Copper Nanoclusters Research Articles

Solid State Fabrication of Copper Nanoclusters and Supraparticles

In this study, we present solid state processes for the fabrication of copper nanoclusters (NCs) and hierarchical supraparticles (SPs). To achieve this, copper salt and thiols are mixed and are then grinded for 10–15 min, and the nano-products are thereby obtained. Interestingly, it was found in this study that the formation of the NCs or SPs is completely dependent on the grinding methods that are used: with mechanical grinding, the products are several nanometer-sized NCs, whereas manual grinding in an agate mortar can obtain Cu SPs with diameters as low as 10 nm all the way up to 200 nm. The photoluminescence emission wavelength of the nano-products is located at ~680 nm. The Stokes shift of the obtained nanomaterials is more than 300 nm. The emission quantum yields of the Cu NCs and SPs are as high as 47.5% and 63%, respectively. Due to their facile fabrication processes and their favorable optical properties, the two as-prepared types of copper nano-materials exhibit great potential for bio-imaging and bio-sensing applications.

Synthesis of copper nanoclusters from Bacopa monnieri leaves for fluorescence sensing of dichlorvos.

In this work, a facile one-step green synthesis was developed for the fabrication of blue fluorescent copper nanocluster (Brahmi-CuNCs) from the extract of Bacopa monnieri (common name is Brahmi) via a microwave method. The as-prepared Brahmi-CuNCs emitted blue fluorescence at 452 nm when excited at 352 nm and showed a quantum yield of 31.32%. Brahmi-derived blue fluorescent CuNCs acted as a probe for fluorescence sensing of dichlorvos. Upon the addition of dichlorvos, the blue emission for Brahmi-CuNCs was gradually turned off, favouring establishment of a calibration graph in the range 0.5-100 μM with a detection limit of 0.23 μM. The as-synthesized Brahmi-CuNCs exhibited marked sensitivity and selectivity towards dichlorvos, favourable for assaying dichlorvos in various samples (cabbage, apple juice, and rice).

Enzyme-Assisted Amplification and Copper Nanocluster Fluorescence Signal-Based Method for miRNA-122 Detection.

At present, a large number of studies have demonstrated that miRNAs can be used as biological indicators for the diagnosis and treatment of diseases such as tumours and cancer, so it is important to develop a new miRNA detection platform. In this work, miRNA-122 is used as the basis for targeting detection agents. We have designed an unlabelled DNA1 that undergoes partial hybridisation and has a 20 T base long strand. The fluorescent signal in this experiment is derived from copper nanoclusters (CuNCs) generated on the circular T-long strand of DNA1. At the same time, DNA1 is able to react with miRNA-122 and achieve hydrolysis of the part bound to miRNA-122 via the action of nucleic acid exonuclease III (Exo III), leaving a part of the DNA, called DNA3, while releasing miRNA-122 to participate in the next reaction, thus achieving circular amplification. DNA3 is able to react with DNA2, which is bound to streptavidin magnetic beads (SIBs) and separated from the reaction solution via the application of a magnetic field. Overall, this is a fluorescence signal reduction experiment, and the strength of the fluorescence signal from the copper nanoclusters can determine whether the target miRNA-122 is present or not. The degree of fluorescence reduction indicates how much DNA1, and thus the amount of target miRNA-122, has been hydrolysed. By evaluating the variations in the fluorescence signal under optimised conditions, we discovered that this method has good sensitivity, with a detection limit as low as 0.46 nM, better than many other previous works on fluorescence signal-based biosensors for miRNA detection. This technique offers high discrimination and selectivity and can serve as a persuasive reference for early diagnosis.

Fluorescent polythymidine-templated copper nanoclusters aptasensor for sensitive detection of tropomyosin in processed shrimp products

Tropomyosin (TM) is the main allergen in shellfish. Developing a novel, simple and accurate method to track and detect TM in food products is necessary. In this work, a label-free fluorescent aptasensor based on polythymidine (poly(T))-templated copper nanoclusters (CuNCs) was designed for sensitive detection of TM in processed shrimp products. Magnetic beads (MBs), aptamer and cDNA were used to construct an MBs-aptamer@cDNA complex as a detection probe, and with the presence of TM, the poly(T)-templated CuNCs attached at the end of the cDNA as the fluorescent signal was released from the complex to turn on the fluorescence. Under optimal conditions, the poly(T)-templated CuNCs aptasensor achieved a linear range from 0.1 to 50 μg/mL (R2 = 0.9980), a low limit of detection of 0.0489 μg/mL and an excellent recovery percentage of 105.29%-108.91% in the complex food matrix, providing a new approach for food safety assurance.

Copper nanoclusters electrochemiluminescence with tunable near-infrared emission wavelength for ultrasensitive detection of matrix metalloproteinase-2

Herein, the methionine (Met)/N-acetyl-L-cysteine (NAC) templated copper nanoclusters (Met/NAC-Cu NCs) with tunable near-infrared region (NIR) electrochemiluminescence (ECL) emission wavelength was firstly synthesized as emitter for the ultrasensitive detection of matrix metalloproteinase-2 (MMP-2). Significantly, the NAC played the role of template and reductant of cupric to acquire Cu NCs, and the surface defect regulator Met was used to connect NAC through -S-S- bond, which could heighten the surface defect of Cu NCs to continuously regulate the maximum ECL emission by successively controlling the molar ratio of Met and NAC, leading to the ECL emission wavelength of Cu NCs ranged from 680 nm to 750 nm. In addition, a rapid target triggered catalyst hairpin assembly (CHA) recycling amplification strategy was constructed through orderly and equidistantly arranging hairpin to increase its local concentration, resulting in greatly accelerated signal amplification efficiency and reaction rate. As a proof of concept, based on Met/NAC-Cu NCs as NIR ECL emitter and effective signal amplification tactic, a super-sensitive ECL biosensor was fabricated to detect target MMP-2 with the detection limit (LOD) as low as 1.65 fg/mL and successfully utilized for detecting of MMP-2 that from Hela and MCF-7 cancer cells. This research provided a wonderful avenue for regulating the optical performance of metal nanoclusters-based ECL emitters, and the developed neoteric NIR ECL emitter with the merits of less photochemical damage and deeper tissue penetration exhibited great potential in ultrasensitive biosensing and high-definition ECL imaging.

A Sensitive Fluorescence Sensor for Tetracycline Determination Based on Adenine Thymine-Rich Single-Stranded DNA-Templated Copper Nanoclusters.

A sensitive fluorescent sensor has been developed for the determination of tetracycline (TC) using adenine thymine (AT)-rich single-stranded DNA (ssDNA) templated copper nanoclusters (CuNCs) as a fluorescent probe. Fluorescent ssDNA-CuNCs were synthesized by employing AT-rich ssDNA as templates and ascorbic acid as reducing agents through a facile one-step method. The as-prepared ssDNA-CuNCs exhibited strong fluorescence with a large Stokes shift (240 nm) and stable fluorescence emission. In the presence of TC, the fluorescent intensity of ssDNA-CuNCs was obviously decreased through the inner filter effect, due to the spectral overlapping between ssDNA-CuNCs and TC. Under the optimal conditions, the strategy exhibited sensitive detection of TC with a linear range from 2 nM to 30 μM and with a limit of detection of 0.5 nM. Furthermore, the sensor was successfully applied for the detection of TC in milk samples. Therefore, it provided a simple, rapid, and label-free fluorescent method for TC detection.

Atomically Precise Copper Nanoclusters for Highly Efficient Electroreduction of CO2 towards Hydrocarbons via Breaking the Coordination Symmetry of Cu Site

AbstractWe propose an effective highest occupied d‐orbital modulation strategy engendered by breaking the coordination symmetry of sites in the atomically precise Cu nanocluster (NC) to switch the product of CO2 electroreduction from HCOOH/CO to higher‐valued hydrocarbons. An atomically well‐defined Cu6 NC with symmetry‐broken Cu−S2N1 active sites (named Cu6(MBD)6, MBD=2‐mercaptobenzimidazole) was designed and synthesized by a judicious choice of ligand containing both S and N coordination atoms. Different from the previously reported high HCOOH selectivity of Cu NCs with Cu−S3 sites, the Cu6(MBD)6 with Cu−S2N1 coordination structure shows a high Faradaic efficiency toward hydrocarbons of 65.5 % at −1.4 V versus the reversible hydrogen electrode (including 42.5 % CH4 and 23 % C2H4), with the hydrocarbons partial current density of −183.4 mA cm−2. Theoretical calculations reveal that the symmetry‐broken Cu−S2N1 sites can rearrange the Cu 3d orbitals with as the highest occupied d‐orbital, thus favoring the generation of key intermediate *COOH instead of *OCHO to favor *CO formation, followed by hydrogenation and/or C−C coupling to produce hydrocarbons. This is the first attempt to regulate the coordination mode of Cu atom in Cu NCs for hydrocarbons generation, and provides new inspiration for designing atomically precise NCs for efficient CO2RR towards highly‐valued products.

Atomically Precise Copper Nanoclusters for Highly Efficient Electroreduction of CO2 towards Hydrocarbons via Breaking the Coordination Symmetry of Cu Site.

We propose an effective highest occupied d-orbital modulation strategy engendered by breaking the coordination symmetry of sites in the atomically precise Cu nanocluster (NC) to switch the product of CO2 electroreduction from HCOOH/CO to higher-valued hydrocarbons. An atomically well-defined Cu6 NC with symmetry-broken Cu-S2 N1 active sites (named Cu6 (MBD)6 , MBD=2-mercaptobenzimidazole) was designed and synthesized by a judicious choice of ligand containing both S and N coordination atoms. Different from the previously reported high HCOOH selectivity of Cu NCs with Cu-S3 sites, the Cu6 (MBD)6 with Cu-S2 N1 coordination structure shows a high Faradaic efficiency toward hydrocarbons of 65.5 % at -1.4 V versus the reversible hydrogen electrode (including 42.5 % CH4 and 23 % C2 H4 ), with the hydrocarbons partial current density of -183.4 mA cm-2 . Theoretical calculations reveal that the symmetry-broken Cu-S2 N1 sites can rearrange the Cu 3d orbitals with as the highest occupied d-orbital, thus favoring the generation of key intermediate *COOH instead of *OCHO to favor *CO formation, followed by hydrogenation and/or C-C coupling to produce hydrocarbons. This is the first attempt to regulate the coordination mode of Cu atom in Cu NCs for hydrocarbons generation, and provides new inspiration for designing atomically precise NCs for efficient CO2 RR towards highly-valued products.

Peptide‐tethered Perylenebisimide Aggregates with Copper Nanoclusters showing Thermoresponsive and Photoresponsive Properties

AbstractA centrally located dipeptide(P) covalently attached to two perylene bisimide units [(PBI)2P] was synthesized and it was used to fabricate a hybrid system by aggregating with blue‐emitting, atomically precise copper nano‐clusters (Cu NCs). The interactions between these components [(PBI)2P] and Cu NCs] was thoroughly investigated by UV‐Vis spectroscopy and field emission gun transmission electron microscopy (FEG‐TEM).The effect of interaction between components on the optical properties of the hybrids was investigated by fluorescence spectroscopy. Interestingly, this hybrid system shows fluorescence thermometric behaviour at the 20–50 °C temperature range with a promising reversible switchable fluorescence property. Photo‐switching property is enhanced significantly in the hybrid compared to that of the peptide tethered pelylene bisimides as it is evident from the improvement of photocurrent gain (Ion/Ioff) from 2.6 in [(PBI)2P] to 6.9 in the hybrid. Modulation of photo‐switching property along with the thermo‐sensitive fluorescence property in this hybrid holds a future promise for fabrication of devices from the peptide based hybrids.

Sensitive fluorescence ELISA with streptavidin scaffolded DNA tetrads for the detection of Escherichia coli O157:H7

Escherichia coli O157:H7 poses a threat to humans. Traditional ELISA is not a sensitive method for the detection of E. coli O157:H7. Here, an efficient method was designed for improving the load capacity of alkaline phosphatase (ALP) with streptavidin scaffolded DNA tetrad (SS-DNAt). With more ALP, more ascorbic acid 2-phosphate was catalyzed to ascorbic acid that was used to synthesize fluorescence poly adenine-thymine-templated copper nanoclusters. Based on SS-DNAt, fluorescence ELISA was successfully proposed for improving the sensitivity for detection of E. coli O157:H7 in milk samples. The method showed a linear range of 104 to 106 cfu/mL. The limit of detection of fluorescence ELISA was 3.75 × 103 cfu/mL and 6.16-fold better than that of traditional ELISA. The recovery of the fluorescence ELISA was 86.7 to 93.6% with the coefficient of variation of 5.6 to 10.5% in milk. This method could be used to detect hazardous material in food.

Determination of 2, 6-dipicolinic acid as an Anthrax biomarker based on the enhancement of copper nanocluster fluorescence by reversible aggregation-induced emission.

The weak fluorescence efficiency of copper nanoclusters (Cu NCs) limits their wide applications in biosensing and bioimaging areas, while the aggregation-induced emission (AIE) effect is anticipated to increase their luminescence intensity. Herein, the weak red emission of Cu NCs is increased considerably by the addition of lanthanide Tb3+, ascribed to theAIE effect. Monitoring of spores contamination can be carried out by determining the level of 2, 6-dipicolinic acid (DPA), which is a marker of spores. Due to the stronger synergy between DPA and Tb3+ for its clamped configuration of adjacent pyridine nitrogen group with the carboxylic acid group, the addition of DPA leads Tb3+ to be taken away from Cu NCs through a stronger coordination effect, causing Cu NCs to return to the dispersed state and weakened fluorescence. Based on this, an "off-on-off" fluorescent probe for DPA sensing was built, in which Tb3+ was used as a bridge to achieve AIE enhanced fluorescence effect on Cu NCs as well as aspecific recognizer of DPA. The detection range for DPA was 0.1-60μM and the detection limit was 0.06μM, which was much lower than the infectious dose of anthrax spores. Since DPA is a unique biomarker for bacterial spores, the method was applied to the detection of actual bacterial spores and satisfactory results were obtained with a detection limit of 4.9*103CFUmL-1.

Rational design of zero-valence and well-dispersed copper nanocluster stabilized by carbon-coated SiO2 for highly effective and ultrafast reduction of nitroarenes

In this work, we present a ligand modification strategy that allows for the regulation of the valence and dispersion state of Cu clusters in the final obtained Cu@C/SiO2 catalyst. Specifically, the phthalic acid (PA) ligand promotes the uniform anchoring of zero-valence Cu nanoclusters on Cu@C/SiO2, resulting in excellent catalytic activity in the selective reduction of toxic 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) with a rate constant (k) of 19.06×10-3 s-1. This value was approximately 2.4- and 31.2-fold higher than that of the CuO/SiO2 and bare CuO catalysts, respectively. Additionally, no significant decline in activity was detected during six successful cycles. Through systematic analysis of structural and electronic properties of the catalyst, we confirmed that the coordination effect of the PA ligand and the carbothermic effect of its carbon derivatives effectively prevent particle aggregation and modulate the valence state of copper species in Cu@C/SiO2, resulting in superior catalytic performance.

In-situ hydrothermal synthesis of Al-rich Cu@ZSM-5 catalyst for furfuryl alcohol upgrading to pentanediols

Bifunctional metal-acid catalysts have been widely used in the process of upgrading the molecules of biomass. As an important bifunctional catalyst, metal @ zeolite exhibits excellent sintering resistance and efficient catalytic performance, which is significant for improving practical applications. While the development of Al-rich zeolite-confined nanocluster catalysts is still a considerable challenge. In this paper, Cu@ZSM-5 (SiO2/Al2O3 = 40) catalyst with Al-rich ZSM-5 zeolite-confined copper nanoclusters were designed and synthesized by the in-situ ligand-assisted hydrothermal crystallization method. The average size of the encapsulation metal clusters was only 2.3 nm after treatment at 400°C for 2 h in a hydrogen environment, which exhibits excellent thermal stability. 27Al MAS NMR and Pyridine-adsorbed IR (Py-IR) spectra confirmed that Al was successfully introduced into the zeolite framework. The intimate metal- Brønsted acidic site distribution enables complete conversion of furfuryl alcohol and 92.1 % selectivity of pentanediols. DFT calculations revealed that the high catalytic activity in catalyzing the ring opening of furfuryl alcohol to pentanediols could be attributed to the unique electronic effect in the Al-rich catalyst Cu@ZSM-5 (SiO2/Al2O3 = 40). The in-situ ligand-assisted hydrothermal crystallization method will be very attractive regarding the simplicity required for industrial production. The Al-rich Cu@ZSM-5 (SiO2/Al2O3 = 40) catalyst was endowed with rich and dense metal-Brønsted acidic sites by a simple in-situ synthesis method, providing a practical and feasible path for the high-value utilization of biomass molecules.

Rapid microwave-assisted synthesis of copper nanoclusters for “on-off-on” fluorescent sensor of tert-butylhydroquinone in edible oil

Copper nanoclusters (CuNCs) are attractive alternatives for fluorescent sensor, due to their low toxicity, strong biocompatibility, and inexpensive manufacturing cost. Herein, fluorescent CuNCs was rapidly synthesized in 2.5 min under microwave irradiation using L-cysteine (L-Cys) as the protective and reducing agent, and an “on-off-on” fluorescent sensor for tert-butylhydroquinone (TBHQ) was developed. In the presence of Fe3+ ions, the fluorescence of L-Cys-CuNCs was quenched (turned off), then recovered after adding TBHQ (turn on). Under the optimized conditions, the TBHQ sensor had a wide linear range (2–350 μmol·L−1) and low detection limit (0.077 μg·mL−1). Furthermore, the relative standard deviation (RSD) were from 1.44% to 8.98% and the recoveries were from 94.53% to 108.99% for the determination of edible oil samples. Besides, the results detected by fluorescence sensor is in accordance with the results obtained in the traditional HPLC method. The microwave-assisted fast synthesis of CuNCs will expected to develop the fluorescent sensors for food safety and environmental analysis.

Inter filter effect between fluorescent copper nanoclusters and Cr(VI) and its application for probing the activity of alkaline phosphatase

Herein, a novel fluorescent sensing strategy for the detection of alkaline phosphatase activity (ALP) was successfully established using highly luminescent glutathione-stabilized copper nanoclusters (GSH-CuNCs) as fluorescent probe. The GSH-CuNCs were synthesized with GSH as stabilizer and ascorbic acid (AA) as reductant. The optical properties of GSH-CuNCs were further investigated using fluorescence and UV–vis spectrophotometry. And its sensing ability for AA and ALP were explored. The fluorescence intensity of GSH-CuNCs was strongly quenched by Cr(VI) due to the inner filter effect (IFE). However, in the presence of AA, the fluorescence of GSH-CuNCs/Cr(VI) probes was restored due to the weakening of the IFE. It also exhibited a good linear range to the concentration of AA in the range of 0.1–500 μM, and the detection limit was 20 nM. In addition, it has been found that the substrate ascorbic acid 2-phosphate (AA2P) had no effect on the fluorescence of the (GSH-CuNCs)-Cr(VI) probe. Since ALP could specifically hydrolyze AA2P into AA, the emission intensity of the probes was restored by an ALP-triggered reaction. As a result, ALP was sensitively and selectively quantified with a wide linear range of 0.1 mU•mL−1 to 200 mU•mL−1 and a low detection limit of 0.02 mU•mL−1. In order to evaluate the practicality of the detection strategy, ALP in real sample analysis was also determined. The results showed that the recoveries and relative standard deviations were acceptable towards the probes. The proposed biosensor could be applied in fields of environmental and biological analysis.

Solvent-Induced Modulation in the Optical Properties of Copper Nanoclusters and Revealing the Isomeric Effect of Templates.

The solvent plays an influential role in controlling the nucleation process of metal nanoclusters (MNCs) and thereby significantly modulates their optical signatures. Herein, we have demonstrated the solvent-induced modulation in the optical properties of copper nanoclusters (CuNCs), primarily governed by the solvent polarity. During the preparation of para-mercaptobenzoic acid (p-MBA)-templated CuNCs, the simultaneous formation of blue-emitting CuNCs (B-CuNCs) and red-emitting CuNCs (R-CuNCs) were observed up to 7 h of reaction time, reflected from the systematic increment in the photoluminescence (PL) intensity at 420 nm and 615 nm, respectively. However, after 7 h of reaction time, the exclusive formation of B-CuNCs was observed. Such simultaneous growth and depletion dynamics of CuNCs result in a significant modulation in their optical properties. The variation of the solvent from water to less polar solvents such as DMSO and DMF restricts this inter-cluster dynamics by stabilizing both the CuNCs (B-CuNCs and R-CuNCs). Thereby, a single-component White Light Emission (WLE) was realized in DMSO with CIE coordinates (0.37, 0.36). The isomeric effect of the templates has also been investigated which extensively controls the optical and catalytic properties of the CuNCs.

E-Beam and γ-rays Induced Synthesis and Catalytic Properties of Copper Nanoclusters-Deposited Composite Track-Etched Membranes.

Effective removal of toxic inorganic and organic pollutants is one of the current leading challenges of wastewater treatment. In this study, the decomposition of methylene blue (MB) under UV light irradiation was investigated in the presence of copper nanoclusters (NCs)-deposited polyethylene terephthalate (PET) track-etched hybrid membranes. PET track-etched membranes (TeMs) with an average pore size of ~400 nm were grafted by functional acrylic acid (AA) monomer under electron beam irradiation after oxidation with H2O2/UV system. The radiation dose varied between 46 and 200 kGy. For the deposition of copper NCs, poly(acrylic acid) (PAA)-grafted membranes saturated with Cu(II) ions were irradiated either by electron beam or γ-rays to obtain copper-based NCs for the catalytic degradation of MB. Irradiation to 100 kGy with accelerated electrons resulted in the formation of small and uniform copper hydroxide (Cu(OH)2) nanoparticles homogeneously distributed over the entire volume of the template. On the other hand, irradiation under γ-rays yielded composites with copper NCs with a high degree of crystallinity. However, the size of the deposited NCs obtained by γ-irradiation was not uniform. Nanoparticles with the highest uniformity were obtained at 150 kGy dose. Detailed analysis by X-ray diffraction (XRD) and scanning electron microscopy (SEM) confirmed the loading of copper nanoparticles with an average size of 100 nm on the inner walls of nanochannels and on the surface of PET TeMs. Under UV light irradiation, composite membranes loaded with NCs exhibited high photocatalytic activity. It was determined that the highest catalytic activity was observed in the presence of Cu(OH)2@PET-g-PAA membrane obtained at 250 kGy. More than 91.9% of the initial dye was degraded when this hybrid membrane was employed for 180 min, while only 83.9% of MB was degraded under UV light using Cu@PET-g-PAA membrane. Cu(OH)2@PET-g-PAA membranes obtained under electron beam irradiation demonstrated a higher photocatalytic activity compared to Cu@PET-g-PAA membranes attained by γ-rays.

Highly photoluminescent tryptophan-coated copper nanoclusters based turn-off fluorescent probe for determination of tetracyclines

Employing cheap Cu nanoclusters to design a novel fluorescent probe have promising opportunities in the field of optical sensors. Here, we fabricated a highly photoluminescent D-tryptophan (D-Trp)-coated Cu nanoclusters (Trp-Cu NCs) by rapid microwave-assisted method to achieve precise quantification of tetracyclines (TC). Due to protecting groups of Trp, the synthesized Trp-Cu NCs have remarkable fluorescence stability with a quantum yield reached 12.5%. A distinct fluorescence quenching with the incremental addition of TC via the internal filtration effect (IFE). Based on turn-off fluorescence within 1 min, a detection method for detecting TC was constructed with a linear range of 0.3–120 μM and a limit of detection (LOD) of 0.12 μM. Besides, the proposed fluorescent probe has been employed for the determination of practical samples such as water samples, milk and honey, and exhibited satisfactory recoveries of 96.1%–108.2%, with relative standard deviations (RSD) lower than 5.0%. This is a sensitive, rapid and easily recognizable Trp-Cu NCs based sensing platform for the determination of TC, which could offer a powerful tool for ensuring food safety.

Synthesis and Structure of Polyhydrido Copper Nanocluster [Cu14H10(PPh3)8(SPhMe2)3]+: Symmetry-Breaking by Thiolate Ligands to form Racemic Pairs of Chiral Clusters in Solid-State

A polyhydrido copper nanocluster, [Cu14H10(PPh3)8(SR)3]+ (HSR = 2,4-dimethylbenzenethiol), adopting a distorted fcc structure, is reported. One cube-vertex copper atom, coordinated by the three thiolate ligands and a PPh3, protrudes outwards from the fcc metal framework. The twisting of the three thiolate ligands about the threefold axis lowers the symmetry from Oh (Cu14) to C3, forming racemic pairs of intrinsic chiral clusters in crystalline solid-state.Graphical

Ce4+-based self-validated portable platform for highly selective and anti-interference visual sensing of phosphate

Construction of a convenient and multi-responsive sensor for visual and real-time detecting of phosphate (Pi) is important to monitor the eutrophication pollution or drinking water quality. Herein, we developed a highly selective and anti-interference fluorescent and colorimetric dual-mode sensor for Pi detection. Since only the Ce4+ ion was used as the center with copper nanoclusters (CuNCs) and 3,3′,5,5′-Tetramethylbenzidine (TMB) as the signal carriers, the construction of the sensor was significantly simplified. The dissociated Ce4+ showed ability of triggering the CuNCs aggregation-induced emission (AIE) and oxidase-like enzyme, independently bringing red fluorescence (AIE of CuNCs) and blue color (oxidized TMB) signals. With the presence of Pi, the strong binding between Pi and Ce4+ through P-O-Ce bond quenched both the fluorescent and colorimetric signals. More significantly, the selective and anti-interference ability were effectively improved by self-validation between fluorescent and colorimetric modes. Meanwhile, combining with smartphone, the Pi lowered at 1 μM could be visually detected. Based on the fluorescent and colorimetric outputs could be directly quantified by the naked eye, a paper-based dual-mode visualization platform was constructed. The reliable dual-mode also showed robust analysis of the Pi in environmental water, indicating its great potential as a simple and efficient tool for field monitoring.