Fabrication of colloidal crystal beads by a drop-breaking technique and their application as bioassays

The fabrication of colloidal crystal beads with controllable size, small size dispersion, and good reproducibility using a drop-breaking technique, is presented. A microfluidic drop-breaking approach simplifies the fabrication apparatus and improves the repeatability. Silicon oil KF-96 containing X-22-821 (20 wt%) was injected as a stabilizer into a polytetrafluoroethylene (PTFE) pipe using a syringe pump, and aqueous suspension containing silica nanoparticles was driven by an automation stage through a dispenser needle. The aqueous suspension was inserted into the PTFE pipe for conducting fabrication. Scanning electron microscopy (SEM) was used to observe the spherical shape of nanoparticles. Bead size and size dispersion of the encoded beads were determined carefully for use in bioassays. The polydispersities of the beads were also less than 3% that is useful in bioassay. Results show that the beads fabricated by drop-breaking method can be used for multiplex bioassay successfully.