title: Sensitive molecular diagnostics using volume-amplified magnetic nanobeads.
abstract: In this letter, we demonstrate a new principle for diagnostics based on DNA sequence detection using single-stranded oligonucleotide tagged magnetic nanobeads. The target DNA is recognized and volume-amplified to large coils by circularization of linear padlock probes through probe hybridization and ligation, followed by rolling circle amplification (RCA). Upon hybridization of the nanobeads in the RCA coils, the complex magnetization spectrum of the beads changes dramatically, induced by the attached volume-amplified target molecules. We show that the magnetization spectrum of the nanobeads can be used for concentration determination of RCA coils down to the pM range, thus creating the opportunity for nonfluorescence-based cost-efficient high-sensitivity diagnostics tool. We also show that the bead incorporation in the coils is diffusion-controlled and consequently may be accelerated by incubating the sample at higher temperatures.
authors.affiliation: Department of Engineering Sciences, Division of Nanotechnology and Functional Materials, Uppsala University, The Angström Laboratory, Box 534, SE-751 21 Uppsala, Sweden.
authors.forename: Mattias
authors.initials: M
authors.lastname: Strömberg
authors.forename: Jenny
authors.initials: J
authors.lastname: Göransson
authors.forename: Klas
authors.initials: K
authors.lastname: Gunnarsson
authors.forename: Mats
authors.initials: M
authors.lastname: Nilsson
authors.forename: Peter
authors.initials: P
authors.lastname: Svedlindh
authors.forename: Maria
authors.initials: M
authors.lastname: Strømme
mesh_terms: D004277:DNA, Single-Stranded / Q000737:chemistry; D008280:Magnetics; D053758:Nanoparticles / Q000032:analysis* / Q000737:chemistry; D012680:Sensitivity and Specificity
chemical_list: D004277:DNA, Single-Stranded