modifications as long as a flow cell is available. The sensitivity of the method is good enough indicating that even single cell analysis seems possible.Electronic supplementary materialThe online version of this article (doi:10.1186/s12951-017-0256-7) contains supplementary material, which is available to authorized users.

Synthesis of gold–silica core–shell nanoparticles by pulsed laser ablation in liquid and their physico-chemical properties towards photothermal cancer therapy

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“…Thus, a damping coefficient, here referred to as a B-value is an indication for amplitude damping rate in order to quantitatively describe cell viability. In the method, which means the real-time, label-free monitoring system of cell viability mentioned above, 39 HeLa cells were allowed to attach onto an oscillating AFM cantilever (SNL-10, k = 0.12 N m −1 , f 0 = 23 kHz, Bruker Corporation). For that purpose, a drop of 100 µL of HeLa cell solution surrounded the installed cantilever, while the AFM was driven in Intermediate Mode at a given frequency of 22 kHz, so that the cell sediment eventually attaches to the surface of the cantilever.…”

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“…The sensitivity of the technique enables the detection of energy consumption of a few ATP molecules, as demonstrated in previous works using finite elements mod-eling or studying conformational changes in quaternary protein structures (31,33). Thus, the NMS can been used to evaluate the fluctuations of a very limited number of viable specimens (single mammalian cells or tens of bacteria) (32,(34)(35)(36)(37).…”

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“…In addition, investigation on the toxicity of nanostructures and biointeractions rely on data from a wide variety of experiments with several different methods and techniques that are chosen on the basis of laboratory capabilities and researchers´ technical expertise [21,22]. Then, there are, as today, no standard cell panels or defined protocols available for assessment of cancer cell responses to NPs; therefore, data arising from those studies are difficult to compile and integrate.…”