Attomolar Electrochemical Detection of DNA Hybridization Based on Enhanced Latex/Gold Nanoparticles

We report a highly sensitive method for detecting DNA hybridization by anodic‐stripping voltammetry, using assemblies of AuNPs as electrochemical labels. The assemblies are made by layer‐by‐layer modification of sub‐micrometer latex spheres, followed by the uptake of the negatively charged AuNPs by ion exchange. The Au content can be considerably enhanced by autocatalytic reduction. Under the optimized conditions of enhancement, using differential pulse voltammetry for the stripping, 30 mer targets common to five strains of E. coli could be calibrated across the range 10 × 10 −18 M to 100 × 10 −18 M with a detection limit of 20 × 10 −18 M , which corresponds to ≈240 DNA hybridizations.