Au Nanoparticle-Based Amplified DNA Detection on Poly-l-lysine Monolayer-Functionalized Electrodes.

Almudena Marti,Jurriaan Huskens

doi:10.3390/nano12020242

Abstract

Affinity sensing of nucleic acids is among the most investigated areas in biosensing due to the growing importance of DNA diagnostics in healthcare research and clinical applications. Here, we report a simple electrochemical DNA detection layer, based on poly-l-lysine (PLL), in combination with gold nanoparticles (AuNPs) as a signal amplifier. The layer shows excellent reduction of non-specific binding and thereby high contrast between amplified and non-amplified signals with functionalized AuNPs; the relative change in current was 10-fold compared to the non-amplified signal. The present work may provide a general method for the detection of tumor markers based on electrochemical DNA sensing.

Highlights

Biosensors are devices that turn the specificity and selectivity of biological reactions into a detectable signal [1]
We developed a sandwich-type assay [25] in the following format (Scheme 1): selfWe developed a sandwich-type assay [25] in the following format (Scheme 1): selfassembly of the PLL pre-functionalized with reactive and oligo(ethylene glycol) (OEG) moieties, immobilization assembly of the PLL pre-functionalized with reactive and OEG moieties, immobilization of of capture probes onto the reactive groups of the PLL layer, their subsequent interaction capture probes onto the reactive groups of the PLL layer, their subsequent interaction with withtarget the target having dual recognition sitesboth for both capture and reporter probes, the having dual recognition sites for capture and reporter probes, and and AuNP-tagged reporter probes that hybridize to the residual bases of the AuNP-tagged reporter probes that hybridize to the residual bases of the target
The results presented here show that Electrochemical impedance spectroscopy (EIS) is a sensitive method to monitor changes at

Summary

Introduction

Biosensors are devices that turn the specificity and selectivity of biological reactions into a detectable signal [1]. High control over the sensor surface allows many possibilities to optimize the sensitivity. To achieve such control, monolayers on surfaces with specific functional groups are used to control analyte selectivity at the molecular scale [2,3,4]. DNA biosensors are constituted of immobilized single-strand DNA probes (ssDNA), which are able to recognize their complementary target sequences by specific hybridization, which triggers the transduction to a physical signal. This hybridization event can be measured electrochemically, optically, or gravimetrically [7]. Electrochemical biosensors are promising for utilization in point-of-care diagnostics due to the fact that they are easy to use, cheap, rapid and portable [8]

Methods

Results

Conclusion