Magnetically Powered Heterogeneous Swarm as Controllable Immunosorbent Probes for Active Motion-Enhanced Photoinitiated Chemiluminescence Detection

Magnetic nanoparticles are widely used in biomedical applications by virtue of their motion capability. However, mostly only magnetic separation or attraction is used, which severely limits their applications. Here, it is proposed to use magnetically powered heterogeneous swarms, an artificial nano-robotic assembly of photosensitizing magnetic nanobeads and chemiluminescent non-magnetic nanobeads, as controllable immunosorbent probes to perform active motion-enhanced photoinitiated chemiluminescence detection. Fe₃O₄@mSiO₂ core-shell magnetic beads loaded with photosensitizer Ce6 and polystyrene (PS) beads loaded with chemiluminescent reagents, 2-(4-(N,N-dimethylamino)phenyl)-3-phenyl-1,4-thioxene (photoenergy cache unit, PCU) and Tris(1,3-diphenyl-1,3-propanedionato)(1,10-phenanthroline)europium (Eu(DBM)₃Phen), are successfully prepared and then conjugated with antibodies. The morphology and motion behavior of the heterogeneous swarm with immunobinding between the two nanobeads, denoted as positive swarm, is significantly different from the heterogeneous swarm without immunobinding, denoted as negative swarm. Smaller area, higher angular velocity, and lower translational velocity are observed in the positive heterogeneous swarms, indicating a significant effect of immunobinding on motion performance of the swarm. Chemiluminescence (CL) signal of the heterogeneous swarm is significantly enhanced by vortex motion promoted incubation process. Besides, non-specific binding is efficiently suppressed by magnetic separation of immunobinding beads from the heterogeneous swarm. The findings demonstrate great potential for using magnetic swarms in immunosorbent detection and the future development of point-of-care instruments.