Fluorescent immunosensing enhanced with a bead-based optoelectrokinetic platform

Bead-based immunosensing is a promising technology in the point-of-care diagnostics due to its high flexibility. For dilute samples, functionalized particles can concentrate dispersed analytes and act as carriers for particle manipulation. To realize rapid and selective diagnosis, a bead-based optoelectrokinetic immunosensing technique, termed rapid electrokinetic patterning (REP), was employed herein to detect a biomarker, lipocalin 1 (LCN1), for diabetic retinopathy. The measurement was made in an aqueous droplet sandwiched between two parallel electrodes. With an electric field and a focused laser beam applying on the microchip simultaneously, the immunocomplexes in the droplet were further concentrated to enhance the fluorescent signal. The detection required only several tens of seconds. The limit of detection (LOD) reached nearly 110 pg/mL. The combined use of bead-based immunoassays and the optoelectrokinetic platform enabled a noninvasive measure to the early diagnosis of diabetic retinopathy.