A disposable bio-nano-chip using agarose beads for high performance immunoassays

Abstract

This article reports on the fabrication of a disposable bio-nano-chip (BNC), a microfluidic device composed of polydimethylsiloxane (PDMS) and thiolene-based optical epoxy which is both cost-effective and suitable for high performance immunoassays. A novel room temperature (RT) bonding technique was utilized so as to achieve irreversible covalent bonding between PDMS and thiolene-based epoxy layers, while at the same time being compatible with the insertion of agarose bead sensors, selectively arranged in an array of pyramidal microcavities replicated in the thiolene thin film layer. In the sealed device, the bead-supporting epoxy film is sandwiched between two PDMS layers comprising of fluidic injection and drain channels. The agarose bead sensors used in the device are sensitized with anti-C-reactive protein (CRP) antibody, and a fluorescent sandwich-type immunoassay was run to characterize the performance of this device. Computational fluid dynamics (CFD) was used based on the device specifications to model the bead penetration. Experimental data revealed analyte penetration of the immunocomplex to 100 μm into the 280 μm diameter agarose beads, which correlated well with the simulation. A dose–response curve was obtained and the linear dynamic range of the assay was established over 1 ng/mL to 50 ng/mL with a limit of detection less than 1 ng/mL.

Transport of biomolecules to binding partners displayed on the surface of microbeads arrayed in traps in a microfluidic cell

“…As a result, diffusive transport is hindered, and one solution which is proposed is to create drains in the wells to enhance convection around the microbead. [25][26][27] The trapping geometry studied here uses an aperture at the back end to accomplish the same goal (as well as providing a gap between the microbead and the top surface of the channel), and is much easier to implement. Another method for constructing a microbead array/probe library in a microfluidic cell is to place the functionalized microbeads in shallow wells arrayed at the bottom of the channel, and then place the channel top on the microbead array.…”

“…21 Well deposition has also been enhanced by using electric and magnetic fields to assist in the capture, [22][23][24] or by using holes placed in the well and connected to a drain to provide fluid suction (see McDevitt et al 25,26 and Ketterson 27 ). The use of traps to array microbeads follows from the studies of arraying cells, or droplets containing cells (e.g., Refs.…”

On the Slow Diffusion of Point-of-Care Systems in Therapeutic Drug Monitoring

“…At the same time, the lack of a simple, easy-to-use, and cheap device that reproducibly measures drugs in patient-friendly matrices slows down the collection of useful PK and PD data able to improve TDM practice (Neef et al, 2008 ). A promising recent study is employing the bio-nanochip device (Jokerst and McDevitt, 2010 ; Du et al, 2011 ) for saliva monitoring of phenobarbital and phenytoin through a micro-bead assisted immunoassay, ready to be employed into a clinical trials for TDM in epileptic children. The chip comprises a programmable chemical processors and assay AEDs with a bead-based immunoassay.…”

Grasping and Releasing Agarose micro Beads in Water Drops

“…Moreover, an enhancement can be observed in food contaminant detection when pre-functionalized agarose micro-beads are employed in these kind of operating systems [43]. Agarose micro beads are suitable as sensors for a wide range of microscaled immunoassays, representing a good physical support for optimized antibody capturing and antigen-antibody interactions, due to an intrinsic nanoporous structure and high surface-to-volume ratios [44]. Furthermore, microfluidic systems with the goal of performing single-cell DNA-extraction and DNA-purification recently include an encapsulation and incubation phase of single cells in agarose beads or droplets in order to enhance the quality of the resulting genetic analysis and improve the observation of mutations circumstances as a key to study, undestand and properly treat cancers [45].…”