Recent Advances in Electrochemiluminescence Biosensors for MicroRNA Detection.

Electrochemiluminescence (ECL) as an analytical technology with a perfect combination of electrochemistry and spectroscopy has received considerable attention in bioanalysis due to its high sensitivity and broad dynamic range. Given the selectivity of bio-recognition elements and the high sensitivity of the ECL analysis technique, ECL biosensors are powerful platforms for the sensitive detection of biomarkers, achieving the accurate prognosis and diagnosis of diseases. MicroRNAs (miRNAs) are crucial biomarkers involved in a variety of physiological and pathological processes, whose aberrant expression is often related to serious diseases, especially cancers. ECL biosensors can fulfill the highly sensitive and selective requirements for accurate miRNA detection, prompting this review. The ECL mechanisms are initially introduced and subsequently categorize the ECL biosensors for miRNA detection in terms of the quenching agents. Furthermore, the work highlights the signal amplification strategies for enhancing ECL signal to improve the sensitivity of miRNA detection and finally concludes by looking at the challenges and opportunities in ECL biosensors for miRNA detection.

Discerning the Relevance of Singlet Oxygen in Pollutant Degradation in Peroxymonosulfate Activation Processes.

Significant efforts have recently been exerted toward construction of singlet oxygen (1O2)-dominated catalytic oxidation systems for selective removal of organic contaminants from wastewater, with peroxides serving as the chemical source. However, the relevance of 1O2 in the removal of pollutants remains ambiguous and requires elucidation. In this study, we scrupulously exclude the significant role of 1O2 in contaminant degradation in various peroxymonosulfate (PMS) activation systems. Multiple experimental results indicate that the activation of PMS catalyzed by CuO, MnO2, Fe-doped g-C3N4 (Fe-CN), or N-doped graphite does not predominantly follow the 1O2 pathway. More importantly, the reactivity of 1O2 is remarkably overestimated in the literature, given its inferior capacity in degradation of a range of heterocyclic contaminants and aromatic compounds possessing electron-withdrawing groups. In addition, the strong physical quenching effect of water, coupled with the low oxidizing ability of 1O2, would notably reduce the utilization efficiency of peroxide, which is particularly apparent in the degradation of micropollutants. We reckon that this study is expected to end the long-running dispute associated with the relevance of 1O2 in pollutant removal.

Microwave Synthesis of Fluorescent Carbon Quantum dots from Araucaria Heterophylla Gum: Application in Drug Detection.

This study employed a green microwave synthesis technique to produce carbon quantum dots (CQDs) from araucaria heterophylla gum extract. The produced CQDs emit a distinct blue fluorescent light, contributing a remarkable quantum yield of 14.69%. Their average particle size measures at 1.62 ± 0.39 nm. Furthermore, these CQDs demonstrate excellent water solubility and maintain high fluorescence stability despite ionic strength, pH and time variations. Moreover, we present here for the first time that the synthesized CQDs demonstrate a rapid, exceptionally sensitive, and discerning fluorescence quenching phenomenon (IFE) concerning Cefprozil (CPR). The fluorescent probe was sensitive and specific with good linear relationships for CPR in the 0-18 µM range. The limit of detection for relationships for CPR was 2.51 µM. This study provides novel opportunities for producing high-quality luminescent CQDs that meet the requirements for various biological and environmental applications.

Pyrene, Anthracene, and Naphthalene-Based Azomethines for Fluorimetric Sensing of Nitroaromatic Compounds.

Special attention is given to the development of rapid and sensitive detection of nitroaromatic explosives for homeland security and environmental concerns. As part of our contribution to the detection of nitroaromatic explosives, fluorescent materials (A), (B) and (C) were synthesized from the reaction of 1,2-diaminocyclohexane with pyrene-1-carbaldehyde, anthracene-9-carbaldehyde and 2-hydroxy-1-naphthaldehyde, respectively. The structures of the prepared fluorescent azomethine probes were confirmed using FTIR, 1H-NMR and 13C-NMR spectroscopies. The basis of the study is the use of the synthesized materials as fluorescent probes in the photophysical and fluorescence detection of some nitroaromatic explosives. Emission increases occurred due to aggregation caused by π-π stacking in synthesized azomethines. To measure the nitroaromatic detection capabilities of fluorescence probes, fluorescence titration experiments were performed using the photoluminescence spectroscopy. It was observed that compound A containing pyrene ring provided the best emission intensity-increasing effect due to aggregation with the lowest LOD value (14.96 µM) for the sensing of 4-nitrophenol. In compounds B and C, nitrobenzene with the lowest LOD (16.15 µM and 23.49 µM respectively) caused the most regular emission increase, followed by picric acid.

Photophysical and Fluorescence Nitroaromatic Sensing Properties of Methylated Derivative of a Pamoic Acid Ester.

Rapid and selective detection of nitroaromatic explosives is very important for public safety, life, and environmental health. Current instrumental techniques suffer from high cost and poor site used. In order to investigate fluorescence sensing of nitroaromatics, we prepare a new small fluorescence probe derived from pamoic acid. This study covers the synthesis of Pamoic acid based [diisopropyl 4,4'-methylenebis(3-methoxy-2-naphthoate)] (2) material and characterization of its structure. The methylation of Pamoic acid ester, which we have successfully synthesized in our previous studies, was carried out in this study. Determination of the photophysical and fluorescent nitroaromatic detection properties of the compound forms the basis of the study. Structural characterization of the synthesized compound [diisopropyl 4,4'-methylenebis(3-methoxy-2-naphthoate)] (2) was characterized using spectroscopic methods. In addition, Molecular structure of the synthesized compound was determined by single crystal X-ray diffraction studies. In the final step, compounds [diisopropyl 4,4'-methylenebis(3-hydroxy-2-naphthoate)] (1) and [diisopropyl 4,4'-methylenebis(3-methoxy-2-naphthoate)] (2) were tested as fluorescent probes for the detection of some nitroaromatic explosives. It is seen that Nitrobenzene provides the best quenching effect on the compound [diisopropyl 4,4'-methylenebis(3-hydroxy-2-naphthoate)] (1) containing the -OH group, with lowest the limit of detection (LOD) value. It was observed that Picric acid provided the best quenching effect with lowest the limit of detection (LOD) value in the compound [diisopropyl 4,4'-methylenebis(3-methoxy-2-naphthoate)] (2) obtained by methylation of the -OH group in the compound [diisopropyl 4,4'-methylenebis(3-hydroxy-2-naphthoate)] (1).

Dual Emission Carbon Dots for Simultaneous Detections of Pb2+ and Fe3+ Ions in Water Via Distinct Sensing Mechanisms.

Herein, dual-emission carbon dots (DE-CDs) were synthesized using a one-pot hydrothermal method. DE-CDs exhibited two well-separated peaks at 433 and 513 nm under ultraviolet excitation. The prepared DE-CDs offer selective detection of Fe3+ ions via inner filter effect (IFE) and Pb2+ ions via aggregation-induced enhancement (AIE). The obtained DE-CDs showed a good affinity for both Fe3+ and Pb2+ ions in the presence of various interfering ions. The limits of detection were 0.797 ppm and 4.739 ppm for Pb2+ and Fe3+, respectively. The finding reveals the huge potential of DE-CDs for the selective detection of multiple targets in one solution.

Schiff Base-functionalized Metal-organic Frameworks for Selective Sensing of Chromate and Dichromate in Water.

In this research, Zn- or Cd-based metal-organic frameworks (coded ZnMOF-1 and CdMOF-1) containing benzene-1,4-dicarboxylic acid (H2bdc) and pyridyl-based Schiff base (4-pyridylcarboxaldehydeisonicotinoylhydrazone (L)) dual ligands were successfully assembled via a conventional solvothermal method. The photoluminescence quenching response of ZnMOF-1 and CdMOF-1 and their sensing sensitivity and selectivity towards various inorganic anions were evaluated in aqueous media. Crystallographic and thermogravimetric studies confirm the formation of both MOFs with good crystallinity and thermal stability. Photoluminescence studies also verify the selectivity of ZnMOF-1 and CdMOF-1 for efficient sensing of inorganic oxyanions (like chromate/dichromate: CrO42- and Cr2O72-). Further, it was noted that only chromate/dichromate (CrO42-/Cr2O72-) anions showed a significant turn-off quenching effect while other anions (like F-, Br-, I-, Cl-, ClO4-, SCN-, SO42-, NO3-, and NO2-) have a low/negligible effect on the photoluminescence intensity of both MOFs. The limit of detection (LOD) of chromate/dichromate by ZnMOF-1 and CdMOF-1 was 9.79/10.94 µM and 2.68/1.48 µM, respectively. A probable mechanism for turn-off quenching response towards chromate and dichromate anions could be attributed to the spectral overlap of both excitation and emission spectra of ZnMOF-1/CdMOF-1 with the absorption spectra of chromate/dichromate anions. As a result, the energy transfer from ZnMOF-1 or CdMOF-1 to the target chromate and dichromate anions decreased fluorescence intensity (i.e., fluorescence quenching effect).

Utilization of erythrosine B in spectrofluorimetric quenching analysis of amlodipine and perindopril in pharmaceutical and biological matrices.

A spectrofluorimetric approach that is sensitive, simple, validated, and cost-effective has been proposed for the estimation of amlodipine (AML) and perindopril (PER) in their bulk powders, pharmaceutical formulations, and spiked human plasma. The recommended approach utilized the quantitative quenching effect of the two cited drugs on the fluorescence intensity of erythrosine B, as a result of complex binary reactions among each drug with erythrosine B at pH 3.5 (Teorell and Stenhagen buffer). The quenching of erythrosine B fluorescence was recorded at 554 nm after excitation at 527 nm. The calibration curve was detected in the range 0.25-3.0 µg ml-1 , with a correlation coefficient of 0.9996 for AML, and 0.1-1.5 µg ml-1 , with a correlation coefficient of 0.9996 for PER. The established spectrofluorimetric approach was validated for the estimation of the cited drugs with high sensitivity regarding International Council on Harmonization guidelines. Therefore, the established approach could be utilized for quality control of the cited drugs in their pharmaceutical formulations.

Photoelectrochemical immunoassay of squamous cell carcinoma antigen based on CuO/nitrogen-doped porous carbon-ZnO biolabeling and a type-II In2O3/AgBiS2 heterojunction.

AgBiS2 was hydrothermally synthesized, In2O3 was synthesized by hydrothermal method and calcination, and the type-II In2O3/AgBiS2 heterojunction material of an optimized composition ratio was cast-coated on a fluorine-doped tin oxide (FTO) slice to fabricate an In2O3/AgBiS2/FTO photoanode. The signal-attenuated photoelectrochemistry sandwich immunoassay of squamous cell carcinoma antigen (SCCA) was realized on this photoanode, on the basis of a bovine serum albumin/secondary antibody/CuO nanoparticles/nitrogen-doped porous carbon-ZnO bionanocomposite that can competitively absorb light and deplete the electron donor ascorbic acid as well as show the steric hindrance and p-n quenching effects. Under the optimized conditions (e.g., at a bias of 0 V vs. SCE), the photocurrent was linear with the common logarithm of SCCA concentration from 2.00 pg mL-1 to 50.0 ng mL-1, with a limit of detection (LOD) of 0.62 pg mL-1 (S/N = 3). The immunoassay of SCCA in human serum samples gave satisfactory recovery (92.0~103%) and relative standard deviation (5.1~7.8%) results.

Ratiometric luminescent sensor based on BSA-coated gold/silver nanoclusters for the selective determination and spatiotemporal imaging of gallic acid in plants.

A new fluorescence sensing strategy has been developed. Four bimetallic nanoclusters, gold/silver, gold/copper, gold/molybdenum and gold/cobalt, were prepared using bovine serum albumin (BSA) as a reducing and stabilizing agent. The fluorescence properties of four nanoclusters were explored by solid-state UV and XPS. The gold/silver nanoclusters (BSA-Au/Ag NCs) with the best ratiometric fluorescence properties for gallic acid (GA) in plants were selected to realize the sensitive detection of GA. GA affected the conformation of BSA, thereby disrupting the luminescent environment of the nanoclusters, resulting in a pronounced fluorescence quenching at 566 nm. The ratiometric fluorescence signal (I566/I453) was used for trace detection of GA in plants. It has a wide response range of 1.25-40.0 µM and a low detection limit of 45.27 nM. GA was detected at 19.49 µM in the plant extract, and the spiked recoveries ranged from 96.09 to 104.6%. In addition, due to the non-toxic and biocompatible properties of BSA, BSA-Au/Ag NCs have also been validated for fluorescence imaging of plant tissues. It realized the comparison of GA content in different parts of plants and the difference of GA content in plants after abiotic stress. Therefore, the developed strategy offers potential application for the analytical study of active substances in plants.

Inner-filter Effect Induced Fluorescence Quenching of Carbon Dots for Cr(VI) Detection with High Sensitivity.

Carbon dots (CDs) were used to develop a sensitive sensing technique for detecting Cr(VI). CDs were made using a hydrothermal technique from citric acid and glutamic acid. These prepared CDs emitted blue fluorescence under excitation of 350 nm (λem = 420 nm), and the fluorescence quantum yield was 48.41%. Transmission electron microscope was used to examine the morphology of the CDs, which had an average size of 2.21 ± 0.39 nm. The elementary composition and bonding structure of the CDs were conducted by XPS and FT-IR spectrum. Cr(VI) quenched the fluorescence of CDs through a static quenching effect and an inner filter effect, allowing Cr(VI) to be detected quantitatively. This approach was used to detect Cr(VI) in two samples of water, with the findings demonstrating that it is reliable and accurate. The fluorescence intensity change was linearly related to the concentration of Cr(VI) in the range from 0.5 to 400 µM, with the detection limit being 0.10 µM. This approach has the virtues of wide detection range, low cost and fast response. The strategy has a great application prospect for detecting Cr(VI) in practical samples.

Co-Quenching Effect between Lanthanum Metal-Organic Frameworks Luminophore and Crystal Violet for Enhanced Electrochemiluminescence Gene Detection.

Exploring new electrochemiluminescence (ECL) luminophores to construct high-efficiency sensing systems is always a hot direction for developing ECL sensors. Compared with other luminophores, metal-organic frameworks (MOFs) exhibit high mass transfer ability for accelerating the reactivity in its pore channels, which is conducive to improving the performance of ECL sensors. In this work, La3+ -BTC MOFs (LaMOFs) are prepared as the highly active reactor and novel ECL luminophore. On this basis, a novel co-quenching effect mechanism is proposed based on double-stranded DNA (dsDNA) triggered cooperation between LaMOFs and crystal violet (CV) molecules. Under the confined pore channels of LaMOFs, CV can play an important role as the photon-acceptor due to the matched absorption spectrum with the ECL spectrum of LaMOFs, and the electron-acceptor on account of its lowest unoccupied molecular orbital level. Based on the proposed co-quenching effect mechanism, a constructed ECL gene sensor shows good assay performance toward p53 gene in the detection range of 1 pm to 100 nm with a detection limit of 0.33 pm. The co-quenching effect integrating LaMOFs with CV is expected to be a versatile approach in the construction of ECL gene sensor, which has good prospect in expanding the application range of ECL technology.

Effects of synthesis methods and different concentrations of Eu3+ ions on the emission properties of Sr2 SiO4 phosphors.

Sr2-x SiO4 -xEu (x = 0.01, 0.02, 0.035, and 0.05) phosphors were synthesized at 1000-1,300°C for 2 h in two different processes, the solid-state reaction (SSR) method and a two-step (TS) method, and these results revealed three important findings. The secondary Sr3 SiO5 phase was observed in 1,300° C-TS-synthesized Sr2-x SiO4 -xEu powder, but no raw materials or secondary phases were observed in the SSR-prepared Sr2-x SiO4 -xEu powders. The concentration quenching effect of Eu3+ ions was really observed in TS-prepared Sr2-x SiO4 -xEu phosphors, which was not observed in SSR-prepared Sr2-x SiO4 -xEu phosphors. High emission intensity of charge transition state (CT) band was observed in the photoluminescence excitation spectra, for that the 265 and 393 nm were used as the excitation wavelengths of Sr2-x SiO4 -xEu phosphors. Sr2-x SiO4 -xEu phosphors under different synthesis processes and excitation wavelengths would have different main emission peaks in the photoluminescence emission spectra. In this study, we also well discussed and explored the relationships of photoluminescence properties with the dipole transitions (electric or magnetic) of Eu3+ ions and the different coordination structures of Sr+2 ions.

Ultrasensitive dual-quenching electrochemiluminescence immunosensor for prostate specific antigen detection based on graphitic carbon nitride quantum dots as an emitter.

Early monitoring of prostate-specific antigen (PSA) is crucial in diagnosis and proactive treatment of prostate disease. Herein, a dual-quenching ternary ECL immunosensor was designed for PSA detection based on graphitic carbon nitride quantum dots (g-CNQDs, as an emitter), potassium persulfate (K2S2O8, as a coreactant), and silver nanoparticles doped multilayer Ti3C2 MXene hybrids (Ag@TCM, as a coreaction accelerator). First, Ag@TCM was immobilized on the surface of a glassy carbon electrode, then g-CNQDs was further adsorbed on Ag@TCM to acquire a higher initial ECL signal at a potential window from - 1.3 to 0.0 V (vs. Ag/AgCl). Ag@TCM not only acted as the coreaction accelerator, but also as a matrix to load enormous g-CNQDs and prostate-specific capture antibody via Ag-N bond. Meanwhile, prostate-specific detection antibody was marked by gold nanoparticles modified manganese dioxide as a dual-quenching probe (Ab2- Au@MnO2). When Ab2-Au@MnO2 was introduced into the ternary ECL system via sandwiched immuno-reaction, the high-sensitive detection of PSA was achieved by the dual-quenching effect, caused by the resonant energy transfer from g-CNQDs (energy donor) to Au@MnO2 (energy acceptor). As a result, this ECL immunosensor showed a good dynamic concentration range from 10 fg·mL-1 to 100 ng·mL-1 with a detection limit of 6.9 fg·mL-1 for PSA detection. The dual-quenching ECL strategy presented high stability and good specificity to open up a new pathway for ultrasensitive immunoassay.

Subsequent monitoring of ferric ion and ascorbic acid using graphdiyne quantum dots-based optical sensors.

Graphdiyne (GDY) as an emerging carbon nanomaterial has attracted increasing attention because of its uniformly distributed pores, highly π-conjugated, and tunable electronic properties. These excellent characteristics have been widely explored in the fields of energy storage and catalysts, yet there is no report on the development of sensors based on the outstanding optical property of GDY. In this paper, a new sensing mechanism is reported built upon the synergistic effect between inner filter effect and photoinduced electron transfer. We constructed a novel nanosensor based upon the newly-synthesized nanomaterial and demonstrated a sensitive and selective detection for both Fe3+ ion and ascorbic acid, enabling the measurements in real clinical samples. For the first time fluorescent graphdiyne oxide quantum dots (GDYO-QDs) were prepared using a facile ultrasonic protocol and they were characterized with a range of techniques, showing a strong blue-green emission with 14.6% quantum yield. The emission is quenched efficiently by Fe3+ and recovered by ascorbic acid (AA). We have fabricated an off/on fluorescent nanosensors based on this unique property. The nanosensors are able to detect Fe3+ as low as 95 nmol L-1 with a promising dynamic range from 0.25 to 200 µmol L-1. The LOD of AA was 2.5 µmol L-1, with range of 10-500 µmol L-1. It showed a promising capability to detect Fe3+ and AA in serum samples. Graphical abstract.

One-step synthesis of amine-functionalized fluorescent silicon nanoparticles for copper(II) ion detection.

Amine-functionalized silicon nanoparticles (A-SiNPs) with intense green fluorescence and photostability are synthesized via a one-step, low-cost hydrothermal method under mild conditions using 3-aminopropyl triethoxysilane (APTES) as a silicon source and L-ascorbic acid (AA) as a reducing reagent. The amine-rich surface not only improves water dispersability and stability of the A-SiNPs but also offers a specific copper(II) ion (Cu2+) coordination capability. The as-prepared A-SiNPs can be directly employed for Cu2+ detection in "turn-off" mode, resulting from Cu2+ coordination-induced fluorescence quenching effect. Under optimal conditions, Cu2+ detection was accomplished with a linear range from 1 to 500 µM and a limit of detection (LOD) at 0.1 µM, which was much lower than the maximum level (~ 20 µM) of Cu2+ in drinking water permitted by the US Environmental Protection Agency (EPA). In addition, the A-SiNPs were successfully used to detect Cu2+ in spiked river water, demonstrating its good selectivity and potential application for analysis of surface water samples. Graphical abstract.

A molecularly imprinted polymer placed on the surface of graphene oxide and doped with Mn(II)-doped ZnS quantum dots for selective fluorometric determination of acrylamide.

A polymer imprinted with acrylamide (AM-MIP) was synthesized on the surface of graphene oxide by surface polymerization of propionamide (serving as a dummy template), methacrylic acid (as the functional monomer) and ethylene glycol dimethacrylate (the cross-linker). ZnS quantum dots (QDs) doped with Mn(II) ions were added to the AM-MIP to act as fluorescence source. The AM-MIP was characterized by infrared spectroscopy, scanning electron microscopy and X-ray powder diffraction, suggesting that the imprinted layer was successfully grafted onto graphene oxide. The fluorescence of the doped QDs is quenched when loading the AM-MIP with acrylamide (AM), and the quenching effect is much stronger than the non-imprinted polymer (AM-NIP). Quenching follows Stern-Volmer kinetics. The combination of imprinting and fluorometric detection offer AM-IIP capability to accumulate trace AM before direct determination, omitting desorption and separation or other methods. The excitation and emission spectra of AM-MIP peak at 325 nm and 601 nm, respectively. Under optimal conditions, fluorescence drops linearly in the 0.5-60 µmol·L-1 acrylamide concentration range, and the detection limit is 0.17 µmol·L-1. The method has been applied to the determination of AM in spiked water samples and gave recoveries in the range from 100.2 to 104.5%, with relative standard deviations in the 1.9 to 3.9% range. In our perception, the AM-MIP presented here is a promising fluorescent probe for the detection of trace acrylamide in food. Graphical abstract Schematic of the preparation of graphene oxide coated with a molecularly imprinted polymer doped with Mn(II)-doped ZnS quantum dots. Propionamide serves as a dummy template. Acrylamide acts as a quencher of fluorescence, and this effect is used for its selective fluorometric determination.

CdTe/ZnS quantum dots as fluorescent probes for ammonium determination.

Novel CdTe/ZnS quantum dot (QD) probes based on the quenching effect were proposed for the simple, rapid, and specific determination of ammonium in aqueous solutions. The QDs were modified using 3-mercaptopropionic acid, and the fluorescence responses of the CdTe/ZnS QD probes to ammonium were detected through regularity quenching. The quenching levels of the CdTe/ZnS QDs and ammonium concentration showed a good linear relationship between 4.0 × 10(-6) and 5.0 × 10(-4) mol/L; the detection limit was 3.0 × 10(-7) mol/L. Ammonium contents in synthetic explosion soil samples were measured to determine the practical applications of the QD probes and a probable quenching mechanism was described. Copyright © 2015 John Wiley & Sons, Ltd.

Pyrenetetrasulfonate-grafted 2D ultrathin metal-organic layer as new electrochemiluminescence emitters for ultrasensitive microRNA-21 assay.

The exploration of novel electrochemiluminescence (ECL) luminophores with excellent ECL properties is a current research hotspot in the ECL field. Herein, a novel high-efficiency Ru-complex-free ECL emitter PyTS-Zr-BTB-MOL has been prepared by using porous ultrathin Zr-BTB metal-organic layer (MOL) as carrier to coordinatively graft the cheap and easily available polycyclic aromatic hydrocarbon (PAH) derivative luminophore PyTS whose ECL performance has never been investigated. Gratifyingly, the ECL intensity and efficiency of PyTS-Zr-BTB-MOL were markedly enhanced compared to both PyTS monomers and PyTS aggregates. The main reason was that the distance between pyrene rings was greatly expanded after the PyTS grafting on the Zr6 clusters of Zr-BTB-MOL, which overcame the aggregation-caused quenching (ACQ) effect of PyTS and thus enhanced the ECL emission. Meanwhile, the porous nanosheet structure of PyTS-Zr-BTB-MOL could distinctly increase the exposure of PyTS luminophores and shorten the diffusion paths of coreactants and electrons/ions, which effectively promoted the electrochemical excitation of more PyTS luminophores and thus achieved a further ECL enhancement. In light of the remarkable ECL property of PyTS-Zr-BTB-MOL, it was employed as an ECL indicator to build a novel high-sensitivity ECL biosensor for microRNA-21 determination, possessing a satisfactory response range (100 aM to 100 pM) and an ultralow detection limit (10.4 aM). Overall, this work demonstrated that using MOLs to coordinatively graft the PAH derivative luminophores to eliminate the ACQ effect and increase the utilization rate of the luminophores is a promising and efficient strategy to develop high-performance Ru-complex-free ECL materials for assembling ultrasensitive ECL biosensing platforms.

Determination of rivaroxaban by utilizing its quenching effect on acetoxymercuric fluorescein reagent in pharmaceutical preparations and in spiked biological matrices.

A simple, precise and inexpensive spectrofluorimetric method has been developed for assay of rivaroxaban raw material and its tablets. The method depends on the quenching effect of rivaroxaban on the fluorescence intensity of acetoxymercuric fluorescein (AMF). Parameters that may affect the reaction such as pH, AMF solution concentration, reaction time and diluting solvents were studied and optimized. The proposed method was applied for determination of rivaroxaban in tablets with percentage recovery of 100.4 ± 0.28, and in organic extract of spiked plasma samples with percentage recovery of 98.40 ± 1.08. The developed method was validated according to ICH guidelines in terms of accuracy, precision, linearity, range, limit of detection (LOD) and limit of quantification (LOQ).