title: Plasmon-enhanced colorimetric ELISA with single molecule sensitivity.
abstract: Robust but ultrasensitive biosensors with a capability of detecting low abundance biomarkers could revolutionize clinical diagnostics and enable early detection of cancer, neurological diseases, and infections. We utilized a combination of localized surface plasmon resonance (LSPR) refractive index sensing and the well-known enzyme-linked immunosorbent assay to develop a simple colorimetric biosensing methodology with single molecule sensitivity. The technique is based on spectral imaging of a large number of isolated gold nanoparticles. Each particle binds a variable number of horseradish peroxidase (HRP) enzyme molecules that catalyze a localized precipitation reaction at the particle surface. The enzymatic reaction dramatically amplifies the shift of the LSPR scattering maximum, λ(max), and makes it possible to detect the presence of only one or a few HRP molecules per particle.
authors.affiliation: Department of Applied Physics, Chalmers University of Technology, 412 96 Göteborg, Sweden.
authors.forename: Si
authors.initials: S
authors.lastname: Chen
authors.forename: Mikael
authors.initials: M
authors.lastname: Svedendahl
authors.forename: Richard P Van
authors.initials: RP
authors.lastname: Duyne
authors.forename: Mikael
authors.initials: M
authors.lastname: Käll
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D003124:Colorimetry / Q000295:instrumentation*; D004797:Enzyme-Linked Immunosorbent Assay / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D015336:Molecular Probe Techniques / Q000295:instrumentation*; D036103:Nanotechnology / Q000295:instrumentation*; D020349:Surface Plasmon Resonance / Q000295:instrumentation*