Dielectrophoretic trapping of nanosized biomolecules on plasmonic nanohole arrays for biosensor applications: simple fabrication and visible-region detection.

Surface plasmon resonance is an optical phenomenon that can be applied for label-free, real-time sensing to directly measure biomolecular interactions and detect biomarkers in solutions. Previous studies using plasmonic nanohole arrays have monitored and detected various biomolecules owing to the propagating surface plasmon polaritons (SPPs). Extraordinary optical transmission (EOT) that occurs in the near-infrared (NIR) and infrared (IR) regions is usually used for detection. Although these plasmonic nanohole arrays improve the sensitivity and throughput for biomolecular detection, these arrays have the following disadvantages: (1) molecular diffusion in the solution (making the detection of biomolecules difficult), (2) the device fabrication's complexities, and (3) expensive equipments for detection in the NIR or IR regions. Therefore, there is a need to fabricate plasmonic nanohole arrays as biomolecular detection platforms using a simple and highly reproducible procedure based on other SPP modes in the visible region instead of the EOT in the NIR or IR regions while suppressing molecular diffusion in the solution. In this paper, we propose the combination of a polymer-based gold nanohole array (Au NHA) obtained through an easy process as a simple platform and dielectrophoresis (DEP) as a biomolecule manipulation method. This approach was experimentally demonstrated using SPP and LSPR modes (not EOT) in the visible region and simple, label-free, rapid, cost-effective trapping and enrichment of nanoparticles (trapping time: <50 s) and bovine serum albumin (trapping time: <1000 s) was realized. These results prove that the Au NHA-based DEP devices have great potential for real-time digital and Raman bioimaging, in addition to biomarker detection.

Electrofusion of cells with different diameters by generating asymmetrical electric field in the microwell array.

This paper reports a superiority of the asymmetric electric field formed in the rectangle microwell array for the electrofusion of splenocytes and myeloma cells with different diameters. The upper substrate with microband electrodes was mounted on the lower substrate with the microwell array. Two electrodes were arranged at the both sides of the microwells on the bottom surface. An attractive force of positive dielectrophoresis was employed to capture splenocytes with smaller diameter and myeloma cells with larger diameter at the right and left of microwells by applying AC electric field. The splenocytes and myeloma cells were fused by the asymmetric electric field that was generated in the microwells by applying DC electric pulse to the bottom electrode at the right side. The asymmetric field could allow to the formation of small openings on the membrane for the fusion of smaller splenocytes by experiencing higher field and the suppression for the disruption of larger myeloma cells by experiencing lower field.