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Bendiocarb, a type of carbamate pesticide, plays a crucial role in controlling a wide range of pests. Due to its harmful impact on humans and the environment, the need for inexpensive, portable, efficient and easy-to-use analytical devices has become essential. In this study, an environmentally friendly paper-based analytical device (PAD) with a chemiluminescence (CL) sensing platform was investigated and characterized for the facile, reliable and sensitive detection of the bendiocarb pesticide. It is based on the enhancing effect of SO32- on the CL reaction of sulfur, nitrogen-doped carbon quantum dots (S,N-CQDs)-KMnO4 in acidic media. According to the experiments, S,N-CQDs and SO32- both are oxidized by KMnO4 to generate (S,N-CQDs*) and (SO2*) in their excited states, emitting at 510 nm. This indicates that an energy transfer process is taking place from SO2* to S,N-CQDs, resulting in a remarkably intensified CL emission. Interestingly, another emission was also observed around 660 nm contributing to about 20 to 25% of the total CL emission. This emission is related to the Mn2+* species produced by reducing MnO4-. The established multi-emission CL system was tested for analytical applications. Under optimal experimental conditions, a good linear relationship was observed between the bendiocarb concentration and the CL intensity of the established CL system. The linear detection range was 0.1-10 μg mL-1, with a limit of detection (LOD) of 0.02 μg mL-1. Finally, the method was successfully applied for the measurements of bendiocarb in water and juice samples. The obtained recovery values (97.5-105.5) verified the suitable accuracy of the results.

Herein, high performance peroxidase-like activity of zinc and cobalt bi-metal metal-organic framework (ZnCo MOF) is reported and applied for the sensitive measurement of atropine. ZnCo MOF was synthesized by the reaction of 2-methylimidazole with Zn and Co (II) cations in aqueous media. The colorimetric and fluorometric experiments were applied to investigate the catalytic activity of obtained MOF, using o-phenylenediamine (OPD) and terephthalic acid (TA) peroxidase substrates, respectively. The results demonstrated the more efficient mimetic behavior of ZnCo MOF compared with common Zn or Co MOFs. Besides, it was found that atropine hindered the catalytic action of ZnCo MOF and this effect was intensified by increasing the atropine concentration. So, it was considered to design a sensitive analytical assay for atropine detection. To assure a high specific recognition, molecularly imprinted polymer (MIP)-based extraction using magnetic graphene oxide supports was applied to extract atropine before its determination. The combination between the high specific extraction and great catalytic activity of ZnCo MOF led to the ultrasensitive and reliable determination of atropine. The best linear range of calibration graph was achieved using fluorometric detection system for 0.1–45 ng mL−1 atropine concentrations, and detection limit (3Sb/m) was 27 pg mL−1. The relative standard deviations (RSD %) for the determination of 1, and 10 ng mL−1 atropine (n = 5) were 2.13% and 3.08%, respectively. The explained fluorometric assay was examined for the measurement of atropine in biological fluids (Recoveries were in the range of 95.90–103.57%), and the results were validated by an official method.

Here, a specific and reliable fluorometric method for the rapid determination of amikacin was developed based on the molecularly imprinting polymer (MIP) capped g-C3N4 quantum dots (QDs). g-C3N4 QDs were obtained by facile and one-spot ethanol-thermal treatment of bulk g-C3N4 powder and showed a high yield fluorescence emission under UV irradiation. The MIP layer was also created on the surface on QDs, via usual self-assembly process of 3-aminopropyl triethoxysilane (APTES) functional monomers and tetraethyl ortho-silicate (TEOS) cross linker in the presence of amikacin as template molecules. The synthesized MIP-QDs composite showed an improved tendency toward the amikacin molecules. In this state, amikacin molecules located adjacent to the g-C3N4 QDs caused a remarkable quenching effect on the fluorescence emission intensity of QDs. This effect has a linear relationship with amikacin concentration and so, formed the basis of a selective assay to recognize amikacin. Under optimized experimental conditions, a linear calibration graph was obtained as the quenched emission and amikacin concentration, in the range of 3–400 ng mL−1 (4.4–585.1 nM) with a detection limit of 1.2 ng mL−1 (1.8 nM). The high selectivity of MIP sites as well as individual fluorescence properties of g-C3N4 QDs offers a high specific and sensitive monitoring method for drug detection. The method was acceptably applied for the measurement of amikacin in biological samples.

Herein, a novel metal-organic framework (MOF) based nanocomposite with efficient catalytic behavior is reported including flake-like copper (II) MOF (CuMOF) and graphitic C3N4 nanosheets (g-C3N4). The g-C3N4@MOF nanocomposite was simply prepared by solvothermal synthesis of CuMOF in the presence of g-C3N4. The characterization analyses using scanning electron microscopy (SEM), X-ray diffractometry (XRD) and some other techniques demonstrated a nano-porous flake-like structure for the synthesized CuMOF, which enveloped the g-C3N4 nanosheets. Furthermore, the investigation of catalytic behavior of synthesized nanomaterial was implemented on H2O2 based reactions. The fluorometric and colorimetric experimentations illustrated that the accompanying of g-C3N4 with CuMOF had a remarkable positive effect on the catalytic behavior of obtained g-C3N4@MOF. This effect was described based on the improved affinity of nanocomposite to adsorb H2O2 and also synergistic action of its components on the dissociation of H2O2 to hydroxyl radicals. Finally, the analytical application of high catalytic activity of new g-C3N4@MOF was designed for the rapid and simple measurement of glucose in blood. After the enzymatic oxidation of glucose, the fluorometric method was applied for the analysis of produced H2O2 using terephthalic acid as peroxidase substrate. The system led to the ultrasensitive glucose determination in the concentration range of 0.1–22 μM, with a detection limit (3S/m) of 59 nM.

The less stability and robustness, high-cost preparation and maintenance of natural enzymes, especially horseradish peroxidase (HRP), challenge researchers to introduce effective alternatives for their wide applications. Herein, the peroxidase-like activity of AuCu bimetal nanoclusters (AuCu NCs) was investigated in the rhodamine B-H2O2 chemiluminescence (CL) system. AuCu NCs could effectively catalyzed the CL reaction, and a high intensive emission intensity was obtained. A comprehensive study was implemented to examine the effects of different stabilizing ligands and Au/Cu ratios on the catalytic activity of obtained NCs. Comparison experiments were also expanded to include Au and Cu nanoparticles with different sizes, too. The results verified the superior catalytic activity of penicillamine-stabilized AuCu bimetal NCs containing 50% cu atoms. Finally, the analytical application of the introduced CL system showed great sensitivity for H2O2 detection, with a detection limit of 0.13 nM. Moreover, the developed CL method was able to measure glucose and xanthine over wide concentration ranges of 0.1 - 400 and 0.1 - 200 μM, respectively. The method also indicated satisfactory reliability, confirmed by standard reference materials.

Specific recognition of organophosphate pesticides (OPs) is a significant challenge for analytical researchers. Herein, surface imprinted terbium-based luminescent metal-organic framework (MOF-76) are presented as a highly specific probe for the measurement of chlorpyrifos (CP). A mesoporous molecular imprinted polymer (mMIP) layer was generated on the surface of nano-sized MOF-76 using CP, as template. The resulting mMIP-capped MOF-76 (mMIP@MOF-76) contained specific sites for adsorption of CP molecules, guaranteeing the selectivity of the designed probe. The high porosity of rod-shape MOF-76, as well as the mesoporous structure of the MIP layer improved the diffusion process and caused the high sensitivity of the probe. The detection process is based on the remarkable quenching effect of CP on the fluorescence emission of mMIP@MOF-76. Plotting the CP concentration against the fluorescence intensity (λex = 285 nm and λem = 544 nm) gave a linear curve in the concentration range 10–1000 ng mL−1 CP, with 3.41 ng mL−1 limit of detection. The designed probe was utilized for CP determination in fruit juice and environmental samples. The combination of the stable MOF-based support, as well as its remarkable fluorescence features and specific MIP sites, led to a highly selective and ultrasensitive detection system. Graphical abstract

Point-of-care (POC) diagnostic devices play significant roles in delivering vital surveillance information and providing proper and timely care to patients. There is a challenge in the development of new diagnostic tools to overcome their current shortcomings in terms of cost issues, accuracy and performance. Herein, a highly efficient paper-based analytical device based on a 2D metal-organic framework (MOF) has been reported for the colorimetric/fluorometric monitoring of glucose. Because of the inherent bifunctional activity of cobalt-terephthalate MOF (CoMOF) nanosheets, great improvements were made to the stability and performance of glucose oxidase (GOX) and to its catalytic effect on the reaction of o-phenylenediamine (OPD) and H2O2. The exceptional behavior of 2D CoMOF, along with a precise smartphone readout, led to the rapid and sensitive colorimetric/fluorometric detection of glucose in biological samples. Paper modified by CoMOF and GOX was stable for a long time, and a yellow-brown color and a high fluorescence emission were observed after the addition of a low volume of sample and OPD solutions. The probe showed a wide linear effectiveness range of 50 μM-15 mM, with colorimetric and fluorometric detection limits of 16.3 and 3.2 μM, respectively. Despite its great simplicity, the developed probe showed high performance and accuracy for the quantification of glucose.

A microfluidic device for simultaneous analysis of total flavonoids and total phenolic acids is presented for the first time. The process was based on the utilization of magnetic zinc-imidazole frameworks (ZIF-4), as a highly efficient media for on-line separation of phenolic acids and flavonoids, which were subsequently detected by a sensitive chemiluminescence (CL) method. Acrylate-based polymeric microchips containing a separation column (12.5 mm length, 3 mm width and 1 mm depth) were fabricated using a 3D-printer, and magnetic ZIF-4 was fixed into the column. The high porosity of the magnetic ZIF-4 made it a suitable adsorbent, guaranteeing an effective separation. The detection limits were in the range of 0.04–0.10 µg mL−1 with relative standard deviation values of (2.19–4.38%). The system was successfully applied for the analysis of flavonoids and phenolic acids in tea and honey samples. The recovery was from 95.4 to 104.1%, indicating a good accuracy of the developed method.

Developing a novel non-enzyme mimetic in biosensors is of great significance. Here, a synergetic peroxidase-like activity was disclosed for mixed MoS2 quantum dots (MoS2 QDs) and graphene quantum dots (GQDs). The high catalytic effect of this mixture was studied on the chemiluminescence system. It was observed that the simultaneous presence of MoS2 QDs and GQDs had a powerful enhancing effect on the chemiluminescence (CL) emission of rhodamine B (RB)-H2O2 reaction. MoS2 QDs and GQDs mixture (prepared with a ratio of 3:2) showed a superior catalytic activity when compared to each of the constituents. A linear relationship was acquired between the CL emission intensity and H2O2 concentration in the range of 1.5-460nmolL-1. On the other hand, since the enzymatic oxidation of cholesterol leads to the production of H2O2; the offered CL system was examined to detect cholesterol after its oxidation by cholesterol oxidase (ChOx) enzyme. Herein, a further improvement was achieved by MoS2 nanosheets. The MoS2 nanosheets increased the performance of ChOx in cholesterol oxidation process. The obtained results confirmed a highly selective and sensitive determination of cholesterol concentration in a linear dynamic range of 0.08-300µmolL-1, with a detection limit (3S) of 35nmolL-1. The developed method was successfully applied for the detection of cholesterol level in human serum samples.

A novel and powerful chemiluminescence (CL) system was developed based on the promoting effect of graphene quantum dots (GQDs)/bisulfite on rhodamine B (RB)-H2O2 CL reaction. GQDs were synthesized by a simple, green and affordable approach and characterized using their distinctive absorption and emission patterns. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) transmission and transmission electron microscopy (TEM) analysis were implemented for complementary studies on the structural and morphological characteristics of GQDs. The simultaneous enhancing effect of the synthesized GQDs and bisulfite on the CL emission of RB-H2O2 reaction provided a more strong and efficient CL system. The mechanism of CL emission was described. Furthermore, HCHO as a well-known pollutant, could selectively diminish the developed CL system. This effect was linearly proportional to HCHO concentration which turned the introduced CL system to a susceptible chemosensor for HCHO. Under the optimized operational condition, the linear changing of CL response was obtained in HCHO concentration ranges of 0.02–5 μg L−1 and 5–11 μg L−1, with limit of detection (LOD) and quantification (LOQ) of 6 ng L−1 and 20 ng L−1, respectively. Ultimately, presented CL chemosensor was served as an accurate tool for determination of formaldehyde concentration in water and wastewater samples.

Herein, a novel paper-based chemiluminescence (CL) assay is reported using a smartphone readout for on-site and reliable analytical applications. The CL system was based on the high-performance improving effect of cobalt-imidazole metal-organic framework (CoMOF) on luminol-hydrogen peroxide (H2O2) CL emission. The CoMOF was grown on paper and used as a support for the CL reaction, which led to an intense CL emission and good reproducibility. More importantly, the stability of luminol, as the CL reagent, was greatly improved in the presence of CoMOF. This high stability, along with the high-yield CL emission, makes the device highly suitable for commercialization. Furthermore, using a smartphone as the detector for the developed device made the process easier and more accessible for public usage. In this work, the new paper-based CL smartphone device was used for the detection of the total phenolic content of food samples. Phenolic compounds (PC) are hydroxyl radical scavengers that can effectively quench the CL emission of the luminol–H2O2–CoMOF system. After optimizing the reaction conditions, the system could detect PC at the μg mL−1 level. Detection limits of 0.12, 0.28, 0.46, 0.85, and 1.23 μg mL−1 were obtained for gallic acid, quercetin, catechin, kaempferol, and caffeic acid, respectively. This work is the first report on the practical application of smartphone CL assays for the estimation of PC. The proposed assay is an easy-to-use, low-cost, portable, and suitable assay for on-site screening purposes.

In this work, an attempt was made to develop a powerful method for the determination of cefixime, as a widely used cephalosporin antibiotic. The method was based on the facile extraction and preconcentration of cefixime using Zn metal–organic framework doped magnetic graphene oxide composite (ZnMOF@MGO), followed by its determination using high-performance liquid chromatography (HPLC). The high surface area, great stability, and distinct features of the new adsorbent made it ideal for very efficient interactions with analyte molecules. ZnMOF@MGO was able to effectively extract cefixime from the complex matrix of real samples. Furthermore, the application of the magnetic-solid phase extraction (MSPE) process provided a low-cost and simple extraction process with a reduced extraction time. The combination of a high-performance extraction with a potent HPLC system resulted in a highly sensitive and selective analytical detection method. The method was able to detect cefixime in a linear range of 0.5–130 ng mL−1, with a detection limit of 0.11 ng mL−1, no important interfering effect was caused by other examined drugs. It was examined for the analysis of cefixime content of pharmaceutical and biological samples and acceptable recovery values were obtained.

Two highly sensitive and selective methods based on fluorescence (FL) and chemiluminescence (CL) emissions of 8-mercaptoquinoline-capped CdS quantum dots (MCQ-CdS QDs) were described for the determination of copper (II) after it’s preconcentration. High fluorescent CdS QDs, synthesized in an aqueous medium, generated a relatively intense CL emission in the presence of potassium permanganate as an oxidant. Furthermore, low quantities of copper (II) ions showed a remarkable quenching effect on both of the CL and FL emissions of MCQ-CdS QDs. Based on this effect, two selective and simple methods were established for Cu2+, and the detection limits of 0.28 and 0.026 ng mL−1 were obtained for the FL and CL methods, respectively. Also, due to the high propensity of MCQ to Cu2+, good selectivity was obtained and no sensible interfering effects from other metal ions were observed. To more sensitize the developed method, an efficient preconcentration process was designed based on the high-yield ultrasound-assisted temperature-controlled ionic liquid dispersive liquid–liquid microextraction (UA-TIL-DLLME) method. Under the optimum conditions, the extracted Cu2+ showed a suppressing effect on the FL and CL emissions of CdS QDs proportional to its initial concentration over the ranges of 0.008–1.4 and 0.001–1.4 ng mL−1, respectively. The limits of detection of 3.7 and 0.37 pg mL−1, respectively, were also achieved. The established methods showed great features and were satisfactorily applied to the monitoring of ultratrace Cu2+ in some different environmental samples.

Two novel, simple and sensitive fluorescence (FL) and chemiluminescence (CL) procedures were established for methamphetamine (MA) determination. l -Cysteine capped CdS quantum dots (QDs) were synthesized by a simple one-step hydrothermal procedure and characterized by their specific absorption and emission spectra. The structure and morphology of QDs were investigated using X-ray diffraction (XRD) pattern, transmission electron microscopy (TEM) and scanning electron microscope (SEM). It is found that the prepared CdS QDs have a remarkable promoting effect on rhodamine B (RhoB)-cetyltrimethylammonium bromide (CTAB)-KMnO4 CL reaction. Based on this influence, a new efficient CL system was introduced. On the other hand, the FL and CL emission intensities of QDs undergo a remarkable alteration in the presence of low quantities of MA. The optimization of the effective parameters was performed and the high sensitivity was obtained in 0.013 mol L− 1 Tris buffer at pH = 6.5 with 0.2 mmol L− 1 CdS QDs. In this condition, MA had a notable linear quenching effect on the FL emission of QDs which formed the basis of simple FL probe for sensitive determination of MA in the range of 6.7–400 ng mL− 1. Also, MA can remarkably enhance the intensity of developed CL system. Under the optimized conditions (0.15 mol L− 1 H2SO4, 0.15 mmol L− 1 RhoB, 0.13 mmol L− 1 QDs, 0.3 mmol L− 1 CTAB and 0.4 mmol L− 1 KMnO4), the improved CL intensity was proportional to the concentration of MA in the range of 0.25–125 ng mL− 1 with limit of detection (3 s) of 0.086 ng mL− 1, which is over 20 times better than the introduced FL method. The developed FL and CL methods were exploited for accurate determination of MA in human urine samples.

A novel and efficient chemiluminescence (CL) probe was developed based on the sensitizing effect of graphene quantum dots (GQDs) on the morin–KMnO4 CL reaction for cypermethrin (CYPM). GQDs were prepared using an economic and green procedure, and characterized with the help of their distinctive emission and absorption patterns. Advanced morphological and structural investigations of the GQDs were conducted using X-ray diffraction (XRD), Fourier transform infrared (FT-IR), and transmission electron microscopy (TEM) analysis. The synthesized GQDs showed a remarkable promoting influence on the CL emission of the morin–KMnO4 reaction in the presence of cetyltrimethylammonium bromide (CTAB), offering a powerful and efficient new CL system. The mechanism of the sensitized CL system was described based on the electron transfer processes. In addition, CYPM, as a potent pollutant, could linearly suppress the emission of the KMnO4–morin–CTAB–GQD CL system. This turned the introduced CL system into a susceptible chemosensor for CYPM. Under the selected operating conditions, a linear relation of the CL response was attained over the CYPM concentration range of 0.3–22.0 mg L−1 with a limit of detection (LOD) of 0.08 mg L−1. The proposed method showed good features for the determination of CYPM and was satisfactorily employed for CYPM evaluation in real environmental water samples.

Developing a selective and sensitive tool for recognizing 2,4,6-trinitrotoluene (TNT) is of great importance from both security and contamination viewpoints. Here, a novel molecularly imprinted polymer (MIP) based chemiluminescence (CL) assay is described for the determination of TNT in environmental samples. ZnO quantum dots (QDs) were synthesized using a simple and economical process and applied as efficient supports for the MIP layer. The MIP layer was produced using (3-aminopropyl)triethoxysilane (APTES) as a monomer and tetraethoxysilane (TEOS) as a cross-linker, in the presence of TNT as the template. The MIP-labeled ZnO QD composite (MIP@QDs) was characterized using photoluminescence emission, X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). The prepared composite showed a remarkable promoting effect on the weak chemiluminescence emission of an alkaline permanganate–rhodamine B (RB) system. This effect was described based on the catalytic activity of the composite. Moreover, in the presence of TNT, its molecules were adsorbed onto specific sites of the MIP and placed near the QDs, resulting in a noticeable decrease in the CL intensity of the KMnO4–RB–MIP@QDs system. Based on this effect, a selective and highly sensitive CL assay was introduced for the TNT determination. Under the optimal conditions, a linear relationship was obtained between the decreased CL intensity and TNT concentration in the ranges 0.02–50 and 50–200 ng mL−1 with a detection limit (3σ) of 6.8 pg mL−1. This method had good selectivity towards TNT but not towards similar species such as 2-nitrotoluene, 2,4-dinitrotoluene, etc.

Currently, researchers are looking for nanomaterials with peroxidase-like activity to replace natural peroxidase enzymes. For this purpose, WS2 quantum dots (WS2 QDs) were synthesized via a solvothermal method, which improved the mimetic behavior. The resulting WS2 QDs with a size of 1&ndash, 1.5 nm had a high fluorescence emission, dependent on the excitation wavelength. WS2 QDs with uniform morphology showed a high catalytic effect in destroying H2O2. The peroxidase-like activity of synthesized nanostructures was studied in H2O2 chemical and electrochemical reduction systems. The mimetic effect of WS2 QDs was also shown in an H2O2&ndash, rhodamine B (RB) chemiluminescence system. For this aim, a stopped-flow chemiluminescence (CL) detection system was applied. Also, in order to confirm the peroxidase-like effect of quantum dots, colorimetry and electrochemical techniques were used. In the enzymatic reaction of glucose, H2O2 is one of the products which can be determined. Under optimum conditions, H2O2 can be detected in the concentration range of 0&ndash, 1000 nmol&middot, L&minus, 1, with a detection limit of 2.4 nmol&middot, 1. Using this CL assay, a linear relationship was obtained between the intensity of the CL emission and glucose concentration in the range of 0.01&ndash, 30 nmol&middot, 1, with a limit of detection (3S) of 4.2 nmol&middot, 1.

Herein, a two dimensional metal-organic framework (2D MOF) is introduced as an efficient adsorbent for simultaneously extraction of fluoroquinolones (FQs) from milk samples. The proposed MOF was synthesized by solvothermal method. The high surface area and high accessible sites of prepared MOF offered a unique adsorbent for solid phase extraction (SPE). The experiments showed the great ability of 2D MOF for the retention of ofloxacin (OF), ciprofloxacin (CIP) and norfloxacin (NOR). It was also found that acetic acid (ACA) solution can effectively elute the adsorbed FQs with a high recovery, eliminating the need for other toxic organic elution solvents, which are utilized for the common C18 cartridges. A 3D printed microchip containing a microcolumn was also examined for the SPE process using magnetic composite of 2D MOF, which was fix inside the column using simple magnet. The extracted analytes were gathered to be analyzed by high performance liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS), as the potent detection system. The results demonstrated the great ability of MOF toward the extraction of tested FQs with a breakdown point of 1200 ng mL−1 for each analyte in their mixed solution. The method showed an acceptable selectivity toward the FQs and no interfering effect was observed by other compounds. It was able to detect OF, NOR and CIP in the range of 0.5–1000 ng mL−1 in milk samples and the detection limits were 0.012, 0.009 and 0.016 ng mL−1, respectively.

A paper-based analytical device (PADs) combined with a powerful chemiluminescence (CL) system was established for the determination of deltamethrin (DM), based on the enhancing effect of polyphosphate (PP) on graphene quantum dots (GQDs)-KMnO4 CL reaction. A possible mechanism for the obtained emission was proposed using the CL spectra, fluorescence and ultraviolet-visible patterns. The reaction of KMnO4 and GQDs can lead to generation of GQDs in excited state (GQDs*), which can emit at 490 nm. Interestingly, PP changes the CL mechanism and the main emitter becomes Mn2+ instead of GQDs leading to a strong emission at 695 nm. Furthermore, the obtained multi-emission CL system was examined for analytical applications. The initial experiments showed that the amplified CL emission of the GQDs-KMnO4 system was selectively quenched in the presence of trace levels of DM, probably due to its effective interaction with GQDs or reaction with KMnO4. This observation led to a facile, reliable and sensitive PADs-CL probe, developed for the determination of DM residue in food samples. Using this CL system and under the optimized experimental conditions, the generated signal is decreased by increasing DM concentration in the range of 0.3−10 μg mL-1 with limit of detection (LOD) of 0.15 μg mL-1.

A novel spectrofluorimetric probe based on Ag nanoparticle (AgNPs)-enhanced terbium (III) (Tb) fluorescence was introduced for the sensitive determination of folic acid (FA). The effect of gold and silver nanoparticles in different size was investigated on the well-known Tb sensitized fluorescence emission of 1, 10-phenantroline (Phen). The greatest fluorescence intensity was observed in the presence of AgNPs with a diameter of ~6 nm maybe due to their highest surface area. Furthermore, it's discovered that FA can form Tb-Phen -FA ternary complexes and cause a notable diminution in this enhanced fluorescence system. Based on this finding, a high sensitive and selective method was developed for the determination of FA. Effects of various parameters like Ag NPs, Phen and Tb(3+) concentration and pH of media were investigated. In the optimum circumstances, the fluorescence emission of AgNPs-Phen-Tb collection was declined linearly by increasing the concentration of FA in the range of 0.5 to 110 nmol L(-1). Limits of detection and quantification were achieved to be 0.21 and 0.62 nmol L(-1), respectively. The method has good linearity, recovery, reproducibility and sensitivity, and was adequately exploited to follow FA content in pharmaceutical, fortified flour and human urine samples.

A new high sensitive, selective, and simple method based on the inhibited effect of gold nanoparticles (Au NPs) on rhodamine B (RB)–ferricyanide (Fe(CN)63 −) chemiluminescence (CL) system has been developed for the determination of Hg2 + in environmental samples. This study is the analytical exploiting of Au NPs inhibiting effect on CL system. RB–Fe(CN)63 − causes a high emission intensity in alkaline condition but undergoes an intense extinction in the presence of Au NPs. This decreasing effect can be attributed to the energy transfer and collisions between RB molecules and Au NPs. Moreover, it is observed that the CL intensity is gradually restored in the presence of mercury (II) due to RB molecules release from the surfaces of Au NPs. Based on this effect, sensitive, and selective turn-on CL assay was developed for the determination of Hg2 +. Under the optimized conditions, CL calibration curve was drawn as a function of Hg2 + concentration, which is linear over the range of 0.013–4.67 μg L− 1 (0.067–23.3 nmol L− 1) with limit of detection (3s) and quantification (10s) of 5.42 and 18 ng L− 1, respectively. The relative standard deviations (RSD%, n = 5) were about 0.7–2.1% for the different concentrations of Hg2 +. The presented assay was satisfactorily applied to the quantification of Hg2 + in the environmental (tap, rain, and river) water samples, which shows good sensitivity and reliability in comparison with the other nanoparticle-based methods; the recoveries were 97–102%.

A fluorescence resonance energy transfer (FRET) system between carbon dots (C-dots) and amine-capped gold nanoparticles (AuNPs) was developed for the selective determination of 2,4,6-trinitrotoluene (TNT). C-dots have an intrinsic florescence emission depending on their exciting wavelength. In the presence of AuNPs, C-dots adsorb on the Au surfaces, and NPs treat as energy acceptor, which can receive light emitted by C-dots, leading to decrease the fluorescence intensity of C-dots. Furthermore, it is observed that nitroaromatic compounds, especially TNT, could restore this fluorescence due to selective interaction with AuNPs via amine groups, and so releasing the C-dots. Based on this effect, a sensitive and selective fluorescence turn-on probe was designed for the determination of TNT. Some important factors including AuNPs and C-dot concentrations and media pH, which would affect the efficiency of the probe, were optimized. Under the optimum experimental conditions, good linear relationships in the range of 7 - 250 nmol L(-1) TNT with the detection limit of 2.2 nmol L(-1) were obtained. The proposed method was satisfactorily applied to the determination of TNT in the environmental water samples. Compared with previous reports, the developed method has relatively high sensitivity, short analysis time, low cost and ease of operation.

An efficient chemiluminescence resonance energy transfer (CRET) induced chemiluminescence (CL) system was developed for the sensitive determination of cyanide ion (CN−) in environmental and biological samples. The selected CL reaction was hydrogen peroxide (H2O2)-bicarbonate (HCO3−) system with an ultra-weak emission at about 470 nm. It was found that glutathione-stabilized CdSe quantum dots (CdSe QDs) superbly increase the obtained CL intensity. The high performance CRET between the CL emitters and CdSe QDs with a broad absorption was mainly responsible for the observed improving effect. The absorption spectrum of QDs completely overlaps with the CL emission wavelength of H2O2-HCO3− system. Besides, CdSe QDs could also catalyze the CL reaction of H2O2-HCO3−, efficiently. On the other hand, it was observed that the gold nanoclusters (Au NCs) could prohibit the CRET system and turn off the CL emission. This diminishing effect can be useful for the analytical application. Herein, it was successfully exploited for the selective recognition of CN−, using its leaching effect on Au NCs. After efficient dissolution of NCs, the CRET to CdSe QDs restored and the CL emission was again turned on. This strategy resulted in a high sensitive and reliable measurement of CN− in the concentration range of 2–225 nM, with a detection limit of 0.46 nM.

Development of a sensitive detection method for the reliable screening of widely used organophosphorus (OP) toxins is a crucial request to control their side-effects. Herein, a novel fluorometric assay based on the acetylcholinesterase (AChE) inhibited enzymatic activity and the new peroxidase-like Fe3O4 nanoparticles@ZIF-8 composite (Fe3O4 NPs@ZIF-8) was developed for the determination of OPs. Magnetic Fe3O4 NPs were encapsulated into ZIF-8 and the high mimetic activity of produced composite was assessed on the oxidation of substrates. This observation was applied to the rapid detection of diazinon as a model OP compound. The sensing tool contains AChE and choline oxidase (CHO) enzymes, peroxidase colorimetric or fluorometric substrate, and Fe3O4 NPs@ZIF-8 as the catalyst. In the presence of mimic Fe3O4 NPs@ZIF-8, the generated H2O2 from the enzymatic reactions of acetylcholine is decomposed to hydroxyl radicals. The radicals oxidize the peroxidase substrates to generate a detectable signal. However, due to the inhibition effect of OPs on the enzymatic activity of AChE, lower H2O2 amounts are produced in the presence of diazinon. Using the fluorometric detection system, the generated signal is decreased proportionally by increasing diazinon concentration in the range of 0.5–500 nM. The limit of detection was obtained 0.2 nM. Consequently, the usage of high performance peroxidase-mimic Fe3O4 NPs@ZIF-8 provided a sensitive bio-assay with a potential to be applied as screening tool for toxic OP compounds. The developed assay was successfully applied for the determination of diazinon in water and fruit juices.

It is reported that a mixture of WS2 nanosheets (WS2 NS) and silver nanoclusters (AgNCs) displays strongly enhanced peroxidase-mimicking activity. The catalytic effect of the mixture was studied by colorimetry, fluorometry, chemiluminescence (CL) and electrochemistry. The effect is interpreted in terms of a difference between the Fermi energy level of the two nanomaterials. This leads to the formation of charge separation regions which act as active sites for enzyme mimetic interaction with the substrates. The mixture of WS2 NS and AgNCs was exploited for the non-enzymatic determination of H2O2 and glucose. A stopped-flow method was applied as a sensitive CL detection system using the bicarbonate-H2O2 reaction. The mixture has a powerful peroxidase mimicking activity on the bicarbonate-H2O2 CL reaction, and this effect is much larger than that of any single constituent. In addition, the CL emission is improved several times by using the stopped-flow technique. Under optimum condition, H2O2 can be determined in the 2.5–1500 nM concentration range. Moreover, glucose levels in human serum can be quantified via glucose oxidase based oxidation which leads to the generation of H2O2. Using this CL assay, a linear relationship was obtained between the intensity of the CL emission and glucose concentration in the range of 0.03–20 μM, with a limit of detection (3S) of 13 nM.

The article describes a highly sensitive and fairly simple chemiluminescence (CL) assay for mercury(II) ions. The CL system consists of an alkaline solution of rhodamine B (RhoB) and KMnO4 whose weak emission undergoes a large enhancement in presence of gold nanoparticles and, in particular, of anisotropic gold nanoprisms (Au-NPr). CL intensity is, however, decreased in the presence of Hg(II) by suppressing the interaction between RhoB and Au-NPr. Based on this finding, a method was developed for the determination of Hg(II). Under optimum conditions, Hg(II) can be quantified in the 67 pM to 33.3 nM concentration range, and the detection limit (at 3 σ) is 27 pM. In comparison to other nanoparticle based methods, the one described here has a strongly improved LOD as shown in the successful analysis of environmental water samples.

Here, Ag nanoparticle/flake-like Zn-based MOF nanocomposite (AgNPs@ZnMOF) with great peroxidase-like activity was applied as an efficient support for molecularly imprinted polymer (MIP) and successfully used for selective determination of patulin. AgNPs@ZnMOF was simply synthesized by creating Ag nanoparticles (Ag NPs) inside the nano-pores of flake-like (Zn)MOF. The high surface area of MOF remarkably improved the catalytic activity of Ag NPs which was assessed by fluorometric, colorimetric and electrochemical techniques. Furthermore, it was observed that patulin could strangely reduce the catalytic activity of AgNPs@ZnMOF, probably due to its electron capturing features. This outcome was the motivation to design an assay for patulin detection. In order to make a selective interaction with patulin molecules, MIP layer was created on the surface of AgNPs@ZnMOF by co-polymerization reaction of 3-aminopropyl triethoxysilane (APTES) and tetraethyl orthosilicate (TEOS) monomers wherein patulin was applied as template agent. Combination between the selective identifying feature of MIP and outstanding peroxidase-like activity of novel AgNPs@ZnMOF nanocomposite as well as the sensitive fluorescence detection system was led to the design of a reliable probe for patulin. The prepared MIP-capped AgNPs@ZnMOF catalyzed the H2O2-terephthalic acid reaction which produced a high florescent product. In the presence of patulin, the fluorescence intensity was decreased proportional to its concentration in the range of 0.1-10µmolL-1 with a detection limit of 0.06µmolL-1. The proposed method was able to selectively measure patulin in a complex media without significant interfering effects from analogue compounds.

A novel and highly sensitive chemiluminescence (CL) method for the determination of ethanol was developed based on the CdS quantum dots (QDs)–permanganate system. It was found that KMnO4 could directly oxidize CdS QDs in acidic media resulting in relatively high CL emission. A possible mechanism was proposed for this reaction based on UV/Vis absorption, fluorescence and the generated CL emission spectra. However, it was observed that ethanol had a remarkable inhibition effect on this system. This effect was exploited in the determination of ethanol within the concentration range 12–300 µg/L, with detection at 4.3 µg/L. In order to evaluate the capability of presented method, it was satisfactorily utilized in the determination of alcohol in real samples. Copyright © 2014 John Wiley & Sons, Ltd.

A versatile, sensitive, and green method based ultrasound-assisted, temperature-controlled, dispersive liquid–liquid microextraction with an ionic liquid and chemiluminescence detection was used for the determination of copper(II) at the ultra-trace level. After complexation by dithizone, copper(II) was extracted into the ionic liquid. Using high temperature and ultrasonic agitation, the copper complex easily migrated into the ionic liquid phase because of the larger contact area. After back extraction, the determination was performed by chemiluminescence based on the catalyzing effect of copper(II) on the decomposition of hydrogen peroxide with rhodamine B. Important parameters that affected the extraction efficiency and chemiluminescence intensity were optimized. Under the optimum conditions, a limit of detection for copper of 0.8 ng L−1 was obtained with a linear calibration relationship. The method was applied to analyze environmental water samples for copper(II) with satisfactory results.

A novel chemiluminescence (CL) system based on the oxidation of bromide by permanganate in sulfuric acid medium is introduced. The enhancing effect of silver nanoparticles (NPs), synthesized by chemical reduction method, on this reaction was studied. It was demonstrated that spherical silver nanoparticles with average size of 18 nm had a most remarkable catalytic effect on this reaction. CL emission wavelengths and UV-vis spectra were used to characterize the system and propose a possible mechanism. Furthermore, it was found that captopril inhibits the action of NPs and decreases the intensity of CL. Based on this phenomenon, a new CL method was developed for the determination of captopril in the 3.0 × 10(-10) to 1.0 × 10(-7) mol L(-1) concentration range with a detection limit (3s) of 0.12 nmol L(-1). The method was successfully applied to the determination of captopril in pharmaceutical formulations, human urine and serum samples.

We describe the effect of different sized gold and silver nanoparticles on the terbium sensitized fluorescence of deferasirox. It is indicated that silver nanostructures, especially 18 nm Ag nanoparticles (AgNPs), have a remarkable amplifying effect compared to Au nanoparticles. Based on this observation, a highly sensitive and selective method was developed for the determination of deferasirox. Effects of various parameters like AgNPs and Tb(3+) concentration and pH of media were investigated. Under the optimal conditions, a calibration curve was plotted as the fluorescence intensities versus the concentration of deferasirox in the range of 0.1 to 200 nmol L(-1), and detection limit of 0.03 nmol L(-1) was obtained. The method has good linearity, recovery, reproducibility and sensitivity, and was satisfactorily applied for the determination of deferasirox in urine and pharmaceutical samples.

We describe a new turn off-on chemiluminescence (CL) method for the sensitive and selective determination of cyanide based on the inhibiting effect of gold nanoparticles (AuNPs) on rhodamine B (RohB)-ferricyanide (Fe(CN)6(3-)) reaction. Free RohB can generate strong chemiluminescence emission when oxidized with Fe(CN)6(3-), but undergoes an intense extinction in the presence of AuNPs. Energy transfer and collisions between RohB molecules and AuNPs are probably the reason for this decreasing effect. Furthermore, it was found that CL intensity gradually recovered in the presence of cyanide due to its interaction with the AuNPs. The relation between the decreased CL intensity and cyanide concentration was exploited to develop a method for the determination of cyanide in the 16.7 - 1333 nmol L(-1) concentration range, with a detection limit of 13.6 nmol L(-1). In comparison with other nanoparticle-based methods, the presented assay shows good sensitivity and reliability for the determination of cyanide. The method was satisfactorily applied to the determination of cyanide in environmental and biological samples.

Gold/silver alloy nanoparticles (Au/Ag NPs) are shown to exert a beneficial effect on the chemiluminescence (CL) reaction of permanganate-formaldehyde in the presence of sodium dodecyl sulfate micelles. The Au/Ag NPs can be prepared by chemical reduction and display better catalytic properties than their monometallic counterparts. Transmission electron microscopy, energy dispersion X-ray spectrometry and UV–vis spectroscopy were used to characterize the Au/Ag NPs. Melamine at even ultratrace level inhibits the action of nanoparticles and therefore decreases the intensity of CL. This finding forms the basis for a method for the determination of melamine in the 0.01–35 ng mL−1 concentration range, with a detection limit of 8 pg mL−1. The method was successfully applied to the determination of minute concentrations of melamine in powdered milk samples.

The surfactant-to-dye binding degree method was used to determine morphine hydrochloride and codeine phosphate. Neutral red and bis(2-ethylhexyl) sulfosuccinate (AOT) were used as the dye and surfactant, respectively, to form dye–surfactant aggregates. Addition of the drug resulted in a decrease in the dye–surfactant binding degree, proportional to the drug concentration. This was measured by monitoring the absorbance changes of the dye at 532 nm. Under the optimum conditions, the calibration graphs were linear up to 32 and 28 µg mL−1 for morphine hydrochloride and codeine phosphate, respectively, with the corresponding detection limits of 0.40 and 0.35 µg mL−1.

A sensitive and selective chemiluminescence method was developed to determine ethylenediaminetetraacetic acid (EDTA) in water samples. It was observed that gold nanoparticles (AuNPs) catalyzed chemiluminescence (CL) reactions of permanganate-aldehydes which underwent an enhancement effect in the presence of iron(III) ions (Fe(3+)). This effect is more remarkable in the presence of EDTA, and a highly intensive CL emission is created in proportion to the EDTA concentration. These observations form the basis of the method for the high sensitive determination of EDTA in the 0.83 - 167 nmol L(-1) concentration range, with a detection limit of 0.25 nmol L(-1). The relative standard deviations for five repeated measurements of 5, 40 and 140 nmol L(-1) EDTA were 1.14, 2.48 and 0.65%, respectively. The method has good selectivity toward EDTA, and there are no interferences from other ions. The offered method has good precision, and was satisfactorily used for the sensitive determination of EDTA in water samples.

A novel enhanced chemiluminescence system was developed by applying gold nanorods (Au NRs) as catalysts in rhodamine B-permanganate reaction. Au NRs with three different aspect ratios were synthesized by seed mediated growth method and characterized by UV–Vis spectra and transmission electron microscopy. It was demonstrated that Au NRs have much higher catalytic effect than spherical nanoparticles on rhodamine B-permanganate chemiluminescence reaction. Among various sizes of Au NRs, those with average aspect ratio of 3.0 were found to have the most remarkable catalytic activity. As an analytical application of the new chemiluminescence system, albumin as a model protein was quantified based on its interaction with NRs. Albumin binds to Au NRs active surfaces and inhibits their catalytic action and therefore decreases the intensity of chemiluminescence. This diminution effect is linearly related to the concentration of the human and bovine serum albumin over the ranges of 0.45–90 and 0.75–123 nmol L−1, respectively with the corresponding limits of detection of 0.18 and 0.30 nmol L−1. The method was successfully applied to the determination of albumin in human and bovine serum samples.