A nanoparticle-based solution DNA sandwich assay using ICP-AES for readout

We report herein a nanoparticle-based methodology for detecting DNA in solution using inductively coupled plasma atomic emission spectrometry (ICP-AES) as a readout tool. This represents the first homogeneous solution assay of biologically significant targets by employing ICP-related techniques. Two types of particles are employed: silica nanoparticles or gold nanoparticles functionalized with oligonucleotides that are capable of hybridizing with half of the target DNA sequence as signal readout components, and magnetic microparticles functionalized with oligonucleotides that are capable of hybridizing with the other half of the sequence as capture components. In the presence of target DNA, three components form typical sandwich structures, and the application of a magnetic field could effectively separate them from the rest of the solution. Subsequent application of ICP-AES effectively provides an inorganic elemental readout for the diagnosis of target DNA.