title: Giant magnetoresistive biochip for DNA detection and HPV genotyping.
abstract: A giant magnetoresistive (GMR) biochip based on spin valve sensor array and magnetic nanoparticle labels was developed for inexpensive, sensitive and reliable DNA detection. The DNA targets detected in this experiment were PCR products amplified from Human Papillomavirus (HPV) plasmids. The concentrations of the target DNA after PCR were around 10 nM in most cases, but concentrations of 10 pM were also detectable, which is demonstrated by experiments with synthetic DNA samples. A mild but highly specific surface chemistry was used for probe oligonucleotide immobilization. Double modulation technique was used for signal detection in order to reduce the 1/f noise in the sensor. Twelve assays were performed with an accuracy of approximately 90%. Magnetic signals were consistent with particle coverage data measured with Scanning Electron Microscopy (SEM). More recent research on microfluidics showed the potential of reducing the assay time below one hour. This is the first demonstration of magnetic DNA detection using plasmid-derived samples. This study provides a direct proof that GMR sensors can be used for biomedical applications.
authors.affiliation: Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305-4045, USA. lxuwind@stanford.edu
authors.forename: Liang
authors.initials: L
authors.lastname: Xu
authors.forename: Heng
authors.initials: H
authors.lastname: Yu
authors.forename: Michael S
authors.initials: MS
authors.lastname: Akhras
authors.forename: Shu-Jen
authors.initials: SJ
authors.lastname: Han
authors.forename: Sebastian
authors.initials: S
authors.lastname: Osterfeld
authors.forename: Robert L
authors.initials: RL
authors.lastname: White
authors.forename: Nader
authors.initials: N
authors.lastname: Pourmand
authors.forename: Shan X
authors.initials: SX
authors.lastname: Wang
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D004279:DNA, Viral / Q000032:analysis*; D005838:Genotype; D008280:Magnetics; D020411:Oligonucleotide Array Sequence Analysis / Q000379:methods*; D027383:Papillomaviridae / Q000145:classification / Q000235:genetics*; D012680:Sensitivity and Specificity
chemical_list: D004279:DNA, Viral