Quenching of the Electrochemiluminescence of Tris(2,2′-bipyridine)ruthenium(II)/Tri-n-propylamine by Pristine Carbon Nanotube and Its Application to Quantitative Detection of DNA

Ruthenium polypyridine complexes combined with oligonucleotides for bioanalysis: a review

Ruthenium complexes are among the most interesting coordination complexes and they have attracted great attention over the past decades due to their appealing biological, catalytic, electronic and optical properties. Ruthenium complexes have found a unique niche in bioanalysis, as demonstrated by the substantial progress made in the field. In this review, the applications of ruthenium complexes coordinated with polypyridine ligands (and analogues) in bioanalysis are discussed. Three main detection methods based on electrochemistry, electrochemiluminescence, and photoluminscence are covered. The important targets, including DNA and other biologically important targets, are detected by specific biorecognition with the corresponding oligonucleotides as the biorecognition elements (i.e., DNA is probed by its complementary strand and other targets are detected by functional nucleic acids, respectively). Selected examples are provided and thoroughly discussed to highlight the substantial progress made so far. Finally, a brief summary with perspectives is included.

Highly efficient electrogenerated chemiluminescence quenching of PEI enhanced Ru(bpy)₃²⁺ nanocomposite by hemin and Au@CeO₂ nanoparticles

In this work, a new signal amplified strategy based on the quenching effect of hemin and Au nanoparticles decorated CeO2 nanoparticles (Au@CeO2 NPs) for ultrasensitive detection of thrombin (TB) is reported for the first time. Herein, the poly(ethylenimine) (PEI) enhanced Ru(bpy)3(2+) nanocomposite was implemented by direct chemical polymerization, which could provide the desirable enhanced initial ECL signal. Furthermore, the detection aptamer of thrombin (TBA 2) was immobilized on Au@CeO2 NPs to form TBA 2/Au@CeO2 conjugates. Then, the G-rich DNA of TBA 2 sequence could fold into a G-quadruplex structure to embed hemin to obtain the quenching probe of hemin/TBA 2/Au@CeO2 conjugates. In the presence of target TB, the sandwiched structure could be formed between capture aptamer (TBA 1), TB and hemin/TBA 2/Au@CeO2 conjugates, thereby resulting in a proportional quenching in ECL response with TB, due to the quenching of both hemin and Au@CeO2 NPs. As a result, the signal-off aptasensor showed a wider linear range response from 10(-13) to 10(-8) M with lower detection limit of 0.03 pM.

A novel label-free electrochemiluminescence aptasensor based on layered flowerlike molybdenum sulfide-graphene nanocomposites as matrix

A label-free and ultrasensitive electrochemiluminescence (ECL) aptasensor was constructed for the detection of thrombin. Molybdenum sulfide-graphene nanocomposites with good conductivity and large surface area were immobilized on glassy carbon electrode (GCE), and then Nafion was fixed to chemosorb the Ru(bpy)3(2+) used as luminescence agent. Subsequently, gold nanoparticles (AuNPs) were modified on the electrode to immobilize the thiol-modified thrombin aptamer for fabrication of the thrombin aptasensor. The proposed ECL aptasensor produced the ultrasensitive detection of thrombin with a low detection limit of 3.6×10(-15)M (S/N=3) and over a wide target concentration range from 1.0×10(-14) to 5.0×10(-9)M. The aptasensor has been successfully applied in the determination of thrombin in human plasma samples of both traumatic and non-traumatic injury patients, indicating its promise in biochemical analysis. The recoveries of thrombin in human plasma samples are between 88.6% and 105.0%, and the RSD values are no more than 3.7%. The results demonstrate that this aptasensor has excellent sensitivity, selectivity and stability.

Flower-like ZnO nanostructure based electrochemical DNA biosensor for bacterial meningitis detection

Zinc oxide (ZnO) nanostructures possessing flower-like morphology have been synthesised onto platinized silicon substrate by simple and economical hydrothermal method. The interaction of physically immobilized single stranded thiolated DNA (ss th-DNA) probe of N. meningitides onto the nanostructured ZnO (ZNF) matrix surface have been investigated using cyclic voltammetry (CV) and electrochemical impeadance spectroscopy (EIS). The electrochemical sensing response behaviour of the DNA bioelectrode (ss th-DNA/ZNF/Pt/Si) has been studied by both differential pulse voltammetric (DPV) as well as impedimetric techniques. The fabricated DNA biosensor can quantify wide range of the complementary target ss th-DNA in the range 5-240 ng μl(-1) with good linearity (R=0.98), high sensitivity (168.64 μA ng(-1) μl cm(-2)) and low detection limit of about 5 ng μl(-1). Results emphasise that the fabricated flower-like ZnO nanostructures offer a useful platform for the immobilization of DNA molecules and could be exploited for efficient detection of complementary target single stranded DNA corresponding to N. meningitides.

Label-free electrochemiluminescence detection of specific-sequence DNA based on DNA probes capped ion nanochannels

A label-free electrochemiluminescence method for detecting specific-sequence DNA has been developed based on DNA probes capped ion nanochannels. This method is simple, inexpensive, and can be potentially expanded for the design of different types of ECL aptasensors.

Electrochemiluminescence immunosensor using poly(l-histidine)-protected glucose dehydrogenase on Pt/Au bimetallic nanoparticles to generate an in situ co-reactant

A new ECL immunosensor based on poly(l-histidine)-protected glucose dehydrogenase on Pt/Au bimetallic nanoparticles to generate co-reactantin situ.

The self-assembled Ru(bpy)3(PF6)2 nanoparticle on polystyrene microfibers and its application for ECL sensing

Ruthenium nanoparticle tris(2,2'-bipyridyl)ruthenium(II) bis(hexafluorophosphate) (Ru(bpy)3(PF6)2, RuNP) was self-assembled on polystyrene (PS) electrospun microfibers. The formation of RuNP is attributed to the sulfonated PS (SPS) microfibers' high adsorptive capability of 94% for Ru(bpy)3(2+), as well as the strong interaction between the Ru(bpy)3(2+) and ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate, BMIMPF6). The RuNP/SPS microfibers exhibited an enhanced electrochemiluminescence (ECL) emission, 2.3 times higher than that from Ru(bpy)3(2+)/SPS microfibers and 6.6 times higher than that from Ru(bpy)3(2+)/SPS continuous thin films. It is worthy of note that, as a result of the hydrophobic nature of the RuNP, the transfer of water-insoluble α-naphthol is accelerated, and thus the α-naphthol ECL quenching efficiency is enhanced. An ECL sensor based on the RuNP/SPS microfibers was fabricated and used to detect low concentrations of α-naphthol. The detection limit was of 1.0 nM (S/N > 3), and the linear response ranged from 0 to 18 μM. This sensor has been successfully applied to measure the α-naphthol content in pesticide carbaryl samples. Our work provides a very simple and cost-effective method to fabricate RuNP on polymer microfibers with great potential in the field of chemo/biosensors.

An efficient phosphorescence energy transfer between quantum dots and carbon nanotubes for ultrasensitive turn-on detection of DNA

We have demonstrated an efficient phosphorescence energy transfer (PET) system for ultrasensitive detection of DNA.