Microfluidic fabrication of photonic encoding magnetized silica microspheres for aptamer-based enrichment of Ochratoxin A

Photonic encoding magnetized silica microspheres were synthesized from a polydisperse system containing silica and Fe₃O₄ nanoparticles by using a microfluidic self-assembly device. The optical and structural properties of the magnetized microspheres were characterized by scanning electron microscopy and reflection spectra. The concentration of Fe₃O₄ nanoparticles in polydisperse system was found to strongly affect the characteristics of magnetized microspheres. They possess a Janus face, are porous, and possess structural color (red). The magnetic characteristic of the synthesized microspheres is not lost after they are immersed in piranha solution for 12 h. The magnetized microspheres were applied to aptamer-based enrichment of the food toxin Ochratoxin A (OTA). Methods for immobilization of OTA aptamer on the microsphere surfaces were investigated. The modified microspheres can extract up to 80% of OTA if the surface of the microspheres is loaded with 275 ng·cm^?2 of aptamer and the number of microspheres is 200. The work provides a new pathway for aptamer-based enrichment of small molecules from complex matrixes.

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Graphical abstract Photonically encoded magnetized silica microspheres were synthesized by using microfluidic self-assembly device. The optical, magnetic and structural properties of the microspheres were investigated. The three-dimensional porous magnetized microspheres were applied to aptamer-based enrichment of the food toxin Ochratoxin A.