Bifunctional oxidase-peroxidase mimicking Fe-Ce MOF on paper-based analytical devices to intensify luminol chemiluminescence: Application for measuring different sugars with a smartphone readout.

This study presents a potent paper-based analytical device (PAD) for quantifying various sugars using an innovative bi-nanozyme made from a 2-dimensional Fe/Ce metal-organic framework (FeCe-BTC). The MOF showed excellent bifunctional peroxidase-oxidase activities, efficiently catalyzing luminol's chemiluminescence (CL) reaction. As a peroxidase-like nanozyme, FeCe-BTC could facilitate the dissociation of hydrogen peroxide (H2O2) into hydroxyl radicals, which then oxidize luminol. Additionally, it was also discovered that when reacting with H2O2, the MOF turns into a mixed-valence MOF, and acts as an oxidase nanozyme. This activity is caused by the generated Ce4+ ions in the structure of MOF that can directly oxidize luminol. The MOF was directly synthesized on the PAD and cascaded with specific natural enzymes to establish simple, rapid, and selective CL sensors for the measurement of different sugars. A cell phone was also used to record light intensities, which were then correlated to the analyte concentration. The designed PAD showed a wide linear range of 0.1-10 mM for glucose, fructose, and sucrose, with detection limits of 0.03, 0.04, and 0.04 mM, respectively. It showed satisfactory results in food and biological samples with recovery values ranging from 95.8 to 102.4 %, which makes it a promising candidate for point-of-care (POC) testing for food control and medicinal purposes.

FeS2 nanosheets-luminol-O2 chemiluminescence method for determination of venlafaxine hydrochloride, imipramine hydrochloride, and cefazolin sodium.

This study introduces a novel chemiluminescence (CL) approach utilizing FeS2 nanosheets (NSs) catalyzed luminol-O2 CL reaction for the measurement of three pharmaceuticals, namely venlafaxine hydrochloride (VFX), imipramine hydrochloride (IPM), and cefazolin sodium (CEF). The CL method involved the phenomenon of quenching induced by the pharmaceuticals in the CL reaction. To achieve the most quenching efficacy of the pharmaceuticals in the CL reaction, the concentrations of reactants comprising luminol, NaOH, and FeS2 NSs were optimized accordingly. The calibration curves demonstrated exceptional linearity within the concentration range spanning from 4.00 × 10-7 to 1.00 × 10-3 mol L-1, 1.00 × 10-7 to 1.00 × 10-4 mol L-1, and 4.00 × 10-6 to 2.00 × 10-4 mol L-1 with detection limits (3σ) of 3.54 × 10-7, 1.08 × 10-8, and 2.63 × 10-6 mol L-1 for VFX, IPM, and CEF, respectively. This study synthesized FeS2 NSs using a facile hydrothermal approach, and then the synthesized FeS2 NSs were subjected to a comprehensive characterization using a range of spectroscopic methods. The proposed CL method was effective in measuring the aforementioned pharmaceuticals in pharmaceutical formulations as well as different water samples. The mechanism of the CL system has been elucidated.

A dual-targeting nanobiosensor for Gender Determination applying Signal Amplification Methods and integrating Fluorometric Gold and Silver Nanoclusters.

A dual-targeting nanobiosensor has been developed for the simultaneous detection of AMELX and AMELY genes based on the different fluorescence signals emitted from gold and silver nanoclusters, AuNCs and AgNCs respectively. In our design, both catalytic hairpin assembly (CHA) and hybridization chain reaction (HCR) have been used as isothermal, enzyme-free and simple methods for signal's amplification. The working principle is based on the initiation of a cascade of CHA-HCR reactions when AMELX is present, in which AuNCs, synthesized on the third hairpin, are aggregated on the surface of the dsDNA product, performing the phenomenon of aggregation induced emission (AIE) and enhancing their fluorescence signal. On the other hand, the presence of the second target, AMELY, is responsible for the enhancement of the fluorescence signal corresponding to AgNCs by the same phenomenon, via hybridizing to the free end of the dsDNA formed and at the same time to the probe of silver nanoclusters fixing it closer to the surface of the dsDNA product. Such a unique design has the merits of being simple, inexpensive, specific and stable and presents rapid results. The detection limits of this assay for AMELX and AMELY are as low as 3.16 fM and 23.6 fM respectively. Moreover, this platform showed great performance in real samples. The design has great promise for the application of dual-targeting nanobiosensors to other biomarkers.

AuNRs attached TiO2 NPs modified by cobalt-imidazolate frameworks as exceptional materials to improve the energy conversion efficiency of dye-sensitized solar cells.

This work reports a significant improvement in both the open-circuit voltage (VOC) and current density (J) of dye-sensitized solar cells (DSSCs) using gold nanorod-modified TiO2 nanoparticles (TiO2/AuNRs) together with a cobalt-imidazolate framework (ZIF-67) as an efficient photoanode. It was demonstrated that adding ZIF-67 (8 wt%) to TiO2 NPs increased the VOC by 160 mV and J by 2.5 times. This observation was described based on the significant increase in the amount of adsorbed dye in the presence of highly porous ZIF-67, which boosts the photoanode's light harvesting. Modifying TiO2 NPs with AuNRs also caused a remarkable enhancement in J (∼ 2.8 times), which can be explained via electron transfer between the TiO2 conduction band and AuNRs. It can result in a more efficient inhibiting effect on the interfacial charge recombination processes in TiO2/AuNRs/ZIF-67 because of the formation of a Schottky barrier at the interface between TiO2 and Au. These effects were confirmed by the reduction in the photoluminescence intensity of TiO2 in the presence of AuNRs. More reduction in the photoluminescence intensity was observed when ZIF-67 was added. The prepared photoanode showed an outstanding improvement in the overall efficiency of the DSSC (η) to 8.38% compared to the bare TiO2-based photoanode (1.83%). The notable improvement in the TiO2/AuNRs/ZIF-67 performance confirmed its practicality for high-efficiency DSSCs.

FeS2 nanosheets-H2 O2 -NaHCO3 chemiluminescence method for procaine hydrochloride determination.

FeS2 nanosheets (NSs) were produced and exploited as a new catalyst for a chemiluminescence (CL) reaction. The characterization of FeS2 NSs was performed using spectroscopic methods. In this regard, transmission electron microscopy images showed that FeS2 NSs have a length of ~0.5-1 µm. The direct optical band gap energy of FeS2 NSs was found to be 3.45 eV. Prepared FeS2 NSs were used to catalyze the NaHCO3 -H2 O2 CL reaction. It was found that procaine hydrochloride (PCH) could reduce the intensity of the FeS2 NSs-NaHCO3 -H2 O2 CL reaction so, with increasing PCH concentrations, the intensity of light emission decreased. Therefore, a simple and sensitive method was introduced to measure PCH with a linear range expanded from 1.00 × 10-6 to 1.00 × 10-3  mol L-1 and an 8.32 × 10-7  mol L-1 limit of detection. Studies related to the effect of foreign species and reaction mechanisms were performed. The application of the approach was verified by quantifying the PCH in the injection.

Novel amino-functionalized magnetic metal-organic framework/layered double hydroxide adsorbent for microfluidic solid phase extraction: Application for vitamin D3.

Vitamin D deficiency is highly prevalent worldwide, especially with limited sun exposure and sun avoidance. Thus, reliable monitoring of vitamin D levels in food and biological samples is vital for medicinal diagnosis. Herein, a potent method for the extraction and determination of vitamin D3 is presented using a microchip-based solid-phase extraction (SPE) device followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) detection. A new magnetic adsorbent based on Fe3O4 magnetic nanoparticles (MNPs) modified ZnFe layered double hydroxide (LDH)/2-aminoterephthalic acid-Zn2+ metal-organic framework (IRMOF-3) composite (IRMOF-3@MLDH) was successfully synthesized and fixed inside a rectangular micro-column (4 × 2 × 12 mm). The porous structure and high surface area of IRMOF-3@MLDH provide abundant adsorbing sites and make it a potent SPE adsorbent, with an exceptional ability to retain vitamin D3. The adsorption isotherm showed that the composite was highly efficient at extracting vitamin D3 with an extraction capacity of 126 mg g-1. The designed extraction microchip simplified the SPE process, paving the way for automated SPE systems. The developed method presented a broad linear range of 5-2000 ng mL-1, with a detection limit of 1.4 ng mL-1. In comparison to conventional silica-based adsorbents, a higher sensitivity was obtained in the determination of vitamin D3 using the IRMOF-3@MLDH adsorbent. The selectivity of the method was also satisfactory, enabling the measurement of vitamin D3 in food and blood samples with high recovery values in the range from 95.2 to 101%. Thus, the newly developed adsorbent and method offer an efficient alternative to the commonly used C18-based approach.

Nickel oxide hollow microsphere for the chemiluminescence determination of tuberculostatic drug isoniazid.

In this article, nickel(II) oxide (NiO) hollow microspheres (HMSs) were fabricated and used to catalyze chemiluminescence (CL) reaction. The studied CL reaction is the luminol-oxygen reaction that was used as a sensitive analytical tool for measuring tuberculostatic drug isoniazid (IND) in pharmaceutical formulations and water samples. The CL method was established based on the suppression impact of IND on the CL reaction. The NiO HMSs were produced by a simple hydrothermal method and characterized by several spectroscopic techniques. The result of essential parameters on the analytical performance of the CL method, including concentrations of sodium hydroxide (NaOH), luminol, and NiO HMSs were investigated. At the optimum conditions, the calibration curve for IND was linear in the range of 8.00 × 10-7 to 1.00 × 10-4  mol L-1 (R2  = 0.99). A detection limit (3S) of 2.00 × 10-7  mol L-1 was obtained for this method. The acceptable relative standard deviation (RSD) was obtained for the proposed CL method (2.63%, n = 10) for a 5.00 × 10-6  mol L-1 IND solution. The mechanism of the CL reaction was also discussed.

Carbon dots-modified paper-based chemiluminescence device for rapid determination of mercury (II) in cosmetics.

Here, a simple and portable paper-based analytical device (PAD) based on the inherent capability of carbon quantum dots (CQDs) to serve as a great emitter for the bis(2,4,6-trichlorophenyl)oxalate (TCPO)-hydrogen peroxide (H2O2) chemiluminescence (CL) reaction is introduced for the detection of harmful mercury ions (Hg2+ ). The energy is transferred from the unstable reaction intermediate (1,2-dioxetanedione) to CQDs, as acceptors, and an intensive orange-red CL emission is generated at ~600 nm, which is equal to the fluorescence emission wavelength of CQDs. The analytical applicability of this system was examined for the determination of Hg2+ . It was observed that Hg2+ could significantly quench the produced emission, which can be attributed to the formation of a stable and nonluminescent Hg2+ -CQDs complex. Accordingly, a simple and rapid PAD was established for monitoring Hg2+ , with a limit of detection of 0.04 µg ml-1 . No interfering effect on the signal was found from other examined cations, indicating the acceptable specificity of the method. The designed assay was appropriately utilized to detect Hg2+ ions in cosmetic samples with high efficiency. It was characterized by its low cost, ease of use, and was facile but accurate and high selective for the detection of Hg2+ ions. In addition, the portability of this probe makes it suitable for on-site screening purposes.

On paper synthesis of multifunctional CeO2 nanoparticles@Fe-MOF composite as a multi-enzyme cascade platform for multiplex colorimetric detection of glucose, fructose, sucrose, and maltose.

This study reports an economical and portable point-of-care (POC) monitoring device based on artificial multi-enzyme cascade systems for multiple detection purposes. The device was made up of a disposable three dimensional microfluidic paper-based analytical device (3D µPAD) with multiple detection zones and a smartphone readout. On-paper synthesis of a multifunctional mimetic composite, based on the CeO2 nanoparticles embedded in the amino-functionalized Fe metal-organic frameworks (CeO2@NH2-MIL-88B(Fe)), for cascade reactions was the main achievement of this work. The 3D µPAD was applied for simultaneous quantification of glucose, fructose, sucrose and maltose, and the detection process consisted of the enzymatic reaction of each sugar by anchored enzymes on the metal-organic frameworks (MOF) and successive oxidation of 3,3',5,5'-tetramethylbenzidine (TMB). Utilizing the new artificial mimicking system improved the color development uniformity and resulted in a reliable detection tool, with excellent detection limits in the range of 20-280 µM. It was directly applied to analyze the sugars levels of human total blood, urine, semen, honey and juice samples with the relative errors of less than 7.7% compared with the HPLC method. The cost-effective and easy-to-use µPAD has a great potential to be used in either medical diagnostics or the food industry. Also, it can be considered as a competitive POC method for patients in disadvantaged communities or emergencies.

Synthesis of rod-like CeO2 nanoparticles and their application to catalyze the luminal-O2 chemiluminescence reaction used in the determination of oxcarbazepine and ascorbic acid.

Rod-like CeO2 nanoparticles (NPs) were produced by the quick precipitation approach and employed as a catalyzer to increase the chemiluminescence (CL) intensity of the luminol-O2 reaction. The transmission electron microscopy (TEM) images of the CeO2 NPs showed that rod-like particles with the length and diameter about 15 nm and 5 nm, respectively, were produced. Furthermore, pharmaceuticals including oxcarbazepine (OXP) and ascorbic acid (AA) showed an inhibitory effect against the CL intensity such that the more concentration of the pharmaceuticals, the less was the CL intensity. Therefore, the new CeO2 NPs-luminol-O2 CL reaction was developed to determine OXP and AA in the pharmaceutical formulations. It is the first CL method established for the quantification of OXP. The linear dynamic range of this method for OXP was from 6.0 × 10-7 to 6.0 × 10-5 mol L-1 and for AA from 1.0 × 10-6 to 1.0 × 10-4 mol L-1.

A handheld 3D-printed microchip for simple integration of the H2O2-producing enzymatic reactions with subsequent chemiluminescence detection: Application for sugars.

Herein, a novel lab-on-a-chip (LoC) device fabricated by 3D printing based on H2O2-producing enzymatic reactions with sensitive chemiluminescence (CL) detection was developed to measure different sugars, including glucose, fructose, sucrose, and maltose, in honey, juice, and rice flour samples. The pumpless microchip included two main parts, separated by new cone-shape blocking valves; part A for sample introduction and subsequent enzymatic reaction, besides the CL reagent (luminol) container, and part B for detection. The specific enzyme(s) were embedded into the pores of the zinc zeolite-imidazole framework (ZIF-8) to improve their storage stability. By opening the valves, H2O2 produced by enzymatic reaction and luminol could flow through the designed channels into the detection zone on part B, where a 2D cobalt-imidazole framework was embedded to improve the luminol-H2O2 CL emission. The obtained signal was proportional to the considered sugar concentration, with the detection limits range of 20-268 µM.

On paper synthesis of metal-organic framework as a chemiluminescence enhancer for estimating the total phenolic content of food samples using a smartphone readout.

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.

A paper-based chemiluminescence detection device based on S,N-doped carbon quantum dots for the selective and highly sensitive recognition of bendiocarb.

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.

CuS nanoparticles-enhanced luminol-O2 chemiluminescence reaction used for determination of paracetamol and vancomycin.

A new chemiluminescence (CL) method was proposed to measure two widely used drugs, including paracetamol (PCM) and vancomycin (VAN). The CL reaction used was the CuS nanoparticles (CuS NPs)-luminol-O2 system. In this system, CuS NPs played the role of catalyst and increased the CL intensity. CuS NPs were easily synthesized by quick-precipitation. CuS NPs were characterized by spectroscopic techniques, and the mean size of NPs was estimated to be about 9 nm. In the developed CL methods, PCM and VAN decreased the CL intensity. In the proposed method, the linear concentration ranges were 4.0 × 10-5-4.0 × 10-4 mol L-1 of PCM and 2.0 × 10-5-6.0 × 10-4 mol L-1 of VAN. The limit of detections were 2.9 × 10-5 mol L-1 and 8.9 × 10-6 mol L-1 for PCM and VAN, respectively. The relative standard deviations (RSD) of the CL method were 2.99 and 4.31 (n = 6) for the determination of 3.0 × 10-4 mol L-1 PCM and VAN, respectively. It was also shown that the CL methods can measure PCM and VAN concentrations in various real samples.

Simultaneous determination of total phenolic acids and total flavonoids in tea and honey samples using an integrated lab on a chip device.

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.

A review of recent developments based on chemiluminescence detection systems for pesticides analysis.

Chemiluminescence is one of the most coveted methods for sensitive determination of pesticides in food and environmental samples. To date, many methods have been developed for qualitative and quantitative analysis of pesticides, ranging from traditional to advanced methods. This study outlines the progress in the conventional and advanced analytical methods, coupled to a chemiluminescence detection system, that are employed for the determination of pesticides in food and environmental samples. Different analytical methods including chromatographic methods, flow-based systems, and paper-based systems are reviewed in this paper. As well, new advances in the application of nanomaterials, aptamer, and molecularly imprinted polymers are highlighted. We also address the challenges and difficulties associated with these methods. Finally, we highlight the future direction in this active field of research.

Magnetic zinc based 2D-metal organic framework as an efficient adsorbent for simultaneous determination of fluoroquinolones using 3D printed microchip and liquid chromatography tandem mass spectrometry.

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.

Dual-function 2D cobalt metal-organic framework embedded on paper as a point-of-care diagnostic device: Application for the quantification of glucose.

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.

Controlled Microwave-Assisted Synthesis of the 2D-BiOCl/2D-g-C3N4 Heterostructure for the Degradation of Amine-Based Pharmaceuticals under Solar Light Illumination.

Designing efficient 2D-bismuth oxychloride (BiOCl)/2D-g-C3N4 heterojunction photocatalysts by the microwave-assisted method was studied in this work using different amounts of BiOCl plates coupled with g-C3N4 nanosheets. The effects of coupling the 2D structure of g-C3N4 with the 2D structure of BiOCl were systematically examined by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy, X-ray diffraction, photoluminescence (PL), lifetime decay measurement, surface charges of the samples at various pH conditions, and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). The prepared photocatalysts were used for the degradation of amine-based pharmaceuticals, and nizatidine was used as a model pollutant to evaluate the photocatalytic activity. The UV-vis DRS and other optical properties indicated the major effect of coupling of BiOCl with g-C3N4 into a 2D/2D structure. The results showed a narrowing in the band gap energy of the composite form, whereas the PL and lifetime analysis showed greater inhibition of the electron-hole recombination process and slightly longer charge carrier lifetime. Accordingly, the BiOCl/g-C3N4 composite samples exhibited an enhancement in the photocatalytic performance, specifically for the 10% BiOCl/g-C3N4 sample. Moreover, the zeta potential of this sample at different pH values was evaluated to determine the isoelectric point of the synthesized composite material. Consequently, the pH was adjusted to match the isoelectric point of the complex materials, which further enhanced the activity. Further degradation of pharmaceuticals was studied under solar light irradiation, and 96% degradation was achieved within 30 min.

Metal-Organic Framework Loaded by Rhodamine B As a Novel Chemiluminescence System for the Paper-Based Analytical Devices and Its Application for Total Phenolic Content Determination in Food Samples.

Herein, a novel paper-based chemiluminescence (CL) device has been reported for the estimation of total phenolic content of food samples. The CL system implemented on the paper was based on a hydrogen peroxide (H2O2)-rhodamine b (RhoB)-cobalt metal organic framework (CoMOF) reaction. It was found that the reaction of H2O2 with RhoB molecules, loaded into the nanopores of CoMOF (R@CoMOF), can produce an intensive CL emission. The experiments on the paper indicated that in the presence of CoMOF, the CL emission was greatly increased. In addition to this strong catalyzing effect, application of CoMOF on the paper improved the stability of the CL system for several days. As a useful analytical application for the obtained paper-based CL device (PCD), it was examined for the detection of phenolic antioxidants. It was observed that the addition of 5 µL of phenolic compounds (PC) on the paper containing the CL reagents can remarkably decrease the CL intensity. This effect was applied to design a simple analytical assay for PC. After the optimization process, the best sensitivity was obtained for gallic acid, quercetin, catechin, kaempferol, and caffeic acid with detection limits of 0.98, 1.36, 1.48, 1.81, and 2.55 ng mL-1, respectively. The relative standard deviations (RSD%) were also less than 5%. This study is the first report on the practical application of PCD using a nanomaterial assisted CL reaction. It is simple, portable, and low-cost and consumes a very low amount of reagents and sample solution. The device was successfully applied in the investigation of total antioxidant capacity of molasses and honey samples.