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

Abstract

A strand displacement reaction-based system was developed for the determination of adenosine triphosphate (ATP). It involved an entropy-driven catalytic cycle that directly employed the ATP aptamer as the catalyst. Introduction of ATP into the system induced the catalyst to form the G-quadruplex conformation and inhibited its catalytic activity. All intermediates in the catalytic cycle processes were identified by polyacrylamide gel electrophoresis analysis. When the oligonucleotides were labeled with a carboxyfluorescein fluorophore and a 4-([4-(dimethylamino)phenyl]azo)benzoic acid quencher, this strand displacement reaction-based catalytic system exhibited a ''switch-on'' response for ATP. Conditions for detecting ATP, such as the toehold length, concentrations of the catalyst and magnesium ion, and incubation temperature, were optimized to obtain a detection limit of 50 nM and a linear response up to 1400 nM of ATP. This target inhibited catalytic cycle provides an enzyme-free biosensing strategy and has potential application in aptamer-based biosensing.

Customizable Aptamer Transducer Network Designed for Feed-Forward Coupling

“…The usefulness of an ARN lies in its ability to transduce a biomolecular input of target analytes into a nucleic acid signal. 18,25,26 When integrated with simple and inexpensive detection technologies, ARNs could one day become a potential replacement for assays that require more intensive labor or expensive equipment. 26 Investigation of more sensitive and well-designed ARN circuit components is critical for the development of sensing technologies for medical diagnostic and environmental applications.…”

“…27 This feed-forward capability has made reaction networks a noted area of interest in aptamer biosensing. 1,13,15,18,28 For example, Cheng et al demonstrated the coupling of the adenosine aptamer into a feed-forward catalytic reaction network employing both target-inhibited and targettriggered approaches to amplify the detection of adenosine. 15,28 Furthermore, they utilized the aptamer strand or its complement to trigger a catalytic cycle in their network design.…”

“…21 Other approaches toward developing a universal aptamer biosensor lack a transduction step and operate as labeled molecular beacons or as simple direct colorimetric devices. 7,13,16,17,19,25 While the feed-forward functionality has been considered by some groups, 1,13,15,18,28 the research community has focused more on modifications to increase the sensitivity of ARNs. Since aptamer biosensors are generally limited by the inherent aptamer−ligand binding affinity (K d ), approaches for designing more sensitive detectors depend on modifying an aptamer strand because its effective binding affinity (K d,eff ) can be improved with targeted alterations to its base sequence, including the hybridization of complementary elements.…”

Enzyme-Free Photoelectrochemical Biosensor Based on the Co-Sensitization Effect Coupled with Dual Cascade Toehold-Mediated Strand Displacement Amplification for the Sensitive Detection of MicroRNA-21

“…Moreover, benefiting from the complete separation of input (light source) and output (photocurrent signal), high sensitivity and low background can be obtained. 7,8 Of course, the enhanced PEC intensity is a key factor in promoting the performance of PEC biosensors, which mainly depends on the photocurrent response efficiency of semiconductor materials. 9 A cosensitization structure with cascade boundary is a promising strategy, which can promote the harvest of light, the separation of charge, and the photocurrent output.…”

“…Based on the incorporation of PEC method and biosensing technique, PEC detection as a newly developed analytical technology, potentially possesses superiorities of simple equipment, self-powering ability, and low cost, which are consistent with the aims of sustainable chemistry. Moreover, benefiting from the complete separation of input (light source) and output (photocurrent signal), high sensitivity and low background can be obtained. , Of course, the enhanced PEC intensity is a key factor in promoting the performance of PEC biosensors, which mainly depends on the photocurrent response efficiency of semiconductor materials . A cosensitization structure with cascade boundary is a promising strategy, which can promote the harvest of light, the separation of charge, and the photocurrent output .…”