Abstract: Provided herein are methods and devices for the detection of analytes. The methods employ particles formed from a first metal conjugated to analytes. The analyte conjugated to the particle formed from the first metal can be accumulated at a working electrode. The first metal can be galvanically exchanged with ions of a second metal to form a layer of the first metal at the working electrode. The first metal can then be electrochemically detected and/or quantified. Using this method, analytes can be detected at low concentrations a few femtomolar via anodic stripping voltammetry, with no washing steps or electrode modifications.

Abstract: Methods and devices electrochemically detect analytes. The methods employ metal particles conjugated to the analytes. The metal particles can serve as an electrochemical label for the analyte to which they are conjugated. The metal particles can be oxidized to form metal ions that can subsequently be electrochemically detected and/or quantified. The metal ions can be electrodeposited as metal on a working electrode. The potential applied at the working electrode can then be varied to reoxidize the deposited metal to metal ions. The intensity of the resulting voltammetric peak reflects the amount of metal deposited on the working electrode, and therefore the amount of metal nanoparticle label and analyte. Sensitivity can tie improved by selectively localizing the analyte-metal particle conjugate in the vicinity of the working electrode. Analytes can be detected at concentrations as low as 767 fM via anodic stripping voltammetry, with no washing steps or electrode modifications.