Rodriguez-Trujíllo, Romén1; Ajine, Mohammad Akram4; Orzan, A.5; Mar, Mikkel Dysseholm2; Larsen, F.1; Clausen, Casper Hyttel1; Svendsen, Winnie Edith6
1 Department of Micro- and Nanotechnology, Technical University of Denmark2 DTU Danchip, Technical University of Denmark3 Nano Bio Integrated Systems, Department of Micro- and Nanotechnology, Technical University of Denmark4 Office for Study Programmes and Student Affairs, Administration, Technical University of Denmark5 Technical University of Denmark6 Copenhagen Center for Health Technology, Center, Technical University of Denmark
A new method for measuring specific protein concentrations in solutions has been developed. The technique makes use of the Coulter effect for detecting and sizing of micro-scaled objects suspended in a buffer fluid. The method is completely label-free as it is only based on the electrical readout when a suspension of microscopic beads flows over a set of electrodes in a microfluidic device. Since no electrode functionalization is needed the same device can be used in a number of different assays. Using goat-anti-rat IgG functionalized polystyrene beads we have shown proof of principle detecting rat IgG in solution. When the analyte (rat IgG) is present oligomers of beads are formed. The electrical readout of the oligomers is different compared to a zero control sample with no rat IgG. Detection of the protein has been performed in a concentration as small as 14 ng/mL. The dynamic range of the system has been demonstrated to be relatively large, ranging from 1 g/mL to 14 ng/mL. The microfluidic system is made from polymer and glass and very little volume of sample (<10 L) is needed for analysis.
Sensors and Actuators B: Chemical, 2014, Vol 190, p. 922-927