DNA-based bioanalytical microsystems for handheld device applications

Abstract

This article reviews and highlights the current development of DNA-based bioanalytical microsystems for point-of-care diagnostics and on-site monitoring of food and water. Recent progresses in the miniaturization of various biological processing steps for the sample preparation, DNA amplification (polymerase chain reaction), and product detection are delineated in detail. Product detection approaches utilizing "portable" detection signals and electrochemistry-based methods are emphasized in this work. The strategies and challenges for the integration of individual processing module on the same chip are discussed.

Fig. 1

Diagrammatic representation of the processing flows in sample preparation.

Fig. 2

(A) Schematic of weir-type filter. A 3.5-μm gap between the top of the etched silicon dam and the Pyrex glass cover provides active filtration of cells based on size. Adapted from ref. . (B) The separation result of E. coli from a mixture containing human blood cells by means of dielectrophoresis on a microfabricated bioelectronic chip. Adapted from ref. .

Fig. 3

(A) Temperature profile of silicon–glass microchamber. Inset: photographs of the PCR microchip showing the integrated Pt heaters and temperature sensors (left) and the 8 μl reaction chamber (right). (B) Layout of a continuous-flow PCR chip. Adapted from ref. .

Fig. 4

(A) Schematic diagram showing eSensor^™'s sandwich hybridization assay with ferrocene-labeled reporter/signaling probe. Adapted from ref. . (B). Pictorial representation of the working principle of the molecular beacon-type capture probe labeled with ferrocene group for the reagentless sequence-specific DNA detection. Adapted from ref. . (C) Electrochemical detection of target DNA sequence using a ferrocene-labeled oligonucleotide-poly(ethylene glycol) triblock macromolecule. Adapted from ref. .

Fig. 5

(A) Schematic of the polycarbonate fluidic chip developed by Motorola Labs. Adapted from ref. . (B) Photos showing the top (left) and bottom (right) views of the integrated PCR–electrochemical chip. WE: gold working electrode; CE: Pt counter electrode; and RE: Pt pseudo reference electrode.