Enrichment of nanoparticles and bacteria using electroless and manual actuation modes of a bypass nanofluidic device

Abstract

Current efforts in nanofluidics aimed at detecting scarce molecules or particles are focused mainly on the development of electrokinetic-based devices. However, these techniques require either integrated or external electrodes, and a potential drop applied across a carrier fluid. One challenge is to develop a new generation of electroless passive devices involving a simple technological process and packaging without embedded electrodes for micro- and nanoparticles enrichment with a view to applications in biology such as the detection of viral agents or cancers biomarkers. This paper presents an innovative technique for particles handling and enrichment based exclusively on a pressure-driven silicon bypass nanofluidic device. The device is fabricated by standard silicon micro-nanofabrication technology. The concentration operation was demonstrated and quantified according to two different actuation modes, which can also be combined to enhance the concentration factor further. The first, "symmetrical" mode involves a symmetric cross-flow effect that concentrates nanoparticles in a very small volume in a very local point of the device. The second mode, "asymmetrical" mode advantageously generates a streaming potential, giving rise to an Electroless Electropreconcentration (EL-EP). The concentration process can be maintained for several hours and concentration factors as high as ~200 have been obtained when both symmetrical and asymmetrical modes are coupled. Proof of concept for concentrating E. coli bacteria by the manual actuation of the EL-EP device is also demonstrated in this paper. Experiments demonstrate more than a 50-fold increase in the concentration of E. coli bacteria in only ~40 s.

Fundamental Studies of Nanofluidics: Nanopores, Nanochannels, and Nanopipets

“…(c) Pressure-driven flow concentrates fluorescent nanobeads in a bypass micro- and nanofluidic device. Reprinted from ref ( 155 ) with permission of The Royal Society of Chemistry. Copyright 2013 The Royal Society of Chemistry.…”

Creating sub-50 nm nanofluidic junctions in a PDMS microchip via self-assembly process of colloidal silica beads for electrokinetic concentration of biomolecules

“…A common device platform for the study of nanofluidics is a two-microchannel system connected by an array of nanochannels as a nanoscale junction. [3-5] …”

Recent Developments in Antibody-Based Assays for the Detection of Bacterial Toxins

“…In this section, we will focus on recent achievements in antibody-based microfluidic systems and highlight the combination with nanomaterials for the detection of bacterial toxins. Generally, the assays performed in microfluidic platforms may be categorized into: (i) chips designed for the miniaturization of traditional assays, e.g., ELISA [91,92]; and (ii) chips integrating sample pretreatment, signal amplification and readout techniques [93,94,95,96,97]. For example, sandwich and competitive ELISAs were combined with a microfluidic device for single-cell studies to reliably identify intracellular proteins and metabolites [98].…”