Facile open-well immunofluorescence enhancement with coplanar-electrodes-enabled optoelectrokinetics and magnetic particles

Electrokinetic manipulation has been proven powerful in enhancing the sensing capability of general-purpose biochips. However, the close-form configuration of biochips and the required use of low electric conductivity limit their practicability. In this study, an open-well microfluidic system facilitated with coplanar-electrodes-enabled optoelectrokinetic concentration and magnetic particles were therefore developed to overcome these challenges. The open side achieves optoelectrokinetic manipulation for biosignal enhancement, enabling free manual operations. Magnetic particles were employed in immunoassays to facilitate the rapid onsite separation of targets. A common cytokine biomarker found in many diseases, that is, tumor necrosis factor alpha (TNF-α), was used for assessing the immunosensing system. In addition to the benefits inherited from the immunoassays, the fluorescent signal enhanced by the optoelectrokinetic technique also featured rapid enhancement in 1 min and a limit of detection of as low as 2.9 pg/mL. The open-well architecture allowed the entire immunosensing process to be completed on site without frequent off-site washing. For a practical test, the TNF-α in human tear fluids was measured by the developed device and validated with a standard enzyme-linked immunosorbent assay (ELISA). The data show consistency in terms of trend. The developed open-well optoelectrokinetic device provides an insight into future facile clinical diagnoses. By simply modifying the surface linkers on the magnetic particles, the technique can be further extended to more other trace biomarker detections.