Denaturation methods for reusable magnetic biosensors.

Nanoscale biosensors for sensitive DNA detection require advanced and precise fabrication techniques, which make them highly expensive and result in low yield rates. For such DNA biosensors, sensor regeneration is highly desirable. In this study, we investigated the effectiveness of various denaturants, including ultrapure water, urea solution, tris-ethylenediaminetetraacetic acid buffer, and dimethyl sulfoxide (DMSO), for the denaturation of target DNAs hybridized to probe DNAs on sensors. We used giant magnetoresistive (GMR) biosensors equipped with a temperature control unit in conjunction with magnetic nanoparticles. To examine the effect of DNA sequence on denaturation efficiency, 14 orthogonal DNA pairs were designed and tested. Furthermore, to maintain a consistent sensitivity in subsequent measurements, we evaluated the integrity of the probe DNAs on the sensors after denaturation. Among all the denaturants tested, 40% DMSO demonstrated excellent performance in the denaturation of probe DNAs covalently bonded to the sensors, without any heating process. This optimal denaturant can be applied to other planar DNA biosensor systems; moreover, GMR biosensors can facilitate the evaluation of newly developed denaturants.