Redox Polyelectrolyte Modified Gold Nanoparticles Enhance the Detection of Adenosine in an Electrochemical Split‐Aptamer Assay

We present an electrochemical sandwich‐type assay based on the splitting of an aptamer into two fragments. Gold nanoparticles are modified with one of the fragments and a redox polyelectrolyte. The first is used as the recognition element, while the other for the electrochemical signal generation. The split‐aptamer used here can detect adenosine, used as a model system for recognizing small molecules. The multiple binding sites on the nanoparticle, along with the high number of redox probes, yield a selective and sensitive assay for adenosine, achieving a limit of detection of 3.1 nM and a linear range up to 75 nM. The obtained results are analyzed in terms of the nanoparticle and electrode architectures. The assay can be easily extended to other small molecules and sandwich assays, representing a promising tool for detecting metabolites at the nanomolar level. Integrating advantages. Modification of AuNP with a split aptamer and a redox polyelectrolyte produces a sensitive electrochemical sandwich assay for adenosine; the redox polyelectrolyte surrounded the nanoparticle provides a label that immediately can generate a signal using square wave voltammetry on a modified screen‐printed electrode. The method‘s sensitivity opens new alternatives for detecting metabolites through a simple amperometric assay using well‐established components of the dignositics industry.