Investigation of the Nonaxisymmetric Bending Property of Pollen Tubes via a Rotary Nanorobotic System

Mechanical properties, such as flexural rigidity and elastic modulus, are important factors deciding how pollen tubes penetrate and navigate inside flowers' styles and finally into ovules. As the ratio of pollen tubes' length to diameter can be far more than several thousand, bending the pollen tubes is an effective method to measure their mechanical properties. However, current techniques, such as microfluidic system, can only bend pollen tubes from one fixed direction. With regard to pollen tubes' irregular shapes and non-uniform properties, the properties achieved from pollen tubes' one direction cannot reflect properties of other directions. Herein, this letter proposes a rotary nanorobotic system that can rotate pollen tubes and thus pollen tubes can be bent and measured from multidirection, instead of one fixed direction. Experiment results indicate that flexural rigidity of the pollen tubes vary as much as 15 times at different directions. This nanorobot-based characterization system could provide us the quantitative data from multidirection, which gives new opportunities for the in-depth understanding of the mechanism of pollen tube guidance inside pistil.