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In this work, a fluorescence chemical sensor continuous detection Al 3+ and phosphates by a Salamo-Salen-Salamo type compound (SL) was employed. The sensor continuously recognized Al 3+ and phosphates with good selectivity and fast response time, and a low limit of detection of 0.25 μΜ and 0.96 μM, at the same time accompanied by a naked-eye identification specificity. The detection mechanism of SL towards Al 3+ is due to the chelating fluorescence enhancement effect and ICT effect, and continuously towards phosphates is due to the collapse of the SL-Al 3+ and coordination interaction between Al 3+ and phosphates, by Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, other spectral characterization and DFT calculation as evidence. In addition, the sensor had good recyclability and reusability. The distribution of Al 3+ and phosphates in zebrafish cells was effectively monitored by confocal microscopy based on the good biocompatibility and tissue permeability of SL. Furthermore, the feasibility of using sensor SL to detect the content of Al 3+ and phosphate ions in certain drugs was quantitatively analyzed through experiments. It was found SL had a good result in practical application., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier B.V.)

Species and sex confirmation of the biological specimen play a crucial role in crime investigation. However, the specimen found in the scene is always trace quantity, which is hard to be analyzed by current methods. Moreover, the time-consuming DNA extraction, sophisticated apparatus, and complex data processing make it difficult to satisfy the demand of speediness and convenience for point-of-care tests. In this study, we first exhibit a phosphate-based visual system for field-based species and sex identification derived from trace bloodstain. By introducing phosphate ion-based colorimetry into loop-mediated isothermal amplification (LAMP) for result interpretation, not only the bloodstain can be directly submitted to mitochondrial variant amplification owing to the enhanced amplification efficiency by pyrophosphate ion hydrolyzation, but also the colorimetric signal can be recognized by the naked eye for result output within 30 min through molybdophosphate generation. Aerosol contamination, the major conflict of LAMP, has been solved once and for all by integrating uracil-DNA glycosylase into this system that still holds on a constant temperature. As a demonstration, cytochrome b and Y-chromosomal amelogenin are employed to identify species and sex respectively, which has achieved a highly sensitive and specific distinguishability under a strong interferential background. Accurate results can be obtained from both the simulative degraded and dated specimen, which indicates that this novel system may serve as a promising tool in forensic practice., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In this study, the effect of contact time, temperature, pH, and coexistences on the adsorption of phosphate ions using the complex nickel-aluminum-zirconium hydroxide (NAZ) was evaluated. Moreover, the recovery of adsorbed phosphate ions from NAZ using desorption solution with different concentrations was demonstrated. The results showed that the quantity of phosphate ions adsorbed gradually increased with time, and the adsorption equilibrium was achieved within 24 h after adsorption. This kinetic data could be well described by the pseudo-second-order model with the correlation coefficient in the value of 0.997. Additionally, the quantity of phosphate which was adsorbed increased as temperature increased, and these results corresponded well with both the Langmuir, the correlation coefficient ranged from 0.920-0.949, and Freundlich models, the correlation coefficient ranged from 0.863-0.995. These results showed that the adsorption of phosphate ion was monolayer adsorption onto the NAZ surface. The optimal pH for removal of phosphate ions from aqueous media was during 4-8. In addition, chloride, nitrate, and sulfate ions did not significantly affect to the adsorption capability of phosphate ions in the complex solution system. Finally, the phosphate ions which were adsorbed onto NAZ could be recovered using sodium sulfate solution (recovery percentage: approx. 50% using sodium sulfate solution at 1000 mmol/L). These results highlight the potential of using NAZ as the cost-effectiveness adsorbent for phosphate ions removal from aqueous media.

Nonmammalian collagens have attracted significant attention owing to their potential for use as a source of cell scaffolds for tissue engineering. Since the morphology of collagen fibrils controls cell proliferation and differentiation, its regulation is essential for fabricating scaffolds with desirable characteristics. In this study, we evaluated the effects of the phosphate ion (Pi) concentration on the characteristics of fibrils formed from swim bladder type I collagen (SBC) and skin type I collagen (SC) from the Bester sturgeon. An increase in the Pi concentration decreased the fibril formation rate, promoted the formation of thick fibrils, and increased the thermal stability of the fibrils for both SBC and SC. However, the SBC and SC fibrils exhibited different fibril formation rates, degrees of fibrillogenesis, morphologies, and denaturation temperatures for the same reaction conditions. Finally, by regulating the Pi concentration, various types of SBC and SC fibrils could be coated on cell culture wells, and fibroblasts could be cultured on them. The results showed that thin fibrils enhance fibroblast extension and proliferation, whereas thick fibrils restrain fibroblast extension but orient them in the same direction. The results of this study suggest that SBC fibrils, which exhibit diverse morphologies, are suitable for use as a novel scaffold material, whose characteristics can be tailored readily by varying the Pi concentration., (Copyright © 2020. Published by Elsevier B.V.)

A nickel-aluminium-zirconium complex-layered hydroxide (NAZ), which was synthesized using each inorganic sulfate mixing ratio of 0.9 : 1.0 : 0.1, was prepared and calcined at different temperatures. The physicochemical properties of the NAZ were analyzed by scanning electron microscopy, specific surface area, number of hydroxyl groups, and pore volume. The specific surface area, number of hydroxyl groups, and pore volume of NAZ was 51.9 m 2 /g, 1.08 mmol/g, and 0.27 μL/g, respectively. The amount of phosphate ion adsorbed onto NAZ was higher than that onto calcined NAZ at different temperatures. Therefore, the interaction between phosphate ions and NAZ was assessed using the elemental distribution analysis and the binding energy. After adsorption, the intensity of phosphorus atoms increased, indicating that the phosphate ions were adsorbed onto the NAZ surface. Additionally, phosphorus peaks (189 eV for 2s and 130 eV for 2p), which were not detected before adsorption, were clearly detected after adsorption. On the other hand, the intensity of the sulfur peak (165 eV for 2p) decreased after adsorption. Thus, we evaluated the ion exchange between phosphate ion and sulfate ion in the interlayer space of the NAZ. As a result, the correlation coefficient between the amount of phosphate ion adsorbed and the amount of sulfate ion released was positively correlated (r=0.960). Therefore, it can be clearly stated that one of the adsorption mechanisms of phosphate ions was related to ion exchange in the interlayer space of the NAZ. These findings are useful for preventing the eutrophication and recovery of phosphate ion in water environments.

In this study, the adsorption capability of phosphate ion using a novel tri-metals complex hydroxide was evaluated for preventing the eutrophication in water environment. A nickel-aluminum-zirconium complex hydroxide (NAZ) was synthesized using each inorganic sulfate mixing ratio of 0.9 : 1.0 : 0.1 and was calcined at different temperatures. The characteristics of the NAZ were analyzed by scanning electron microscopy images, X-ray diffraction analysis, elemental distribution, and binding energy. Moreover, the amount adsorbed of phosphate ion onto uncalcined and calcined NAZ was measured. That of phosphate ions onto the uncalcined was the largest of all. These results suggested that the adsorption of phosphate ions tends to depend on the physicochemical properties (e.g., amount of hydroxyl groups, pore volumes, and pH) of the adsorbents. Moreover, the adsorption mechanism of phosphate ions was evaluated on the basis of binding energy and elemental analysis. After adsorption, the binding energy of phosphorus P (2s and 2p) peaked and the sulfur peak intensity S(2s) reduced. This result indicated that the adsorption mechanism of phosphate would be exchanged with sulfate ions.

In this study, we prepared novel Mg/Fe/Al hydroxides (MFA series: denoted by MFA1, MFA2, MF, and MA) and investigated their properties using scanning electron microscopy, X-ray diffraction, the specific surface area, and amount of hydroxyl groups. Additionally, the phosphate adsorption capabilities of the MFA series or Fe-Mg type hydrotalcites (FHT3.0 and FHT5.0) were evaluated by examining the effects of the solution pH and contact time, and analyzing the adsorption isotherm and desorption characteristics. In MFA1, a strong correlation exists between the amount of adsorbed phosphate ions and surface hydroxyl groups, with a correlation coefficient of 0.95. The adsorption kinetics data fitted using the pseudo-second-order model performs better than the pseudo-first-order model. The adsorption isotherm data were also fitted using both the Freundlich and Langmuir models. Finally, the phosphate ions adsorbed on the MFA1 surfaces were desorbed using sodium hydroxide solution. These results indicate that MFA1 offers great potential for phosphate ion adsorption from aqueous solutions and functions as a renewable adsorbent.

In this work, an upconversion luminescence (UCL) nanosensor for fast detection of ferric ion (Fe3+) and phosphate ion (Pi) is developed based on the inner-filter effect (IFE) between NaYF4:Yb/Er upconversion nanoparticles (UCNPs) and Fe3+-hypocrellin B (HB) complex. Fe3+-HB complex has strong absorption band (450–650 nm), which overlaps with the green emission peak of UCNPs at 545 nm. By adding Fe3+ and Pi, the UCNPs-HB system produces the red-shift change of absorption spectrum, which leads to the "on–off-on" process of IFE. So, with the specific recognition ability of HB for Fe3+ and the competitive complexation of Pi for Fe3+, the proposed nanosensor utilizes the UCL change to achieve the detection of the targets. For the detections of Fe3+, the linear range is 10–600 μM with a limit of detection (LOD) of 2.62 μM, and for Pi, the linear range is 5–100 μM with a LOD of 1.25 μM. The results for selectivity, precision, and recovery test are also satisfactory. Furthermore, the real sample detection shows that the proposed nanaosensor has a great potential in environmental and biological systems. An upconversion luminescence (UCL) nanosensor based on the inner-filter effect (IFE) between upconversion nanoparticles (UCNPs) and Fe3+-hypocrellin B (HB) complex for the detection of Fe3+ and phosphate ion has been proposed, which is promising to be a convenient and sensitive assay for monitoring Fe3+ and phosphate ion in different environments and biological systems. [ABSTRACT FROM AUTHOR]

In the current study, Phosphate removal from aqueous solutions was studied using bimetallic Al/Cu modified natural zeolites (Z-Al/Cu). The Z-Al/Cu was synthesized in situ using simple chemical reduction and impregnation methods. The morphologies and structures of natural zeolites (NZ) and Z-Al/Cu were characterized by SEM, XRD, FTIR, and BET. Batch sorption experiments were carried out using various factors that can potentially influence the removal efficiency (initial pH, initial solution concentration, and adsorbent dosage). Experimental results showed higher adsorption of Z-Al/Cu as compared to NZ, indicating that the Al/Cu impregnation provides more adsorption sites to phosphate. The maximum adsorption of phos- phate by the adsorbent was 99.32% at optimum pH 2, contact time of 60 min, and phosphate concentration of 25 mg/L. When the contact time between the adsor- bent and adsorbate increased above the optimum time, the adsorption efficiency decreased due to the onset of the desorption process. Characterization results indicated that Al/Cu was successfully supported on the zeolites. Adsorption of phosphate by Z-Al/Cu adsorbent fitted well with Langmuir adsorption isotherm and pseudo-second-order kinetics within R² = 0.913 and 0.999 respectively, which sug- gested that the adsorption process was a surface chemical reaction and mainly in a monolayer coverage manner. Reduction of removal efficiency, with regeneration cycles and in the presence of SO42-, was observed. [ABSTRACT FROM AUTHOR]

A bis‐heteroleptic Ru(II) complex, 1[PF6]2, of substituted pyridyl‐1,2,3‐triazole ligand (L1) has been developed for the photoluminescence(PL) detection of phosphate (HP2O73−/PPi) and Ag+ ion in distilled CH3CN and mixed aqueous buffer (carbonate‐bicarbonate buffer/CH3CN; v/v, 9.5 : 0.5; 0.1 M; pH 10.6) at two different wavelengths, respectively. The multianalyte probe, 1[PF6]2 showed significant PL enhancement in the presence of H2PO4−, PPi, and Ag+ with low detection limits of 0.48 μM, 0.43 μM, and 0.46 μM, respectively. The PL enhancement with phosphate ions is due to the triazole C−H⋅⋅⋅anion H‐bonding interaction that has been supported by 1H NMR titration (for PPi) and single‐crystal X‐ray structure (for H2PO4−). A unique Ag(I)‐triazolide complex formation is responsible for the PL enhancement in Ag+ ion detection. Triplet state TDDFT calculations were carried out to explain the PL enhancement of 1 ⋅ PPi and 1‐Ag adducts. In 1‐Ag, the L1 ligand becomes a better σ‐donor as well as π‐donor. Consequently, the 3MLCT‐3MC energy gap is increased and the 1‐Ag emits efficiently from the 3MLCT state. The probe also shows low cytotoxicity against Hela cells and is used for intracellular Ag+ imaging. [ABSTRACT FROM AUTHOR]

An anion exchanger ('Cell-AE') was prepared by grafting acrylonitrile (AN) onto carbon cloth waste followed by subsequent modification with hydrazine hydrate and dimethyl sulfate. The effect of radiation dose and monomer concentration was investigated. The nitrate ( NO 3 - ) and phosphate ( PO 4 3 - ) sorption potentials of the 'Cell-AE' was evaluated via batch mode. The 'Cell-AE' showed a higher adsorption affinity towards PO 4 3 - than NO 3 - . Similarly, the PO 4 3 - and NO 3 - adsorption was described by Dubinin–Radushkevich (D-R) and Redlich-Peterson (R-P) models, respectively. The present study conclusively proffered a potential mitigation approach to carbon cloth waste management. [ABSTRACT FROM AUTHOR]

Phosphorus (as phosphate ions) is an essential ingredient that is commonly used in agriculture as both a fertilizer as well as in industry as a detergent which causes significant water pollution. The nanomaterials are mainly involved in removing these ions due to their high surface area. In this study, magnesium oxide nanoparticles (MgO NPs) has been synthesized by microwave method. XRD, AFM and SEM were used to investigate the synthesized MgO nanoparticles. The average particles size of MgO NPs calculated to be range (25-39 nm), and has a cubic structure. The synthesized nanoparticles were tested to remove phosphate ions from aqueous solutions. From the resulted, which found that at a pH 12, temperature 298°C the highest adsorption efficiency of phosphate (72%) as a contact time was 150 minutes. It was found that the adsorption mechanism was spontaneous and endothermic by thermodynamic measurements. Generally, the data indicated a good effectiveness of MgO in the removal of phosphate. [ABSTRACT FROM AUTHOR]

Response mechanism of the electrode is elucidated in terms of (hydrogen) phosphate accelerating oxidation of CoII to CoIII for the first time. Cyclic voltammetric techniques in conjunction with XRD, XPS and Raman characterizations have demonstrated unambiguously the response of cobalt (II) hydroxide electrode involves a phosphate and hydrogen ion dependent charge transfer process. Phosphate ions induce Co(OH) 2 transformed into CoOOH within interlayer adsorption and restored the initial state after reduction. Meanwhile, the in common structural between Co(OH) 2 and CoOOH prevents extensive structural convertibility upon cycling, result in the advantage of reversibility in phase transformation. Demonstrated sustainable technique offered the determination of phosphate with robust reproducibility (1000 cycles), long storage stability (6 months) and selectivity (potential interference: Cl−, NO 3 −, SO 4 2− and HCO 3 −), achieving a detection limit of 5 × 10−8 M over a wide linear range up to 1.28 mM. Presented work provided insights into the unique selectivity towards phosphate in cobalt based sensors, which may inspire the rational design of Co(OH) 2 -based electrodes with superior electrochemical performance or extended applications. [Display omitted] • Response mechanism of the electrode is elucidated in terms of phosphate accelerates oxidation of CoII to CoIII for the first time. • Phosphate ions are capable of inducing Co(OH) 2 transforms into CoOOH within interlayer adsorption, and restored the initial state after reduction. • Demonstrated an innovative and feasible method for detecting phosphate concentrations with lower detection limit, robust reproducibility, and anti-interference by Co(OH) 2 electrode. [ABSTRACT FROM AUTHOR]

Han, J.-Y.; Lee, J.; Lee, Y.-G., and Jang, A., 2017. Solid-state ion selective lab chip sensor for on-site measurement of orthophosphate in small volumes of liquid. In: Lee, J.L.; Griffiths, T.; Lotan, A.; Suh, K.-S., and Lee, J. (eds.), The 2nd International Water Safety Symposium. Journal of Coastal Research, Special Issue No. 79, pp. 50-54. Coconut Creek (Florida), ISSN 0749-0208. This paper described the characterization of the assembled solid-state ion-selective lab chip sensor to potentiometrically measure phosphate ion. Since the assembled chip sensor is easy to setup and does not require any sample preparations, it is an ideal technique to study the measurement of phosphate in small volumes of liquids or in estuarine sediments. The size of the proposed lab chip is 12 mm × 21 mm, and the microfluidic channel has the width of 2 mm, length of 5 mm, and depth of 150 μm. All electrodes have the length of 500 μm, width of 200 μm, and spacing of 200 μm. The potential response of the assembled phosphate ion-selective lab chip sensor showed a linear regression in the range of 1×10−5 to 1×10−3 M with a slope of 54 mV/decade. In addition, the experimental results showed a good precision, indicating that relative standard deviation (RSD) was 3.5%. [ABSTRACT FROM AUTHOR]

Different molar ratios of a Ni/Co binary hydroxide (NiCo82, NiCo91, and Ni100) were prepared and calcined at 270 °C (NiCo82-270, NiCo91-270, and Ni100-270). The properties of the adsorbents and the amount of adsorbed phosphate ions were evaluated. The adsorbents calcined at 270 °C had a nickel oxide structure. The amount of adsorbed phosphate ions, the amount of hydroxyl groups, and the specific surface area of the calcined adsorbents at 270°C were greater than those of the uncalcined adsorbents. The amount of adsorbed phosphate ions was related to the amount of hydroxyl groups and the specific surface area; the correlation coefficients were 0.966 and 0.953, respectively. The adsorption isotherm data for NiCo91 and NiCo91-270 were fit to both the Freundlich and Langmuir equations. The amount of adsorbed phosphate ions increased with increasing temperature. The experimental data fit the pseudo-second-order model better than the pseudo-first-order model. A neutral pH was optimal for phosphate ion adsorption. In addition, the phosphate ions that were adsorbed onto NiCo91-270 could be recovered using sodium hydroxide, and the adsorbent was useful for the repetitive adsorption/desorption of phosphate ions. Collectively, these results suggest that NiCo91-270 is prospectively useful for the adsorption of phosphate ions from aqueous solutions. [ABSTRACT FROM AUTHOR]

A coumarin based simple fluorescent “turn-on” probe, 4-Hydroxy-3-[(2-hydroxy-5-methoxybenzylidene)-amino]-chromen-2-one ( HMC ), to detect metal ion based on the chelation enhanced fluorescence (CHEF), was synthesized by condensing 3-amino-4-hydroxycoumarin and 2-hydroxy-5-methoxybenzaldehyde. It was found to be highly selective and sensitive sensor for Al 3+ in 90% aqueous methanol (MeOH: 0.01 M HEPES Buffer; 9:1; v/v) at pH 7.4 in fluorescence spectroscopy. Fluorescence intensity enhancement along with 10 nm blue shift was observed only in the presence of Al 3+ . The HMC binds Al 3+ in 1:1 stoichiometry with a binding constant, K a = (9.9 ± 0.04) × 10 3 M −1 and the detection limit was calculated to be as low as 1.62 μM. The binding mode of interaction with Al 3+ and the chelate complex formation was supported with the help of a 1 H NMR spectroscopy titration, ESI–MS and also by theoretical studies. Moreover, the HMC ·Al 3+ ensemble subsequently detected the biologically important phosphate ions and nucleotides via fluorescence quenching. The live cell imaging study indicated that HMC is highly efficient in the detection of exogenous Al 3+ in living cell. [ABSTRACT FROM AUTHOR]

Genetic variation has been proven to be a promising biomarker for disease occurrence and development. However, current genotyping strategies are limited by cumbersome DNA purification, sophisticated apparatus, and complex data interpretation, which makes it difficult to satisfy the demand of speediness and convenience for precision medicine. This research is dedicated to establishing a visual genotyping method by tracing phosphate ions generated during loop-mediated isothermal amplification (LAMP) for point-of-care diagnostic test scenarios. By introducing pyrophosphatase, phosphate ions from pyrophosphate ion hydrolyzation serve as a signal generator firstly for genotyping, which not only enables the result to be interpreted with the naked eye through molybdophosphate generation, but also enhances the amplification efficiency to facilitate direct genotyping from blood and saliva without DNA purification. By virtue of the high sensitivity and the enhanced amplification efficiency of LAMP, as low as 0.1 μL of 20% blood or saliva is enough for clear result presentation within 30 min. In addition to visual interpretation, the result can also be determined with a microplate reader. As proof of concept, the genotype of anglotensin-converting enzyme has been successfully identified. Thus, we propose that this novel strategy may serve as a promising tool for straightforward genotyping. [Display omitted] • Genotyping results can be interpreted with the naked eye based on colorimetry. • Genotype can be identified from blood or saliva directly avoiding DNA purification. • Genotyping results can be obtained within 30 min via only a simple heater. [ABSTRACT FROM AUTHOR]

Objective This study assessed the osseointegration of grit-blasted titanium (Ti) implants with a hydrophilic phosphate ion-incorporated oxide surface in rabbit cancellous bone, and compared its bone healing with commercially available phosphate-incorporated clinical implants obtained by micro-arc oxidation (TiUnite, TU implant). Material and methods The hydrophilic phosphate-incorporated Ti surface (P implant) was produced by hydrothermal treatment on grit-blasted moderately rough-surfaced clinical implant. The TU surface was used as a control. The surface characteristics were evaluated by field emission-scanning electron microscopy, X-ray photoelectron spectroscopy, optical profilometry, and inductively coupled plasma-atomic emission spectroscopy ( ICP- AES). Thirty-two threaded implants with lengths of 10 and 3.3 mm diameter (16 P implants and 16 TU implants) were placed in the femoral condyles of 16 New Zealand White rabbits. Histomorphometric analysis, removal torque tests, and surface analysis of the torque-tested implants were performed 4 weeks after implantation. Results The P and TU implants displayed micro-rough surface features with similar R a values at the micron-scale. ICP- AES analysis revealed that both the P and TU implants released phosphate ions into the solution. The torque-tested P and TU implants exhibited a considerable quantity of bone attached to the surface. The P implants exhibited significantly higher bone-implant contact percentages, both in terms of the all threads region and the total lateral length of implants compared with the TU implants ( P < 0.01), but no statistical difference was found for the removal torque values. Conclusion These results suggest that the phosphate-incorporated Ti oxide surface obtained by hydrothermal treatment achieves rapid osseointegration in cancellous bone by increasing the degree of bone-implant contact. [ABSTRACT FROM AUTHOR]

Al-containing CaO–SiO2–H2O phases were prepared by hydrothermal treatment of mixtures of paper sludge ash (PSA) with various silica and calcia sources and their properties were determined with particular reference to the simultaneous uptake of ammonium and phosphate ions, which are implicated in the eutrophication of lakes and ponds. After examination of various silica and calcia sources, Ca(OH)2 and SiO2 sol were selected as the most appropriate starting materials. Dry milling was found to be superior to wet milling in avoiding contamination from the milling media during mixing. Nine samples with three different Ca/Si ratios and Al2O3 contents were prepared with various mass ratios of Ca(OH)2, PSA and SiO2. The chemical compositions of the hydrothermal products of these mixtures moved towards the tieline of CaSiO3-PSA, with respect to the starting compositions. The major phase formed in all samples was poorly crystalline C–S–H(I), with hydroxysodalite also formed in the Al-containing mixtures. All the products showed a capacity for the simultaneous uptake of ammonium and phosphate ions. The saturated sorption capacities calculated from the Langmuir equation ranged from 0. 9 to 2. 4mmol/g for the ammonium ion and from 3. 3 to 5. 2mmol/g for the phosphate ion. Since the sorption capacities for both ions increased with increasing Ca contents of the product, substitution of Ca2+ for NH4 + and the formation of calcium phosphate phases such as apatite and brushite by precipitation are thought to be the main sorption mechanisms. [Copyright &y& Elsevier]

Fabrication and characterization of a fiber optic surface plasmon resonance (SPR) based phosphate ion sensor utilizing the coating of cobalt oxide (CoO) over the gold coated unclad core of the fiber have been carried out. The interaction between CoO layer and incoming phosphate ion changes the effective refractive index of the CoO layer which affects the resonance wavelength in the SPR spectrum. The performance of the sensor has been evaluated in acidic solution (pH 4) of inorganic phosphate salt (KH 2 PO 4). The sensor probe has been found to be irreversible implying one time use of the probe or disposable probe. However, the probe works for 0–100 ppm (0–1.03 mM) concentration range of the phosphate ion (H 2 PO 4 -). The sensor possesses maximum sensitivity of 0.3155 nm/ppm with 4.96 ppm as the limit of detection. The sensor is highly selective, fast in response and is suitable to determine the phosphate ion concentration in soil. Since the probe has been fabricated on optical fiber it has the advantages of simplicity, miniaturization and low cost. • A highly selective SPR based fiber optic phosphate ion sensor suitable for soil is reported. • The probe is fabricated by coating a layer of cobalt oxide over gold coated unclad core of the fiber. • The interaction of phosphate ions with cobalt oxide layer changes its RI resulting in the shift in resonance wavelength. • The sensor works in the range 0–100 ppm of phosphate ion. • The limit of detection of the sensor is 4.96 ppm. [ABSTRACT FROM AUTHOR]

• Oxidized UiO-66(Ce/Zr) exhibits oxidase-like activity and specific Pi adsorption. • Pi adsorption brings differential impacts towards different chromogenic substrates. • A dual-channel ratiometric colorimetric assay is established for Pi detection. Phosphate ion (Pi) is an inorganic anion widely distributed and commonly regarded as a significant indicator of water eutrophication, and thus it is urgent to develop convenient, cost-effective and reliable analytical approaches for the monitoring of Pi for water quality control. In this work, we propose the high-performance dual-channel ratiometric colorimetric sensing of Pi based on the analyte-triggered differential oxidase-mimicking activity changes of oxidized Ce-Zr bimetal-organic frameworks (oxidized UiO-66(Ce/Zr)). By integrating two types of metal nodes with different functions into one framework structure, the proposed oxidized UiO-66(Ce/Zr) not only exhibits excellent activity to catalyze the chromogenic oxidation of both 3,3′,5,5′-tetramethylbenzidine (TMB) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) due to oxidase-like active Ce4+/Ce3+ sites but also provides main Zr4+ sites to specifically recognize Pi. When Pi is in presence, it is rapidly adsorbed onto oxidized UiO-66(Ce/Zr) and changes the surface chemistry of the latter, leading to differential enzyme-like activity changes towards the two chromogenic substrates TMB and ABTS. Based on this finding, a dual-channel ratiometric colorimetric method was established for the sensitive determination of Pi. Compared to conventional single-signal colorimetric sensors, our method offered a widened linear detection scope from 3.3 to 666.7 μM. Also, robust and accurate analysis of Pi in various water matrices was demonstrated, indicating our method's great potential in practical applications. [ABSTRACT FROM AUTHOR]

• Interaction between PO43- and Mg2+ was assessed via elemental distribution analysis. • The product was changed with initial concentration of phosphate ion. • MgHPO4 · 3H2O was produced at the initial concentration of 15,000 mg/L. In this study, the mechanism of the reaction between phosphate and magnesium hydroxide ions was assessed. In particular, the effect of initial concentration and contact time on the removal of phosphate ions from aqueous media using magnesium hydroxide was demonstrated. The evaluations were conducted after analyses entailing scanning electron microscopy, powder X-ray diffraction, and elemental distribution. The rate of removal of phosphate ions using magnesium hydroxide increased with increase in the initial phosphate ion concentration. Under our experimental conditions, the products after the removal of phosphate ions were magnesium hydroxide, magnesium potassium phosphate hexahydrate, and magnesium hydrogen phosphate trihydrate when the initial concentration was low (5 to 2000 mg/L), medium (from 4000 to 8000 mg/L), and high (15,000 mg/L), respectively. When the initial concentration was 15,000 mg/L, the product changed with elapsed time. Our findings indicated that the crystalline structure changed from that of magnesium potassium phosphate hexahydrate to that of magnesium hydrogen phosphate trihydrate (after 6 h). These results serve as useful information regarding the interaction between phosphate and magnesium ions at high concentrations of phosphate ions in aqueous media. [ABSTRACT FROM AUTHOR]

A simple, highly selective and ultra-sensitive "off-on-off" fluorescent chemosensor L for successive detection of Al3+ and PO 4 3− was synthesized and characterized. Sensor L showed a remarkable and highly selective fluorescence enhancement towards Al3+ against other interfering cations, owing to the suppression of intramolecular charge transfer (ICT) mechanism and CH N isomerization. A good linear relationship (R2 = 0.9974) was obtained between the fluorescence emission intensity of L and the concentration of Al3+ (0.025–2.0 μM) with the detection limit of 3.8 nM, which is much lower than the most literature reported. And the binding stoichiometry between L and Al3+ is 1:1 according to Job's Plot and ESI-MS. The resultant complex can be further utilized as a secondary probe for determination of PO 4 3− with the detection limit as low as 0.56 μM. Meanwhile, the sensor L was successfully applied to detect Al3+ in real water, illustrating that sensor L was a promising alternative route for Al3+ detection. Additionally, the sensing mechanism of L to Al3+ was further demonstrated in detail by IR and 1H NMR titration experiment. The successive recognition feature of sensor L has the potential to quantitative analysis of Al3+ and PO 4 3− in environment samples. Unlabelled Image • Sensor L was simply synthesized based on 2,4-dihydroxybenzaldehyde and o -aminophenol by one synthetic step. • Sensor L showed ultra sensitive and high selective response towards Al3+ with much low detection limit of 3.8 nM. • The resultant L-Al3+ complex was further used for successive recognition of PO 4 3-. [ABSTRACT FROM AUTHOR]