Contacts:

Romen Rodriguez-Trujillo, DTU Nanotech, Building 345 East, room 251, rrtr@nanotech.dtu.dk

Winnie E. Svendsen, DTU-Nanotech, Building 345Ø, room 258, Winnie.Svendsen@nanotech.dtu.dk

Lab-on-a-chip device for protein detection: a) Electrical model of a particle between two electrodes on a microfluidic channel and b) Schematic of a functionalized bead with attached antibodies (blue) and proteins (red).

Background

Assays measuring protein concentrations for specific proteins belong to the category of assays known as immunoassays. The strategy used by these assays to measure specific protein concentrations is to capture desired proteins from a sample and convert this capture into a measurable signal. In order to capture these molecules the immunoassays utilize the specific binding affinity of proteins to antibodies. Dominating within immunoassays detection technologies are the fluorescence (ELISA) and chemi-luminescence (luminex) based techniques. These techniques use optical (fluorescent) detection so that they have to induce at least one extra binding step after the capture of the protein of interest by the corresponding antibody. This binding step labels the captured protein with e.g. a fluorophore and thereby converting the capture of the protein into a measurable optical signal.

Project Description

The objective of this project is to develop a microfluidic device for performing protein detection by means of impedance measurements on protein-coated beads. The presence of the protein is sensed directly by the change on the impedance of the bead due to the attachment of the protein and no additional binding step is needed. This will simplify the detection system with respect to the existing optical based technologies reducing time and costs of any envisaged assay. In the NaBIS group we are currently following this line of research.

The whole system will consist of a chip containing a microfluidic channel for mixing the sample with proteins together with the beads, as well as electrodes in a further microfluidic channel for the detection of the beads. For measuring the concentration of the proteins, the Coulter counter principle, which measure changes in impedance between two electrodes, will be applied. The readout will be done by monitoring the impedance response of the system in time. The measured bead impedance will be different depending on the amount and kind of protein that is attached to the surface.

The project is already started and running and there is a chip system, which can detect bead transitions. The student job during the project could be to design and fabricate an optimized chip for impedance detection, make measurements with it as well as work on the functionalization of the beads with the complex antibody-protein. The project can be tailored to fit individual wishes and two students could simultaneously work in the same project as we are exploring various different strategies.