Hairpin DNA as a Biobarcode Modified on Gold Nanoparticles for Electrochemical DNA Detection

Abstract

Hairpin DNA (hpDNA) as a novel biobarcode was conjugated with gold nanoparticles (AuNPs) and a reporter DNA (rpDNA) to form hpDNA/AuNP/rpDNA nanoparticles for the detection of an oligonucleotide sequence associated with Helicobacter pylori as a model target. The rpDNA is complementary to about a half-portion of the target DNA sequence (tDNA). A capture DNA probe (cpDNA), complementary to the other half of the tDNA, was immobilized on the surface of a gold electrode. In the presence of tDNA, a sandwich structure of (hpDNA/AuNP/rpDNA)/tDNA/cpDNA was formed on the electrode surface. The differential pulse voltammetry (DPV) detection was based on [Ru(NH3)5(3-(2-phenanthren-9-yl-vinyl)-pyridine)](2+), an electroactive complex that binds to the sandwich structure by its intercalation with the hpDNA and the double-stranded DNA (dsDNA) of the sandwich structure. The several factors--high density of biobarcode hpDNA on the surface of AuNPs, multiple electroactive complex molecules intercalated with each hpDNA and dsDNA molecule, and the intercalation binding mode of the electroactive complex with the DNA sandwich structure--contribute to the DNA sensor with highly selective and sensitive sensing properties. The DNA sensor exhibited a detection limit of 1 × 10(-15) M (i.e., 1 fM), the DNA levels in physiological samples, with linearity down to 2 × 10(-15) M. It can differentiate even one single mismatched DNA from the complementary tDNA. This novel biobarcode-based DNA sensing approach should provide a general platform for development of direct, simple, repetitive, sensitive, and selective DNA sensors for various important applications in analytical, environmental, and clinical chemistry.

Advances in nanomaterials and their applications in point of care (POC) devices for the diagnosis of infectious diseases

“…With a great surface-to-volume ratio, NPs could potentially bind a greater density of capture probes. This indirectly magnifies the ECM signals ultimately generated (Cui et al, 2015;Sun et al, 2015). At the same time, signal-to-noise (SNR) ratio is improved.…”

“…Interestingly, the reporter DNA only carried a sequence complementary to half of the target Helicobacter pylori sequence. The other half was recognized by a capture probe anchored to a gold electrode (Cui et al, 2015). With a great surface-to-volume ratio, NPs could potentially bind a greater density of capture probes.…”

Detection of Helicobacter pylori in dental plaque using a DNA biosensor for noninvasive diagnosis

“…[23][24][25][26][27] Among different sensitivity enhancing strategies in DNA biosensors, nanostructure-based labelling method combined with sandwich DNA sensing has emerged as an effective way to approach the PCR detection sensitivity. [25][26][27][28][29] Au nanoparticles (AuNPs) have become one of the most-employed labelling nanomaterials for fabricating sensitive DNA biosensors, thanks to their large surface to volume ratio, excellent biocompatibility, terric electrocatalytic activity, dramatic electrical conductivity, and excellent chemical and physical stability. 25,[29][30][31][32] In contrast, electrochemical DNA biosensors, with the advantages of simple and fast, sensitive, accurate, specic, free of interference from color, and cheap instrumentation, have emerged as a promisingly practical strategy for DNA detection in physiological/biological samples.…”

Nanomaterials for molecular signal amplification in electrochemical nucleic acid biosensing: recent advances and future prospects for point-of-care diagnostics

“…110 More generally, recent research efforts have been focused on surface engineering of nanoparticle labels, with a view to increasing the loading capacity of redox indicators. For example, one can functionalize gold nanoparticles with dsDNA or ssDNA to increase the number of possible binding sites for RuHex 118 or methylene blue labels, 119 respectively. Alternatively, gold nanoparticles can form hybridizationinduced aggregates upon target recognition, which offer more binding sites for RuHex.…”