Detection of Target ssDNA Using a Microfabricated Hall Magnetometer with Correlated Optical Readout

Kan-Sheng Chen,Peng Xiong,P. Bryant Chase,Khaled Aledealat,Steven M. Hira,Geoffrey F. Strouse,Stephan von Molnár,Gerard J. Sullivan,Mark Field

doi:10.1155/2012/492730

Abstract

Sensing biological agents at the genomic level, while enhancing the response time for biodetection over commonly used, optics-based techniques such as nucleic acid microarrays or enzyme-linked immunosorbent assays (ELISAs), is an important criterion for new biosensors. Here, we describe the successful detection of a 35-base, single-strand nucleic acid target by Hall-based magnetic transduction as a mimic for pathogenic DNA target detection. The detection platform has low background, large signal amplification following target binding and can discriminate a single, 350 nm superparamagnetic bead labeled with DNA. Detection of the target sequence was demonstrated at 364 pM (<2 target DNA strands per bead) target DNA in the presence of 36 μM nontarget (noncomplementary) DNA (<10 ppm target DNA) using optical microscopy detection on a GaAs Hall mimic. The use of Hall magnetometers as magnetic transduction biosensors holds promise for multiplexing applications that can greatly improve point-of-care (POC) diagnostics and subsequent medical care.

Highlights

The ability to detect and discriminate specific nucleic acid sequences within a biological mixture has implications for genome sequencing and single-nucleotide polymorphism (SNP) detection, biowarfare target detection, and the development of an efficient point-of-care (POC) device for pathogen identification [1,2,3,4,5,6]
Coupling the extreme sensitivity of Hall-based magnetic detection, which operates over a wide magnetic field and temperature range, with the versatility and specificity of DNA base pairing can allow the realization of a new biological detection strategy that will improve POC diagnostics and subsequent medical treatment
The use of a SPM nanobead does not hinder the specificity of Watson-Crick base pairing for the target nucleic acid as evidenced by sequence-specific DNA hybridization (Figure 2 and Figure S2)

Summary

Introduction

The ability to detect and discriminate specific nucleic acid sequences within a biological mixture has implications for genome sequencing and single-nucleotide polymorphism (SNP) detection, biowarfare target detection, and the development of an efficient point-of-care (POC) device for pathogen identification [1,2,3,4,5,6]. Through the integration of biology with nanotechnology, a detection platform utilizing magnetic transduction can capitalize on the high biological specificity of DNA base pairing, the scalability of nanotechnology, the selectivity of self-assembled monolayer technology, and the sensitivity of magnetic transduction [7, 8]. Coupling the extreme sensitivity of Hall-based magnetic detection, which operates over a wide magnetic field and temperature range, with the versatility and specificity of DNA base pairing can allow the realization of a new biological detection strategy that will improve POC diagnostics and subsequent medical treatment. In this paper the detection of a 35-base pair DNA target sequence is demonstrated at the single-bead level on a Hall magnetometer biosensor. The detection strategy utilizes three-strand DNA annealing to colocalize a superparamagnetic (SPM) bead labeled probe strand, a label-free target strand, and a receptor strand at the surface of the Hall device. At the concentrations of DNA used in the mimic, the device platform can be optimized for clinical

Methods

Results

Conclusion