Sensitive Fluorescence Detection Research Articles

Sensitive and Discriminative Fluorescent Detection of Volatile Primary Aliphatic Diamine Vapors from Monoamines

The discriminative detection of volatile primary aliphatic diamines (VPADs) is a relevant and timely issue. This paper explores the distinctive optical features of H-type and J-type aggregates on paper-based (PB) films, namely H-PB and J-PB films, respectively, of a Lewis acidic Zn(salen)-type complex upon chemisorption of vapors of ditopic VPADs versus those of monotopic volatile amines. While volatile monotopic Lewis bases upon chemisorption give rise to mono-adducts accompanied by enhancement of the fluorescence, in contrast, VPADs act as ditopic bases forming di-adducts with distinct optical properties, leading to fluorescence quenching. This behavior enables the sensitive and discriminative detection of VPAD vapors from those of volatile monoamines. For example, for ethylenediamine (EDA), using J-PB films, sensitive detection is achieved with a LOD down to 6.6 ppm, lower than the OSHA permissible exposure limit of 10 ppm for EDA, and a linear dynamic range up to 100 ppm. Instead, H-PB films enable the detection of EDA vapors at higher ppm concentrations (up to 3000 ppm) with a linearity of up to 1000 ppm. Thus, the combination of both H-PB and J-PB films of the Zn(salen)-type complex represents a unique example of the sensitive and discriminative detection of EDA vapors in such a wide concentration range.

Bifunctional MOFs Nanozyme with Peroxidase Activity and Stimulus-responsive Fluorescent for Determination of Glyphosate.

Establishing a fast and simple method for determining glyphosate (Glyp) is crucial for safeguarding the environment and protecting human well-being. In this work, a copper benzenedicarboxylate (CuBDC) metal-organic frameworks (MOFs) with peroxidase-like property and stimulus-responsive fluorescent was prepared by binding Cu2+ with terephthalic acid (TA). The presence of Glyp can coordination with Cu2+ ion and block the peroxidase-like properties of CuBDC, thereby suppressing the catalysis the oxidation of TA into fluorescent product 2-hydroxyterephthalic acid (HTA). Based on these facts, a simple, rapid and sensitive fluorescence detection strategy for Glyp was developed. The fluorescence decreases linearly in the 0.5-10µg/mL Glyp concentration range, and the limit of detection was calculated to be 23.99 ng/mL. Furthermore, the dual-functional CuMOFs-based label-free strategy was effectively employed for detecting Glyp in river water samples. With good performance and practicability, this strategy provides a potential application in the convenient and reliable determination of Glyp in the environment.

AIE Active Polymeric Fluorescent Nanoaggregates from Glycogen for Sensitive Detection of Tetracycline.

Detection and monitoring of environmental contaminants such as antibiotic residues in aquatic environments is challenging. To address this, a variety of detection methods has been developed; out of which optical sensing using fluorescence is found as one of the most robust methods. However, most of the reported sensors are made from metal ions using tedious synthetic processes, on the other hand, optical sensors using biosourced polymers are rarely reported. Herein, an anionic glycogen functionalized aggregation induced emission (AIE) active system; NCMCTPN was prepared using a simple Schiff base condensation reaction of tetraphenylethene amine (TPENH2) and carboxymethyl cellulose dialdehyde (NCMCA) and its self-assembled polymeric nanoaggregates were explored for sensitive and selective turn-off fluorescence detection of a broad-spectrum tetracycline antibiotic, in an aqueous medium with a limit of detection of 127.5 ppb. The combination of factors such as inner filter effect and photoinduced electron transfer from the polymeric nanoaggregates to tetracycline through activation of a non-radiative decay process is possibly responsible for the high sensitivity of the fluorescent nanoprobe towards the antibiotic.

A compact, palm-sized isothermal fluorescent diagnostic intelligent IoT device for personal health monitoring and beyond via one-tube/one-step LAMP-CRISPR assay

The demand for accurate, user-friendly, and sensitive at-home nucleic acid testing solutions is rising due to occasional outbreaks of various infectious diseases and a growing desire for an improved quality of life. In response, we developed the WeD-mini, a compact, palm-sized isothermal fluorescent diagnostic IoT device that weighs just 61 g. The WeD-mini features a uniquely designed, highly sensitive optical sensing system, ultra-low power consumption, a minimalist industrial design, and an intelligent operating algorithm. It integrates real-time fluorescence detection and automatic result interpretation via a smartphone, with results seamlessly uploaded to the ‘EzDx Cloud’ for comprehensive health management and spatio-temporal disease mapping. The device supports various assays that operate at different temperatures and with varying fluorescence emission intensities, such as RPA (39 °C, low intensity), LAMP (65 °C, high intensity), and LAMP-PfAgo (65/95 °C, high intensity), while maintaining precise temperature control and exceptional fluorescence detection sensitivity. Additionally, we engineered a more thermostable AapCRISPR-Cas12b variant that operates effectively at 63 °C, enhancing compatibility with LAMP to create a robust One-Tube/One-Step LAMP-CRISPR assay. Adaptable for at-home testing of SARS-CoV-2 and influenza viruses, the WeD-mini achieved 100% sensitivity and specificity with the newly established One-Tube/One-Step LAMP-CRISPR assay. Furthermore, the WeD-mini shows potential applications in detecting meat adulteration, monitoring respiratory diseases in pets, and conducting wastewater surveillance, making it suitable for a wide range of personal and public health use cases.

Sensitive and rapid fluorescent detection of metronidazole based on stable light-emitting vinylene-linked covalent organic framework

Development of ultra-sensitive and rapid fluorescent nanoprobe for quantitative and targeted monitoring of metronidazole is of crucial practical significance, but is of great challenge. Herein, a vinyl-linked covalent organic frameworks (sp2-BNTP-COF) was fabricated via integrating the 1,3,5-tris-(4-formylphenyl) triazine with 5,5′-bis(cyanomethyl)-2,2′-bipyridine into the skeleton. As-obtained sp2-BNTP-COF exhibited excellent luminescence characteristics with an absolute fluorescence quantum yield of 8 %. However, fluorescent emission of sp2-BNTP-COF could be sharply quenched via metronidazole based on internal filtration effect. A sensitive fluorescent strategy was built for targeted monitoring of metronidazole. Furthermore, the analysis operation could be accomplished within 20 s, which was desirable for point-of-care monitoring of metronidazole. Therefore, this work not only provides a reliable method for the sensitive, rapid, and quantitative detection of metronidazole residues based on the sp2-BNTP-COF, but also paves the way for exploring stable luminescent vinyl-linked COFs materials as promising fluorescent nanoprobes for targeted monitoring of antibiotic residues.

Highly sensitive and selective ratiometric fluorescence and colorimetric detection of Cr(VI) via in situ encapsulation of green/red carbon quantum dots in zeolite

To overcome the limitations arising from non-uniform particle size and solid-state aggregation of carbon quantum dots (CQDs), a novel dual-emissive ratiometric fluorescence probe, GCQDs@SBA-15/RCQDs@SBA-15 (G-RCQDs@SBA-15), has been successfully constructed by simplifying the synthesis process through in situ synthesis of CQDs in SBA-15 to further enhance their optical properties for highly sensitive detection of Cr(VI). The probe G-RCDs@SBA-15, based on green-emission carbon quantum dots (GCQDs) encapsulated in mesoporous molecular sieves SBA-15, provides the response signal, while red-emission carbon quantum dots (RCQDs) encapsulated in SBA-15 serve as an internal reference. The probe exhibits a satisfactory limit of detection (LOD) of 0.336 μM, which is 52 % lower than GCQDs/RCQDs. Importantly, the probe shows superior selectivity in detecting Cr(VI) compared to other metal ions. The fluorescence signal ratio of the probe decreases with increasing Cr(VI) concentration, resulting in a distinct change of fluorescence color from green to red. Based on UV–vis and fluorescence lifetime analysis, Inner filter effect (IFE) is considered the primary potential mechanism for the fluorescence color transition of G-RCDs@SBA-15 following the addition of Cr(VI). G-RCQDs@SBA-15 not only inherits the excellent optical properties of GCQDs and RCQDs but also shows high fluorescence and chemical stability. Considering the sensitive photoconversion properties of G-RCQDs@SBA-15, a smartphone-based laboratory device in combination with RGB analysis software has been used for Cr(VI) detection by directly capturing and analyzing fluorescence images. In addition, the sensing system is validated in the actual lake water samples, exhibiting recoveries from 83.3 % to 96.3 %, indicating its excellent practicality for Cr(VI) detection in real samples.

Fabrication and Fluorescence Analysis of Rhodamine Dyes in Polycarbonate Serpentine Microfluidic System.

The synthesis of rhodamine dyes (R6G and R1010) and their fluorescence characterization within polymer-based microfluidics, offers an exciting and novel approach in materials science and chemical analysis. This work investigates the emission of polycarbonate substrates (PC) by UV-visible. The ablation threshold (16mj.sec-1) of PC at 193nm wavelength after that ablation process continued to produce microfluidic serpentine channels on PC by using G-Code. The fluorescence characteristics of Rhodamine 6G and Rhodamine 101 are investigated. Absorption and emission at peak wavelength were analyzed against R6G and R101 concentrations. Furthermore, the refractive indices of both R6G and R101 vis concentrations are examined. As a result at low concentrations, there was the highest overlapping, and at high concentrations, there was the smallest overlapping. R101 showed better photostability and a more consistent diffusion, whereas R6G had a faster diffusion and stronger fluorescence intensity. These differences were caused by the different molecular structures of the dyes and their interactions with the PCmicrochannel. Incorporating R6G and R101 dyes into a polycarbonate PC microfluidic chip would enhances both the resolution and sensitivity of fluorescence detection. The limited microfluidic setup facilitates ultra-high-resolution investigation and minimizing sample volumes, making it suitable for applications requiring precise measurements. The innovation relies on the utilization of the unique fluorescence characteristics of R6G (Rhodamine 6G) and R101 (Rhodamine 101) dyes to enhance the performance of polycarbonate microfluidic devices. R6G has high fluorescence quantum yield and stability, rendering it suitable for sensitive detection, while R101 offers superior brightness and improved resistance to photobleaching. Incorporation of these dyes into polymeric microfluidics improves sensitivity and facilitates real-time, dynamic sample analysis. This method offers a portable, economical solution with high-throughput capabilities, greatly enhancing both analytical and process accuracy across a variety of applications.

Synthesis of P-Rich Carbon Quantum Dots for Sensitive Fluorescent Detection of 2-Methylimidazole.

Using o-phenylenediamine as carbon source and phytic acid as phosphorus source, two P-rich carbon quantum dots RCDs and BCDs were synthesized successfully by changing the reaction temperature and time of hydrothermal method. It was found that RCDs with red emission could realize sensitive detection of 2-methylimidazole, and 2-methylimidazole had no obvious quenching effect on BCDs with blue emission, which made RCDs a sensitive, quick and selective fluorescence sensor for 2-methylimidazole detection. Under the optimal experimental conditions, the fluorescence intensity of RCDs decreased with the increasing of 2-methylimidazole concentration. The detection of 2-methylimidazole concentration by the carbon quantum dots sensor showed a good linear relationship in the range of 5 ~ 110 µM, and the low detection limit was 0.61 µM (S/N = 3). The sensor is able to detect 2-methylimidazole in lake water, enabling the application of real samples. The results show that this work provides a simple fluorescence method to detect 2-methylimidazole in water.

Construction of white light “On-Off-On” supramolecular materials for relay detection of Fe3+ and H2PO4−

White light materials are of great interest due to their wide potential applications in lighting devices, displays and probes. Herein, a novel bis-component white light-emitting supramolecular polymer gel TBG was facilely constructed from tripodal pyridine amides and tripodal imidazole by host–guest self-assembly process. Interestingly, the TBG exhibits strong aggregation-induced emission and can be used for highly efficient and sensitive fluorescence detection of ions (Fe3+ and H2PO4−) via the fluorescence “On-Off-On” pathway. The limits of lowest detection limits (LODs) for Fe3+ and H2PO4− were calculated to be 10.08 nM and 21.87 nM, respectively. Meanwhile, the xerogel of TBG could adsorb and separate Fe3+ from aqueous solutions, and the adsorption rate reached 99 %. In addition, a thin film based on the TBG could be used as a convenient test kit for the fluorescence detection of Fe3+ and H2PO4−.

Ionophore-based nanospheres enable selective and sensitive fluorescence detection of copper ions

A novel ionophore-based fluorescent nanosensor has been successfully fabricated for the sensitive and selective detection of Cu2+ ions. The nanosensor was constructed through self-assembly of amphiphilic block copolymers, incorporating elesclomol as a Cu2+ ionophore and long-chain dialkylcarbocyanines (DiD) as a fluorescent dye. This design exhibits an "ON/OFF" fluorescence response, where Cu2⁺ ions are selectively sequestered within the nanosensors, resulting in fluorescence quenching of DiD. This strategy enables rapid and highly selective Cu2⁺ sensing with remarkable fluorescence quenching efficiency (up to 93.5 %) and an exceptionally low detection limit of 28.6 nM. The linear detection range extends over two orders of magnitude (0.05–10 μM). Furthermore, the feasibility of this nanosensor for practical applications was confirmed through successful determination of Cu2+ in real water and beer samples, with excellent recovery rates. This nanosensor offers advantages of simplicity, rapidity, and cost-effectiveness, holding significant potential for sensitive and selective Cu2+ detection in various biological and environmental samples.

Sensitive and selective fluorescence detection of acetamiprid using oxidized single-walled carbon nanohorns and cryonase-assisted signal amplification

To address the low accuracy of pesticide residue detection in traditional Chinese medicine, we developed a biosensor for acetamiprid detection. First, an oxidized single-walled carbon nanohorn capable of adsorbing and quenching fluorescence was prepared. Second, a novel fluorescence sensing system was constructed based on this nanomaterial. The detection performance of the sensor system was evaluated, which revealed that fluorescence quenching by the biosensor was primarily due to the adsorption of the aptamer by the nanomaterials. Optimal conditions were found to be a nanomaterial mass concentration of 800 ng/mL and an incubation time of 70 min, which resulted in the best fluorescence response. Under these optimal conditions, the system was used to detect acetamiprid residues in traditional Chinese medicine. The fluorescence intensity showed a strong linear relationship with acetamiprid concentration, with a correlation coefficient of 0.9985 and a detection limit of 6.33 ng/mL. In the sample test, the biosensor demonstrated high accuracy, with good average recovery rates and low relative standard deviation. The system showed excellent selectivity and detection performance, with no interference from other pesticides.

Insights into the Mechanisms of Single-Photon and Two-Photon Excited Surface Enhanced Fluorescence by Submicrometer Silver Particles.

Surface enhanced fluorescence (SEF) based on noble metal nanoparticles is an effective means to achieve high sensitivity in fluorescence detection. Currently, the physical mechanism behind enhanced fluorescence is not fully understood. This paper measures the fluorescence signals of Dihydroporphyrin f methyl ether (CPD4) under both single-photon and two-photon excitation based on submicrometer silver particles with rough morphologies, achieving enhancement factors of 34 and 45 times, respectively. On this basis, by combining the radiative field characteristics produced by the silver particles, a stimulated radiation model of molecules is established to elucidate the changes in the molecular photophysical process when influenced by silver particles. Moreover, the fluorescence lifetime of the molecules was measured, showing that the presence of silver particles induces an increase in the molecular radiative decay rate, causing the fluorescence lifetime to decay from 3.8 ns to 3 ns. The results indicate that the fluorescence enhancement primarily originates from the submicrometer silver particles' enhancement effect on the excitation light. Additionally, the fluorescence signal emitted by the molecules couples with the silver particles, causing the local surface plasmon resonances generated by the silver particles to also emit light signals of the same frequency. Under the combined effect, the fluorescence of the molecules is significantly enhanced. The findings provide a theoretical foundation for understanding the fluorescence enhancement mechanism of silver particles, adjusting the enhancement effect, and developing enhanced fluorescence detection devices based on submicrometer silver particles, holding significant practical importance.

Stochastic bipedal dual-DNA walkers for fast and sensitive detection of apurinic/apyrimidinic endonuclease1 and inhibitor screening

DNA walkers have emerged as a powerful tool in various biosensors, enabling the detection of low-abundance analytes with their precise programmability and efficient signal amplification capacity. However, many existing approaches are hampered by limited reaction kinetics. Herein, we designed a stochastic bipedal dual-DNA walkers (SBDW) that can traverse at high speed on AuNP-based three-dimensional (3D) tracks powered by Exo III. The SBDW exhibited superior reaction kinetics and are up to least 2.25 times faster than traditional DNA walkers, reaching a plateau within 40 min. This advancement allows for rapid and highly sensitive fluorescence detection of a significant base excision repair enzyme of APE1 with a detection limit of 0.001 U/mL. In comparison to traditional DNA walkers, this platform enables highly sensitive and specific APE1 assays in cell lysate and facilitates rapid and accurate screening of APE1 inhibitors. Given its rapid, sensitive, specific, and reliable analysis features, the strategy shows great promise in drug discovery and clinical diagnosis.

Rapid assessment of acetophenone using an anti-interfering triple-emission Ln3+-functionalized HOF@MOF sensor

The development of high-performance sensors for rapidly detecting acetylacetone (AP) in water samples is necessary because its release into the environment can result in many vital problems for human health and environment. Herein, we first designed a hybrid by integrating HOF with ZIF-8 through a sequential growth strategy. By separately introducing blue-emitting SiQDs and green- and red-emitting Tb3+ and Eu3+ into ZIF-8 and HOF, the resultant ZIF-8@SiQDs@HOF@Eu3+@Tb3+ comprised three emission peaks at 484, 545 and 620 nm, all of which could be employed as switch-off responsive peaks to low concentrations of AP with a detection limit of 0.79 ppm. However, in environments with high concentrations of AP, a turn-on signal at 484 nm was observed. Thereupon, the ratiometric fluorescence intensity of the ternary emission varied within different concentration ranges, accompanied by the fluorescence color evolution from red to salmon to plum to purple to final blue. Moreover, a portable sensing film was fabricated for rapid warning, sensitive and visual determination of AP in complicated environments. Therefore, this triple-emission sensor with wide color variations and strong anti-interference advantages could promote further research to improve the selectivity, sensitivity and inherent self-correction of multimodal fluorescence detection and the ease of sensing operation.

The potential of indocyanine green fluorescence detection in surgical cut margin of breast conserving surgery.

Fluorescence-guided surgery (FGS) is a cutting-edge technology that uses near-infrared (NIR) fluorescence imaging to guide surgeons in surgery. Indocyanine green (ICG) is a fluorescent dye, which can be used for in vivo imaging of tumor cells. We aimed to explore the use of ICG fluorescence-guided technology as a rapid intraoperative margin assessment method for breast cancer surgery. In addition, we also compared the dose selection of ICG. This was a non-randomized prospective cohort study. Data were collected between August 2021 and October 2022 in the Division of Breast Surgery, Department of General Surgery, Nanjing Drum Tower Hospital, the Affiliated Hospital of Medical School, Nanjing University. Upon specimen removal, tumor margins were immediately analyzed by ICG fluorescence detection and then sent to the pathology department for intraoperative frozen section analysis and subsequent routine pathological examination. Abnormal margin rates were calculated and compared using intraoperative frozen section analysis and under the guidance of ICG fluorescence. The study included 69 cases of breast cancer patients who underwent tumor resection assisted by ICG fluorescence-guided technology, including 18 patients with a 0.5 mg/kg dose and 51 patients with a 1.0 mg/kg dose. According to the study findings, the ICG test achieved a sensitivity of 81.82% and a specificity of 75.82%. At a dose of 0.5 mg/kg, the sensitivity was 66.67% whereas the specificity was 93.33%. At the dose of 1 mg/kg, the sensitivity was 87.5%, and the specificity was 74.42%. Similarly, for intraoperative frozen section analysis, the sensitivity was 81.82%, but the specificity was enhanced to 94.83%. Positive surgical cut margin was not identified in 2/69 by ICG fluorescence and frozen section analysis respectively. The sensitivity of ICG fluorescence detection is comparable to that of frozen section analysis, but the specificity is poor. The sensitivity increased and the specificity decreased at 1 mg/kg compared to the 0.5 mg/kg dose. ICG fluorescence can be used as a supplementary tool for frozen section analysis. These findings support further development and clinical performance assessment of ICG fluorescence.

Dual-driven AND molecular logic gates for label-free and sensitive ratiometric fluorescence sensing and inhibitors screening

Due to the complexity of regulatory networks of disease-related biomarkers, developing simple, sensitive, and accurate methods has remained challenging for precise diagnosis. Herein, an “AND” logic gates DNA molecular machine (LGDM) was constructed, which was powered by the catalytic hairpin assembly (CHA). It was coupled with dual-emission CdTe quantum dots (QDs)-based cation exchange reaction (CER) for label-free, sensitive, and ratiometric fluorescence detection of APE1 and miRNA biomarkers. Benefiting from synergistic signal amplification strategies and a ratiometric fluorometric output mode, this LGDM enables accurate logic computing with robust and significant output signals from weak inputs. It offers improved sensitivity and selectivity even in cell extracts. Using dual-emission spectra CdTe QDs, with a ratiometric signal output mode, ensured good stability and effectively prevented false-positive signals from intrinsic biological interferences compared to the approach relying on a single signal output mode, which enabled the LGDM to achieve rapid, efficient, and accurate natural drug screening against APE1 inhibitors in vitro and cells. The developed method provides impetus to streamline research related to miRNA and APE1, offering significant promise for widespread application in drug development and clinical analysis.

Structural distinction and highly sensitive fluorescent detection properties of Cd-based multifunctional sensors with three flexible isomers

Many environmental pollutants are found and need to be detected and treated with the rapid development of industry. Three novel Cd (II) coordination polymers (Cd-CPs) (1–3), with the formula of [Cd(2-HDBB)(4,4′-bbpy)](1), [Cd(3-HDBB)(4,4′-bbpy)](2) and [Cd(4-HDBB)(4,4′-bbpy)0.5·2H2O](3) based on three soft organic isomers: n-(3,5-dicarboxylato benzyloxy) benzoic acid (n = 2, 3 or 4-H3DBB), with one linear N-donor ligand 4,4′-bis(imidazolyl) biphenyl (4,4′-bbpy) have been synthesized hydrothermally and characterized in detail. The significant structural differences are both coordination polymers 1 and 2 featuring two-dimensional networks, while 3 with 1D ladder-like chain due to the change of isomers. Despite structural differences, the series of Cd-CPs exhibits similar fluorescence sensing properties. Fluorescent sensing properties exhibit all the Cd-CPs have been discovered to detect Fe3+, Cr2O72−, tetracycline (TET) and nitrobenzene (NB) selectively and sensitively with the low detection limits, respectively. The results of theoretical calculation verified the fluorescence detection mechanism of NB by these cadmium complexes. Therefore, the Cd-CPs might be used as an excellent multi-functional luminescent sensor in the future.

Sensitive fluorescence detection of miRNA-124 in cardiomyocytes under oxidative stress using a nucleic acid probe

MicroRNAs (miRNAs) are small noncoding RNAs of 18–25 bases. miRNAs are also important new biomarkers that can be used for disease diagnosis in the future. Studies have shown that miR-124 levels are significantly elevated during acute myocardial infarction (AMI) and play a key role in the cardiovascular system. A variety of methods have been established to detect myocardial infarction-related miRNAs. However, most require complex miRNA extraction and isolation, and these methods are virtually undetectable when RNA levels are low in the sample. It may lead to biased results. Thus, it is necessary to develop a technique that can detect miRNA without extracting it, which means that intracellular detection is of great significance. Here, we improved the traditional silicon spheres and obtained a biosensor that could effectively capture and detect specific noncoding nucleic acids through the layer-by-layer assembly method. The sensor is protected by hyaluronic acid so it can successfully escape the lysosome into the cell and achieve detection. With the help of a full-featured microplate reader, we determined that the detection limit of the biosensor could reach 1 fM, meeting the needs of intracellular detection. At the same time, we prepared an oxidative stress cardiomyocyte infarction model and successfully captured the overexpressed miR-124 in the infarcted cells to achieve in situ detection. This study could provide a new potential tool to develop miRNAs for sensitive diagnosis in AMI, and the proposed strategy implies its potential for biomedical research.

A ratiometric fluorescence sensing system for rapid detection of glyphosate in miscellaneous beans

To establish a ratiometric fluorescence sensing system for the detection of glyphosate, nitrogen-sulfur doped carbon quantum dots nano-fluorescent probe was prepared by one-step hydrothermal method. At an excitation wavelength of 360 nm, the emission peak with maximum fluorescence intensity was obtained at 470 nm. The generation of 2.3-diaminophenazine by o-phenylenediamine oxidation produces a new fluorescence emission peak at 570 nm and a decrease in fluorescence at 470 nm. The fluorescence peaks at 470 and 570 nm form a ratio state. In the presence of glyphosate, reduces the oxidation of 2.3-diaminophenazine, this results in enhanced fluorescence at 470 nm and weakened fluorescence at 570 nm. Under the best conditions, the ratiometric fluorescence sensing system has good selectivity, the linear at glyphosate concentrations of 0.005–10 µg/mL, the limit of detection was 2.88 µg/kg, the limit of quantitation was 4.07 µg/kg. In addition, it is worth mentioning that this developed sensing system has shown good detection performance in 10 miscellaneous samples, the simple, efficient, and highly sensitive ratiometric fluorescence detection sensing strategy is provided.

Highly selective fluorescence turn-on sensor for·thiol compounds detection

As a kind of commonly-used synthetic materials for many pesticides, thiol compounds, once being leaked, can cause serious harm to the environment and humans. Therefore, the efficient detection of thiol compounds is essential. In this study developed a turn-on fluorescent probe (Cu@Zn-CP) for the highly sensitive fluorescence detection of thiol compounds. The probe was constructed based on a zinc coordination polymer (Zn-CP), whose fluorescence was quenched through the effective doping of Cu2+ ions. After the introduction of methyl thioglycolate (MTC), a rapid fluorescence turn-on response was generated within 90 s with a low detection limit of 23 ppb. Even after being reused for five cycles, the sensor maintains excellent detection performance and demonstrates good recyclability. It can also detect MTC in river water, with a spike recovery rate between 98–103 %. Furthermore, the designed Cu@Zn-CP exhibits good universality for detecting multifarious thiol compounds, including L-cysteine, glutathione, monothioglycerol, and 2-hydroxy-1-ethanethiol. This result provides a potential recyclable fluorescent sensor for thiol compounds.