UV-Spectroscopic Detection of (Pyro-)Phosphate with the PUB module

Despite the prevalence of ortho- and pyrophosphate in biochemistry, operationally simple and versatile high-throughput methodologies for their quantification are lacking. We herein introduce PUB, a module for phosphate detection by continuous UV-spectroscopic monitoring of 5-bromouridine phosphorolysis. The PUB module employs cheaply available, bench-stable reagents and can be employed for continuous and discontinuous reaction monitoring in biochemical assays to detect (pyro-)phosphate concentrations spanning almost four orders of magnitude, as demonstrated with representative use-cases.

Colorimetric Phosphate Detection Using Organic DFB Laser-Based Absorption Spectroscopy

A novel compact laser absorption spectrometer is developed for colorimetric detection. We demonstrate the realization of the system as well as example measurements of phosphate in water samples based on the malachite green (MG) method. A phosphate concentration range of to (which corresponds to a molar concentration range of to ) is investigated. This photometer demonstrates the ease of integration of organic distributed feedback (DFB) lasers and their miniaturizability, leading the way toward optofluidic on-chip absorption spectrometers. We constructed an optically pumped organic second-order DFB laser on a transparent substrate, including a transparent encapsulation layer, to have access to both emission directions of the surface-emitting laser. Using the two different surface emission directions of the laser resonator allows monitoring of the emitted light intensity without using additional optical elements. Based on these advances, it is possible to miniaturize the measurement setup of a laser absorption spectrometer and to measure analytes, such as phosphate.

A Novel Assay for Phosphoserine Phosphatase Exploiting Serine Acetyltransferase as the Coupling Enzyme

Phosphoserine phosphatase (PSP) catalyzes the final step of de novo L-serine biosynthesis—the hydrolysis of phosphoserine to serine and inorganic phosphate—in humans, bacteria, and plants. In published works, the reaction is typically monitored through the discontinuous malachite green phosphate assay or, more rarely, through a continuous assay that couples phosphate release to the phosphorolysis of a chromogenic nucleoside by the enzyme purine nucleoside phosphorylase (PNP). These assays suffer from numerous drawbacks, and both rely on the detection of phosphate. We describe a new continuous assay that monitors the release of serine by exploiting bacterial serine acetyltransferase (SAT) as a reporter enzyme. SAT acetylates serine, consuming acetyl-CoA and releasing CoA-SH. CoA-SH spontaneously reacts with Ellman’s reagent to produce a chromophore that absorbs light at 412 nm. The catalytic parameters estimated through the SAT-coupled assay are fully consistent with those obtained with the published methods, but the new assay exhibits several advantages. Particularly, it depletes L-serine, thus allowing more prolonged linearity in the kinetics. Moreover, as the SAT-coupled assay does not rely on phosphate detection, it can be used to investigate the inhibitory effect of phosphate on PSP.

A Colorimetric Dip Strip Assay for Detection of Low Concentrations of Phosphate in Seawater

Nutrient pollution remains one of the greatest threats to water quality and imposes numerous public health and ecological concerns. Phosphate, the most common form of phosphorus, is one of the key nutrients necessary for plant growth. However, phosphate concentration in water should be carefully monitored for environmental protection requirements. Hence, an easy-to-use, field-deployable, and reliable device is needed to measure phosphate concentrations in the field. In this study, an inexpensive dip strip is developed for the detection of low concentrations of phosphate in water and seawater. In this device, ascorbic acid/antimony reagent was dried on blotting paper, which served as the detection zone, and was followed by a wet chemistry protocol using the molybdenum method. Ammonium molybdate and sulfuric acid were separately stored in liquid form to significantly improve the lifetime of the device and enhance the reproducibility of its performance. The device was tested with deionized water and Sargasso Sea seawater. The limits of detection and quantification for the optimized device using a desktop scanner were 0.134 ppm and 0.472 ppm for phosphate in water and 0.438 ppm and 1.961 ppm in seawater, respectively. The use of the portable infrared lightbox previously developed at our lab improved the limits of detection and quantification by a factor of three and were 0.156 ppm and 0.769 ppm for the Sargasso Sea seawater. The device’s shelf life, storage conditions, and limit of detection are superior to what was previously reported for the paper-based phosphate detection devices.

An astonishing simple cerium-based chemosensor for fluorescent selective phosphate detection in aquaeous medium

<div><div><div><p>Phosphate ions are socially important chemicals. They are involved in crucial processes such as for example in medicine or agriculture. However, their sensing with a chemosensor is ardous due to their chemical properties. In this context, a remarkable chemosensor would reveal an outstanding affinity, a high selectivity and a low detection limit in favor of an analyte. This has long been addressed in the past by chemists in synthesizing com- plex chemical architectures as receptors but with questionable successes. Astonishingly, here, for phosphate detection, we address this problem profiting by a simple fluorescent indicator displacement assay (FID) with only commercially available chemicals. We used cerium ammonium nitrate (CAN) combined with a fluorophore to probe phosphate ions in aqueous mediums. The inorganic complex detects phosphate ions in low millimolar concentrations either spectrophotometrically or with the naked-eye with high selectivity and affinity over other anions. To our knowledge, this is the first description of a simple sensitive, selective and high affinity cerium-based chemosensor for the fluorescent selective naked-eye detection of phosphate in aqueous medium. It proved useful for the detection of phosphate in Coca-Cola©.</p></div></div></div>

A Co-Nanoparticles Modified Electrode for On-Site and Rapid Phosphate Detection in Hydroponic Solutions

Conventional strategies for determining phosphate concentration is limited in efficiency due to the cost, time, and labor that is required in laboratory analysis. Therefore, an on-site and rapid detection sensor for phosphate is urgently needed to characterize phosphate variability in a hydroponic system. Cobalt (Co) is a highly sensitive metal that has shown a selectivity towards phosphate to a certain extent. A disposable phosphate sensor based on the screen-printed electrode (SPE) was developed to exploit the advantages of Co-nanoparticles. A support vector machine regression model was established to predict the concentration of phosphate in the hydroponic solutions. The results showed that Co-nanoparticles improve the detection limit of the sensor in the initial state. Meanwhile, the corrosion of Co-nanoparticles leads to a serious time-drift and instability of the electrodes. On the other hand, the coefficient of variation of the disposable phosphate detection chip is 0.4992%, the sensitivity is 33 mV/decade, and the linear range is 10−1–10−4.56 mol/L. The R2 and mean square error of the buffer-free sensor in the hydroponic solution are 0.9792 and 0.4936, respectively. In summary, the SPE modified by the Co-nanoparticles is a promising low-cost sensor for on-site and rapid measurement of the phosphate concentration in hydroponic solutions.

An astonishing simple cerium-based chemosensor for fluorescent selective phosphate detection in aquaeous medium

<div><div><div><p>Phosphate ions are socially important chemicals. They are involved in crucial processes such as for example in medicine or agriculture. However, their sensing with a chemosensor is ardous due to their chemical properties. In this context, a remarkable chemosensor would reveal an outstanding affinity, a high selectivity and a low detection limit in favor of an analyte. This has long been addressed in the past by chemists in synthesizing com- plex chemical architectures as receptors but with questionable successes. Astonishingly, here, for phosphate detection, we address this problem profiting by a simple fluorescent indicator displacement assay (FID) with only commercially available chemicals. We used cerium ammonium nitrate (CAN) combined with a fluorophore to probe phosphate ions in aqueous mediums. The inorganic complex detects phosphate ions in low millimolar concentrations either spectrophotometrically or with the naked-eye with high selectivity and affinity over other anions. To our knowledge, this is the first description of a simple sensitive, selective and high affinity cerium-based chemosensor for the fluorescent selective naked-eye detection of phosphate in aqueous medium. It proved useful for the detection of phosphate in Coca-Cola©.</p></div></div></div>