Confined gold nanoparticles enhance the detection of small molecules in label-free impedance aptasensors

Abstract

A controlled architecture of nanoelectrodes, of a similar size to small molecule-binding aptamers, is synthesized inside nanoporous alumina. Gold nanoparticles with a controlled size (about 2 nm) are electrogenerated in the alumina cavities, showing a fast electron transfer process toward ferrocyanide. These uncapped nanoparticles are easily modified with a thiol-containing aptamer for label-free detection of adenosine monophosphate by electrochemical impedance spectroscopy. Our results show that the use of a limited electrical conducting surface inside an insulating environment can be very sensitive to conformational changes, introducing a new approach to the detection of small molecules, exemplified here by the direct and selective detection of adenosine monophosphate at the nanomolar scale.

Modified Nucleoside Triphosphates for In-vitro Selection Techniques

“…Nowadays, nucleic acids are not only considered as genetic information messengers or repositories. New functions and applications of these molecules, like catalysis and molecular recognition have emerged in the last 25 years (Klussmann, 2006 ), impacting different fields like: therapeutics (Tei et al, 2015 ), target validation (Rodríguez et al, 2015 ), molecular biology (Lee et al, 2015 ), diagnostics (Wandtke et al, 2015 ), and analytical chemistry (Li and Lu, 2009 ; Mascini, 2009 ; Peinetti et al, 2015 ). The term “functional oligonucleotide” was coined in reference to these new functions.…”

Aptamers for Diagnostics with Applications for Infectious Diseases

“…Nanoporous anodized aluminum oxide surfaces have more recently been used for providing a nanoporous surface through which electron movement can be controlled by aptamer-analyte binding. In these aptasensors, the aptamers are attached to a gold surface, which is provided by 2 nm gold nanoparticles [36] or by a surface coating created by sputtering [37]. The structural change in the aptamer due to binding of the analyte reduces access of [Fe(CN)6] 3−/4− to the gold surface [36], which can be measured by EIS.…”

“…In these aptasensors, the aptamers are attached to a gold surface, which is provided by 2 nm gold nanoparticles [36] or by a surface coating created by sputtering [37]. The structural change in the aptamer due to binding of the analyte reduces access of [Fe(CN)6] 3−/4− to the gold surface [36], which can be measured by EIS. Even in the absence of a redox probe, a good EIS signal can be obtained due to a combination of steric hindrance and change in electrical conductance around the pores resulting from the structural changes that occur in the highly negatively charged aptamers upon binding their targets [37].…”

Formation of redox-active self-assembled polyelectrolyte–surfactant complexes integrating glucose oxidase on electrodes: Influence of the self-assembly solvent on the signal generation

“…Among the main areas that have received particular attention is the one devoted to electrode modification toward its application to biological and environmental analysis, where materials such as carbon nanotubes [3][4][5][6], nanorods [7][8][9], and nanoparticles [10][11][12][13] have shown their great potentials. Another approach is the use of electroactive polyelectrolyte films containing species that can be oxidized and reduced in a reversible way [14,15].…”