Ensembles of nanoelectrodes modified with gold nanoparticles: characterization and application to DNA-hybridization detection

Abstract

A new method to increase the active area (A act ) of nanoelectrode ensembles (NEEs) is described. To this aim, gold nanoparticles (AuNPs) are immobilized onto the surface of NEEs using cysteamine as a cross-linker able to bind the AuNPs to the heads of the nanoelectrodes to obtain the so-called AuNPs-NEEs. The analysis of the cyclic voltammograms recorded in pure supporting electrolyte showed that the presence of the nanoparticles reflects in an, approximately, ten-times increase in the electrochemically active area of the ensemble. The measurement of the amount of electroactive polyoxometalates, which can be adsorbed on the gold surface of NEEs vs. AuNPs-NEEs, confirmed a significant increase of active area for the latter. These evidences indicate that there is a good electronic connection between the AuNPs and the underlying nanoelectrodes. The possibility to exploit AuNPs-NEEs for biosensing application was tested for the case of DNAhybridization detection. After immobilization on the gold surface of AuNPs-NEEs of a thiolated singlestranded DNA, the hybridization with complementary sequences labeled with glucose oxidase (GOx) was performed. The detection of the hybridization was achieved by adding to the electrolyte solution the GOx substrate (i.e., glucose) and a suitable redox mediator, namely the (ferrocenylmethyl) trimethylammonium (FA + ) cation; when the hybridization occurs, an electrocatalytic increase of the oxidation current of FA + is recorded.Comparison of electrocatalytic current recorded at DNA modified NEEs and AuNPs-NEEs indicate, for the latter, a significant increase in sensitivity in the detection of the DNA-hybridization event.

Triggerable Mutually Amplified Signal Probe Based SERS-Microfluidics Platform for the Efficient Enrichment and Quantitative Detection of miRNA

“…Each AuNP is coated with a single layer of dense DNA strands that are attached via a gold–thiol bond. The probes utilize the superior properties of AuNP, such as its SERS-enhancing efficiency , and its ability to increase the probability of DNA hybridization due to the adsorption of AuNPs. The TMAS-1 nanoprobe contains H1 hairpin DNA strands that are immobilized on AuNP, named, while TMAS-2 contains complexes of H2-AuNP.…”

Bioelectroanalysis with nanoelectrode ensembles and arrays

“…15 Design of DNA hybridization sensor based on NEE assembly: (a) activation of -COOH groups of the PC surface and immobilization of the capture amino-end DNA probe on to the activated carboxylic functionalities; (b) hybridization of DNA-GOx conjugate on to modified PC surface (reprinted, with permission, from Ref. [88]) Fig. 16 Schematic illustration of two DNA biorecognition systems The probe DNA strand is first attached to the polymer membrane; the target GOx-conjugated strand is then hybridized.…”

“…One way of reducing this drawback has recently been proposed [88]-increasing the nanoelectrode area not by etching the templating polymer but depositing gold nanoparticles on the gold nanodisc electrodes. The gold nanoparticles (AuNPs) are immobilized on the surface of NEEs Step 1: αMUC16 immobilized on the 3D NEE exposed wires.…”

SERS-Microfluidic Approach for the Quantitative Detection of miRNA Using DNAzyme-Mediated Reciprocal Signal Amplification

“…Detection Principle for miR-141 Using the SERS-Microfluidic Approach. In Figure 2A, the RSA-1 probe is a functional H2 strand attached to AuNP via the gold−thiol bond and modified with Cy3(purple dot) as a Raman signal molecule at the end of the hairpin DNA H2 strands, and AuNPs show the SERS effect and improve the efficiency of DNA hybridization due to the adsorption of AuNPs; 21,22 whereas, the RSA-2 probe is modified with the Rox (green dot) at the end of the hairpin DNA H3 strands. In the absence of miR-141, H1 hairpin DNA strands, which can specifically identify miR-141, could not be opened, and thus, the RSA-1 probes are in the "SERS on" state and the target-trigger selfassemble DNAzyme cycle reaction could not be activated.…”