Magnetic molecularly imprinted microsensor for selective recognition and transport of fluorescent phycocyanin in seawater

Phycocyanin with excellent fluorescence characteristics and important physiological significance is an effective indicator for cyanobacterial bloom assessment due to its close relationship with cyanobacterial biomass. Molecularly imprinted polymers (MIPs) have attracted great interest owing to their recognition specificity; micromotor-driven targeted transport capability holds considerable promise. Herein, we propose an attractive magnetic microsensor for selective recognition, enrichment and transport of label-free fluorescent phycocyanin by combining MIPs and catalytic micromotors. The MIP-based catalytic microsensor was fabricated using phycocyanin as the imprinting molecule, Ni (0.55%) as the magnetic navigation material, and Pt (24.55%) as the solid support/catalyst to facilitate free movement in solutions, as well as an additional magnetic field was employed for trajectory control. The autonomous self-propulsion microsensor vividly displayed their motion states, presenting two different trajectories. The movement velocity was calculated based on the body-deformation model, suggesting a linear positive correlation between the velocity and hydrogen peroxide concentration, with a high average speed of 163 μm s^-1. In addition, highly efficient targeted identification and enrichment abilities were demonstrated based on the magnetically imprinted layer. More excitingly, no obvious interference was found from complicated matrices such as seawater samples, along with real-time visualization of phycocyanin loading and transport. The sensing strategy would not only provide potential applications for rapid microscale monitoring of algae blooms, but also enrich the research connotations of protein imprinting.