Enhanced Ultrasensitive Photoelectrochemical Probe for Phosphate Detection in Water Based on a Zirconium–Porphyrin Framework

Abstract

Excessive phosphate poses a serious ecological and human health risk, and thereby, monitoring its trace concentration is of great significance to environmental protection and human health. In this work, a zirconium−porphyrin framework (PCN-222) with excellent stability and unique luminescence properties was designed to modify the surface of the indium tin oxide electrode, which was first used as a photoelectrochemical (PEC) probe for phosphate detection. The PCN-222-modified PEC probe demonstrated an excellent selectivity and stability and indicated a linear response to phosphate in the range of 0−10 6 nM with a limit of detection (LOD) as low as 1.964 nM. To the best of our knowledge, this is the phosphate probe with the lowest LOD, and this is also the first signal-on PEC probe toward phosphate based on PCN-222. More importantly, the PEC probe can be validated for the good applicability of trace phosphate detection in real water samples, indicating a good application prospect. Finally, a series of electrochemical and spectroscopic studies have proved that phosphate can bind to the indium tin oxide (ITO)/PCN-222 electrode, which shortens the distance of the space charge region while reducing the bandwidth and thus facilitates the transfer of photogenerated electrons across the energy band barrier to reduce O 2 in the electrolyte, producing an enhanced cathodic photocurrent signal. The proposed strategy of the highly sensitive PEC probe provides a promising platform for more effective label-free phosphate monitoring in the environment and organisms.

Au/Lum/RhB@Ag-DMcT ICP-Based Double-Ratio Colorimetric and Fluorometric Dual Mode Assay and Multi-Responsive Coffee Ring Chips for Point-of-Use Analysis of Phosphate Ions

“…However, owing to the rapid expansion of urbanization, anthropogenic discharges of steadily increasing Pi to the natural ecosystems may promote the excessive propagation of algae and plankton, and the eutrophication eventually deteriorated water quality. Thus, Pi is also a well-known characteristic indicator of contamination in water bodies. − Accordingly, the quantitative detection of Pi levels with effectiveness and reliability is of great practical significance for both human health assessment and environmental ecosystem protection.…”

Rational design of COF–MOF composites for ratiometric fluorescence detection of phosphate

“…[7][8][9] To date, several MOF-based fluorescent probes including transition metal organic frameworks and lanthanide organic frameworks have been prepared for the detection of phosphate. [10][11][12][13][14][15][16][17][18] The main principle of transition metal organic framework probes is based on the interaction of phosphate with Zn 2+ and Zr 4+ . Since transition metal ions cannot emit fluorescence, they usually need to be combined with fluorophores to construct a fluorescent probe which limits the development of fluorescent MOFs.…”

“…Since transition metal ions cannot emit fluorescence, they usually need to be combined with fluorophores to construct a fluorescent probe which limits the development of fluorescent MOFs. 15,16 In contrast, lanthanide organic frameworks exhibit a sharp emission resolution, longer fluorescence lifetime, large Stokes shift and more flexible coordination number which attracted a lot of attention for the detection of analytes. 17,18 For example, Eu 3+ ions, as part of the rare-earth family, have been widely investigated as redemitting activators due to their 5 D 0 -7 F J ( J = 0-4) leap from UV excitation.…”

Metalloporphyrin-Based Metal–Organic Framework Nanorods for Peroxidase-Like Catalysis

“…Recently, metal–organic frameworks (MOFs) and their derivatives have attracted much attention in biosensing research because of their uniform structure, tunable electronic/optical properties, versatile chemistry, and high intrinsic specific surface area. − Water-stable Porous Coordinated Network-222 (PCN-222)-based nanostructures contain many exposed inherent porphyrin active sites that exhibit potential biomimetic catalytic activities. − Abundant Lewis acids on PCN-222 can highly enhance the adsorption of base molecules, allowing open-framework structures free access to oxidation/reduction products and thus promoting the whole catalytic process . In the natural catalytic oxidation of H 2 O 2 , horseradish peroxidase (HRP) shows high catalytic activity because of its natural metal enzyme site (iron porphyrins) .…”