Detection In Real Water Samples Research Articles

From coconut petiole residues to fluorescent carbon dots via a green hydrothermal method for Fe3+ detection

Incinerating agricultural residues to recover energy is a popular method for reducing solid waste pollution and resource waste caused by the huge amount of coconut petiole residues. However, this process not only has the risk of secondary air pollution, but also the added value of comprehensive utilization is not high. In this paper, coconut petiole residues were used as eco-friendly and economical raw materials to synthesize carbon dots (CCDs) via a simple hydrothermal method. Furthermore, given the important reference significance of Fe3+ concentration in assessing the quality of water environment and human body health, the obtained CCDs were utilized for Fe3+ detection. The prepared spherical CCDs with an average diameter of 1.39 nm and a carbon skeleton dominated by benzene ring structure have surface functional groups that endow them with good water solubility. The CCDs with a quantum yield of 1.39% emit strong blue fluorescence under ultraviolet radiation (365 nm), and show favorable fluorescence stability with excitation-dependent and concentration-dependent emission behaviors. Based on the synergetic effect of static and dynamic quenching, the CCDs exhibit favorable selectivity and detection sensitivity toward Fe3+ with a linear range of 0.005 to 0.2 mM and a detection limit of 2.3 μM, and also show the feasibility of Fe3+ detection in real water samples. This work is in favor of the high value-added conversion of coconut petiole residues. In addition, the development and use of bio-based CCDs as fluorescence sensors may be beneficial to monitoring and protecting public health and the environment.

Cuttlefish ink-based N and S co-doped carbon quantum dots as a fluorescent sensor for highly sensitive and selective para-nitrophenol detection.

Para-nitrophenol (PNP) is an important raw material for organic synthesis and its extensive use has produced a series of environmental problems. Here, we develop a highly sensitive and selective fluorescent detection method for PNP with cuttlefish ink-based carbon quantum dots (CQDs). The cuttlefish ink, which is rich in eumelanin, is utilized as the only precursor to synthesize the CQDs via a one-step hydrothermal method. The resultant CQDs were co-doped with nitrogen and sulfur and exhibited excellent fluorescence properties. Two optimal emissions can be observed at the excitation/emission wavelengths of 320/385 nm and 390/465 nm, respectively. In the presence of PNP, the two emissions are remarkably quenched. PNP can be measured in the linear detection concentration range of 1.25-50 μM (Em = 385 nm and R2 = 0.9884) or 1.25-27.5 μM (Em = 465 nm and R2 = 0.9818) with a detection limit of 0.05 μM. Significantly, it is found that a much wider linear detection range of 0.05-125 μM with a lower detection limit of 0.039 μM (3σ/k) can be achieved when log(I385 nm + I465 nm) was utilized to quantify PNP. The investigations of the sensing mechanism suggested that the inner filter effect and photoinduced electron transfer of PNP and N,S-CQDs leads to fluorescence quenching. The sensing method is successfully applied for PNP detection in real water samples with satisfactory recoveries (91.18-103.14%). A new sustainable waste-prevention strategy of cuttlefish ink and a feasible alternative to PNP detection methods is provided in this article.

A iridium(III) complex-based ‘turn-on’ fluorescent probe with two recognition site for rapid detection of thiophenol and its application in water samples and human serum

Abstract A new iridium(Ⅲ) complex-based near-infrared ‘turn-on’ fluorescent probe Ir-DNBS was synthesized for fast (9 min), highly selective and sensitive (LOD: 62.5 nM) thiophenol detection. Photophysical and spectral characterization (NMR, HRMS) results demonstrated that the recognization mechanism of probe for thiophenol was based on thiolate-mediated nucleophilic elimination reaction (SNAr). Upon addition with thiophenol to PBS/DCM/DMSO solution (pH = 7.4) of probe Ir-DNBS, obvious orange red fluorescence with maximum emission wavelength at 620 nm was observed with a large Stokes shift (200 nm) and long lifetime (135 ns). The practical utility of probe Ir-DNBS was also investigated by thiophenol detection in real water samples and human serum.

Novel application of a fluorescent dye based on triphenylamine: Rapid detection of hydrazine in living cells and in vitro

Based on the multi-functionalization of organic compounds, this work mainly presented a new application of triphenylamine-based fluorescent dye T-Probe in the rapid detection of hydrazine (N 2 H 4 ) both in vivo and in vitro. As an important organic intermediate, which displayed high selectivity and rapid response to N 2 H 4 in DMSO/PBS buffer (4/6, v/v) solution in the presence of other competitive species (such as K + , Cu 2+ , Ni 2+ , NO 2 − , NO 3 − , SCN − , S 2− , SO 4 2− , SO 3 2− , HSO 3 − , Cl − , CO 3 2− , OAc − , NH 4 + , HS − , Cys, BSA, Aniline、CH 3 NH 2 , N2H4, etc.). The sensing property for N 2 H 4 was further investigated through UV–Visible, dynamic light scattering, X-ray diffraction, fluorescence spectrophotometric analyses as well as DFT/TD-DFT calculations. The results indicated that the target sensor T-Probe possessed high anti-interference ability, specificity, extremely detection limit (8.47 nM), especially immediate response speed (within 3 min) to N 2 H 4 , and whole detection process also could be dramatically observed through “naked-eye” fluorescence color change (from Cyan to Blue) under 365 nm UV lamp irradiation, Furthermore, 1 H NMR and fluorescence titration experiment were also conducted to confirm the sensing mechanism. In extended application aspect, the fluorescent dye T-Probe could provide a new analytical method for N 2 H 4 detection in real water samples and visualize monitoring biological samples in living cells. • Synthesis of conjugated chemo-sensor T-Probe. • T-Probe realized hydrazine detection with higher sensitivity, fast response time and lower limit of detection. • The probe was successfully applied for detection of hydrazine in real water samples and in living cells.

Reusable, facile, and rapid aptasensor capable of online determination of trace mercury

Herein, we reported a homemade waveguide-based evanescent wave aptasensor for the facile online monitoring of mercury pollution. The aptasensor exploited the high selectivity of hairpin structure-based thymidine–Hg2+–thymidine coordination chemistry (T–T mismatch) for Hg2+ recognition and the stably regenerable capability of DNA-functionalized waveguide surfaces. The presence of Hg2+ caused the T–T mismatch of Cy5.5-labeled T-rich single-stranded DNA sequences. The formed hairpin structures blocked the further hybridization of T-rich single-stranded DNA sequences with the complementary DNA strands that are modified on the waveguide surface; this phenomenon was accompanied by the decrease in the fluorescent signals excited by the evanescent wave. The limit of detection in real water samples was determined to be 0.2 μg/L, which was comparable with that of 0.4 μg/L in an ultrapure water under controlled conditions. And the linear range was observed from 1.4 µg/L to 240.7 µg/L. The negligible environmental matrix effect on the performance ensured the reliability of the proposed aptasensor. Moreover, the cross reactivity of this method toward other investigated metal ions was negligible. Through the delicate surface modification with DNA molecules covalently, the chip was reused at least 31 times with a relative standard deviation (RSD) of less than 19%. A Hg2+ pollution accident was successfully detected within 30 min, shedding new light in pollution monitoring, environment restoration, and emergency treatment.

Tunable multicolour S/N co-doped carbon quantum dots synthesized from waste foam and application to detection of Cr3+ ions.

In this study, by adjusting sulfuric acid concentrations, tunable multicolour S/N-carbon quantum dots (CQDs) were synthesized from waste foam as the raw material. The S/N-CQDs presented blue, blue-green, green, green-yellow and yellow emission with an emission peak shifting from 475 to 589 nm and with optimum excitation wavelengths of 385, 405, 440, 450, and 500 nm, respectively. Using transmission electron microscopy, the S/N-CQDs were seen to be spherical in morphology with a size around 6-8 nm. Fourier transform infrared spectra and X-ray photoelectron spectroscopy indicated that the surface of the S/N-CQDs was highly oxidized and sulfur doped. The fluorescence mechanism of multicolour S/N-CQDs emission was mainly related to a band gap change caused by the surface state. Blue-emitting S/N-CQDs were used as a fluorescent probe that was highly selective and sensitive to Cr3+ ions, with a low detection limit of 6 μM. The waste foam-derived S/N-CQDs exhibited promising potential for ion detection in real water samples due to its excellent fluorescence activity.

Novel fluorescence probe based on bright emitted carbon dots for ClO- detection in real water samples and living cells.

Low-toxic and environmentally friendly carbon dots (CDs) have been extensively applied in various fields. CDs usually demonstrate excellent selectivity and high sensitivity, especially in ion detection. However, the most commonly used CDs are excited by ultraviolet (UV) light and emit weak fluorescence light, limiting their application in some fields. Herein, novel fluorine and nitrogen codoped carbon dots (FNCDs) were prepared by a simple hydrothermal method and used as a fluorescent probe for ion detection. The FNCDs were excited by blue light and emitted strong green fluorescence, and the photoluminescence quantum yield was as high as 56.7%. The fluorescence of the FNCDs could be rapidly quenched by ClO- ions, indicating their potential application for ClO- detection. The fluorescence of the FNCDs was quenched by ClO- ions in less than 1min, and the intensity of the fluorescence decreased linearly as the ClO- concentration increased from 0 to 20μM. The detection limit was calculated to be as low as 8.2nM, indicating high sensitivity of the FNCDs probe. The quench effect of the ClO- ions on the FNCDs probe fluorescence was not affected by other ions, demonstrating excellent selectivity of the FNCDs probe. Because of their excellent biological compatibility, the FNCDs were also successfully used to identify exogenous ClO- in living cells. These FNCDs have promising prospects as novel sensitive and inexpensive probes for the detection of pollutants and in the pathological studies of clinical diseases.

Ultrasensitive Detection of Nitrite through Implementation of N-(1-Naphthyl)ethylenediamine-Grafted Cellulose into a Paper-Based Device.

Reported herein is the immobilization of N-(1-naphthyl)ethylenediamine (NED) on cellulose via an epichlorohydrin (ECH)-based covalent attachment and the implementation of the functionalized cellulose into an ultrasensitive, paper-based device for nitrite detection. The reported functionalization procedure resulted in a 12.9-fold higher functionalization density than the density that results from the previously reported procedures, and the subsequent device allows for nitrite detection limits in synthetic freshwater and real seawater of 0.26 and 0.22 μM, respectively. The sensor is efficient in a wide range of temperature, humidity, turbidity, and salinity conditions and has been successfully applied for nitrite detection in real water samples.

Controlled-synthesis of alumina-graphene oxide nanocomposite coupled with DNA/ sulfide fluorophore for eco-friendly “Turn off/on” H2S nanobiosensor

Hydrogen sulfide (H2S) is a toxic environmental pollutant and crucial gas-signaling agent of human physiology. There is an urgent need for developing a sensitive and selective detection approach for H2S. Herein, a novel turn off/on response approach using γ-Al2O3 nanorods anchored on the surface graphene oxide (GO) nanosheets and coupled with DNA/sulfide fluorophore (SF) for H2S detection at room temperature was developed. The fluorescent fluorophore, DNA/SF, remains quenched on the super quencher γ-Al2O3–GO hybrid surface. In the existence of H2S, DNA/SF fluorophore was detached from γ-Al2O3–GO hybrid surface because of the strong physical adsorption interaction between H2S molecules and γ-Al2O3–GO surface. The recovered fluorescence intensity gave direct insight about H2S concentration in the medium. The developed γ-Al2O3–GO/DNA/SF nanobiosensor shows high sensitivity with 75 to 2.5 μM linear detection range of H2S, and a high binding constant of 9.8 × 103 M−1. The nanobiosensor is very selective toward H2S in the presence of various interfering anions and thiols and used for H2S detection in real water samples. γ-Al2O3–GO/DNA/SF nanobiosensor provides a cheap, simple, and highly selective H2S detection method at room temperature.

A flow chemiluminescence paper-based microfluidic device for detection of chromium (III) in water

In this work, a solely gravity and capillary force-driven flow chemiluminescence (GCF-CL) paper-based microfluidic device has been proved for the first time as a new platform for inexpensive, usable, minimally-instrumented dynamic chemiluminescence (CL) detection of chromium (III) [Cr(III)], where an appropriate angle of inclination between the loading and detection zones on the paper produces a rapid flow of CL prompt solution through the paper channel. For this study, we use a cost-effective paper device that is manufactured by a simple wax screen-printing method, while the signal generated from the Cr(III)-catalyzed oxidation of luminol by H2O2 is recorded by a low-cost and luggable CCD camera. A series of GCF-CL affecting factors have been evaluated carefully. At optimal conditions, two linear relationships between GCF-CL intensities and the logarithms of Cr(III) concentrations are obtained in the concentration ranges of 0.025–35[Formula: see text]mg/L and 50–500[Formula: see text]mg/L separately, with the detection limit of 0.0245[Formula: see text]mg/L for a less than 30[Formula: see text]s assay, and relative standard deviations (RSDs) of 3.8%, 4.5% and 2.3% for 0.75, 5 and 50[Formula: see text]mg/L of Cr(III) ([Formula: see text]). The above results indicate that the GCF-CL paper-based microfluidic device possesses a receivable sensitivity, dynamic range, storage stability and reproducibility. Finally, the developed GCF-CL is utilized for Cr(III) detection in real water samples.

An ESIPT characteristic “turn-on” fluorescence sensor for Hg2+ with large Stokes shift and sequential “turn-off” detection of S2– as well as the application in living cells

An excited state intramolecular proton transfer (ESIPT) characteristic “turn-on” fluorescence sensor for Hg2+ with large Stokes shift was fabricated and then it had ability to sequentially detect S2– by the “turn-off” fluorescent signal in aqueous media. On account of it, a simple fluorescence probe ol-PIP based on the phenanthro[9,10-d]imidazole moiety bearing two phenol fragments was synthesized. Probe ol-PIP showed gradually the fluorescence enhancement with the increasing of water fraction due to the aggregation affect. Sequentially, the moderate fluorescence emission of ol-PIP in aqueous media was continuously and selectively illumined by the successive addition of Hg2+ with about 180 nm Stokes shift. Furthermore, the persistent “turn-on” fluorescence intensity could be quenched to the original state of ol-PIP in presence of S2–. This on–off sensing process was sustained for five times with the alternative addition of Hg2+ and S2–. The limits of detection for Hg2+ and S2– were 6.45 × 10–7 and 3.46 × 10–7 M, respectively. In addition, ol-PIP was successfully applied in Hg2+ detection in real water samples; simultaneously, ol-PIP with low cytotoxicity was also successfully used as a bioimaging reagent to detect Hg2+ and S2– in living cells.

One-step synthesized fluorescent nitrogen doped carbon dots from thymidine for Cr (VI) detection in water

A novel, simple and low-cost nitrogen doped carbon dots (N-CDs) fluorescent sensor for sensitive detection of Cr (VI) was developed via one-step hydrothermal method using thymidine as carbon source. As-prepared N-CDs exhibited the ability of sensitive and selective detection of Cr (VI) through the inner filter effect (IFE). The performances of N-CDs were investigated with the characterization methods of transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Under the optimized conditions, a good logarithm correlation between the fluorescence intensity of N-CDS and the concentration of Cr (VI) was obtained ranging from 0.1 μM to 430 μM (R2 = 0.992), with a low detection limit (LOD; S/N = 3) of 1.26 nM. The fluorescent sensor showed good repeatability, reproducibility and stability. Furthermore, N-CDs fluorescent sensor had a good applicability for Cr (VI) detection in real water samples with acceptable recoveries, and the detection results were consistent with the inductively coupled plasma mass spectrometry (ICP-MS) results, indicating this fluorescent sensor has a great potential for the environmental monitoring.

Anthracene based AIEgen for picric acid detection in real water samples.

In this work, a new anthracene Schiff base derivative (AS) was successfully synthesized and characterized by pivotal analytical techniques. Based on the contented results, the AS molecule was employed for photophysical investigation using UV-Visible absorption, steady state and time resolved fluorescence techniques. The photophysical studies reveal that the AS possesses modest molar absorption coefficient (104) and weak fluorescence (ϕ = 0.006). The weak fluorescence of AS is due to intramolecular photoinduced electron transfer (PET). Intriguingly, the weak fluorescence intensity of AS is enhanced dramatically by the gradual addition of water up to 90% as well as appearance of long lived fluorescence decay. The enhancement in the fluorescence intensity and lifetime clearly indicates that this molecule has aggregation-induced emission (AIE) property. Further, the AIE property of AS is utilized for sensitive detection of picric acid (PA). The fluorescence of aggregated AS is quenched regularly with the sequential addition of PA concentration. The higher Stern-Volmer constant (2.61 × 105 M-1) and excellent detection limit of 93 nM designate the AS aggregates as potential candidate for explosive detection. The mechanism behind the quenching of fluorescence can be ascribed to inner filter effect, which is supported by spectral overlap analysis and fluorescence lifetime measurements. The suitability of AS aggregates for practical applications is realized by the detection of trace amounts of PA in real water samples.

A new double-emission fluorescent probe for fast detection of thiophenols in aqueous solution and living cells

A new fluorescent probe was designed and synthesized according to the photo-induced electron transfer theory (PET) and the results of density functional theory calculation. The synthesized probe had a larger Stokes shift (130 nm) and double emission peak in response to highly toxic thiophenols, which could be applied in rapid and high sensitive detection of thiophenol in aqueous solution. A 25-fold fluorescence intensity enhancement was achieved and the fluorescent intensity at 460 nm had a linear relationship to the thiophenol in concentration range of 0–2.0 μM. Furthermore, a remarkable detection limit (6 nM) could be achieved. 50-fold other species have no interference to the detection. The practical utility of the probe was demonstrated by live HeLa cells imaging and thiophenol detection in real water samples. In linear range of 0–2.0 μM, the probe showed good recoveries (from 95% to 108%) for thiophenol detection in natural water samples. This method possesses high sensitivity, lower detection limit and fast response (i.e., 10 min, which is shorter than the average time response of other reported methods), indicating that the synthesized probe would be promising for real-time detection of thiophenols.

Monitoring 2,3',5,5'-tetrachlorobiphenyl with a rapid and sensitive environmental aptamer sensor.

Polychlorinated biphenyl (PCB) detection in the environment is significant for both environmental protection and human health. Herein, a highly sensitive aptamer sensor has been established by employing a 2,3',5,5'-tetrachlorobiphenyl (PCB72) targeting aptamer as a highly specific recognition element and a gold/silver (Au@Ag) nanocomposite as the surface-enhanced Raman spectroscopy (SERS) substrate for detecting environmental PCB72. The Au@Ag nanoparticles (NPs) exhibit a strong SERS enhancement and provide an efficient substrate for immobilizing the PCB72 aptamer and Raman signal labelled molecule, 4-mercaptobenzoic acid (4-MBA). The targeted PCB72 could competitively bind with the PCB72 aptamer, resulting in a few aptamers sticking to the Au@Ag NPs and the "hot spot" strengthening effect of the substrate. Under optimal conditions, this aptamer sensor exhibits great performance with high sensitivity, excellent selectivity and stability for the monitoring of PCB72, which shows an excellent linear correlation ranging from 1 to 1000 pg mL-1 with a limit of detection of 0.3 pg mL-1. Furthermore, this aptamer assay exhibits high specificity and selectivity for PCB72 with the detection error of less than 0.27 for other PCBs and 0.21 for other interfering species, even if the coexisting interferents are 100-fold concentration in the system. Additionally, the recognition mechanism of the binding of aptamers to PCB72 is analyzed via UV-vis spectroscopy and molecular docking simulations, which suggest that PCB72 could insert into the aptamers. Furthermore, this method is successfully utilized for PCB72 detection in real water samples with a simple pre-treatment. In general, this work provides a new and effective method using an environmental aptamer sensor for rapid and sensitive PCB72 detection.

Lateral flow aptamer assay integrated smartphone-based portable device for simultaneous detection of multiple targets using upconversion nanoparticles

Simultaneous detection of multiple targets with different analyte-recognition reactions in the same sample in a rapid, low-cost and reliable way has immense potential with widespread applications in food safety, medical diagnostics and environmental monitoring. Herein, we developed a lateral flow aptamer assay (LFAA) integrated smartphone-based portable device for highly sensitive and precise detection of multiple targets, using aptamers functionalized multi-colored upconversion nanoparticles as probes. The developed LFAA can provide rapid and sensitive analysis of three different kinds of targets (i.e., small molecules, ions and bacteria) without significant cross-reaction by using separate color channels. By using the competitive format, the concentration of each target can be determined from the color intensity of the corresponding colored band. With the LFAA, we have achieved detection ranges of 10–104 ppb, 0.01–50 μg/mL and 150–2000 CFU/mL and detection limits of 5 ppb, 3 ng/mL and 85 CFU/mL for mercury ions, ochratoxin A and Salmonella (as template analytes), respectively. The LFAA was further used for detection in real water samples (i.e., tap water) within 30 min. Subsequently, a smartphone-based device was used instead of a CCD camera to read the results, which could make the detection process rapid and portable. Therefore, the developed LFAA holds great potential as a sensitive, specific, convenient and stable platform for point-of-care detection of multiple targets in various fields.

A colorimetric and turn-on NIR fluorescent probe based on xanthene system for sensitive detection of thiophenol and its application in bioimaging

Developing fluorescent probes for specific detection of extremely toxic thiophenols is pretty significant in the field of environment, chemistry and biology. We report herein a turn-on red fluorescent xanthene-based probe (RD-Probe) for detecting thiophenol with high selectivity over other analytes including aliphatic thiols. The probe could play the part of a “naked-eye”colorimetric indicator toward thiophenol. Moreover, the relative fluorescence intensity at 653 nm displayed good linearity with the concentration of thiophenol ranging from 0 to 6 μM, and the limit of detection for thiophenol could be as low as 15 nM. Furthermore, the practicability of RD-Probe has been successfully proved through the quantitative thiophenol detection in real water samples and fluorescence bioimaging of thiophenol in HeLa cells.

Novel Sensor Based on Poly (1,2‐Diaminoanthraquinone) for Individual and Simultaneous Anodic Stripping Voltammetry of Cd2+, Pb2+, Cu2+ and Hg2+

AbstractA novel electrochemical sensor based on glassy carbon electrode (GCE) modified by poly (1,2‐diaminoanthraquinone) (P1,2‐DAAQ) has been developed for individual and simultaneous determination of Cd2+, Pb2+, Cu2+ and Hg2+ using square wave anodic stripping voltammetry (SWASV). P1,2‐DAAQ was characterized by cyclic voltammetry (CV) and scan electron microscope (SEM). Several analytical parameters such as the type of electrolyte solution, polymer film thickness, metal deposition time and deposition potential were investigated and optimized. Optimal conditions were obtained by using five scan cycles for polymer synthesis and 120 seconds at −1.6 V for metal electrodeposition in acetate buffer solution. Good linear responses to Cd2+, Pb2+, Cu2+ and Hg2+ in the concentration range from 0 to 120 μg/L were obtained. The limit of detections (LOD) for simultaneous determination of Cd2+, Pb2+, Cu2+ and Hg2+ were 0.3 μg/L, 0.58 μg/L, 1.94 μg/L and 0.26 μg/L, respectively. The developed method was also applied for their detection in real water samples for which favorable results obtained compared with those obtained using inductively coupled plasma – optical emission spectroscopy (ICP‐OES).

Dual enzyme-free amplification strategy for ultra-sensitive fluorescent detection of bisphenol A in water

An ultra-sensitive strategy for bisphenol A (BPA) detection based on dual enzyme-free strategies: hybridization chain reaction (HCR) and enzyme-strand recycling reaction has been developed. The BPA aptamer can form hairpins structure by the partly self-complementary sequence. In the presence of BPA, the released BPA aptamer sequence can trigger the HCR between two hairpins to from a long nicked double-helix DNA. The tails of hairpins on the duplex DNA were closely enough to hybridize with molecular beacon (MB) on the gold nanoparticles (AuNPs) to circularly cleave the loop of MB, leading to a “turn-on” fluorescent signal. This method exhibited high sensitivity for BPA detection in a linear rang from 0.2 to 1000 pM with 0.05 pM of limit of detection. Moreover, it was successfully used for BPA detection in real water samples. Importantly, this method was simple without complex enzymatic procedure and high cost, showing a promising future for on-site detection of BPA in practical application.

A water-soluble fluorescence “turn on” chemosensor for Cu2+ signaling: A combined photophysical and cell imaging study

A simple and effective fluorescence “turn on” chemosensor (ZPA) has been synthesized for rapid, sensitive and selective detection of copper ions (Cu2+) in fully aqueous buffer. The binding interaction between ZPA and Cu2+ was investigated through UV–vis absorption, fluorescence measurement, mass spectroscopy, and IR spectrum analysis. Cu2+ could specifically bind with the hydroxyl-O and imine-N atom in ZPA with high affinity (Ka = 6.08 × 107 M−1). Coordination of Cu2+ to ZPA restricting the photoinduced electron transfer (PET) process in free ZPA and generating a more rigid ZPA/Cu2+ complex with an extended π-electron conjugation system, sequentially leading to the fluorescence enhancement of ZPA. The detection limit (calculated to be 1.49 × 10−8 M) was far below the limit in the World Health Organization (WHO) guidelines for drinking water (30 μM) and the sensing process was fully reversible. Practical applications of ZPA for Cu2+ detection in real water samples were investigated with satisfactory results. Endowed with attributes like high binding affinity, specificity, relatively long excitation/emission properties and excellent bio-compatibility, ZPA demonstrated outstanding fluorescent imaging of intracellular Cu2+ in living cells.