Wide Linearity Research Articles

Ti3C2Tx MXene‐Polyaniline Nanocomposite as an Adsorbent in Microextraction by Packed Sorbent for the Analysis of Parabens in Water and Juice Samples

ABSTRACTHerein, a novel Ti3C2Tx MXene and polyaniline nanocomposite is successfully synthesized and used for the highly efficient extraction of parabens. Polyaniline (PANI) nanofibers have formed a porous and peculiar π–π conjugated structure on hydrophilic MXene sheets, providing numerous adsorption sites for microextraction of analytes with moderate polarities such as parabens. The method is simple and sensitive, using microextraction by packed sorbent coupled with a high‐performance liquid chromatography‐ultraviolet detector. Under the optimal conditions, the method provides suitable preconcentrating factors of 28–35, ultrahigh sensitivity with low limits of detection of 0.3–0.5 µg/L, wide linearity of 0.3.0–200 µg/L with coefficients of determination ≥ 0.9983, and satisfactory precision with relative standard deviations ≤ 10.7%. The outstanding performance has been confirmed in well water and orange juice samples, with recoveries in the range of 93.1%–101.2% for water and 90.6%–103.4% for orange juice samples, respectively.

Sensitive Electrochemical Determination of Quercetin in Fruit Juice Using an Aluminum Hydroxide Oxide–Titanium Carbide MXene Composite

A hybrid material composed of aluminum hydroxide oxide (AlOOH) and titanium carbide (Ti3C2) nanosheets was synthesized and used for electrochemical sensing of quercetin. The Ti3C2 nanosheets were synthesized using a selective etching technique, followed by the hydrothermal growth of AlOOH on the nanosheet surfaces. Cyclic voltammetry and differential pulse voltammetry were performed to evaluate the electrochemical properties of the AlOOH@Ti3C2 nanocomposites. Under optimal conditions, the AlOOH@Ti3C2 modified electrode exhibited wide linearity and high sensitivity. The practicality of the sensor was verified through an interference study and real sample analysis. Additionally, the sensing platform exhibited outstanding operational and storage stability.

Hydrophobic melamine sponge incorporated with carbon dots as a green sorbent for micro-solid phase extraction of triazole fungicide residues in edible fungi samples

Fabrication of hydrophobic melamine sponge incorporated with carbon dots was investigated to extract triazoles prior to HPLC-DAD quantitation. The melamine sponge was simply incorporated with carbon dots via thermal treatment under facile conditions. The optimum conditions were melamine sponge (MeS) (1 × 1 × 1 cm3), 10 mL of standard solution, 0.04 M citric acid, functionalized at 250 °C for 5 h, and the analytes was then eluted from as-prepared material using acetonitrile (200 µL). Operating the best conditions, wide linearity was gained with R2 ≥ 0.99, for all analytes. Detection limits established varied between 3–10 μg L−1. Such approached method demonstrates excellent applicability for accurately and efficiently determining triazole fungicides in edible fungi samples, and a good recovery was also obtained. In addition, the desirable method validation and cost effective, not only its potential for reuse, but also provides it a better alternative for matrix purification. The appraisal estimated by two methods, confirmed its superior environmental friendliness.

Development of novel digital PCR assays for the rapid quantification of Gram-negative bacteria biomarkers using RUCS algorithm.

Rapid and accurate identification of bacterial pathogens is crucial for effective treatment and infection control, particularly in hospital settings. Conventional methods like culture techniques and MALDI-TOF mass spectrometry are often time-consuming and less sensitive. This study addresses the need for faster and more precise diagnostic methods by developing novel digital PCR (dPCR) assays for the rapid quantification of biomarkers from three Gram-negative bacteria: Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Utilizing publicly available genomes and the rapid identification of PCR primers for unique core sequences or RUCS algorithm, we designed highly specific dPCR assays. These assays were validated using synthetic DNA, bacterial genomic DNA, and DNA extracted from clinical samples. The developed dPCR methods demonstrated wide linearity, a low limit of detection (∼30 copies per reaction), and robust analytical performance with measurement uncertainty below 25 %. The assays showed high repeatability and intermediate precision, with no cross-reactivity observed. Comparison with MALDI-TOF mass spectrometry revealed substantial concordance, highlighting the methods' suitability for clinical diagnostics. This study underscores the potential of dPCR for rapid and precise quantification of Gram-negative bacterial biomarkers. The developed methods offer significant improvements over existing techniques, providing faster, more accurate, and SI-traceable measurements. These advancements could enhance clinical diagnostics and infection control practices.

Development of an ultrasensitive electrochemical aptasensor based on aptamer/rGO/SPGE for the detection of Botulinum neurotoxin A (BoTN/A) in food samples

Consumption of Botulinum neurotoxin A (BoTN/A) contaminated foods has increased the public health issues which necessitates the development of rapid and simple diagnostic tools for their sensitive detection. Electrochemical aptasensors can replace existing biosensors and traditional methods of BoTN/A detection in foods. These aptasensors are simple, quick response, economic, precise, sensitive, accurate and reproducible. In the present study, an electrochemical aptasensor was constructed by immobilizing BoTN/A specific aptamer and reduced graphene oxide (rGO) onto screen printed gold electrode (SPGE) for the detection of BoTN/A in spiked food samples. The specificity of this aptasensor was achieved by conjugating BoTN/A specific aptamer on rGO/SPGE. Test sample containing BoTN/A form aptamer-BoTN/A complex onto SPGE which was directly proportional to BoTN/A concentration. Formation of aptamer-BoTN/A complex reduced the surface of working SPGE for redox reactions. Thus decreased the current peaks that was taken as measuring signal of BoTN/A in test food sample. BoTN/A aptasensor showed optimum response at pH 6.5 and 30 °C temperature. The responsetime of BoTN/A/aptamer/rGO/SPGE was 6 s. In optimum conditions aptamer/rGO/SPGE BoTN/A aptasensor exhibited wide linearity ranges from 1-100 pM and 1 pM limit of detection (LOD). The analytical recoveries of aptamer/rGO/SPGE BoTN/A aptasensor at 5 pM and 10 pM BoTN/A were 98.5 % and 99.8 % respectively. The proposed aptasensor showed unique sensitivity, reproducibility and accuracy. Moreover, aptamer/rGO/SPGE aptasensor was used for the detection of BoTN/A in five different types of food samples.

Computationally Optimized Graphene-Based Electrochemical Sensor with Enhanced Signal Stability for the Determination of the Antimicrobial Agent 9-aminoacridine

A hydrophobic aryl diazonium salt has been synthesized from 3,5-bis(trifluoromethyl)aniline and utilized to covalently modify graphene nanoplatelets and carbon nanotubes. The modified nanomaterials were applied on a screen-printed electrode/ion sensing membrane interface resulting in reduced potential drift to 100 μV h−1 compared to control sensors. Characterization was achieved through X-ray photoelectron spectroscopy. The electrode’s response was optimized using response surface methodology and then utilized for determination of 9-Aminoacridine (9-AA) in pharmaceutical gel dosage form and spiked human plasma without prior extraction steps. 9-AA is a fluorescent dye with antimicrobial activity that eradicates a range of microorganisms that can cause oral sores or broken skin and it has been recently used as anticancer among other uses as fluorescent dye and pH indicator. Accurate determination of 9-AA could help in adjusting dosages for each application. The optimized sensor was validated per IUPAC guidelines and obtained a wide linearity range from 1.0 × 10–7 M to 1.0 × 10–2 M, correlation coefficient of 0.9997, improved Nernstian slope 59.72, long term stability, and lower limit of detection (9.0 × 10–8 M). Furthermore, Analytical Eco-scale and AGREE methods were utilized to evaluate the presented method’s greenness.

Impedimetric Biosensor of Silver Molybdate Anchored on rGO Sheet for Detection of Breast Cancer Mucin‐1 Biomarker

AbstractThis work aims to detect the Mucin‐1 (MUC1) breast cancer biomarker using a label‐free impedimetric biosensor of silver molybdate anchored on reduced graphene oxide (Ag2MoO4‐rGO). A hydrothermal method has been employed to synthesize the Ag2MoO4‐rGO nanocomposite. Subsequently, they have been studied through analytical characterization techniques to study the electrocatalytic activity, electroactive surface area, surface functionalities, and morphologies to determine the suitability of the material for biosensor fabrication. Results reveal that the Ag2MoO4‐rGO nanocomposite possesses excellent electroconductivity and surface properties that have significant characteristics for the biosensor's performance. A biosensor has been fabricated by the immobilization of Ag2MoO4‐rGO nanocomposite and anti‐MUC1 antibody on a glassy carbon electrode. The electroanalytical studies revealed that the biosensor has excellent sensitivity and detection performance having a wide linearity of 100 fg mL−1–5 ng mL−1 and a low limit of detection of 2.70 fg mL−1. Moreover, the remarkable selectivity, reproducibility, stability, and detection in serum samples determine the high performance of the biosensor. Therefore, the presented biosensor could be a promising diagnostic tool that shows the remarkable potential to efficiently detect the breast cancer MUC1 biomarker in patient's serum samples.

Preparation and evaluation of polymeric ionic liquid functionalized microparticles as the efficient adsorbent for pipette tip solid phase extraction of sulfonamides

Sulfonamides (SAs) residues are commonly found in environmental samples, which is highly concerning for public safety and environmental protection. The detection of SAs is quite important but challenging. In this work, a kind of polymeric ionic liquid functionalized microparticles (PIL-FM) was synthesized via a simple free radical polymerization reaction, and applied as the adsorbent for pipette tip solid phase extraction (PT-SPE) of three SAs from river water, milk powder and honey samples. The adsorption performance of PIL-FM on SAs were evaluated using adsorption kinetics and adsorption isotherms, and the results showed that PIL-FM had the best selectivity for SMZ with the maximum adsorption capacity was as high as 45.05 mg·g−1. The extraction process was optimized and the adsorption mechanism was preliminarily discussed. PIL-FM has the excellent selectivity for SAs mainly because of the strong π-π interaction, and the electrostatic repulsion between them in the elution step also has a positive impact. Under optimal conditions, combined with HPLC, this PT-SPE method had wide linearity (0.2–100 μg·L−1, R2 ≥ 0.9998) and low limits of detection (0.06–0.08 μg·L−1). The intra-day and inter-day repeatability were found to be 3.7 %–4.6 % and 4.5 %–6.2 %, respectively. The suggested PT-SPE method is simple, low cost, rapid, and efficient to extract SAs, and can be applied for the monitoring of SAs residues in the aquatic environment and in food.

Preparation of core-shell magnetic molecularly imprinted polymers on Fe3O4 nanosphere via self-polycondensation for magnetic solid-phase extraction of 2,4-dinitrophenol in environmental water samples

ABSTRACT In this study, a core-shell magnetic molecularly imprinted polymers (MMIPs) adsorbent targeting 2,4-dinitrophenol (2,4-DNP) as a template molecule was developed by surface polymerisation and applied for magnetic solid-phase extraction prior to the determination of 2,4-DNP in environmental water samples via high-performance liquid chromatography. Different experiments were carried out to optimise the magnetic solid-phase extraction conditions. Subsequently, the adsorption capacity and selectivity of prepared MMIPs were investigated. Theoretical analysis demonstrated that the experimental data fitted well to the pseudo-second-order model, suggesting that chemical adsorption might be the rate-limiting step, with a maximum adsorption capacity of 21.76 mg g−1. Under the optimised conditions, this method showed relatively wide linearity within the concentration range of 0.0025 μg·mL−1−0.5 μg·mL−1, with a relative standard deviation of 2.5%–6.2%. The detection limit and quantification limit were 0.23 µg·L−1 and 0.76 µg·L−1, respectively.

A selective, sensitive and fast LC-MS/MS method for cabotegravir quantification in rat plasma and pharmacokinetic investigations.

This study presents a novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for quantifying cabotegravir (CAB) in rat plasma. A novel, sensitive, and rapid LC-MS/MS method has been developed and validated. Furthermore, protein precipitation technique allowed us to lowered the limit of quantification (LOQ) to nanogram levels, allowing detection of smaller CAB amounts in plasma samples. A review of scientific literature reveals that this method is superior than published methods in terms of runtime, sensitivity, wide linearity, and cost, using LC-MS/MS to quantify CAB in biological samples. CAB reached its maximum concentration (Cmax) of 78.401 μg/mL in rat plasma at 1.50 h (Tmax). Linearity was evaluated across 0.05-1000 μg/mL for CAB using five calibration curves with at least nine standards each with r2 > 0.9997. The intra- and inter-day precision and accuracy results were below 15% and acceptable as per Food and Drug Administration (FDA) guidelines. Stability of compounds were established in a battery of stability studies, that is, benchtop, autosampler, and long-term storage stability as well as freeze thaw cycles. The validated method can be used as a routine method to support pharmacokinetic studies.

Rapid ion pair-based surfactant-assisted liquid-liquid microextraction with solidification of floating organic drop for simultaneous spectrophotometric determination of selected anionic dyes in food samples

Ion pair-based surfactant-assisted liquid-liquid microextraction with solidification of floating organic drops has been developed to extract Allura red (AR), tartrazine (TAR), and fast green (FG) prior to spectrophotometric determination. Cetyltrimethylammonium bromide (CTAB) was employed as ion-pairing agent to enhance the hydrophobic behavior of anionic dyes. 1-undecanol and ethanol were used as the extraction and dispersion solvents, respectively. The dyes were quantitatively extracted in the presence of KCl (0.15 mol L−1) at pH 4.0. The method exhibits wide linearity (15.0–1500.0 μg L−1 for AR, 35.0–2000.0 μg L−1 for TAR, and 3.0–1200.0 μg L−1 for FG) with preconcentration factors of 19.6, 20.1, and 19.9, respectively. The detection limit was 3.7. 9.5, and 0.83 μg L−1 for AR, TAR, and FG, respectively. The relative standard deviation did not exceed 2.1 %. The procedure was applied for the determination of these dyes in food samples.

Enhanced enzymatic electrochemical detection of an organophosphate Pesticide: Achieving Wide linearity and femtomolar detection via gold nanoparticles growth within polypyrrole films

The indiscriminate use of pesticides in agriculture demands the development of devices capable of monitoring contaminations in food supplies, in the environment and biological fluids. Simplicity, easy handling, high sensitivities, and low limits-of-detection (LOD) and quantification are some of the required properties for these devices. In this work, we evaluated the effect of incorporating gold nanoparticles into indigo carmine-doped polypyrrole during the electropolymerization of films for use as an acetylcholinesterase (AChE) enzyme-based biosensor. As proof of concept, the pesticide methyl parathion was tested towards the inhibition of AChE. The enzyme was immobilized simply by drop-casting a solution, eliminating the need for any prior surface modification. The biosensors were characterized with cyclic voltammetry, scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. The assays for the detection of methyl parathion with films containing polypyrrole, indigo carmine and AChE (PPy–IC–AChE) presented a sensitivity of 5.7 μA cm−2 g−1 mL and a LOD of 12 nmol L−1 (3.0 ng L−1) with a linear range from 1.3 x 10−7 mol L−1 to 1.0 x 10−5 mol L−1. The introduction of gold nanoparticles (AuNP) into the film (PPy–IC–AuNP-AChE) led to remarkable improvements on the overall performance, such as a lower redox potential for the enzymatic reaction, a 145 % increase in sensitivity (14 μA cm−2 g−1 mL), a wider detection dynamic range (from 1.3x10−7 to 1.0x10−3 mol L−1), and a very low LOD of 24 fmol L−1 (64 ag mL−1). These findings underscore the potential of using AuNPs to improve the enzymatic performance of biosensor devices.

Molecularly imprinted polymers-coated magnetic covalent organic frameworks for efficient solid-phase extraction of sulfonamides in fish

In this study, covalent organic frameworks (COFs) were grown in situ on magnetic nitrogen-doped graphene foam (MNGF), and the resulting composite of COFs-modified MNGF (MNC) was wrapped by molecularly imprinted polymers (MNC@MIPs) for specifically capturing SAs. A magnetic solid phase extraction (MSPE) method for SAs was established using MNC@MIPs with good magnetic responsiveness. The adsorption performance of MNC@MIPs was superior to that of non-molecularly imprinted polymers (MNC@NIPs), with shorter adsorption/desorption time and higher imprinting factors. A high-efficiency SAs analytical method was developed by fusing HPLC and MNC@MIPs-based MSPE. This approach provides excellent precision, a low detection limit, and wide linearity. By analyzing fish samples, the feasibility of the approach was confirmed, with SAs recoveries and relative standard deviations in spiked samples in the ranges of 77.2–112.7 % and 2.0–7.2 %, respectively. This study demonstrated the potential use of MNC@MIPs-based MSPE for efficient extraction and quantitation of trace hazards in food.

Simultaneous targeting and monitoring of free antigen and in-situ membrane antigen in prostate cancer cells via an aggregation-induced emission-based bifunctional probe

The precise clinical diagnosis of prostate cancer still presents inherent challenges, and usually a monitoring of multiple biomarkers is required. In this study, a new aggregation-induced emission (AIE)-based bifunctional strategy was developed for the simultaneous detection of prostate cancer-specific in situ membrane antigens (PSMA) and free antigens (PSA). First, a bifunctional fluorescent probe with double sensing sites (a PSA-specific sensing site and a PSMA-targeted ligand) was constructed. In the presence of PSA, it specifically binds to the PSA-specific sensing site of the probe, resulting in the restoration of the fluorescence signal, enabling linear sensing of PSA. For the detection of PSMA, the PSMA-targeted ligand modified on the probe can specifically recognize PSMA, inducing the aggregation of the AIE material and resulting in an enhanced fluorescence signal. Moreover, a liposome-based artificial cell was developed to simulate the real prostate cancer cell, and it was used to investigate the feasibility of monitoring the two types of antigens. Utilizing this bifunctional fluorescent strategy, a dual-analysis of free serum antigen biomarker of PSA and in-situ membrane antigen of PSMA was achieved. The assay exhibited a wide linearity range for PSA detection from 0.0001 to 0.1 μg/mL, with a low limit of detection (LOD) of 6.18 pg/mL. For PSMA, the obtained LOD is 8.79 pg/mL, with a linearity range from 0.0001 to 0.1 μg/mL. This strategy allows us to simultaneously assess the levels of two types of biomarkers in living human prostatic cancer cells, providing a highly accurate and selective tool for early screening and monitoring of prostatic cancer.

Molecule Engineering Metal-Organic Framework-Based Organic Photoelectrochemical Transistor Sensor for Ultrasensitive Bilirubin Detection.

The functionalization of metal-organic frameworks (MOFs) with organic small molecules by in situ postsynthetic modification has garnered considerable attention. However, the precise engineering of recognition sites using this method remains rarely explored in optically controlled bioelectronics. Herein, employing the Schiff base reaction to embed the small molecule (THBA) into a Zr-MOF, we fabricated a hydroxyl-rich MOF on the surface of titanium dioxide nanorod arrays (U6H@TiO2 NRs) to develop light-sensitive gate electrodes with tailored recognition capabilities. The U6H@TiO2 NR gate electrodes were integrated into organic photoelectrochemical transistor (OPECT) sensing systems to tailor a sensitive device for bilirubin (I-Bil) detection. In the presence of I-Bil, coordination effects, hydrogen bonding, and π-π interactions facilitated strong binding between U6H@TiO2 NRs and the target I-Bil. The electron-donating property of I-Bil influenced the gate voltage, enabling precise control of the channel status and modulation of the channel current. The OPECT device exhibited exceptional analytical performance toward I-Bil with wide linearity ranging from 1 × 10-16 to 1 × 10-9 M and a low limit detection of 0.022 fM. Leveraging the versatility of small molecules for boosting the functionalization of materials, this work demonstrates the great potential of the small molecule family for OPECT bioanalysis and holds promise for the advancement of OPECT sensors.

Dispersive micro Solid-Phase extraction with Bimetallic Ni, Zn-MOF sorbent and gas chromatography method for Organophosphorus pesticide determination in environmental water samples

A dispersive micro solid-phase extraction coupled with the GC-FID method was developed to determine three Organophosphorus pesticides: Fenitrothion, Chlorpyrifos, and Diazinon. Various sorbents, including Fe3O4 NPs, Zn-MOF, Ni-MOF, Bimetallic Ni, Zn-MOF, and Fe3O4 NPs@SiO2@ Bimetallic Ni, Zn-MOF, were synthesized and evaluated for their extraction efficiency of OPPs. Fe3O4 NPs@SiO2@ Bimetallic Ni, Zn-MOF was identified as the optimal sorbent based on its performance. The affective factors in the procedure were optimized using one factor of the time and experimental design methods. The significant factors in this method included sorbent amount, extraction time, and desorption solvent volume with an optimum value of 37 mg, 8.3 min, and 231 µL, respectively. Under optimized conditions, the method exhibited distinct linear ranges for Fenitrothion, Chlorpyrifos, and Diazinon, ranging from 0.24 to 259, 0.17–234, and 0.25–247 ng mL−1, respectively, with high corresponding R2 values (0.9947, 0.9929, and 0.9943). The limits of detection (LOD) were determined based on three times the standard deviation of the blank sample divided by the slope of the calibration curve for each OPP to be 0.07, 0.05, and 0.07 ng mL−1 for Fenitrothion, Chlorpyrifos, and Diazinon, respectively, while the limits of quantification (LOQ) were 0.24, 0.17, and 0.25 ng mL−1. Precision was assessed by calculating intra-day and inter-day relative standard deviation (RSD%) values in one day and three consecutive days with three replicates of each analysis for three concentrations of 10, 25, and 50 ng mL−1, which were found to be below 4.27 %, 4.35 %, and 4.32 % for Fenitrothion, Chlorpyrifos, and Diazinon, respectively, for intra-day analysis, and below 5.43 %, 5.11 %, and 5.29 % for inter-day analysis, respectively. Additionally, the enrichment factor (EF) values for Fenitrothion, Chlorpyrifos, and Diazinon with a concentration of 20 ng mL−1 were determined to be 78.6, 82.4, and 75.7, respectively. Analysis of spiked real samples in two concentrations of 5.0 or 25.0 ng mL−1, such as tap water, river water, dam water, and well water, revealed recovery percentages in the range of 91.2 % to 97.7 %, with relative standard deviations ranging from 3.79 % to 4.98 %, further validating the method’s reliability for practical applications. Overall, the method provides wide linearity, low LODs and LOQs, responsible RSDs, high EFs, and proper recovery percentages for determining OPPs.

Facile preparation of covalent-organic framework composites for magnetic solid-phase extraction of naphthaleneacetic acid in food prior to HPLC-UV analysis

Novel magnetic covalent organic frameworks (COFs) were prepared by one-pot synthetic strategy and employed as an efficient adsorbent for magnetic solid-phase extraction (MSPE) of naphthaleneacetic acid (NAA) in food samples. Depending on the predesigned the hydrogen bonding, π-π and hydrophobic interactions of magnetic COFs, the efficient and selective extraction process for NAA was achieved within 15 min. The magnetic COFs adsorbent combined with HPLC-UV was devoted to develop a novel quantitative method for NAA in complex food. The method afforded good coefficient in range of 0.002–10.0 µg mL-1 and low limit of detection was 0.0006 µg mL-1. And the newly established method afforded less adsorbent consumption, wider linearity and lower LODs than the reported analytical methods. Ultimately, the method was successfully applied to determine NAA in fresh pear, tomato and peach juice. The magnetic COFs based MSPE coupled with HPLC-UV method provided a simple, efficient and dependable alternative to monitor trace NAA in food samples.

A developed highly selective and sensitive electrochemical sensor using gold nanoparticles on Cerium Stannate/MXene as an electrode matrix for detection of metol in various environmental and biological samples

Metol (MTL) is a highly significant organic compound that plays a crucial role in numerous applications as a monochromatic material. It has an impact on humans, plants, and animals and it raises serious environmental concerns. The present scenario necessitates the development a rapid, cost-effective, precise, and specific method for detecting metol in environmental and biological samples. In this study, the electrochemical sensor was developed using a modified electrode based on the Au@Ce2Sn2O7/MXene nanocomposite. The nanocomposite was thoroughly examined through phase composition analysis, elemental analysis, and morphological studies. The modified electrode exhibits exceptional selectivity, cyclic stability, storage stability, and reproducibility. The proposed sensor shows a wide linearity range (0.00125 to 1021.96 μM), low detection limit (5.63 nM), and high sensitivity (0.403 μA·μM–1·cm–2). The suggested sensor's consistency was confirmed by real-time monitoring of MTL in several environmental and biological samples with a high percentage of recovery.

A luminescent metal–organic framework composite as a turn-on sensor for the selective determination of monosodium glutamate in instant noodles

This work reports the development and application of a new fluorescent nanoprobe sensor depending on using luminescent metal organic framework (LMOF). The developed sensor composed of hybridized Ca 1,3,5-benzenetricarboxylic acid metal organic framework with microcrystalline cellulose (Ca-BTC/MCC MOF) as a fluorescent probe for the determination of the monosodium glutamate (MSG), a non-chromophoric food additive. The developed sensor was characterized using a high-resolution scanning electron microscope (HR-SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The Ca-BTC/MCC MOF hybrid, examined under the HR-SEM, showed morphological features different from the MCC and the Ca-BTC MOF. The diffraction patterns of Ca-BTC/MCC composites clearly displayed the characteristic Ca-BTC MOF diffraction bands, indicating that MCC was successfully incorporated in the formation of crystalline MOF hybrids. The FTIR spectra show the bands of MCC, as well as the bands of Ca-BTC MOFs. The prepared nanoprobe was successfully applied as a sensitive sensor for the determination of MSG in food sample. The method was validated following the International ICH (Q2)R2 guidelines in terms of precision, trueness and other main analytical figures of merit, comprised the green profile and practicability metrics. A wide linearity range was achieved (5–50 µg/mL) with good correlation coefficient (R2 ≥ 0.9993). The recoveries (%) were found in the range of 100.0 to 101.5 and the RSDs (%) were in the range of 0.1 to 0.9 %.These results show that the developed nanoprobe was selective, and highly accurate to determine this important food additive in the seasonings of instant noodles, also showing a reduced environmental impact based on the metrics currently accepted for the evaluation of the green profile and practicability.

Efficient and environmentally friendly uric acid voltametric sensor based on Ni-MOF and carboxylated multi-walled carbon nanotubes nanocomposites

Uric acid (UA) levels are significant in the monitoring of human health, making their detection very important. In this paper, a simple and innovative electrochemical method for the detecting UA was established, using a sensing platform based on hybrid electrodes of Nickel-Metal Organic Framework (Ni-MOF) and carboxylated multi-walled carbon nanotubes (MWCNTs-COOH). Detailed investigations into the electrocatalytic activity of Ni-MOF/MWCNTs-COOH/GCE for The Ni-MOF/MWCNTs-COOH exhibited remarkable catalytic activity for UA oxidation. The detection limit was 0.005 μM, with a sensitivity calculation result of 6.377 µA µM−1, and a wide linearity interval (0.03–10 μM, 10–300 μM). Utilizing its high sensitivity and selectivity, this sensor was used for the measurement of UA in biological fluids, including human serum and urine samples, recovery amounts being 96.6–100.8 %, and 98.9–101.3 %. This work is highly significant; offering new perspectives for the application of Ni-MOF based chemical sensors in the realms of environmental monitoring and healthcare.