High performance electrophoresis system for site-specific entrapment of nanoparticles in a nanoarray

Abstract

A nanoarray, integrated with an electrophoretic system, was developed to trap nanoparticles into their corresponding nanowells. This nanoarray overcomes the complications of losing the function and activity of the protein binding to the surface in conventional microarrays by using minimum amounts of sample. The nanoarray is also superior to other biosensors that use immunoassays in terms of lowering the limit of detection to the femto- or atto-molar level. In addition, our electrophoretic particle entrapment system (EPES) is able to effectively trap the nanoparticles using a low trapping force for a short duration. Therefore, good conditions for biological samples conjugated with particles can be maintained. The channels were patterned onto a bi-layer consisting of a PMMA and LOL coating on conductive indium tin oxide (ITO)-coated glass slide by using e-beam lithography. The suspensions of 170 nm-nanoparticles then were added to the chip that was connected to a positive voltage. On top of the droplet, another ITO-coated-glass slide was covered and connected to a ground terminal. Negatively charged fluorescent nanoparticles (blue emission) were selectively trapped onto the ITO surface at the bottom of the wells by following electric field lines. Numerical modeling was performed by using commercially available software, COMSOL Multiphysics to provide better understanding about the phenomenon of electrophoresis in a nanoarray. Simulation results are also useful for optimally designing a nanoarray for practical applications.