Reversible switchable wettability of intrinsic micro/nanostructured pollen microcarriers via pH-induce from superhydrophobicity to superhydrophilicity

The wettability of microcarriers is influenced by surface chemistry and surface micro-nanostructure. Reproducible fabrication and precise control of microcarriers with complex structures are expensive and challenging. It is expected that the fabrication of reversible super-wetting carriers without the need for a template or complex winding processing will greatly promote the application of super-wetting materials. Hence, it should be possible to obtain super-wetting microcarriers by regulating intrinsic micro-nanostructured pollen microcarriers' surface chemistry. A systematic study was performed using different solvents to regulate the wettability of sporopollenin. The changes in surface structure and surface chemistry were studied, and the regulation mechanism of sporopollenin reversible wettability was determined. Tuning pH could induce the wettability transition of sporopollenin, and this wettability transition was reversible. In addition, studies have also shown that the intrinsic micro-/nanostructures of sporopollenin were the basis for the realization of super-wettability, and the protonation and deprotonation of the carboxyl group of the pectin layer were the keys to switching between superhydrophobic and superhydrophilic properties. This is the first report on the fabrication of reversible wetting-regulated microcarriers based on intrinsic micro-nanostructures, indicating that it is possible to use sporopollenin to fabricate reversible wetting-regulated super-wetting microcarriers.