Inherently Fluorescent Nanowires For Cellular Mechanosensing

How mechanical cues trigger cellular events is currently an intensive research area and measuring the forces involved requires multiple and highly sensitive probes. Arrays of vertical nanowires have been shown to measure cellular forces down to 15 pN, providing there is a high precision in the determination of the nanowire deflection1, 2. Current approaches involve the use of either organic fluorophores to coat the nanowires, or scanning electron microscopy (SEM) to determine the deflection of the nanowires. However, organic fluorophores are prone to photo-bleaching and SEM can only measure the forces at a given time point and may also give rise to artifacts due to cell shrinkage during the dehydration step. Our approach is to use epitaxial, vertical, gallium phosphide (GaP) nanowires with a top-segment made of gallium indium phosphide (GaInP), which is inherently fluorescent3. The nanowires are grown using metal-organic-vapor-phase-epitaxy (MOVPE), which allows for excellent control over nanowire diameter, length and material composition. GaInP is strongly fluorescent and photo stable, which enable the precise determination of the nanowire tips for a long period of time. (1) Hallstrom, W.; Lexholm, M.; Suyatin, D. B.; Hammarin, G.; Hessman, D.; Samuelson, L.; Montelius, L.; Kanje, M.; Prinz, C. N., Nano Letters 2010, 10, 782-787. (2) Suyatin, D. B.; Hallstrom, W.; Samuelson, L.; Montelius, L.; Prinz, C. N.; Kanje, M., Journal of Vacuum Science & Technology B 2009, 27, 3092-3094. (3) Adolfsson, K.; Persson, H.; Wallentin, J.; Oredsson, S.; Samuelson, L.; Tegenfeldt, J. O.; Borgstrom, M. T.; Prinz, C. N., Nano Letters 2013, in press.