Carbon Nanotubes as a Low Background Signal Platform for a Molecular Aptamer Beacon on the Basis of Long-Range Resonance Energy Transfer

Abstract

Although holding the advantages of both an aptamer and a molecular beacon (MB), a molecular aptamer beacon (MAB) needs complicated and expensive modifications at both of its ends and usually has a high background signal because of the low energy transfer efficiency between the donor and the acceptor. To overcome these shortcomings, in this study, we develop a long-range resonance energy transfer (LrRET) system by separating the donor from the acceptor, wherein only one end of the MAB is fluorescently labeled and acts as the energy donor and multiwalled carbon nanotubes (MWCNTs) are introduced as the energy acceptor. To test the feasibility of the newly designed MAB system, adenosine triphosphate (ATP) has been employed as a proof-of-concept target. It is found that the fluorescence of the designed MAB is completely quenched by MWCNTs, supplying a very low background signal. Then the quenched fluorescence is recovered significantly with the addition of ATP, so that ATP can be detected in the range of 0.8-80 μM with a limit of detection of 0.5 μM (3σ). Compared with the conventional fluorescence resonance energy transfer, the efficiency of LrRET between the dye and MWCNTs is much higher. Since only one end of the MAB needs the modification, the present strategy is simple and cost-effective. Furthermore, the use of MWCNTs can greatly reduce the fluorescence background of the MAB and supply a high sensitivity, showing its generality for detection of a variety of targets.

Competitive fluorescence anisotropy/polarization assay for ATP using aptamer as affinity ligand and dye-labeled ATP as fluorescence tracer

“…The linear detection range with FA measurement was from 0.5 μM to 20 μM (y = 0.220-0.004x, R 2 = 0.990; y is FA value). The sensitivity of this competitive aptamer FA assay is comparable to those of aptamer FA assays [10,13,15,[29][30][31], and it is also comparable to that of some other aptamer-based assays for ATP with different detection methods [21,32,33]. The generated maximum FA/FP change in our method is much higher than that of some aptamer FA assays [15,[29][30][31].…”

Determination of Adenosine Triphosphate by a Target Inhibited Catalytic Cycle Based on a Strand Displacement Reaction

“…This designed system provides a sensitive method for the detection of ATP, with better sensitivity than many aptamer-based biosensing systems (He et al 2011;S. Zhang et al 2009;J. Zhen et al 2010) (limits of detection vary from 0.11 mM to 10 mM) and is comparable with some enzyme-based amplification systems (Li, Fu et al 2012;) (limits of detection are 0.1 mM and 10 mM, respectively).…”

Quencher-free molecular aptamer beacons (QF-MABs) for detection of ATP

“…Recently, a molecular aptamer beacon (MAB), an MB-based oligonucleotide probe having a target-specific aptamer sequence in the loop part, was found to probe its target with high specificity. 10 As an application of conventional MABs, single fluorophore labeled MAB systems were reported, in which multi-walled carbon nanotubes (MWCNTs) 11 or GOs 12 act as a quencher.…”