A Simple Separation Method of the Protein and Polystyrene Bead-Labeled Protein for Enhancing the Performance of Fluorescent Sensor

Abstract

Dielectrophoresis- (DEP-) based separation method between a protein, amyloid beta 42, and polystyrene (PS) beads in different microholes was demonstrated for enhancement of performance for bead-based fluorescent sensor. An intensity of ∇|E|2 wasrelative to a diameter of a microhole, and the diameters of two microholes for separation between the protein and PS beads weresimulated to 3 μm and 15 μm, respectively. )e microholes were fabricated by microelectromechanical systems (MEMS). )eseparation between the protein and the PS beads was demonstrated by comparing the average intensity of fluorescence (AIF) byeach molecule. Relative AIF was measured in various applying voltage and time conditions, and the conditions for allocating thePS beads into 15 μm hole were optimized at 80 mV and 15 min, respectively. In the optimized condition, the relative AIF wasobserved approximately 4.908 ± 0.299. Finally, in 3 μm and 15 μm hole, the AIFs were approximately 3.143 and 1.346 by 2 nm ofprotein and about - 2.515 and 4.211 by 30 nm of the PS beads, respectively. )e results showed that 2 nm of the protein and 30 nmof PS beads were separated by DEP force in each microhole efectively, and that our method is applicable as a new method to verify an efficiency of the labeling for bead-based fluorescent sensor ∇|E|2