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 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 ununiform properties, properties achieved from pollen tubes' one direction cannot reflect properties of other directions. Herein, this paper proposes a rotary nanorobotic system that can rotate pollen tubes and thus pollen tubes can be bent and measured from multi-direction, instead of one fixed direction. Experiment results indicate that flexural rigidity of pollen tubes vary as much as fifteen times at different directions. This nanorobot based characterization system could provide us the quantitative data from multi-direction, which gives new opportunities for the in-depth understanding of the mechanism of pollen-tube guidance inside pistil.