Greater Selectivity Research Articles

Efficient and fast recovery of indium with phosphate-functionalized polyaniline porous carbon self-supported electrode by electrosorption-deposition strategy

Extraction of indium, that an important strategic resource, is limited by the low extraction capacity in the acidic environment, and sluggish adsorption kinetics. Electrodes and adsorption technologies can be combined to improve extraction capacity and kinetics, having high exploitation in metal recovery. A novel phytic acid-doped polyaniline/porous carbon (PA-PANI/PC) carbon cloth self-supported electrode is developed for extracting In(Ⅲ) from aqueous solutions by electrosorption-deposition strategy in this work. A series of characterization analysis show that PA-PANI/PC exhibits electrics double-layer capacitance and pseudocapacitance as well as abundant specific binding sites for In(Ⅲ) and improved hydrophilicity, which all conducive to the extraction of In(Ⅲ). As expected, PA-PANI/PC-2 exhibits the maximum extraction capacity of 284.67 mg/g within 60 min at pH 2.5, which represents the highest reported capacity for the extraction of In(Ⅲ), to date. Benefiting from complexation with phosphate groups, In(Ⅲ) can be directly recovered in the form of precipitation, avoiding backwashing with concentrated acid. Furthermore, the adsorbent maintains great affinity and selectivity for In(Ⅲ) even in multi-component simulated system. The low-cost adsorbent PA-PANI/PC based on simple and low-energy electrosorption-deposition process shows potential in terms of effectively recovering In(Ⅲ) from practical ore fluid.

Ultrasensitive Chemiluminescence Probes Designed from Covalent Inhibitors for SRAS-CoV-2 Mpro Detection.

In the postpandemic era, the emergence of "long COVID" from SARS-CoV-2 has brought ongoing negative impacts on individual health and society. The development of more efficient methods for drug screening and monitoring viral activity remains a critical need. The main protease (Mpro), due to its important role in the virus lifecycle, high conservation, and specificity, is considered an ideal biomarker for SARS-CoV-2. Herein, we have developed several chemiluminescence probes based on different substrates modified from covalent inhibitors targeted at Mpro. Among these, the best probe, MPCL-2, exhibits a rapid response (<20 min), an extremely low limit of detection (LoD; 0.11 nM), great selectivity, and chemical stability. After validating the probe's mechanism of action, MPCL-2 can also be used for real-time, in-situ imaging of enzymes in cells infected with the authentic virus and has the potential for real-time, in-situ Mpro imaging in vivo. Compared to other methods reported to date, the probe demonstrates superior performance and broader applicability, such as in drug screening or virus activity monitoring. Further, the unique design strategy for the substrate can be adopted to develop sensitive probes for other pathogens.

A new compact potentiometric electrode for pH monitoring built upon a glass substrate with a Ce-doped SnO2 layer.

A novel compact potentiometric electrode specifically designed for pH monitoring, featuring a good construction on a glass substrate coated with a cerium-doped tin oxide (Ce-doped SnO2) layer. The Ce-doped SnO2 thin film was created by spray-pyrolysis it on a glass substrate. Field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) were used to characterize the deposited metal oxide coating. As a miniature potentiometric electrode, the synthesized Ce-doped SnO2/glass substrate was utilized to measure a broad pH range (pH 2-12) in aqueous solutions. The electrode had a perfect near-Nernstian response (slope of -58.6 ± 0.7 mV per decade), high potential stability, mechanical durability, and great selectivity towards some common interfering cations and anions. These characteristics made it ideal for quality control and assurance purposes. The electrode's performance parameters and validation measurements were assessed using established procedures. The Ce-doped SnO2-based electrode satisfactorily monitored the pH of several genuine water, drink, and fruit juice samples, and the data compared well with those obtained using a traditional pH glass electrode. The integration of Ce-doped SnO2 as the active material marks a significant advancement, providing enhanced electrochemical stability, improved sensitivity, and a wider pH detection range compared to conventional electrodes. The compact design not only reduces the sensor's footprint but also facilitates its application in miniaturized and portable pH monitoring devices, making it highly suitable for advanced analytical and environmental sensing applications.

Novel surfactant-free electro-nanofabricating strategy for highly sensitive and selective colorectal cancer MicroRNA analysis

A label-free nanostructured electrochemical biosensor utilizing graphene quantum dot (GQD) decorated with gold nanoparticles (AuNPs), known as Au-GQD-NS, is presented to colorectal cancer (CRC) biomarker early detection, micro RNA-223 (miR-223). Thiolated DNA probes (Cap-223) are immobilized onto a fabricated and highly conductive nanostructure platform, which improves accessibility and miR-223 recognition. To analyze the nanostructured surface, various sophisticated techniques such as FESEM, EDAX, AFM, and electrochemical approaches are employed. Electrochemical approaches including DPV, EIS, and CV are applied to investigate the electroactivity of substrate, immobilization of Cap-223 on Au-GQD-NPs and subsequent hybridization with the miR-223. The electro-nanofabricated biosensor showcases a wide linear detection range (zepto M to nano M) with an impressively suitable LOD (0.024 atto M). The biosensor selectivity is demonstrated through discrimination studies between target and mismatched miRNA sequences (miR-9 and miR-21). This biosensor also exhibits significant potential for quantitative evaluation of miR-223 in real samples, enabling its applications in point-of-care (POC) detection of CRC. In addition, the Au-GQD-NS substrate is nano-fabricated in absent of surfactants and stabilizers, providing secure anchors for immobilization of cap-223. The well-established strategies for cap-223 immobilization and hybridization with miR, combined with superior electron exchange rate compared to uncovered FTO, upgrade the biosensor’s execution. Significantly, the biosensor demonstrates efficient miR-223 detection in human serum. Overall, this nano-fabricated biosensor shows great promise for miR-based early detection of CRC, and therefore, offering great sensitivity, selectivity, and favorable hydrophilicity for translational medicine investigation and clinical applications.

Validation of the QuEChERSER Method for 245 Pesticides and Environmental Contaminants in Barley and Hemp by Low-Pressure GC: Comparison of Triple Quadrupole MS/MS and Orbitrap HRMS for Qualitative and Quantitative Analysis.

Monitoring labs are a fundamental link in the food safety chain, and regulatory demands in a competitive economy call for analytical methods that are simpler, faster, more rugged, and broader in scope. The QuEChERSER mega-method introduced in 2021 meets these monitoring needs, which includes high sample throughput, automated cleanup of extracts, and fast low-pressure gas chromatography (LPGC). The goal of this work was to extend the QuEChERSER method to additional matrices and more analytes using LPGC, including comparison of the analytical performances of two different mass spectrometric (MS) analyzers: triple quadrupole tandem MS/MS and orbital ion trap (orbitrap) high-resolution (HR)MS. The QuEChERSER mega-method was validated for 245 pesticides and environmental contaminants in barley grains and hemp pellets using automated instrument top sample preparation (ITSP) coupled with LPGC-MS/MS or LPGC-HRMS (orbitrap). Targeted MS/MS detection proved to be more sensitive than orbitrap using full data acquisition, leading to lower limits of quantification (LOQs) with more analytes yielding acceptable recoveries (70-120%) and repeatabilities (RSDs <20%). In barley, 89% of the compounds met validation criteria in MS/MS and 74% in HRMS, which in hemp were 81% and 66%, respectively. Qualitatively, orbitrap HRMS yielded 1% false positives compared to 3-4% in MS/MS, but due to the higher LOQs, the rates of false negatives were 14-17% in orbitrap vs. 6-10% in MS/MS for the different matrices. The QuEChERSER mega-method including ITSP+LPGC coupled with MS/MS or orbitrap analysis is a robust approach for multiple applications. In the comparison, MS/MS outperformed the orbitrap in terms of sensitivity, but the orbitrap advantages of easier method development, greater selectivity, and possibility for nontargeted/retrospective analysis permit even broader expansion of analytical scope in the future. ITSP+LPGC- MS/MS or HRMS (orbitrap) analysis as part of the QuEChERSER mega-method is a useful and efficient way to monitor for contaminants in foods.

Thiol-linked hyaluronic acid-mediated encapsulation of RCR-stabilized gold nanoclusters for hyaluronidase sensing and cellular imaging

Encapsulating peptide-stabilized gold nanoclusters (AuNCs) with thiolated hyaluronic acid (HA-SH) and selectively adding cysteine to the peptide sequence increased their photoluminescence. We found that peptide compositions with cysteine in the middle emitted the most. RCR-stabilized AuNCs can be purified using size-exclusion chromatography to characterize their optical characteristics, chemical composition, and possible structure. Our findings show that RCR-stabilized AuNCs have a unique chemical structure, microsecond photoluminescence lifetime, good quantum yield, and near-infrared emission peak. Due to Au-S bonding and electrostatic interactions, RCR-stabilized AuNCs were encapsulated with HA-SH to create nanocomposites. HA-SH-AuNCs had a longer emission peak, greater particle size, and better photostability than RCR-stabilized AuNCs. HAase break down HA in HA-SH-AuNCs, changing their structure and size. Thus, centrifugation makes it easier to separate HA-SH-AuNCs from HAase-digested ones. Similar to earlier sensors, HA-SH-AuNCs have great sensitivity and selectivity for HAase, with a linear range of 0.5–6.0 U/mL and a detection limit of 0.39 U/mL. They were useful for urine HAase determination, with spike recovery of 103 % to 107 %. HA-SH-AuNCs further served as a platform for targeted imaging of CD44 receptor-expressing cancer cells, demonstrating bioimaging and clinical diagnostic potential.

Development of HPLC-UV method for determination of Nilotinib in spiked human plasma with greenness assessment

One of the approved second-generation tyrosine kinase inhibitors (Nilotinib) shows great efficacy and selectivity in the treatment of patients with chronic or accelerated phase chronic myelogenous leukemia, and in resistant/ intolerant to prior therapy cases. For the analysis of Nilotinib in synthetic mixture and human plasma samples, a new reversed-phase high-performance liquid chromatographic method was developed. Determination was performed successfully using RP–18 column and a mobile phase consisting of 10 mM potassium dihydrogen phosphate buffer (pH = 5.5), methanol, and acetonitrile in the ratio 37:37:26 (v/v/v). Isocratic mode of elution with flow rate 1.2 ml/min and UV detection at 265 nm were applied. The method was validated for linearity in the range 0.5–24.0 µg/ml and best accuracy and precision results were obtained at temperature 40 °C. The percentage recovery of the analyzed drug was in the range 88.0–106.0 %. Moreover, the proposed RP-HPLC method was evaluated in terms of greenness, whiteness and blueness using three newly developed ecological metrics – The Analytical Greenness software, White Analytical Chemistry and Blue Applicability Grade Index. Good results were obtained and the technique was proved effective, specific and suitable for implementation in routine quality control and clinical laboratory practice for therapeutic drug monitoring.

Single-atom ruthenium nanozyme-induced signal amplification strategy in photoelectrochemical aptasensor for ultrasensitive detection of chloramphenicol

To develop ultrasensitive and rapid antibiotics residue detection method is crucial for ensuring food safety and protecting human health. Herein, a novel photoelectrochemical (PEC) aptasensor integrated with single-atom ruthenium (Ru) nanozyme-mediated catalytic precipitation as a valuable signal amplification strategy, have been established for ultrasensitive chloramphenicol (CAP) detection. Particularly, the exceptional peroxidase-mimicking activity of single-atom Ru nanozyme is responsible for accelerating the oxidation of 4-chloro-1-naphthol (4-CN) to produce insoluble precipitate on the electrode, which in turn causes a notable reduction in the photocurrent. Whereas, when CAP is present, the aptamer is liberated away the electrode because of its potent affinity with CAP, resulting in an elevation of the photocurrent signal, enhancing the detection sensitivity. Importantly, the signal amplification strategy combines the effective photoactive material of Au nanoparticles/CdS quantum dot/TiO2 composites, a PEC aptasensor for determination of CAP with an ultralow detection limit of 4.12 pM is achieved in a self-powered mode with great selectivity and accuracy. This work proposes a novel reasonable approach utilizing high-activity single-atom nanozyme to induce signal amplification strategy for the advancement of single-atom nanozyme in ultrasensitive PEC biosensor, and further creates new avenues for ultrasensitive detection beyond antibiotics residue.

A room-temperature NO2 gas sensor based on Zn2+ doped Cu2O/CuO composites with ultra-high response

Metal oxide semiconductors (MOS) have attracted increasing interest in gas sensors recently due to their exceptional design flexibility and superior gas sensing capabilities. However, the high operating temperatures and reliance on light activation in MOS-based gas sensors limit their potential applications. In this work, the Zn2+ doped Cu2O/CuO composites were successfully fabricated by one-step hydrothermal method for the detection of NO2 gas at room temperature. The experimental results show that the optimal Zn-Cu2O/CuO composite presents responses that are 2.9, 3.4, 3.1 times higher than those of the pure Cu2O/CuO composite to 10, 5 and 1 ppm NO2. Additionally, the response and recovery times are shortened by factors of 3.1 and 1.4, respectively. Notably, the detection limit of the Zn-Cu2O/CuO composite is 2 ppb at room temperature, significantly below China's annual average NO2 concentration limit of ∼18 ppm. Furthermore, the Zn-Cu2O/CuO based sensor demonstrates the great selectivity, repeatability and long-term stability for NO2 detection. The gas sensitivity enhancement mechanism is thoroughly discussed. This result provides a new approach for the effective detection of ppb-level NO2 by CuO-based gas sensing materials at room temperature.

Overview of Baker's Yeast as a Biocatalyst

Biocatalysis is an approach to green chemistry. A crucial step in the synthesis of or-ganic compounds is the reduction of aldehydes and ketones to secondary alcohols. The use of a biocatalyst, such as enzymes or entire cells, has not affected this process.. It offers great selectiv-ity, high specificity, and an environmentally friendly approach to synthesis. Dried baker's yeast mediates the conversion of optically active alcohols from aromatic aldehydes and ketones. This work highlights applications of Baker's yeast in synthesizing pharmaceutical intermediates and chiral building blocks, demonstrating its practical relevance. Sustainable technology is based on the ideas and measurements of sustainable development and green for good enantioselectivity across several organic solvents.

Comparison Between Brain and Cerebellar Autoradiography Using [18F]Flortaucipir, [18F]MK6240, and [18F]PI2620 in Postmortem Human Brain Tissue.

Our objective was to evaluate the invitro binding properties of [18F]flortaucipir, 6-(fluoro-18F)-3-(1H-pyrrolo[2,3-c]pyridin-1-yl)isoquinolin-5-amine ([18F]MK6240), and 2-(2-([18F]fluoro)pyridin-4-yl)-9H-pyrrolo[2,3-b:4,5c']dipyridine ([18F]PI2620) head-to-head in postmortem human brain tissue. Methods: Autoradiography was used to assess uptake of [18F]flortaucipir, [18F]MK6240, and [18F]PI2620 in control and Alzheimer disease (AD) autopsy-confirmed brain tissues. The study focused on the analysis of the prefrontal cortex, hippocampus, and cerebellum sections in 12 controls and 12 AD cases, as well as whole-brain hemisphere in 1 control and 1 AD sample, for each radiotracer. The binding values of [18F]flortaucipir, [18F]MK6240, and [18F]PI2620 were calculated from regions of interest manually drawn in the prefrontal, hippocampal, and cerebellar cortices. Results: For all 3 radioligands investigated, we observed significant tracer binding differences between control and AD tissues in the whole-brain hemisphere, prefrontal cortex, and hippocampus but not in the cerebellar cortex. [18F]MK6240 and [18F]PI2620 had higher effect sizes to differentiate control and AD cases than did [18F]flortaucipir. Bland-Altman analyses revealed strong correlations between [18F]MK6240, [18F]PI2620, and [18F]flortaucipir, with the highest agreement found for [18F]MK6240 versus [18F]PI2620. Conclusion: The 3 radioligands showed comparable diagnostic properties to assess tau aggregates invitro. Binding to AD brain tissues was higher for [18F]MK6240 and [18F]PI2620 than for [18F]flortaucipir. Additionally, [18F]MK6240 and [18F]PI2620 had greater selectivity, displaying decreased uptake in control brain tissue compared with [18F]flortaucipir. These results might provide insights on ongoing initiatives to create a universal scale for tau imaging studies.

Review and Prospects of Xanthan Application in Water Contaminants Removal

This review explores the novel perspectives and application of xanthan in the removal of emerging water contaminants. Xanthan is a nontoxic, biocompatible, and biodegradable biopolymer of microbial origin. Industrial production of xanthan is usually conducted by aerobic submerged batch cultivation of the bacterium Xanthomonas campestris ATCC 13951 on the medium containing glucose or sucrose under optimal conditions, and findings of researchers worldwide indicate that xanthan can be successfully biosynthesized on media containing different waste streams, using various Xanthomonas strains. Common application of xanthan is in the food industry as a stabilizer, thickener, and emulsifier because of its high viscosity at lower concentrations and excellent solubility in hot and cold water. The application of xanthan is not only limited to the food and other branches of industry, but also to medicine, biomedical engineering, agriculture, and wastewater treatment. Recent studies have confirmed the excellent photocatalytic activity and emulsifying capacity of xanthan biosynthesized on waste-based media, which offers promising potential for its application in the decontamination of environment. Moreover, the xanthan-based hydrogel has great selectivity for the cationic dye and on the other side, chemically modified xanthan has a great potential as an adsorbent for the removal of metal ions.

Modulating the chemical environment of Ni2+ for the oxidative dehydrogenation of ethane: The formation of LAS(Al3+/Ga3+)-Ni-OH site

The oxidative dehydrogenation of ethane to ethylene (ODHE) usually suffers from the issues of ethane conversion-ethylene selectivity seesaw. Herein, a series of alumina-supported Ni and Ga catalysts with different molar ratios of Ni to Ga were synthesized by facile impregnation method constructing the Lewis acid site (LAS) strategy to obtain great ethylene selectivity (97 %). The variation of Ni:Ga ratio adjusted the ionic substitution ability, redox ability and acidity, thus regulate the chemical environment of Ni2+ to the formation of LAS(Al3+/Ga3+)-Ni-OH structure, which was proposed to be the active site for selective oxidation of ethane to ethylene, as proved by H2-TPR, ToF-SIMS, quasi in-situ XPS and in-situ FTIR. Moreover, the probable mechanism of ODHE reaction was proposed that C2H6 molecules were mainly adsorbed on LAS sites and activated on Ni-OH site of the catalyst. The pulse test further suggested that O- was mainly associated with the generation of CO2 and Ni(2-n)+ was connected with the production of CH4. It is highlighted that adjusting the Ni-related species and oxygen species on the catalyst surface are crucial to further improve the ethylene selectivity.

Development of a Candidate 11C-Labeled Selective Phosphodiesterase 1 Radioligand for Positron Emission Tomography.

Phosphodiesterases (PDEs) constitute a superfamily of phosphohydrolytic enzymes that regulate intracellular second messenger signaling by hydrolyzing cyclic adenosine monophosphate and cyclic guanosine monophosphate. Among the 11 subfamilies of PDEs, phosphodiesterase 1 (PDE1) stands out due to its broad implications in central and peripheral pathologies. There are three subtypes of PDE1: PDE1A, PDE1B, and PDE1C. While PDE1A and PDE1C are distributed in both the brain and peripheral organs, PDE1B is predominantly expressed in the brain, rendering it an attractive drug target for neurological and psychological disorders. Despite continuous efforts dedicated to the development of novel PDE1 inhibitors, a suitable PDE1 radioligand for human use is currently lacking. In this study, we present the identification and preclinical evaluation of [11C]PF-04822163, a selective radioligand candidate for imaging PDE1 with positron emission tomography. PF-04822163 exhibits excellent potency toward PDE1 and demonstrates great target selectivity over other PDEs. Then, PF-04822163 was labeled with carbon-11 (half-life, 20 min) in favorable radiochemical yields (25 ± 10%, decay-corrected) and high molar activities (106-194 GBq/μmol). Further, in vitro and in vivo evaluations in rodents suggested that [11C]PF-04822163 displayed good brain penetration and a rapid washout. Despite these promising performance characteristics of [11C]PF-04822163, only marginal specific binding was observed in vivo. Further optimization of the scaffold is warranted to obtain favorable pharmacological and ADME properties.

Methanol for Hydrogenation and Methylation of Carbonyls: Advances and Challenges in Homogeneous Catalysis

AbstractThe catalytic dehydrogenation of methanol to give formaldehyde or formic acid, followed transfer hydrogenation and/or tandem (de)hydrogenation for the hydrogenation and C-methylation of carbonyls, offers advantages over traditional methods, including milder reaction conditions, improved safety, greater selectivity, and enhanced sustainability. This account provides a comprehensive overview of homogeneous catalysts reported for the transfer hydrogenation and C-methylation of various substrates, including ketones, chalcones, esters, and amides, using methanol as both a hydrogen donor and methylation source. We provide specific examples and mechanistic insights for each strategy, offering a thorough and concise overview of recent advancements from 2014 to 2024.1 Introduction2 Methanol Activation Strategies3 Hydrogenation of Carbonyls4 Methylation of Carbonyls5 Outlook and Summary

Mandarin Peels-Derived Carbon Dots: A Multifaceted Fluorescent Probe for Cu(II) Detection in Tap and Drinking Water Samples.

Carbon dots (CDs) derived from mandarin peel biochar (MBC) at different pyrolysis temperatures (200, 400, 600, and 800 °C) have been synthesized and characterized. This high-value transformation of waste materials into fluorescent nanoprobes for environmental monitoring represents a step forward towards a circular economy. In this itinerary, CDs produced via one-pot hydrothermal synthesis were utilized for the detection of copper (II) ions. The study looked at the spectroscopic features of biochar-derived CDs. The selectivity of CDs obtained from biochar following carbonization at 400 °C (MBC400-CDs towards various heavy metal ions resulted in considerable fluorescence quenching with copper (II) ions, showcasing their potential as selective detectors. Transmission electron microscopic (TEM) analysis validated the MBC-CDs' consistent spherical shape, with a particle size of <3 nm. The Plackett-Burman Design (PBD) was used to study three elements that influence the F0/F ratio, with the best ratio obtained with a pH of 10, for 10 min, and an aqueous reaction medium. Cu (II) was detected over a dynamic range of 4.9-197.5 μM and limit of detection (LOD) of 0.01 μM. Validation testing proved the accuracy and precision for evaluating tap and mountain waters with great selectivity and no interference from coexisting metal ions.

Flexible MOF@fabrics composites: The in-situ growth of metal-organic frameworks on cotton and selectively adsorption of gold(III) from aqueous solution

Metal-organic frameworks (MOFs) show great potential applications in dealing with heavy metal pollution due to their unique large specific surface area, tunable pore size, and diverse active groups. However, the powder form of MOFs has suffered from the disadvantages of difficult recycling and secondary contamination after adsorption of heavy metals, which seriously limits their practical application. Therefore, in this work, we prepared a series of bifunctional zirconium-based MOFs cotton fabric composites (MCFC) via in situ growth of MOFs on carboxylated cotton fabric, exhibiting large specific surface area, adjustable pore size, and effective adsorption ability. The prepared CF-UiO-66-(OH)2-FA shows an excellent adsorption efficiency of Au(III) more than 99.990 %, and the saturated adsorption amount is up to 190.98 mg·g−1 at 25 °C. Meanwhile, the kinetic experiment analysis demonstrated that the Au(III) adsorption behavior of MCFC follows pseudo-second-order (PSO) kinetic model. More importantly, it also exhibits great selectivity in adsorbing Au(III) from the mixture of multiple metal ions coexisted solution. The results of adsorption thermodynamics and adsorption isotherms indicate that adsorption is monolayer and a spontaneous, exothermic process. And the ideal adsorption and separation process could be finished by quickly filtrating with a single or multi-layer MCFC. Excellent adsorption performance even after four cycles of adsorption. Therefore, the fabricated MCFC shows great processability, flexibility, collectability and reusability in adsorbing and recycling precious metal ion from wastewater.

A Versatile Ultra-High-Performance Liquid Chromatography-Full-Scan High-Resolution Mass Spectrometry Method to Quantify Wine Polyphenols.

Polyphenols are responsible for wine colour and astringency, and, as antioxidants, they also have beneficial health properties. In this work, we developed a robust full-scan high-resolution mass spectrometry method for the quantification of 90 phenolic compounds in wine samples (either red, rosé, or white wine), using a UHPLC-OrbitrapTM system. With this method, we could conduct a detailed analysis of phenolic compounds in red, rosé, and white wines with great selectivity due to sub-ppm mass accuracy. Moreover, accessing the full-scan spectrum enabled us to monitor all the other compounds detected in the sample, facilitating the adaptability of this method to new phenolic compounds if needed.

Copper nano metal-organic framework paper-based sensor for dual optical detection of biogenic amines to evaluate the food freshness

The improvement of food safety and the reduction of food loss and waste require the development of new bioanalytical tools that provide chemical information about the composition of food that is of great value for improving traceability and extending the shelf life of food. Herein, a Cu-based metal-organic framework has been synthesized and immobilized onto cellulose paper disks for colorimetric and fluorescent detection and quantification of biogenic amines in food. The color of the nano metal-organic framework changes from green to brown in the presence of low amounts of biogenic amine vapors. Also, the fluorescence emission of the nano metal-organic framework greatly decreases after exposing the cellulose disks to amine vapors. The developed sensing paper disk exhibits a quick response to the presence of volatile biogenic amines, very low detection limits, and great selectivity. Also, the paper sensor was used for real-time monitoring of biogenic amines in bass samples at different temperature conditions, being a highly valuable method for evaluating food freshness and safeguarding food safety.

Novel Colorimetric and Near-Infrared Ratiometric Fluorescent Probe for Sensing Cysteine in Food Samples, Plants, and Living Cells.

Cysteine (Cys) is a crucial biothiol that acts a significant function in food samples and biological systems, including plant roots and living cells. Hence, we developed a novel colorimetric and near-infrared ratiometric fluorescent probe (CT), composed of coumarin and tetrahydroacridine-conjugated indole salt, for the detection of Cys. Upon reaction with Cys, the probe undergoes a specific N-substitution reaction, resulting in a notable colorimetric change and a significant ratiometric fluorescent response in both visible and near-infrared emission channels. These dual-channel ratiometric fluorescence changes are completely independent, enabling the probe to obtain great selectivity, sensitivity, and exceptional detection accuracy. Leveraging these attributes, the probe was employed to provide accurate quantitative analysis of Cys in food samples. Furthermore, confocal imaging demonstrated that the probe could monitor both exogenous and endogenous Cys levels in living cells and track Cys changes in plant roots under heavy metal stress. This work presents a dependable and accurate imaging solution for tracking and identifying Cys of real food, plants, and living cells.