Aptamer based turn-off fluorescent ATP assay using DNA concatamers

A label-free fluorescent probe for the detection of adenosine 5'‑triphosphate via inhibiting the aggregation-induced emission enhancement of glutathione modified silver nanoclusters triggered by zinc ion

It is important to establish sensitive and simple analysis methods for adenosine 5'‑triphosphate (ATP). A label-free fluorescent probe for the determination of ATP was constructed based on glutathione modified silver nanoclusters (AgNCs/GSH). AgNCs/GSH showed aggregation-induced emission enhancement (AIEE) property in the organic solvent. The effects of metal ions on the fluorescence of AgNCs/GSH were also studied. Only zinc ion enhanced the fluorescence of AgNCs/GSH obviously. This was because Zn²⁺ coordinated with AgNCs/GSH to cause the aggregation of AgNCs/GSH, which was sufficiently proved by TEM. With the addition of ATP, Zn²⁺ bound with ATP through ZnOP bond and the binding between Zn²⁺ and AgNCs/GSH was inhibited. Hence the fluorescence of AgNCs/GSH was decreased with increasing the ATP concentration. The fluorescence response was linear in the ATP concentration range of 1-110 μM, and the detection limit was 0.8 μM. Then this method was successfully applied for determining ATP in the samples of human urine and rat serum, the recoveries were in the range of 97.6%-103%.

A terbium-based metal-organic framework@gold nanoparticle system as a fluorometric probe for aptamer based determination of adenosine triphosphate

This study reports on a method for fluorometric aptasensing of adenosine triphosphate (ATP). It is based on the interaction of dispersed (red) and agglomerated (blue) gold nanoparticles (AuNPs) with a water-dispered terbium(III) based metal-organic framework (Tb-MOF). The dispersed AuNPs quench the emissions of the Tb-MOF, while the aggregated AuNPs have little effect. Under the condition of high salt concentration, the free aptamer against ATP does not stabilize the AuNPs against aggregation. This causes a color change from red to blue and weak quenching of the fluorescence of the Tb-MOF (with peaks at 489 nm and 544 nm after excitation at 290 nm). On addition of ATP, it will be bound by its aptamer to form a complex that is adsorbed on the AuNPs. This protects the AuNPs from salt-induced aggregation and the color (with a peak at 525 nm) remains red. The two fluorescence bands of the Tb-MOF are therefore suppressed by fluorescence resonance energy transfer (FRET) between Tb-MOF and the dispersed AuNPs. Fluorescence drops linearly in the 50 nM to 10 μM ATP concentration range, and the detection limit is 23 nM. ATP analogs such as guanosine triphosphate, uridine triphosphate, cytidine triphosphate, adenosine monophosphate and cyclic adenosine monophosphate have no obvious interference. The method was successfully applied to the determination of ATP in (spiked) human plasma samples and gave satisfactory recoveries. Graphical abstract Schematic of a terbium-based metal-organic framework@gold nanoparticle system as a fluorometric probe for aptamer based determination of adenosine triphosphate. The dispersed gold nanoparticles (AuNPs) quench the fluorescence of the terbium-based metal-organic framework (Tb-MOF), while the aggregated AuNPs have little effect. In the presence of adenosine triphosphate (ATP), the aptamer-ATP complexes provide greater protection towards AuNPs than aptamer alone under high salt condition. Based on this, a novel Tb-MOF@AuNP platform is established for ATP detection.

Nanosensing of ATP by fluorescence recovery after surface energy transfer between rhodamine B and curcubit[7]uril-capped gold nanoparticles

The authors describe a method for functionalization of gold nanoparticles (AuNPs) with the supramolecular host molecule, curcubit[7]uril (CB[7]) which can bind rhodamine B (RhB). The fluorescence of RhB is quenched by the AuNPs via surface energy transfer. On addition of ATP, a dimeric RhB-ATP complex is formed and RhB is pushed out of CB[7]. Hence, fluorescence increases by a factor of 8. This fluorescence recovery effect has been utilized to develop a new detection scheme for ATP. The assay, measured at fluorescence excitation and emission wavelengths of 500 nm and 574 nm respectively, works in the 0.5-10 μM concentration range and has a 100 nM detection limit. The method is not interfered by UTP, GTP, CTP, TTP, ascorbic acid and glutathione. Graphical abstract Schematic of a method for determination of ATP in the 500 nM to 10 μM concentration range by using fluorescence recovery after surface energy transfer (SET) between rhodamine B (RhB) and gold nanoparticles capped with curcubit[7]uril (CB[7]).

Sensitive fluorescence detection of ATP based on host-guest recognition between near-infrared β-Cyclodextrin-CuInS2 QDs and aptamer

We have developed a near-infrared (NIR) fluorescent aptamer-based sensor for sensitive detection of adenosine-5'-triphosphate (ATP) by using a ATP-binding aptamer and β-Cyclodextrin-CuInS₂ quantum dots (β-CD-CuInS₂ QDs). The fluorescence of β-CD-CuInS₂ QDs has a slight enhancement with the addition of ATP-binding aptamer due to the host-guest recognition between aptamer and β-CD. When ATP is added, it will bind to aptamer to form G-quadruplexes. Aptamer-ATP complexes can enter into the hydrophobic cavities of β-CD and result in great enhancement of the fluorescence intensity. Under the optimum conditions, the fluorescence intensity of β-CD-CuInS₂ QDs is proportional to the concentration of ATP, which shows a good linear response toward ATP concentration range of 6-1200μmolL^-1, the detection limit for ATP is 3μmolL^-1. The present assay shows a good selectivity for ATP over other biologically important proteins, and it is applied to the determination of ATP in human serum sample with satisfactory results.