Standardized Nanomechanical Atomic Force Microscopy Procedure (SNAP) for Measuring Soft and Biological Samples.
Hermann SchillersCarmela RiannaJens SchäpeTomas LuqueHolger DoschkeMike WälteJuan José UriarteNoelia CampilloGeorgios P A MichanetzisJustyna BobrowskaAndra DumitruElena T HerruzoSimone BovioPierre ParotMassimiliano GalluzziAlessandro PodestàLuca PuricelliSimon ScheuringYannis MissirlisRicardo GarciaMichael OdoricoJean-Marie TeulonFrank LafontMalgorzata LekkaFelix RicoAnnafrancesca RigatoJean-Luc PellequerHans OberleithnerDaniel NavajasManfred RadmacherPublished in: Scientific reports (2017)
We present a procedure that allows a reliable determination of the elastic (Young's) modulus of soft samples, including living cells, by atomic force microscopy (AFM). The standardized nanomechanical AFM procedure (SNAP) ensures the precise adjustment of the AFM optical lever system, a prerequisite for all kinds of force spectroscopy methods, to obtain reliable values independent of the instrument, laboratory and operator. Measurements of soft hydrogel samples with a well-defined elastic modulus using different AFMs revealed that the uncertainties in the determination of the deflection sensitivity and subsequently cantilever's spring constant were the main sources of error. SNAP eliminates those errors by calculating the correct deflection sensitivity based on spring constants determined with a vibrometer. The procedure was validated within a large network of European laboratories by measuring the elastic properties of gels and living cells, showing that its application reduces the variability in elastic moduli of hydrogels down to 1%, and increased the consistency of living cells elasticity measurements by a factor of two. The high reproducibility of elasticity measurements provided by SNAP could improve significantly the applicability of cell mechanics as a quantitative marker to discriminate between cell types and conditions.
Keyphrases
- atomic force microscopy
- living cells
- single molecule
- high speed
- single cell
- minimally invasive
- fluorescent probe
- high resolution
- drug delivery
- cell therapy
- hyaluronic acid
- solid phase extraction
- tissue engineering
- patient safety
- mesenchymal stem cells
- extracellular matrix
- simultaneous determination
- network analysis
- drug induced