A novel and ultrasensitive fluorescent probe derived from labeled carbon dots for recognitions of copper ions and glyphosate

A dual-signals fluorometric and colorimetric peptide-based probe for Cu(II) and glyphosate detection and its application for bioimaging and water testing

A novel dual-signal fluorometric and colorimetric probe FMDH (5-FAM-Met-Asp-His-NH2), incorporating a tripeptide (Met-Asp-His-NH2) linked to 5-carboxyfluorescein (5-FAM), was firstly synthesised. FMDH demonstrated exceptional selectivity and sensitivity, rapid response, wide pH response range and robust anti-interference capabilities for monitoring Cu2+. This was achieved through a distinctive naked-eye colorimetric and fluorescent quenching behaviour. A good linearity within the range of 0-3 μM (R2 = 0.9914) was attained, and the limit of detection (LOD) for Cu2+ was 47.4 nM. Furthermore, the FMDH-Cu2+ ensemble responded to glyphosate with notable selectivity and sensitivity. A good linear correlation (R2 = 0.9926) was observed at the lower concentration range (2.4-7.8 μM) and achieving a detection limit as low as 29.9 nM. The response time of FMDH with Cu2+ and glyphosate were less than 20 s, and the pH range of 7-11 that was suitable for practical application under physiological pH conditions. MTT assays confirmed that FMDH offers good permeability and low toxicity, facilitating successful application in imaging analysis of Cu2+ and glyphosate in living cells and zebrafish. In addition, FMDH was employed in the detection of these analytes in real water samples. Cost-effective, highly sensitive and easily prepared FMDH-impregnated test strips were developed for the efficient visual detection of Cu2+ and glyphosate under 365 nm UV light. Increasing concentrations of Cu2+ and glyphosate resulted in notable colour changes under 365 nm UV light, enabling visual semi-quantitative analysis via a smartphone colour-analysis App.

A novel "Turn-Off-On" fluorescent probe for specific sequential detection of Cu2+ and glyphosate and its application in biological imaging

As common pollutants, Cu2+ and glyphosate pose a serious threat to human health and the ecosystem. Herein, a fluorescent probe (E)-7-(diethylamino)-N'(4-(diethylamino)-2-hydroxybenzyl)-2-oxo-2H chromophore-3-carbazide (DDHC) was designed and synthesised for the sequential recognition of Cu2+ and glyphosate. DDHC has the advantages of a short synthesis path, easy-to-obtain raw materials, good anti-interference ability, and strong stability. The interaction of the DDHC-Cu2+ complexes with glyphosate allows the amino and carboxyl groups in glyphosate molecules to coordinate with Cu2+ strongly, competing for the Cu2+ in the DDHC-Cu2+ complexes and releasing the DDHC, leading to the recovery of fluorescence. The recognition was further validated through Job's plot, HRMS, and DFT calculations. In addition, the successful recovery of Cu2+ and glyphosate in different environmental water samples fully demonstrates the practical application potential of DDHC. Especially, DDHC has low cytotoxicity and can enter zebrafish and HeLa cells, rapidly reacting with Cu2+ and glyphosate in the body, generating visible fluorescence quenching and recovery phenomena, achieving real-time visual monitoring of exogenous Cu2+ and glyphosate in zebrafish and HeLa cells. The targeting and dual selectivity of DDHC greatly enhance its potential application value in the field of detection, providing important theoretical support for studying the fate of multiple pollutants in the environment.

Rational design of peptide-based fluorescent probe for sequential recognitions of Cu(II) ions and glyphosate: Smartphone, test strip, real sample and living cells applications

A new peptide-based fluorescent probe named DMDH with easy-to-synthesize, excellent stability, good water solubility and large Stokes shift (225 nm) was synthesized for highly selective sequential detections of copper ions (Cu2+) and glyphosate (Glyp). DMDH demonstrated great detection performance towards Cu2+via strong fluorescence quenching, and forming non-fluorescence DMDH-Cu2+ ensemble. As a new promising cascade probe, the fluorescence of DMDH-Cu2+ ensemble was significantly recovered based on displacement approach after glyphosate was added. Interestingly, the limit of detections (LODs) for Cu2+ and glyphosate were 40.6 nM and 10.6 nM, respectively, which were far lower than those recommended by the WHO guidelines for drinking water. More importantly, DMDH was utilized to evaluate Cu2+ and glyphosate content in three real water samples, demonstrating that its effectiveness in water quality monitoring. Additionally, it is worth noting that DMDH was also applied to analyze Cu2+ and glyphosate in living cells in view of significant cells permeability and low cytotoxicity. Moreover, DMDH soaked in filter paper was used to create qualitative test strips and visually identify Cu2+ and glyphosate through significant color changes. Furthermore, smartphone RGB color recognition provided a new method for semi-quantitative testing of Cu2+ and glyphosate in the absence of expensive instruments.

Semi-quantitative and visual detection of Cu2+ and glyphosate in real samples and living cells using fluorescent and colorimetric dual-signals peptide-based probe

The excessive emission of copper ions (Cu2+) and the abuse of glyphosate (Glyp) have caused serious harm to the ecological environment and human health, so it is important to develop a fast and convenient method for the analysis of Cu2+ and glyphosate to ensure environmental and food safety. Herein, a dual-signals peptide-based probe (FASRH) with fluorescent and colorimetric was prepared using 5-carboxyl fluorescein modified tetrapeptide (Ala-Ser-Arg-His-NH2). FASRH was successfully used to recognize Cu2+ as a fluorescence "on-off" probe, forming the FASRH-Cu2+ complex with non-fluorescence. As a new promising cascade probe, FASRH-Cu2+ complex probe has high selectivity (only Glyp), good sensitivity (50.2 nM), good anti-interference ability and wide pH range (7.0-11.0) for the detection of glyphosate by ligand replacement method. In addition, the recognizable color changed markedly under 365 nm UV light and natural light. Notably, FASRH not only achieved accurate monitoring of Cu2+ and glyphosate in two real water samples, but also successfully applied to detect Cu2+ and glyphosate in live Hacat cells based on low cytotoxicity. Moreover, it is worth noting that FASRH-impregnated test strips exhibited significant fluorescence and colorimetric color changes for Cu2+ and glyphosate via naked eye. Furthermore, smartphone-assisted FASRH was used for the portable detection of Cu2+ and glyphosate based on the advantages of simplicity, low cost and fast response.

Fluorometric detection of copper and imidacloprid using nitrogen-doped graphitic carbon dots: A promising method for environmental monitoring

Pesticides in environmental samples pose significant risks to ecosystems and human health since they require precise and efficient detection methods. Imidacloprid (IMI), a widely used neonicotinoid insecticide, exemplifies these hazards due to its potential toxicity. This study addresses the urgent need for improved monitoring of such contaminants by introducing a novel fluorometric method for detecting IMI using nitrogen-doped graphite carbon dots (N-GCDs). The sensor operates by quenching fluorescence through the interaction of Cu2+ ions with N-GCDs. Subsequently, IMI binds to the imidazole group, chelates with Cu2+, and restores the fluorescence of N-GCDs. This alternating fluorescence behavior allows for the accurate identification of both Cu2+ and IMI. The sensor exhibits linear detection ranges of 20-100 nM for Cu2+ and 10-140 μg/L for IMI, with detection limits of 18 nM and 1.2 μg/L, respectively. The high sensitivity of this sensor enables the detection of real-world samples, which underscores its potential for practical use in environmental monitoring and agricultural safety.

Construction of a novel fluorescent probe for sensitive determination of glyphosate in food and imaging living cells

Glyphosate is a widely used broad-spectrum herbicide in agriculture and horticulture to control a variety of weeds and undesirable plants. However, the excessive use of glyphosate has raised a number of environmental and human health concerns. It is urgent to develop tools to detect glyphosate. Herein, a novel dual-signal probe CCU-Cu2+ was designed and synthesized on the basis of CCU. CCU exhibited excellent selectivity and great sensitivity for Cu2+ which were based on both fluorescence "turn-off" reaction and comparative color visualisation methods. Due to the strong chelating ability of glyphosate on Cu2+, the CCU-Cu2+ complex was applied to glyphosate detection in practical samples. The experimental results in vitro showed that the CCU-Cu2+ complex was highly selective and rapid, with a low detection limit (1.6 μM), and could be recognised by the naked eye in the detection of glyphosate. Based on the excellent properties of the CCU-Cu2+ complex, we also constructed a smartphone-assisted detection sensing system for glyphosate detection, which has the advantages of precision, sensitivity, and high interference immunity. Moreover, the CCU-Cu2+ complex was also successfully employed for exogenous glyphosate imaging in living cells. These characteristics demonstrated that CCU-Cu2+ holds significant potential for detection and imaging of glyphosate in bio-systems.

Prussian blue analogues of Ni-Co-MoS2 nanozymes with high peroxidase like activity for sensitive detection of glyphosate and copper

The rational development of efficient nanozymes for the colorimetric detection of targets is still challenging. Herein, Prussian blue analogues of Ni-Co-MoS2 nano boxes were fabricated for colorimetric detection of glyphosate and copper ions owing to its peroxidase like activity. At the sensing system, the Ni-Co-MoS2 nano boxes display high peroxidase activity, which could catalytically oxidize the colourless TMB to blue colour oxTMB. In presence of glyphosate in this sensing system the blue colour is diminished, ascribed to the inhibit the catalytic activity of Ni-Co-MoS2 nano boxes. Concurrently, the addition of copper ion, which result in blue colour was reappear due to the generation of glyphosate-copper complex formation. The Ni-Co-MoS2 nano boxes based colorimetric sensing platform was developed to sensitive detection of glyphosate and copper ions with low detection limit of 3 nM for glyphosate and 3.8 nM for copper. This method also displays satisfactory outcomes from real samples analysis and its good accuracy. Therefore, this work provides a great potential for rapid detection of the targets from the environments.

Bright photoactivatable probes based on triphenylethylene for Cu2+ detection in tap water and tea samples

Photoactivatable probes can switch fluorescence on from a weak or nonemission state to improve the sensitivity of the sensing system. In this work, we successfully constructed three highly emissive photoactivatable probes, 2-DP, 1-2-DP and 2-2-DP, for Cu2+ detection. Under UV irradiation, the photoluminescence quantum yields of 2-DP, 1-2-DP and 2-2-DP display approximately 52.4-, 11.5- and 49.2-fold enhancement, respectively. Cu2+ selectively quenches the bright photoactivated fluorescence, resulting in an approximately 38-fold fluorescence reduction. The highly selective fluorescence response to Cu2+ yields an excellent low detection limit of 5.8 nM. Moreover, the photoactivatable probes were successfully applied for Cu2+ determination in tap water and tea samples with recovery ranges of 95%-105% and 97%-106%, respectively. This work provides a more sensitive and efficient methodology for Cu2+ detection in heavy metal pollution and food safety.

A novel Cu(II)-assisted peptide fluorescent probe for highly sensitive detection of glyphosate in real samples: real application in test strips and smartphone

Glyphosate (Glyp) is an organophosphorus herbicide, and its abuse causes potential harm to the environment and human health. Thus, the development of simple and portable methods for rapid and visual detection of glyphosate is of great importance. Herein, we successfully developed a new fluorescent probe L with dansyl fluorophore as a fluorescent dye and tetrapeptide (Ala-Ser-Arg-His-NH2) as a recognition group. According to the design, L exhibited a specific fluorescence quenching response to Cu2+ and formed an L-Cu2+ ensemble with a molecular ratio of 2:1, demonstrating a limit of detection (LOD) as low as 12.04 nM. Interestingly, the L-Cu2+ ensemble as a relay response probe exhibited a specific fluorescence "off-on" response to glyphosate without interference from other pesticides and anions based on the strong complexation of glyphosate and Cu2+. The LOD of the L-Cu2+ ensemble for glyphosate was calculated as 12.59 nM. Additionally, the results of three recovery experiments with real samples showed that L has good practicability and accuracy in detecting glyphosate. Test strips were also fabricated to achieve facile detection of glyphosate to demonstrate the practical application potential of the L-Cu2+ ensemble. The L-Cu2+ ensemble was integrated with a smartphone for semi-quantification of glyphosate in a field environment under a 365 nm UV lamp.

Ratio fluorescence test strip visualized by amino-functionalized metal-organic framework for rapid sensing of glyphosate

As glyphosate is a broad-spectrum herbicide extensively used in agriculture worldwide, rapid glyphosate detection is essential for food safety and human health. Herein, a ratio fluorescence test strip was prepared and coupled with an amino-functionalized bismuth-based metal-organic framework (NH₂-Bi-MOF) that bonded with copper ion for rapid visualization and determination of glyphosate. NH₂-Bi-MOF had excellent fluorescence performance, and the copper ion, a Lewis acid, was selected as the quencher. The strong chelation of glyphosate with copper ion and its quick interaction with NH₂-Bi-MOF would turn on the fluorescence signal, thus enabling the quantitative sensing of glyphosate, with a linear range of 0.10-200 µmol L^-1, and recoveries between 94.8% and 113.5%. The system was then expanded to a ratio fluorescence test strip, in which the fluorescent ring sticker was set as a binding-in self-calibration to reduce errors from the angle and light dependency. The method realized the visual semi-quantitation referring to a standard card, as well as the ratio quantitation using the gray value output with LOD of 0.82 µmol L^-1. And the as-developed test strip was accessible, portable, and reliable, thus offering a platform for the rapid on-site detection of glyphosate and other residual pesticides.

Glyphosate Separating and Sensing for Precision Agriculture and Environmental Protection in the Era of Smart Materials

The present article critically and comprehensively reviews the most recent reports on smart sensors for determining glyphosate (GLP), an active agent of GLP-based herbicides (GBHs) traditionally used in agriculture over the past decades. Commercialized in 1974, GBHs have now reached 350 million hectares of crops in over 140 countries with an annual turnover of 11 billion USD worldwide. However, rolling exploitation of GLP and GBHs in the last decades has led to environmental pollution, animal intoxication, bacterial resistance, and sustained occupational exposure of the herbicide of farm and companies' workers. Intoxication with these herbicides dysregulates the microbiome-gut-brain axis, cholinergic neurotransmission, and endocrine system, causing paralytic ileus, hyperkalemia, oliguria, pulmonary edema, and cardiogenic shock. Precision agriculture, i.e., an (information technology)-enhanced approach to crop management, including a site-specific determination of agrochemicals, derives from the benefits of smart materials (SMs), data science, and nanosensors. Those typically feature fluorescent molecularly imprinted polymers or immunochemical aptamer artificial receptors integrated with electrochemical transducers. Fabricated as portable or wearable lab-on-chips, smartphones, and soft robotics and connected with SM-based devices that provide machine learning algorithms and online databases, they integrate, process, analyze, and interpret massive amounts of spatiotemporal data in a user-friendly and decision-making manner. Exploited for the ultrasensitive determination of toxins, including GLP, they will become practical tools in farmlands and point-of-care testing. Expectedly, smart sensors can be used for personalized diagnostics, real-time water, food, soil, and air quality monitoring, site-specific herbicide management, and crop control.