How can the sensitivity of sensors be significantly increased?

Daniel Mandler, Chemistry, Hebrew University of Jerusalem, Jerusalem, Israel (daniel.mandler@mail.huji.ac.il)
Noa Casper, Chemistry, Hebrew University Of Jerusalem, Jerusalem, Israel
Din Zelikovich, Chemistry, Hebrew University Of Jerusalem, Jerusalem, Israel

The detection and quantification of extremely low levels of biomolecules, drugs, and toxins that are often present in trace amounts and in particular in different environments, is highly challenging. Most of the highly sensitive analytical techniques, such as mass spectrometry, chromatography, and advanced spectroscopy, require complex instrumentation, skilled operators, and controlled laboratory conditions, making them expensive and impractical for on-site or routine use.

We have developed a new approach, termed nanoparticle-imprinted matrix (NAIM), that is based on the imprinting of nanoparticles (NPs) for the very selective detection of NPs based on their size, shape, and surface chemistry. This contribution takes the NAIM approach and applies it to the very sensitive detection of small molecules.

The central innovation of the proposed work lies in coupling chemical amplification with dual selectivity. Gold nanoparticles (AuNPs) were functionalized with a molecular recognition unit, i.e., mercaptophenylboronic acid (MPBA), that undergoes a significant structural upon analyte, i.e., dopamine (DA) binding. These functionalized nanoparticles were imprinted in a thin film made by electropolymerization of aryldiazonium precursors. Subsequent removal of the nanoparticles generates nanocavities that were complementary in shape and surface chemistry to the analyte-bound functionalized NPs, allowing selective reuptake only of the nanoparticles carrying the target molecule. Therefore, the oxidation of these reuptaken metallic nanoparticles provided a highly amplified electrochemical signal, directly correlated to the analyte concentration.