The novel label-free optical method for DNA and cwll quantification, coined as "pinwheel assay", is based on the phenomenon that silica-coated superparamagnetic beads aggregate in the presence of DNA and a rotating magnetic field under chaotropic conditions. This assay requires simple and inexpensive instrumentation, and has proven to be as sensitive as conventional fluorescence methods. The pinwheel assay is being applied in clinical diagnostics, such as blood analysis and drug susceptibility testing, etc, which provides a rapid and cost-effective alternative to conventional techniques.
