Photonic crystal hydrogel beads used for multiplex biomolecular detection

A microfluidic device was used to generate droplets of monodispersed silica nanoparticles in poly (ethylene glycol) diacrylates (PEG-DA), which were then polymerized into hydrogel beads by UV irradiation. The nanoparticles in the beads were assembled into ordered lattices and locked in the network of the hydrogel. Therefore, the beads showed photonic crystal features, whose reflection peaks were used as the coding elements of biomolecular carriers. And huge coding capacity could be gained by changing the volume fraction of the silica nanoparticles in the droplets. The beads provided homogeneous water surroundings so that some shortcomings in bioassay introduced by the presence of solid surface of carriers could be avoided. Their application in oligonucleotide detection demonstrated potential advantages of hydrogel beads as encoded carriers in multiplex biomolecular detection.