Firefly bioluminescent assay of ATP in the presence of ATP extractant by using liposomes

A facile label-free G-quadruplex based fluorescent aptasensor method for rapid detection of ATP

The present work demonstrates a simple, rapid and label-free ATP detection method using a fluorescent aptasensor that is based on G-quadruplex formation. In the absence of ATP, the Thioflavin T (ThT) dye binds to the G-rich ATP aptamer and forms an ATP aptamer/ThT G-quadruplex complex, which results in high fluorescence intensity. Upon addition of ATP, the ATP aptamer/ThT complex will be replaced by the formation of an ATP aptamer/ATP complex. During this process, separation of the ThT dye from the ATP aptamer/ThT complex decreases the fluorescence intensity of the reaction mixture dramatically. This fluorescence aptasensor is highly sensitive and rapid, with a detection limit of 18nM and a total reaction time of only 10min. Furthermore, this method is cost-effective and simple, removing the requirement for labeling the detection reagents with a fluorophore-quencher pair.

Highly Specific Bacteriophage-Affinity Strategy for Rapid Separation and Sensitive Detection of Viable Pseudomonas aeruginosa

A virulent bacteriophage highly specific to Pseudomonas aeruginosa (P. aeruginosa) was isolated from hospital sewage using a lambda bacteriophage isolation protocol. The bacteriophage, named as PAP1, was used to functionalize tosyl-activated magnetic beads to establish a bacteriophage-affinity strategy for separation and detection of viable P. aeruginosa. Recognition of the target bacteria by tail fibers and baseplate of the bacteriophage led to capture of P. aeruginosa onto the magnetic beads. After a replication cycle of about 100 min, the progenies lysed the target bacteria and released the intracellular adenosine triphosphate. Subsequently, firefly luciferase-adenosine triphosphate bioluminescence system was used to quantitate the amount of P. aeruginosa. This bacteriophage-affinity strategy for viable P. aeruginosa detection showed a linear range of 6.0 × 10² to 3.0 × 10⁵ CFU mL^-1, with a detection limit of 2.0 × 10² CFU mL^-1. The whole process for separation and detection could be completed after bacteria capture, bacteriophage replication, and bacteria lysis within 2 h. Since the isolated bacteriophage recognized the target bacteria with very high specificity, the proposed strategy did not show any signal response to all of the tested interfering bacteria. Furthermore, it excluded the interference from inactivated P. aeruginosa because the bacteriophage could replicate only in viable cells. The proposed strategy had been applied for detection of P. aeruginosa in glucose injection, human urine, and rat plasma. In the further work, this facile bacteriophage-affinity strategy could be extended for detection of other pathogens by utilizing virulent bacteriophage specific to other targets.

Bioluminescence assay for cell viability

Theoretical aspects of the adenosine triphosphate bioluminescence assay based on the use of the firefly luciferin-luciferase system are considered, as well as its application for assessing cell viability in microbiology, sanitation, medicine, and ecology. Various approaches for the analysis of individual or mixed cultures of microorganisms are presented, and capabilities of the method for investigation of biological processes in live cells including necrosis, apoptosis, as well as for investigation of the dynamics of metabolism are described.

A label-free electrochemiluminescent sensor for ATP detection based on ATP-dependent ligation

In this work, we describe a new label-free, sensitive and highly selective strategy for the electrochemiluminescent (ECL) detection of ATP at the picomolar level via ATP-induced ligation. The molecular-beacon like DNA probes (P12 complex) are self-assembled on a gold electrode. The presence of ATP leads to the ligation of P12 complex which blocks the digestion by Exonuclease III (Exo III). The protected P12 complex causes the intercalation of numerous ECL indicators (Ru(phen)3(2+)) into the duplex DNA grooves, resulting in significantly amplified ECL signal output. Since the ligating site of T4 DNA ligase and the nicking site of Exo III are the same, it involves no long time of incubation for conformation change. The proposed strategy combines the amplification power of enzyme and the inherent high sensitivity of the ECL technique and enables picomolar detection of ATP. The developed strategy also shows high selectivity against ATP analogs, which makes our new label-free and highly sensitive ligation-based method a useful addition to the amplified ATP detection arena.

Real-time monitoring of small biological molecules by ligation-mediated polymerase chain reaction

We develop a ligation-mediated polymerase chain reaction (PCR) for real-time detection of small biological molecules in a high-throughput format. This method is extremely sensitive with a detection limit of as low as 18.8 fM for ATP and 17.3 fM for NAD(+), and it can discriminate target molecules from their analogues as well.

Spectroscopic study of the interaction between adenosine disodium triphosphate and gatifloxacin-Al3+ complex and its analytical application

A new and sensitive spectrofluorimetric method has been proposed to determine trace amount of adenosine disodium triphosphate (ATP). The method is based on the fluorimetric interaction between gatifloxacin (GFLX)-aluminium (III) (Al(3+) ) complex and ATP and studied using UV-visible and fluorescence spectroscopy. Weak luminescence spectra of Al(3+) were enhanced after complexation with GFLX at 423 nm upon excitation at 272 nm due to energy transfer from the ligand to the Al(3+) ion. It was observed that the FL emission spectrum of GFLX-Al(3+) was enhanced significantly by the addition of ATP. Under the optimal conditions, the enhancement of FL intensity at 423 nm was responded linearly with the concentration of ATP in the range 1.3 × 10(-10) - 1.0 × 10(-8) mol L(-1) with correlation coefficient (r) of 0.9981. The limit of detection (LOD) was found to be 1.1 × 10(-11) mol L(-1) for ATP with the standard deviation (RSD) of 1.21% for five repeated measurement of 2.3 × 10(-8) mol L(-1) ATP. The presented method is simple, sensitive, free from coexisting interferents and can be applied successfully to determine ATP in the real samples.

Dual recognition unit strategy improves the specificity of the adenosine triphosphate (ATP) aptamer biosensor for cerebral ATP assay

Adenosine triphosphate (ATP) aptamer has been widely used as a recognition unit for biosensor development; however, its relatively poor specificity toward ATP against adenosine-5'-diphosphate (ADP) and adenosine-5'-monophosphate (AMP) essentially limits the application of the biosensors in real systems, especially in the complex cerebral system. In this study, for the first time, we demonstrate a dual recognition unit strategy (DRUS) to construct a highly selective and sensitive ATP biosensor by combining the recognition ability of aptamer toward A nucleobase and of polyimidazolium toward phosphate. The biosensors are constructed by first confining the polyimidazolium onto a gold surface by surface-initiated atom transfer radical polymerization (SI-ATRP), and then the aptamer onto electrode surface by electrostatic self-assembly to form dual-recognition-unit-functionalized electrodes. The constructed biosensor based on DRUS not only shows an ultrahigh sensitivity toward ATP with a detection limit down to the subattomole level but also an ultrahigh selectivity toward ATP without interference from ADP and AMP. The constructed biosensor is used for selective and sensitive sensing of the extracellular ATP in the cerebral system by combining in vivo microdialysis and can be used as a promising neurotechnology to probing cerebral ATP concentration.

A novel sensitive and selective ligation-based ATP assay using a molecular beacon

In this paper, a novel, facile fluorometric ATP assay with high sensitivity and excellent selectivity has been reported. This approach utilizes a molecular beacon, T4 DNA ligase and two short oligonucleotides. In the presence of ATP, the T4 DNA ligase catalyzes the ligation reaction and the ligation product restores the fluorescence of the molecular beacon. Owing to the high sensitivity of the molecular beacon and T4 DNA ligase's high substrate dependence, this novel ATP assay demonstrates exceptional selectivity and high sensitivity down to 0.14 nM in homogeneous solution. Cellular ATP concentrations in several cell lines have been determined by measuring the lysate sample containing 8.0 × 10(3) cells.

A highly selective turn-on ATP fluorescence sensor based on unmodified cysteamine capped CdS quantum dots

Unmodified cysteamine capped nanocrystalline cadmium sulfide quantum dots (Cys-CdS QDs) were demonstrated as a selective turn-on fluorescence sensor for sensing adenosine-5'-triphosphate (ATP) in aqueous solution for the first time. The fluorescence intensity of the Cys-CdS QDs was significantly enhanced in the presence of ATP. In addition, the fluorescence intensity of the Cys-CdS QDs increased when increasing ATP concentrations. On the other hand, other phosphate metabolites and other tested common anions did not significantly alter the fluorescence intensity of the Cys-CdS QDs. In addition, this sensor showed excellent discrimination of pyrophosphate (PPi) from ATP detection. The proposed sensor could efficiently be used for ATP sensing at very low concentration with LOD of 17 μM with the linear working concentration range of 20-80 μM. The feasibility of the proposed sensor for determining ATP in urine samples was also studied, and satisfactory results were obtained.

Fluorescence detection of adenosine triphosphate using smart probe

A novel fluorescent probe for adenosine triphosphate (ATP) assay based on DNA ligation is proposed in this article. This approach uses a novel smart probe, T4 DNA ligase, and two short oligonucleotides. In the presence of ATP, the T4 DNA ligase catalyzes the ligation reaction and the ligation product restores the fluorescence of the smart probe. This method is very sensitive with a 0.5-nM limit of detection. Compared with current assay methods, the strategy is simpler, cheaper, and 40 times more sensitive.

ATP microelectrode biosensor for stable long-term in vitro monitoring from gastrointestinal tissue

We have developed a stable and selective ATP biosensor for long-term in vitro tissue monitoring. The electrode was fabricated by entrapping glucose oxidase (GOx) and hexokinase (HEX) in a poly-phenol film on a Pt microelectrode. The biosensor was stable to a fixed concentration of glucose for over 20 min and had a limit of detection of 9.9 ± 3.2 nM, with a sensitivity of 45.8 ± 1.22 pA μM(-1). Most significantly of all, the response on the ATP biosensor did not alter in the presence of 1mM ascorbic acid, 5 μM dopamine, 5 μM serotonin, 5 μM ADP and 5 μM AMP. The ATP biosensor was also shown to have excellent stability over 7 days, and showed only a 23.92 ± 3.55% loss in sensitivity. The ATP biosensor was utilised for the in vitro detection of ATP from gastrointestinal tissue. The ATP biosensor response was stable for 5h during in vitro recordings from ileum tissue. ATP release was shown to be greater from the mucosal surface in the ileum compared to the colon.

Bioluminescent assay of microbial ATP in postmortem tissues for the estimation of postmortem interval

To study the relationship between changes of microbial ATP in four kinds of murine tissues and the postmortem interval (PMI), healthy SD rats were sacrificed and their muscles, livers, spleens and kidneys were sampled at different postmortem intervals. The concentration of microbial ATP was detected using bioluminescent assay and the data was statistically analyzed. The concentration of microbial ATP in muscle increased with PMI time. The peak appeared at the 7th day after death, and at the 10th day, microbial ATP in muscle tissue increased again. In internal organs, the peaks of microbial ATP were observed at the 8th day after death and the level decreased during 8-10 d. The differences in microbial ATP concentration in liver, spleen and kidney were not statistically significant. During day 0 to day 9 after death, the correlation was best between PMI and microbial ATP in muscle. With PMI as the independent variable, the cubic polynomial regression equation was Y=0.02X(3)-0.166X(2)-0.666X+13.412 (R (2)=0.989, P<0.01). In internal organs, the best correlation was found between PMI and microbial ATP during day 0 to day 10. With PMI as the independent variable, the cubic polynomial regression equation was Y=0.016X(3)-0.127X(2)-0.809X+13.324 (R (2)=0.986, P<0.01). There existed high correlations between PMI and microbial ATP concentration in rat tissues. Since only a small amount of tissue was needed for the detection and the sample was not affected by self-decomposition, the method may extend the time range of PMI estimation.

Immunomagnetic separation and rapid detection of bacteria using bioluminescence and microfluidics

This paper describes an immunomagnetic separation of target bacterial cells from others by using magnetic bead. The surface of bead was coated with antibodies which can capture specific organism. The binding efficiency of immunomagnetic bead (IMB) capturing target bacterial cells was higher than 98% when the concentrations of target and interferent bacterial cells were at the same level. The concentration of bacteria was determined indirectly by detecting adenosine 5'-triphosphate (ATP) employing bioluminescence (BL) reaction of firefly luciferin-ATP. Benzalkonium chloride (BAC) was used as an ATP extractant from living bacterial cells. We found that BAC could enhance the light emission when the concentration of BAC was less than 5.3 x 10(-2)% (w/v) and the BL intensity reached its maximum at the concentration of BAC was 2.7 x 10(-2)%, which was 10-fold stronger than that without BAC. Based on the principle of the IMB, a microfluidic chip combined with immunofluorescence assay for separating and detecting bacteria simultaneously was also developed. The IMBs were magnetically fixed in the bead-beds of chip channels with a 3-mm diameter of NdFeB permanent magnet. The target bacterial cells can be captured magnetically and observed by a fluorescent microscope.

Amperometric ATP microbiosensors for the analysis of chemosensitivity at rat carotid bodies

The physiological application of amperometric adenosine triphosphate (ATP) microbiosensors for characterizing the stimulus-response at rat carotid bodies superfused with high potassium concentrations, during normoxic hypercapnia, and during hypoxia is demonstrated using the peripheral arterial chemoreceptors in the carotid body of rats as a model system. Amperometric microbiosensors based on glucose oxidase (GOD) and hexokinase (HEX) immobilized within a polymer matrix at the surface of Pt disk microelectrodes (diameter: 25 microm) are positioned at a distance of approximately 100 microm above the carotid body surface for detecting extracellular ATP. A linear calibration function of ATP microbiosensors in the physiologically relevant concentration range of 0-40 microM ATP enables quantitative detection of ATP released at the carotid body surface in response to physiological stimuli. It is shown that these stimuli induce extracellular ATP release from the carotid body at levels of 4-10 microM. Other electroactive neurotransmitters such as, e.g., catecholamines are coreleased by the carotid body at hypercapnic, hypoxic and high-potassium stimulus, are simultaneously detected utilizing a dual-electrode assembly with an ATP microbiosensor and a second bare channel providing a colocalized reference measurement for ATP quantification.

Spectroscopic study on the interaction of acridine yellow with adenosine disodium triphosphate and its analytical application

The interaction of adenosine disodium triphosphate (ATP) with acridine yellow and its analytical application have been studied. In an alkalescent medium, adenosine disodium triphosphate react with acridine yellow to form an ion-association by virtue of electrostatic attraction and hydrophobic interaction, resulting in a remarkable enhancement of resonance light scattering (RLS) intensity of acridine yellow. The maximum scattering wavelength is at 325 nm. The spectral characteristics of the ion-associates, the effective factors and the optimum conditions have been investigated. The enhanced RLS intensity is directly proportional to the concentration of ATP in the range of 0.80-20.0 microg ml(-1) with the detection limit 0.086 microg ml(-1). The method has been successfully applied to the quick determination of ATP in tablet and injection samples. The results of the present method are in agreement with those obtained by the method in the Chinese Pharmacopoeia.