Surface-modified elastomeric nanofluidic devices for single nanoparticle trapping

Our work focuses on the development of simpler and effective production of nanofluidic devices for high-throughput charged single nanoparticle trapping in an aqueous environment.Single nanoparticle confinement using electrostatic trapping has been an effective approach to study the fundamental properties of charged molecules under a controlled aqueous environment.Conventionally,geometry-induced electrostatic trapping devices are fabricated using SiOx-based substrates and comprise nanochannels imbedded with nanoindentations such as nanopockets,nanoslits and nanogrids.These geometry-induced electrostatic trapping devices can only trap negatively charged particles,and therefore,to trap positively charged particles,modification of the device surface is required.However,the surface modification process of a nanofluidic device is cumbersome and time consuming.Therefore,here,we present a novel approach for the development of surface-modified geometry-induced electrostatic trapping devices that reduces the surface modification time from nearly 5 days to just a few hours.We utilized polydimethylsiloxane for the development of a surface-modified geometry-induced electrostatic trapping device.To demonstrate the device efficiency and success of the surface modification procedure,a comparison study between a PDMS-based geometry-induced electrostatic trapping device and the surface-modified polydimethylsiloxane-based device was performed.The device surface was modified with two layers of polyelectrolytes(1:poly(ethyleneimine)and 2:poly(styrenesulfonate)),which led to an overall negatively charged surface.Our experiments revealed the presence of a homogeneous surface charge density inside the fluidic devices and equivalent trapping strengths for the surface-modified and native polydimethylsiloxane-based geometry-induced electrostatic trapping devices.This work paves the way towards broader use of geometry-induced electrostatic trapping devices in the fields of biosensing,disease diagnosis,molecular analysis,fluid quality control and pathogen detection.