Polyaniline-based magnetically-driven microbots for improving enantioselective separation toward amino acids

Enantioselective separation plays a crucial role in pharmaceutical, agrochemical, and food industries. To improve the efficiency of enantioselective separation is still highly desirable and challenging. Here, an enantioseparation method was developed by employing magnetically-propelled microbots. The microbots were fabricated by sputter coating of the Ni layer onto the helical polyaniline (PANI) microfibers. Under a conical magnetic field, microbots exhibited the rotation-swing forward motion. Physical simulation showed that motion of the microbots leads to the forming of turbulence, showing micro-mixing effect and enhanced fluid diffusion. The microbots displayed higher separation efficiency and better stability for enantioselective separation of four kinds of racemic amino acids, compared to the PANI microfibers, with the enantiomeric excess (ee%) of 69.8 % for alanine. Magnetically-propelled motion of the microbots should increase the possibility of collision and recognition of amino acids with the PANI, enabling the improvement of the enantioseparation efficiency. This microbot-based methodology paves a promising way for highly efficient enantioselective separation.