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In this work, it was found that organotin-functionalized tungstophosphates PW9-TM-SnRCOO and P2W15-TM-SnRCOO (PW9 = [PW9O34]9−; P2W15 = [P2W15O56]12−; TM = Mn, Co, Zn; R = CH2CH2) exhibited mimicking horseradish peroxidase (HRP) activity, with the catalytic activity of PW9-TM-SnRCOO being higher than that of P2W15-TM-SnRCOO. Among the polyoxometalates (POMs), those containing Zn ions demonstrated the highest catalytic activity. Furthermore, a recyclable POM-based ZIF-nanocomposite, Na8K2[Zn2{Sn(CH2)2COO}2(B-α-PW9O34)2]·13H2O@ZIF-67 (PW9-Zn-SnRCOO@ZIF-67), was designed and synthesized using a convenient one-step method at room temperature. As a mimic enzyme of HRP for the catalytic oxidation of o-phenylenediamine (OPD), PW9-Zn-SnRCOO@ZIF-67 exhibited enhanced catalytic activity and anti-interference ability. Moreover, the introduction of the POM-estertin derivative significantly improved the acid resistance of ZIF-67. PW9-Zn-SnRCOO@ZIF-67 can be further used as a colorimetric sensor material for the detection of acetone with a wide linear range (0.01–4.0 mM), a low detection limit (0.0074 mM), and good reusability. These results demonstrate that organotin-functionalized POMs@ZIFs, as a new class of non-enzymatic sensor materials, have wide application prospects for the detection of acetone in real water samples. [ABSTRACT FROM AUTHOR]

CRISPR/Cas systems are increasingly utilized for sensitive miRNA detection through enzyme-based pre-amplification. To address challenges such as high costs, non-specific amplification, and interference from primer residues in pre-amplification strategies, herein a dual amplification CRISPR miRNA assay was developed by combining enzyme-free HCR with single-particle analysis. Attomolar detection limits, excellent selectivity, and practicability were achieved by applying this method. [ABSTRACT FROM AUTHOR]

Sample preparation presents a major challenge in point-of-care (POC) diagnostic assays, including ones requiring whole blood as the starting specimen. This study presents an integrated sample preparation device -- which we call PRECISE -- that performs both plasma separation and nucleic acid extraction, enabling streamlined sample preparation from whole blood requiring only a commercially available blood collection tool and a syringe, and no other external equipment or electricity. Plasma separation is performed using a dual-membrane filter (which filters out blood components while limiting membrane clogging) integrated into the cartridge, and nucleic acid extraction is performed by users moving magnets (to mix the samples, and along a guided track). The plasma filtration demonstrated recovery on par with lab-based centrifugation, and the extraction module showed performance similar to benchtop-based magnetic bead extraction. A sample-to-result demonstration on 50 μL of whole blood spiked with virions of hepatitis C virus (HCV), operating the PRECISE cartridge in 16 minutes followed by benchtop PCR, showed a limit of detection (~6770 IU mL-1) on the order of the minimal requirements of target product profile for POC HCV detection. Future work on the PRECISE cartridge, building on POC accessibility and fast sample preparation demonstrated in this work, may enable detection of bloodborne pathogens from whole-blood specimens collected at the POC. [ABSTRACT FROM AUTHOR]

The increasing demand in healthcare for accessible and cost-effective analytical tools is driving the development of reliable platforms to the customization of therapy according to individual patient drug serum levels, e.g. of anti-psychotics in schizophrenia. A modifier-free microfluidic paper-based electroanalytical device (μPED) holds promise as a portable, sensitive, and affordable solution. While many studies focus on the working electrode catalysts, improvements by engineering aspects e.g. of the electrode arrangement are less reported. In our study, we demonstrate the enhanced capabilities of the 3D electrode layout of μPED compared to 2D μPED arrangements. We especially show that screen printing can be employed to prepare 3D μPEDs. We conducted a comparison of different 2D and 3D electrode arrangements utilizing cyclic voltammetry in [Fe(CN)6]3−/4−, along with square-wave voltammetry for clozapine (CLZ) sensing. Our findings reveal that the utilization of the 3D μPED leads to an increase in both the electrochemically active surface area and the electron transfer rate. Consequently, this enhancement contributes to improve sensitivity in the CLZ sensing. The 3D μPED clearly outperforms the 2D μPED arrangement in terms of signal strength. With the 3D μPED under the optimized conditions, a linear dose–response for a concentration range from 7.0 to 100 μM was achieved. The limit of detection and sensitivity was determined to be 1.47 μM and 1.69 μA μM−1 cm−2, respectively. This evaluation is conducted in the context of detection and determination of CLZ in a human blood serum sample. These findings underscore the potential of the 3D μPED for future applications in pharmacokinetic analyses and clinical tests to personalize the management of schizophrenia. [ABSTRACT FROM AUTHOR]

Black carbon (BC) generated from vehicle engine exhaust is a global environmental concern and a freely available carbon source. Herein, onion-like nanocarbon (ONC) isolated from diesel soot (DS) has been surface-functionalized with a small amine named ethylenediamine (en). The amine-functionalized ONC designated as f-en-ONC shows maximum emission at 430 nm under excitation at 350 nm. The aqueous solution of f-en-ONC emits a blue color on UV-light illumination and displays a quantum yield of ∼18%. Among the different tested biomolecules, f-en-ONC selectively detects glutamic acid (GLA) through fluorescence-based quenching. The limit of detection for GLA was found to be ∼ 17.3 μM. Based on spectral overlap studies, UV-visible spectra, and the Stern–Volmer plot, the dynamic quenching mechanism was suggested for the fluorescence-based sensing of GLA. Further, the water-soluble f-en-ONC was used as a bioimaging probe for cancer cells. [ABSTRACT FROM AUTHOR]

The enzyme-like activity of noble metal nanomaterials has been widely demonstrated. However, as an important noble metal, iridium (Ir) and its alloy nanomaterials have been less studied, particularly regarding the effect of Ir content on enzyme-like activity. Here, we demonstrated for the first time that a low Ir content can greatly improve the peroxidase-like activity of Pt-based nanozymes. When the weight percentage of Ir was 3.45% in trimetallic PtAuIr hollow nanorods (HNRs) and 2.86% in bimetallic PtIr HNRs, their specific activity increased by approximately 70% compared to their PtAu and Pt counterparts, respectively. However, a slightly higher percentage of Ir significantly diminished the enhancement effect on their specific activity. Density functional theory (DFT) calculations show that the rate-determining step (RDS) energy barrier of the nanozyme with low Ir content is lower than that of the nanozyme with slightly higher Ir content. Furthermore, we studied the kinetic properties of the PtAuIr nanozyme using TMB as the substrate. Its Michaelis–Menten constant (Km) and Vmax were 1.756 mM and 2.152 × 10−6 M s−1, respectively. Additionally, a colorimetric detection platform based on the PtAuIr nanozyme was established and applied to detect o-phenylenediamine (OPD), with a detection limit as low as 0.076 μM. This study highlights the important role of the Ir content in Pt-based nanozymes and demonstrates that PtAuIr nanozymes have potential applications in environmental detection. [ABSTRACT FROM AUTHOR]

A functionalized Hf(IV)-based metal–organic framework (MOF) was synthesized, characterized, and successfully employed as a highly sensitive and selective fluorometric sensor for (1,1-diamino-2,2-dinitroethylene) FOX-7, which is a significant nitro explosive. The fluorescent sensor (MOF), denoted as CSMCRI-KNC′, exhibited a turn-off fluorescence signal towards FOX-7 in a water medium even in the presence of other potentially competitive explosives. The limit of detection (LOD) value for the detection of FOX-7 is fairly low (189 nM), and the response time is extremely rapid (<20 s). The sensing mechanism was investigated in detail and found to be based on non-covalent interactions, fluorescence resonance energy transfer (FRET), and photo-induced electron transfer (PET) processes. The sensing medium (water), detection time, sensitivity, and selectivity demonstrate the great potential of CSMCRI-KNC′ in the fluorescence-based sensor field. Additionally, the MOF was utilized as an efficient, recyclable, and heterogeneous catalyst for Knoevenagel condensation between barbituric acid and aromatic aldehydes in the presence of ethanol in an eco-friendly reaction medium. The present catalytic methodology has several attractive features, including mild reaction conditions, a short reaction time, high atom economy, and tolerance of various functional moieties. The catalyst could be recovered and reused successively without any remarkable loss in its catalytic activity. Moreover, the "hot filtration method (Sheldon's test)" has also been established to ensure the heterogeneity of the catalyst. Furthermore, the plausible mechanism of the catalysis is well presented. [ABSTRACT FROM AUTHOR]

In contrast to natural enzymes, nanozymes show promising advantages of low cost and high stability for analytical applications. The simple mix of L -phenylalanine (F) and Cu2+ produces two-dimensional nanosheets of a coordination polymer with a high surface area ratio and rich exposed active sites as a novel catalyst. As the mimetic of natural laccase, this nanozyme (F–Cu) can catalyze the oxidative coupling reaction of 2,4-dichlorophenol (2,4-DP) and 4-aminoantipyrine (4-AP) to produce a distinct red product, thus establishing an intuitive and simple method for the detection of thiram. In the range of 0–7.5 μM, the absorbance intensity was linearly related to the concentration of thiram, and the detection limit was 0.0845 μM. The F–Cu nanozyme was successfully applied to the colorimetric detection of thiram in real samples. [ABSTRACT FROM AUTHOR]

In this study, a novel electrochemiluminescent (ECL) sensor for highly sensitive detection of trilobatin (Tri) was developed based on silver metal–organic frameworks (AgMOFs) and nitrogen-doped carbon quantum dots (N-CDs). N-CDs exhibited high ECL intensity but poor ECL stability, while AgMOFs had a large specific surface area, high porosity, and good adsorption properties. Compositing both of them not only improved the ECL stability of N-CDs, but also enhanced the ECL strength of materials, so AgMOF@N-CD composites were used as the luminophore of the sensor. Under the optimized conditions, the ECL sensor showed a linear range of 1.0 × 10−7 M to 1.0 × 10−3 M for the detection of Tri, and the detection limit was as low as 5.99 × 10−8 M (S/N = 3). In addition, the sensor had excellent reproducibility, stability, and anti-interference ability. It could be utilized for the detection of Tri in real samples with recoveries of 95.78–102.26%, indicating that the constructed ECL sensor for detecting Tri possessed better application prospects. [ABSTRACT FROM AUTHOR]

Glyphosate (GLY) is widely applied in agriculture and horticulture as a herbicide. The development of genetically modified plants has caused abuse of GLY, with excessive residues potentially causing harm to human health. Consequently, a novel method needs to be built to detect GLY in soybeans and corn. Computer simulation was used to design an excellent hapten which was used to produce an anti-GLY monoclonal antibody (mAb) with outstanding sensitivity and affinity, and its 50%-inhibitory concentration (IC50) was 128.59 ng mL−1. Afterwards, an immunochromatographic assay strip was developed based on the mAb. In soybeans and corn, the visual detection limits were 1 mg kg−1 and 0.2 mg kg−1, while the cut-off values were 50 mg kg−1 and 5 mg kg−1, respectively. The reliability of the strips was proved by the existing methods. Thus, a rapid method to detect GLY residues on-site in soybeans and corn was established. [ABSTRACT FROM AUTHOR]

Herein, we proposed a novel metal–organic gel (YTU-G-1) for efficient adsorption and portable sensing of gaseous iodine. YTU-G-1 exhibits an unprecedentedly high detection sensitivity (KSV = 2.21 × 106 L mol−1) and an extremely low limit of detection (LOD) down to the pmol level (481 pmol L−1). YTU-G-1 also shows a marked iodine adsorption capacity of 1.398 g g−1. A wearable membrane was successfully fabricated via the electrospinning technique, which exhibits excellent skin-compatibility and serves as a portable tool for sensitive response to potential on-site nuclear emergencies. [ABSTRACT FROM AUTHOR]

With more than 30 million medical applications annually, 99mTc is the most widely used radioisotope. Nevertheless, the discharge of 99mTc and its radioactive nuclear isomer 99Tc through medical facilities into the aqueous environments is mostly unknown. This is related to the low absolute Tc mass used in medical examinations and consequent trace levels of Tc emitted from respective facilities. In this work, a new approach employing automated on-line extraction chromatography and anion-exchange chromatography was developed and coupled to inductively coupled plasma-mass spectrometry. The extraction column was filled with TK201 resin to preconcentrate, purify and elute pertechnetate ([99Tc]TcO4−) as the most relevant Tc species. The eluting 99Tc fraction was focused and separated on an anion-exchange chromatography column and directly calibrated into a mass flow using an on-line isotope dilution-like approach named isobaric dilution analysis. To accommodate ultra-trace levels in strong matrices with high grades of particulate contamination, the automated method was complemented by a newly developed manual filtration and preconcentration workflow with TK201 impregnated filter disks, reaching a combined preconcentration factor as high as 4615. An aerosol desolvation nebulization system was used additionally to boost sensitivity, achieving an ultimate limit of detection (LOD) as low as 0.70 ± 0.02 fg kg−1. As proof of concept, a wastewater sample from a retention basin of a local university hospital was collected. This wastewater contained 99Tc emitted in diagnostic procedures and levels were determined to be as low as 89 ± 4 fg kg−1. [ABSTRACT FROM AUTHOR]

Samples with very high Ca/Mg ratios present challenges for measuring their Mg isotope ratios. Here, we present an efficient method to separate Mg from samples with high Ca/Mg matrices, which also allows for quantitative separation of Sr, Ca and K. The method comprises a three-step chromatographic separation using DGA and AG50W-X12 (200–400 mesh) cation exchange resin. By utilising the automated sample purification system prepFAST MC™ for two of the three separations, the labour is substantially minimised. This analytical approach results in a quantitative Mg yield and a pure Mg solution, with other cations reduced to below the limit of detection (<53 ng mL−1). We demonstrate the efficacy of this method using a set of geochemical reference materials with Ca/Mg ratios ranging from 1.32 to 1271 mol mol−1. This approach enhances sample throughput and ensures high-quality separations in carbonate samples characterised by high Ca/Mg ratios. [ABSTRACT FROM AUTHOR]

The determination of rare earth elements (REEs) in seawater, especially marine sediment porewater and open-ocean seawater, is challenging because of their ultra-trace concentrations (ng L−1 to pg L−1) and the high salinity of the matrix (approximately 35‰ NaCl), which limits their application in marine science. Herein, we developed an online method for accurate analysis of ultra-trace REEs in seawater using a traditional Q-ICP-MS. The key aspects were: (i) high sensitivity detection in standard mode with no collision/reaction cell functioned, (ii) online automated matrix removal and preconcentration using a commercially available seaFAST system, (iii) use of membrane desolvation to enhance the sensitivity and limit the interferences of LREE oxides on HREEs, and (iv) monitoring and correction of variations in REE signal intensities caused by instrument drift using standard–samples–standard bracketing and an indium internal standard for normalization. The detection limits (0.1–8.0 pg L−1) and procedural blank values (<3 pg L−1 except for La, Ce, and Nd) of this method were low enough for accurate determination of REEs in seawater, even for REE concentrations at tens of picograms per liter level. The good accuracy and long-term precision (30 h, average: 3.5%, 1σ RSD, n = 10) were achieved for all the REEs as verified using certified seawater reference standards NASS-7 and CASS-6, and a 10 ng L−1 artificial seawater standard, respectively. Each run required only approximately 8 mL of sample and 12 min for the measurement, which are suitable values for practical application. The developed method was used to analyze various natural seawater samples, which demonstrated its effectiveness for exploring subtle changes in REE concentrations, fractionation patterns and anomalies in different marine environments. [ABSTRACT FROM AUTHOR]

Residues of β-lactam antibiotics (β-LA) in the environment have posed a great threat to human health, while lacking a simple, effective, and universal sensing method. Herein, basic fuchsin and graphdiyne (GDY) were used as precursors to prepare the first reported acidity/basicity-sensitive GDY quantum dots (S-GDY QDs). We propose a novel fluorescence-sensing strategy for β-LA detection based on the ability of β-lactamases to catalyze β-LA to form carboxylic acid, which further induces a change in the acidity/basicity of the solution and causes a decrease in the fluorescence intensity of S-GDY QDs. Furthermore, a fluorescence test strip sensing platform integrated with a smartphone was established to achieve rapid, portable, and visual monitoring of β-LA. Using penicillin G as a model, a detection limit as low as 15.7 nM was achieved, showing important implications for β-LA detection. [ABSTRACT FROM AUTHOR]

Aflatoxin B1 (AFB1) is one of the most harmful mycotoxins to human and environmental health. In this paper, a novel electrochemical AFB1 immunosensor using attapulgite composite N-phenylglycine as a conductive material is developed. The strong π–π and electrostatic interactions between the AFB1 antibody and the nanomaterial are investigated. The developed electrochemical AFB1 immunosensor exhibits high sensitivity, with a detection limit of 0.011 ng mL−1 and a quantitation limit of 0.035 ng mL−1 (S/N = 3). The recoveries for three different concentrations of AFB1 range from 97.5% to 104.6%, with a relative standard deviation of stability less than 2.0%. ATP-PNPG possesses more oxygen defects and adsorbed oxygen than ATP-NPG. These properties enhance its electronegativity and make it more conducive to detecting low concentrations of AFB1 through electrochemical sensing technology. Finally, the electrochemical AFB1 immunosensor demonstrates good selectivity, stability, and reusability for detecting AFB1 in corn samples, exhibiting a high recovery rate. [ABSTRACT FROM AUTHOR]

Many common explosives are mostly composed of nitro-compounds. Picric acid (PA) has emerged as a potential alternative due to its great explosive capability. Moreover, PA is also a serious groundwater contaminant due to its high-water solubility. As a result, the development of advanced sensors and catalysts to enable the precise detection and elimination of PA in water and food samples is critical for public health and the environment. In the present investigation, we developed NaxLiyPr(MoO4)2:Tb3+@Arg and NaxLiyPr(WO4)2:Tb3+@Arg (x = 10 mmol and y = 5 mmol) via a hydrothermal process and established their potency for photoluminescence (PL) detection and photocatalytic degradation of PA. The characterization of the produced nanoparticles was done by various techniques. The PL characteristics of NaxLiyPr(MoO4)2:Tb3+@Arg show that it is highly sensitive and selectively detects PA in an aqueous medium. The predominant emission band at 545 nm exhibited a distinguished quenching with the introduction of PA solution in the colloidal solution of the prepared nanomaterials. The NaxLiyPr(MoO4)2:Tb3+@Arg demonstrated exceptional selectivity and sensitivity against PA, with a limit of detection (LOD) of 0.44 ppm and a quenching constant (KSV) of 2.74 × 104 M−1. Alternatively, the NaxLiyPr(WO4)2:Tb3+@Arg showed remarkable photocatalytic activity for PA degradation. The UV-Vis spectroscopy findings specify that NaxLiyPr(WO4)2:Tb3+@Arg (Eg = 2.95 eV) might operate as a superior photocatalyst compared to NaxLiyPr(MoO4)2:Tb3+@Arg (Eg = 3.38 eV) nanoparticles. The degradation efficacy of NaxLiyPr(WO4)2:Tb3+@Arg towards PA is around 96.7% within 60 minutes of UV irradiation and the photocatalyst's reusability was monitored to ensure good stability. This remarkable photocatalytic activity of NaxLiyPr(WO4)2:Tb3+@Arg was ascribed to increased migration efficiency of photo-generated electrons and holes. [ABSTRACT FROM AUTHOR]

A new multifunctional Schiff base probe AnQn containing dual fluorophores (anthracene-quinoline) has been synthesised via a facile one-pot reaction. This probe demonstrated the ability to selectively discriminate group IIIA metal ions (Al3+ and Ga3+) via a dual-mode fluorescent turn-on response. Upon excitation at the same wavelength (λex 320 nm), AnQn displayed two distinct emission bands for Al3+ (λem = 410 nm) and Ga3+ (λem = 487 nm) in acetonitrile solutions. The detection limits calculated for Al3+ and Ga3+ were found to be as low as 9.2 nM and 230 nM, respectively. A 1 : 1 complexation between AnQn and Al3+/Ga3+ has been established using Job's plot, FT-IR, ESI-MS, 1H NMR and DFT analyses. The practical applicability of the probe was assessed through logic gate analysis, low-cost paper strip experiments and real water sample analysis. Intriguingly, AnQn exhibited an aggregation-induced-emission (AIE) behaviour in a semi-aqueous (CH3CN : H2O) medium, resulting in the formation of highly fluorescent green aggregates, which could be clearly evidenced by SEM images and time-resolved fluorescence (TRF) analyses. Interestingly, the resultant AnQn aggregates were further utilized as a viable fluorescent platform to selectively recognize heavy Pd2+ ions as well as highly explosive picric acid with excellent limit of detection. [ABSTRACT FROM AUTHOR]

Isothermal nucleic acid amplification tests (NAATs) are a vital tool for point-of-care (POC) diagnostics. These assays are well-suited for rapid, low-cost POC diagnostics for infectious diseases compared to traditional PCR tests conducted in central laboratories. There has been significant development of POC NAATs using paper-based diagnostic devices because they provide an affordable, user-friendly, and easy to store format; however, the difficulties in integrating separate liquid components, resuspending dried reagents, and achieving a low limit of detection hinder their use in commercial applications. Several studies report low assay efficiencies, poor detection output, and poorer limits of detection in porous membranes compared to traditional tube-based protocols. Recombinase polymerase amplification is a rapid, isothermal NAAT that is highly suited for POC applications, but requires viscous reaction conditions that has poor performance when amplifying in a porous paper membrane. In this work, we show that we can dramatically improve the performance of membrane-based recombinase polymerase amplification (RPA) of HIV-1 DNA and viral RNA by employing a coin cell-based vibration mixing platform. We achieve a limit of detection of 12 copies of DNA per reaction, nearly 50% reduction in time to threshold (from ∼10 minutes to ∼5 minutes), and an overall fluorescence output increase up to 16-fold when compared to unmixed experiments. This active mixing strategy enables reactions where the target and reaction cofactors are isolated from each other prior to the reaction. We also demonstrate amplification using a low-cost vibration motor for both temperature control and mixing, without the requirement of any additional heating components. [ABSTRACT FROM AUTHOR]

Electrochemical detection of pollutants (e.g. heavy metals) in real samples often requires the adjustment of pH to allow optimal sensitivity. Such sample pretreatment can be challenging for on-site applications as it implies the use of valves, pumps and storage of base or acid solutions. We report here the use of an electrochemical approach for the control of water sample pH. It offers the possibility for local pH adjustment while simultaneously detecting Pb2+, whose detection sensitivity is pH dependent. An effective electrochemical method through local electrochemical acidification is performed to detect Pb2+ within a desired pH range without the need to add chemical reagents. Local acidification is based on water electrolysis. An anodic potential is applied to an acidifier to rapidly electrogenerate protons. This allows the sample pH to be tailored to the optimal detection condition. Reduction of the Pt oxide layer formed on the acidifier is key to obtain repeatable results in Pb2+ detection. On-site sample acidification is combined with anodic stripping voltammetry to reach a detection limit of 6 ppb (30 nM), which is lower than the World Health Organization guideline value for Pb2+ level in drinking water. [ABSTRACT FROM AUTHOR]

Detecting multiple targets in complex cellular and biological environments yields more reliable results than single-label assays. Here, we introduced an electrochemical biosensor equipped with computing functions, acting as a smart automaton to enable computing-based detection. By defining the logic combinations of miR-21 and miR-122 as detection patterns, we proposed the corresponding AND and OR detection automata. In both logic gate modes, miR-21 and miR-122 could be replaced with single-stranded FO or FA, modified with Fc, binding to the S chain on the electrode surface. This process led to a significant decrease in the square wave voltammetry (SWV) of Fc on the same sensing platform, as numerous ferrocene (Fc)-tagged DNA fragments escaped from the electrode surface. Experimental results indicated that both automata efficiently and sensitively detected the presence of the two targets. This strategy highlighted how a small amount of target could generate a large current signal decrease in the logic automata, significantly reducing the detection limit for monitoring low-abundance targets. Moreover, the short-stranded DNA components of the detection automata exhibited a simple composition and easy programmability of probe sequences, offering an innovative detection mode. This simplified the complex process of detection, data collection, computation, and evaluation. The direct detection result ("0" or "1") was exported according to the embedded computation code. This approach could be expanded into a detection system for identifying other sets of biomarkers, enhancing its potential for clinical applications. [ABSTRACT FROM AUTHOR]

Cytokines are important immune modulators, and pivotal biomarkers for the diagnostic of various diseases. In standard analytical procedure, each protein is detected individually, using for instance gold standard ELISA protocols or nucleic acid amplification-based immunoassays. In recent years, DNA nanotechnology has been employed for creating sophisticated biomolecular systems that perform neuromorphic computing on molecular inputs, opening the door to concentration pattern recognition for biomedical applications. This work introduces immuno-PUMA (i-PUMA), an isothermal amplification-based immunoassay for ultrasensitive protein detection. The assay couples the convenience of supported format of an ELISA protocol with the computing capabilities of a DNA/enzyme circuit. We demonstrate a limit of detection of 2.1 fM, 8.7 fM and 450 aM for IL12, IL4 and IFNγ cytokines, respectively, outperforming the traditional ELISA format. i-PUMA's versatility extends to molecular computation, allowing the creation of 2-input perceptron-like classifiers for IL12 and IL4, with tunable weight sign and amplitude. Overall, i-PUMA represents a sensitive, low-cost, and versatile immunoassay with potential applications in multimarker-based sample classification, complementing existing molecular profiling techniques. [ABSTRACT FROM AUTHOR]

A significant focus of carbon dot research is on enhancing the fluorescence emission performance of biomimetic carbon dots to improve their application value in practical analysis. In this study, fish scales were used as a precursor, and citric acid was introduced to improve the quantum yield of carbon dots. The results showed that under 350 nm excitation, citric acid-modified carbon dots (CDs-FS/CA) exhibited a maximum fluorescence emission of 411 nm, and the emission behavior was independent of the excitation wavelength, with a quantum yield of 35.5%. This high quantum yield could be attributed to the presence of citric acid and the participation of hydroxyapatite in fish scales. The CDs-FS/CA had a moderate degree of graphitization, smaller and more concentrated particle size distribution, and a high proportion of pyrrole N. They showed good fluorescence performance through the synergistic effect of surface state sp2 C and different N-doped surface states. A good linear relationship in the range of 0–50 μmol L−1 was obtained using CDs-FS/CA for trace detection of quercetin, with a limit of detection of 3.8 nmol L−1, and good recovery in actual sample detection. These results offer a reference for enhancing the quantum yield of CDs obtained from alternative biomass sources and indicate the encouraging commercial feasibility of CDs derived from waste biomass for detecting trace amounts of quercetin. [ABSTRACT FROM AUTHOR]

Bioactive NAD+ mediated multiple biocatalytic pathways in metabolic networks. Refining the structure of NADH oxidase-like (NOX) mimics to efficiently replenish NAD+ has been promising but challenging in NAD+-dependent dehydrogenase electrochemical cascade biosensing. Herein, we discovered that PtOx structures, formed via lattice oxygen translocation from WO3 to Pt NPs at the interface, potentially activate and modulate the NOX-like functionality in Pt@WO3 nanosheets. Incorporating PtOx leads to a more positive valence of Pt species within Pt/PtOx@WO3−x, where the PtO2 species serve as preeminent reaction sites for NADH coordination, activation, and dehydrogenation. Consequently, such nanozymes display enhanced NOX-like activity towards NADH oxidation in comparison to Pt@WO3. Ultimately, the 650-Pt/PtOx@WO3−x nanozyme is employed in an electrochemical cascade biosensor for β-hydroxybutyrate (HB) detection, achieving a calculated detection limit of 25 μM. This study offers insights into PtOx activation in Pt-based NOX mimics and supports the future development of NAD+/NADH-dependent electrochemical biosensors. [ABSTRACT FROM AUTHOR]

The abuse of tetracycline (TC) has led to serious threats to human health and the environment. Therefore, the rapid and sensitive detection of tetracycline is of particular importance. Herein, we successfully synthesised a bimetallic nanozyme D-Fe/Co-MOF with oxidase activity and established a colourimetric sensor. The complex of Fe2+ in D-Fe/Co-MOF and TC can release hydroxyl radicals (˙OH) and promote the oxidation of TMB. As a result, the colour of the detection system significantly changes, enabling the sensitive colourimetric detection of TC. Compared with the existing Fe/Co-MOF sensor, D-Fe/Co-MOF can effectively reduce the detection error caused by hydrogen peroxide decomposition, improving the accuracy of TC detection. Under the optimal conditions, the absorbance at 652 nm showed a good linear relationship with TC concentration in the range of 0.35–220 μg mL−1. The detection limit was as low as 0.0719 μg mL−1, considerably lower than the national safety standard. The proposed colourimetric sensor was also successfully used for the detection of TC in actual milk samples, and the results were in good agreement with those obtained via liquid chromatography. The proposed strategy for the detection of TC in food is expected to contribute to ensuring food safety and human health. [ABSTRACT FROM AUTHOR]

In this work, agaric derived porous carbon (A-dPC) was obtained through high-temperature pyrolysis of biomass soaked in HNO3 solution as a carbon source, and zinc oxide nanorods (r-ZnO) were synthesized by a hydrothermal method. A-dPC and r-ZnO were combined under ultrasound to form zinc oxide nanorods/agaric derived porous carbon nanocomposites (r-ZnO/A-dPCNs). The A-dPC, r-ZnO and r-ZnO/A-dPCNs were characterized utilizing X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Brunauer–Emmett–Teller (BET). The r-ZnO/A-dPCNs/GCE showed good electrocatalytic activity in the detection of acetaminophen (PA), dopamine (DA) and luteolin. Under the optimal conditions, the sensor is capable of detecting PA and DA contemporaneously, has a wide linear range (0.10 μM–200.0 μM and 0.10 μM–100.0 μM) and low detection limits of 0.033 μM to PA and 0.022 μM to DA and meanwhile, it also can be used to detect luteolin with a wide linear range (0.010 μM–80.0 μM) and low detection limit (0.0012 μM). In addition, the sensor can be applied to detect PA, DA and luteolin in actual samples, and it exhibits good selectivity and stability. [ABSTRACT FROM AUTHOR]

Nanotheranostics aims to perform a premature and non-invasive diagnosis combined with therapy focused on the specific place where the disease is by using nanomaterials. To evaluate the ability to penetrate and retain the inorganic nanoparticles (NPs) in the cells, analytical techniques such as Single-Particle ICP-MS (SP-ICP-MS) are required to characterize these NPs. SP-ICP-MS provides not only the size distribution and concentration of NPs but also the concentration of the dissolved elements. In recent years, direct alkaline dilution of blood, serum, and urine is performed in clinical laboratories for routine analysis. This alkaline diluent is named clinical diluent and it is a mixture of ammonia, EDTA, 2-propanol, Triton X100, and purified water. In this work, a methodology to characterize AuNPs in blood and urine samples using SP-ICP-MS has been developed. Samples were directly diluted with clinical diluent before multiquadrupole ICP-MS analysis. The effect of this clinical diluent on the behaviour and stability of AuNPs has been studied. Good stability of AuNPs was observed for both the particle size and particle concentration (<17% difference in 10 days). Moreover, analytical parameters of this method such as linearity, detection limit, accuracy, and precision in blood and urine samples were studied for both the particle size and particle concentration. Linearity was evaluated for particle size (from 10 to 100 nm) and particle concentration (from 5 × 10³ to 1 × 104 NP per mL). Furthermore, recoveries between 88% and 103% for the NP concentration and between 100% and 110% for the nanoparticle size were obtained. Dissolved and gold nanoparticle detection limits have also been estimated. [ABSTRACT FROM AUTHOR]

A new one-dimensional hybrid [APCHA]Cu2I4 was designed and applied as an X-ray scintillator. It exhibits broad-band green emission with a high PLQY of 74.80% and excellent stability. It demonstrates radioluminescence property with a light yield of 28 336 photons MeV−1, detection limit of 41 nGyair s−1, and high spatial limit of 13.95 lp mm−1 in X-ray imaging. [ABSTRACT FROM AUTHOR]

Reported herein is an ultra-sensitive turn-off fluorescence sensor for hydrogen peroxide based on its reaction with bimane 1. This reaction is highly efficient, resulting in a detection limit of 7.9 pM. It also maintains sensor efficacy when adsorbed on paper and enables both solution-state and vapor-phase detection. [ABSTRACT FROM AUTHOR]

In this study, we present a pioneering approach for the electrochemical detection of levofloxacin (LVO) in human blood serum utilising iron vanadate nano-bulbs FeVO4 (FVO) decorated on a two-dimensional conjugated polymer matrix g-C3N4 (CN). The iron vanadate nano-bulbs are synthesised via a simple hydrothermal approach and integrated into a 2D conjugated polymer matrix, providing a high surface area and numerous active sites for improved sensing of LVO with a detection limit of 0.06 μM, a broader linear range of 0.25–320 μM, and high sensitivity and selectivity towards LVO. The findings highlight the significant role of vanadium in electrocatalysis, unveiling the sensor's enhanced electrochemical properties and repeatability, reproducibility and stability. This work underscores the potential of FVO nano-bulbs in developing efficient and sensitive electrochemical sensors for pharmaceutical monitoring, providing a valuable tool for real-time drug toxicity analysis. [ABSTRACT FROM AUTHOR]

One of the principal gaseous pollutants that endangers the environment and human health is nitrogen dioxide (NO2) gas, mainly emitted through combustion sources. Even at quantities of tens of ppb, prolonged exposure to NO2 can cause asthma symptoms or reduced respiratory function. Therefore, NO2 sensors with high sensitivity, accuracy, and low detection limits are highly desirable for protecting the environment and human health. Focusing on this issue, a low-cost and easy synthetic procedure was adopted for heteroatom (N, B)-doped reduced graphene oxide and a mesoporous MgFe2O4-based nanocomposite. Higher electrical conductivity of reduced graphene oxide and the defect generation due to heteroatom doping synergises with the sensing capabilities of mesoporous MgFe2O4. The designed sensor can sense up to a lower concentration of 10 ppm at room temperature. Along with the developed sensor's higher sensing capability, its good recyclability makes it favorable for detecting toxic gaseous analytes. The combined effect of higher surface area (N2 adsorption–desorption isotherm) and defect generation due to heteroatom doping and mesoporosity of MgFe2O4 spinel was the reason behind the higher response. [ABSTRACT FROM AUTHOR]

This study describes the rational development and synthesis of a benzothiazole-salicylaldehyde Schiff base probe 1. This probe is designed to function as a ratiometric fluorescent probe specifically for detecting ClO− ions, utilizing the imine bond as the fluorophore unit. Upon interaction with ClO− ions, probe 1 exhibits a redshift in its absorption spectrum from 435 nm to 450 nm. Moreover, in its emission spectrum, there is a ratiometric emission enhancement observed at 610 nm, providing a clear indication of the presence of ClO− ions. The sensitivity of probe 1 for detecting ClO− ions is quantified, revealing a lowest detection limit of 5.5 μM, indicating its potential for sensitive detection even at low concentrations of ClO− ions. Additionally, it has been successfully utilized for biological imaging purposes, demonstrating low cytotoxicity, which is crucial for its applicability in biological systems. [ABSTRACT FROM AUTHOR]

Herein, the serendipitous discovery of two water-recyclable and reusable fluorescent sensors IMPC (cyan–blue–cyan) and IMPC-OH (green–blue–green) is reported for sensing nerve agent simulants diethylcyanophosphonate and diethylchlorophosphate, respectively, with high sensitivity, short response time, and low detection limits. The unique features of these probes are their regeneration with the addition of a green and cheap solvent, namely water in CHCl3, and ease of fabrication into a portable paper-strip system that can also be regenerated. Various spectroscopic studies were employed to understand the mechanism of sensing and regeneration of both probes; the results reveal that water plays a critical role in the hydrolysis of the adduct formed with DCNP and DCP, which enables the retrieval of the probe with its original fluorescence. [ABSTRACT FROM AUTHOR]

Electrochemical detection methods hold many advantages over their optical counterparts, such as operation in complex sample matrices, low-cost and high volume manufacture and possible equipment miniaturisation. Despite these advantages, the use of electrochemical detection is currently limited in the clinical setting. There is a wide range of potential electrode materials, selected for optimal signal-to-noise ratios and reproducibility when detecting target analytes. The use of carbon paste electrodes (CPEs) for electrochemical detection can be limited by their analytical performance, however they remain very attractive due to their low cost and biocompatibility. This paper presents the fabrication of an easy-to-make and use graphite powder/paraffin wax paste combined with a substrate produced via additive manufacturing and confirms its functionality for both direct and indirect electrochemical measurements. The produced CPEs enable the direct voltammetric detection of hexaammineruthenium(III) chloride and dopamine at an experimental limit of detection (ELoD) of 62.5 μM. The key inflammatory biomarker Interleukin-6 through an enzyme-linked immunosorbant assay (ELISA) was also quantified, yielding a clinically-relevant ELoD of 150 pg ml−1 in 10% human serum. The performance of low-cost and easy-to-use CPEs obtained in 0.5 hours is showcased in this study, demonstrating the platform's potential uses for point-of-need electroanalytical applications. [ABSTRACT FROM AUTHOR]

One of the principal gaseous pollutants that endangers the environment and human health is nitrogen dioxide (NO2) gas, mainly emitted through combustion sources. Even at quantities of tens of ppb, prolonged exposure to NO2 can cause asthma symptoms or reduced respiratory function. Therefore, NO2 sensors with high sensitivity, accuracy, and low detection limits are highly desirable for protecting the environment and human health. Focusing on this issue, a low-cost and easy synthetic procedure was adopted for heteroatom (N, B)-doped reduced graphene oxide and a mesoporous MgFe2O4-based nanocomposite. Higher electrical conductivity of reduced graphene oxide and the defect generation due to heteroatom doping synergises with the sensing capabilities of mesoporous MgFe2O4. The designed sensor can sense up to a lower concentration of 10 ppm at room temperature. Along with the developed sensor's higher sensing capability, its good recyclability makes it favorable for detecting toxic gaseous analytes. The combined effect of higher surface area (N2 adsorption–desorption isotherm) and defect generation due to heteroatom doping and mesoporosity of MgFe2O4 spinel was the reason behind the higher response. [ABSTRACT FROM AUTHOR]

A new rim-differentiated pillar[5]arene (RD-P5) has been synthesized and immobilized onto an Al2O3 surface for the rapid detection of perfluoroalkyl acids. This P5-Al2O3 surface provides a novel approach for measuring perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) using contact angle measurements, with limits of detection down to 10 ng L−1. [ABSTRACT FROM AUTHOR]

Herein, we have developed a non-enzymatic, isothermal amplification assay (NIA sensor) based on a catalytic hairpin assembly (CHA) reaction for quantifying the relative abundance of Akkermansia muciniphila. Through detection of the MUC-1437 gene (limit of detection: 8.3 fM) in a dynamic range from 10 fM to 1 nM, the NIA sensor shows high sensitivity and selectivity in preclinical models of mice fed a normal or high-fat diet (HFD), and treated with antibiotics (ATB). The NIA sensor, which operates without the use of any enzymes, leading to simplicity and cost-effectiveness, has great potential for biosensing research and clinical diagnostic applications. [ABSTRACT FROM AUTHOR]

We report hereby a sensitive and rapid label free colorimetric assay of two amino acids, viz. L -arginine (L -Arg) and L -cysteine (L -Cys), through silver sol synthesized via a wet chemical method using 2-boronobenzoic acid (2- BBA) as a reducing and capping reagent in an aqueous alkaline medium. 2-BBA was synthesized in situ by the reaction of 2-formylphenylboronic acid (2-FBPA) and silver nitrate through Tollen's method. The as-synthesized silver sol exhibited the formation of nanocubes having their most predominant size in the range of 20–25 nm upon their TEM scanning and exhibiting an SPR band at 401 nm in their UV-vis spectrum. The same were further characterized by SEM, EDX, AFM, FTIR, XPS, DLS, and zeta potential measurements also. Separate interaction of the two amino acids, viz., L -Arg and L -Cys, with diluted AgNCs (1 : 2; AgNCs and Millipore water V/V) exhibited two different colors, pinkish grey and blue, respectively accompanied by distinctive shifts in their surface plasmon resonance (SPR) band also. The detection limits were found to be 6 μM and 3 μM for L -Arg and L -Cys respectively. Furthermore, L -Arg and L -Cys were quantified in a pharmaceutical sample each with their respective recovery rates of 99.2% and 90.1%. These AgNCs exhibited rich SERS characteristics also by intensifying the Raman peaks of L -Arg and L -Cys. Only a few one-pot aqueous chemical syntheses of silver nanocubes have been reported previously. Most probably, this is the third report of its kind. To the best of our knowledge, no silver nanoprobe exhibiting simultaneous detection of L -Arg and L -Cys has been reported to date. [ABSTRACT FROM AUTHOR]

Hypochlorite (ClO−) is an important oxidant and disinfectant in the human body and in nature. Nevertheless, it may exert an adverse impact on the environment and biological systems when its concentration is not appropriate. It is necessary to develop an accurate method for detecting ClO−. Herein, an isopinocamphone-based fluorescent probe DMTI for selective recognition of ClO− was successfully synthesized. DMTI exhibited an obvious fluorescence enhancement towards ClO− accompanied by a color shift from colorless to bright blue. The experimental results displayed that the probe DMTI had the merits of high selectivity, good sensitivity, and a wide detection pH range (6–10) for ClO− detection, and the detection limit reached 2.6 × 10−7 mol L−1. The sensing mechanism of DMTI to ClO− was confirmed by the 1H NMR and HRMS analyses. More importantly, the probe DMTI has been effectively utilized to detect ClO− in environmental water samples, living cells and zebrafish encouraged by its excellent performance. [ABSTRACT FROM AUTHOR]

Multi-stimuli responsive polycyclic aromatic hydrocarbons offer advantages of high selectivity, sensitivity, and versatility as they can integrate multiple inputs and outputs to achieve the desired applications in a flexible manner. In this context, carbazole and its derivatives have been extensively studied due to their tunability, outstanding electrochemical properties and good environmental stability. However, most of the studies used the polymeric forms of carbazole derivatives which requires energy-intensive synthesis. Recently, it has been reported that the self-assembled monolayers of carbazole derivatives offer more advantages over their polymeric forms in terms of stability and efficiency. Herein, we introduce a carbazole-based low molecular weight gelator achieved with synthetic ease, exhibiting a multi-stimuli response behaviour, i.e. sensing of cyanide ions and electrochromism, in its solution state. Further, the compound forms a gel in dioxane–H2O and DMF–H2O mixtures and exhibits aggregation-induced emission (AIE). The mechanistic pathways of sensing have been investigated and the limit of detection is found to be 1.25 nM, which is significantly lower than the permissible limit established by the WHO. Furthermore, possibilities of extending the electrochromism and sensing in the gel state using carbazole derivatives have been explored and the results indicate that low molecular weight carbazole derivatives are promising candidates for electrochromism and sensing applications. [ABSTRACT FROM AUTHOR]

In this work, Au/Bi2O3 was synthesized by loading Au nanoparticles (NPs) onto β-Bi2O3 by a simple solution reduction method. β-Bi2O3 was synthesized by a precipitation-thermal decomposition procedure, which results in significantly improved SERS detection limits down to 10−9 M for methylene blue (MB) and 10−7 M for methyl orange (MO) as probe molecules, comparable to those reported for the best semiconductor SERS substrates. In particular, further deposition of Au NPs (5.20% wt%) onto β-Bi2O3 results in a two-order-of-magnitude enhancement in detection sensitivity, achieving a detection limit of 10−11 M for MB and 10−9 M for MO. Under ultraviolet/visible irradiation, the Au/Bi2O3 hybrids substrate exhibits superior self-cleaning ability due to its photocatalytic degradation ability which can be applied repeatedly to the detection of pollutants. The advanced composite substrate simultaneously achieved ultra-low mass loading of Au NPs, outstanding detection performance, good reproducibility, high stability and self-cleaning ability. The development strategy of low load noble metal coupled high performance semiconductor β-Bi2O3 to obtain nano-hybrid materials provides a method to balance SERS sensitivity, cost effectiveness and operational stability, and can be synthesized in large quantities, which is a key step towards commercialization and has good reliability prospects. [ABSTRACT FROM AUTHOR]

Vertical flow assay (VFA) is an effective point-of-care (POC) diagnostic tool for widespread application. Nevertheless, the lack of multi-target detection and multi-signal readout capability still remains a challenge. Herein, a brand new VFA scheme for multi-target saliva detection based on electronic tags was proposed, where AlGaN/GaN HEMT sensors modified with different bio-receptors as electronic tags endowed the VFA with multi-target detection capability. In addition, the use of electronic tags instead of optical tags allowed the VFA to simultaneously carry out direct multi-target readouts, which ensure effective POC diagnostics for saliva analysis. Moreover, by integrating a hydrophilically optimized micro-sieve, impurities like sticky filaments, epidermal cells and other large-scale charged particles in saliva were effectively screened, which enabled the direct detection of saliva using AlGaN/GaN HEMT sensors. Glucose, urea, and cortisol were selected to verify the feasibility of the multi-target e-VFA scheme, and the results showed that the limit of detection (LOD) was as low as 100 aM. The linear response was demonstrated in the dynamic range of 100 aM to 100 μM, and the specificity, long-term stability and validity of the actual saliva test were also verified. These results demonstrated that the as-proposed e-VFA has potential for application in saliva detection for simultaneous multi-target detection, and it is expected to achieve the real-time detection of more biological targets in saliva. [ABSTRACT FROM AUTHOR]

The solvothermal method of producing spherically shaped and highly fluorescent tiny (∼3 nm) nitrogen-doped carbon quantum dots (NCQDs) with high quantum yield (43%) from Ixora coccinea flowers and o-phenylenediamine has been approached sustainably. Since these NCQDs exhibit excitation-dependent fluorescence activity, they were used to detect the Fe3+ ion selectively in real-time in human blood serum, because it is a component of human blood. The limit of detection (LOD) of the NCQDs was found to be 60 nM. We also synthesized palladium nanoparticles utilizing the NCQDs without additional reducing or stabilizing agents because these quantum dots serve as both. Numerous characterization techniques were used to characterize the nanoparticles, and all the characterizations showed the presence of NCQDs, which stabilize the nanoparticles. Palladium nanoparticles' small size (4 nm) and large surface area (35.77 m2 g−1) enable them to exhibit strong catalytic activity in Suzuki–Miyaura coupling and cyanation processes. It is obvious that synthetic palladium nanoparticles and NCQDs have a variety of uses in the fields of catalysis and sensing respectively. [ABSTRACT FROM AUTHOR]

Drug resistance presents a significant obstacle in treating human ovarian cancer. The development of effective methods for detecting drug-resistant cancer cells is pivotal for tailoring personalized therapies and prognostic assessments. In this investigation, we introduce a dual-mode detection technique employing a fluorogenic aptamer probe for the qualification of P-glycoprotein (P-gp) in drug-resistant ovarian cancer cells. The probe, initially in an "off" state due to the proximity of a quencher to the fluorophore, exhibits increased fluorescence intensity upon binding with the target. The fluorescence enhancement shows a linear correlation with both the concentration of P-gp and the presence of P-gp in drug-resistant ovarian cancer cells. This correlation is quantifiable, with detection limits of 1.56 nM and 110 cells per mL. In an alternate mode, the optimized fluorophores, attached to the aptamer, form larger complexes upon binding to the target protein, which diminishes the rotation speed, thereby augmenting fluorescence polarization. The alteration in fluorescence polarization enables the quantitative analysis of P-gp in the cells, ranging from 100 to 1500 cells per milliliter, with a detection limit of 40 cells per mL. Gene expression analyses, protein expression studies, and immunofluorescence imaging further validated the reliability of our aptamer-based probe for its specificity towards P-gp in drug-resistant cancer cells. Our findings underscore that the dual-mode detection approach promises to enhance the diagnosis and treatment of multidrug-resistant ovarian cancer. [ABSTRACT FROM AUTHOR]

Nowadays, kidney dysfunction is a common health issue due to the modernized lifestyle. Even though medications are commercially available to treat kidney diseases, early diagnosis is crucial and challenging. Clinically, measuring urine creatinine and pH has gained significant interest as a way to diagnose kidney diseases early. In the present work, we attempted to develop a low-cost, robust, accurate and naked-eye colorimetric method to determine both creatinine levels and pH variations in artificial urine samples using a simple 3D-printed hybrid microfluidic device. Creatinine was detected by the incorporation of the traditional Jaffe test onto the hybrid paper–PMMA microfluidic device and pH (4–8) was measured by a simple anthocyanin test. Notably, the tests were established without employing any sophisticated or costly instrument clusters. The developed 3D-printed microfluidic probe showed a limit of detection (LOD) of 0.04 mM for creatinine over a concentration range of 1–10 mM, with a regression coefficient (R2) of 0.995 in laboratory conditions. Interestingly, the experimental data obtained with artificial urine exhibited a wide linear range from 0.1 mM to 5 mM under different pH values ranging from 4 to 8 in the presence of matrices commonly found in urine samples other than proteins, indicating the potential use of this method in pre-clinical analysis. Since the wide linear range of urine creatinine in artificial urine samples falls well below the clinically relevant concentrations in humans (0.07–0.27 mM), the developed lab-on-chip device is further suitable for clinical evaluation with proper ethical clearance. This 3D-printed hybrid microfluidic colorimetry-based creatinine detection and pH indicator platform can be beneficial in the healthcare sector due to the on-site testing capability, cost-effectiveness, ease of use, robustness, and instrument-free approach. [ABSTRACT FROM AUTHOR]

Properly fusing various photophysical processes in a single chromo-fluorophore platform is crucial for developing a highly selective and sensitive chromo-fluorogenic probe to detect various target analytes. Moreover, deciphering the mechanistic approach for understanding the detection mechanism for any target analyte is paramount to facilitate the construction and development of new efficient probes for the selective detection and quantification of different target analytes. In this report, we introduce a phthalimide-based chromo-fluorogenic scaffold, DAID, fusing intramolecular charge transfer (ICT), photoinduced electron transfer (PET), and excited-state intermolecular proton transfer (ESIPT) processes in a single molecular platform. DAID showed turn-on and ratiometric chromo-fluorogenic behaviors toward trivalent transition metal ions Al3+, Fe3+, and Cr3+ in a 20% (v/v) water–DMSO mixture. A visual colorimetric change was detected in the DAID solution by incorporating trivalent transition metal ions. A remarkable turn-on green color emission enhancement was noticed in the DAID solution in the presence of these trivalent ions. The limit of detection and limit of quantification for these trivalent transition metal ions were in the nM range and were superior to those of other methods reported in the literature. Time-resolved fluorescence-lifetime-decay, 1H-NMR titration, and high-resolution mass spectrometric analysis were carried out to elucidate the detailed mechanistic aspects to understand the detection mechanism for the identification of the trivalent transition metal ions employing the DAID probe. The successful demonstration of DAID for practical applications is encouraging for its further application in a variety of fields, fusing and deciphering the various photophysical processes in a single chromo-fluorophore platform, which would enable researchers to develop new efficient probes to selectively detect various target analytes. [ABSTRACT FROM AUTHOR]

Nanoparticles (NPs) are ubiquitous because they find applications in nanomedicine, materials science, and consumer products to name a few, and eventually end up in the environment. The various techniques available to analyze NPs each have strengths and limitations. This study focuses on improving the single particle inductively coupled plasma mass spectrometry (spICPMS) technique to address the limitations of existing methods and improve the size detection limit for Pt and Au NPs. Infrared heating of the spray chamber and connection to the torch is used to pre-evaporate the aerosol and improve the transport efficiency. Eight modified cyclonic spray chambers with a volume ranging from 25 to 125 mL, where an IR emitter is inserted in a modified baffle and the gap between the top of the baffle and the top service of the spray chamber was varied, are tested for the characterization of NPs to see their effect on sensitivity, detection limit, and transport efficiency. The results indicate that the 50 mL modified spray chamber with a 2 mm gap between the top of the baffle and the top service of the spray chamber offers the best detection limit for Pt. It enhances sensitivity and precision and allows accurate characterization of Au and Pt NPs without any measurement of the transport efficiency. Furthermore, this sample introduction system provided similar improvements in sensitivity and detection limit when used with the same nebulizer on two different spICPMS instruments. [ABSTRACT FROM AUTHOR]

A new method for the rapid quantification of neptunium 237 in nuclear effluent was developed. This method is based on the direct measurement of neptunium 237 by ICP-MS/MS in mass-shift mode as NpO and using 20% CO2 as a reaction gas. These measurement conditions allowed the best signal-to-noise ratio at m/z 253 (237Np16O) to be obtained by the efficient elimination of the interferences due to the abundance sensitivity of uranium 238 and hydrides of uranium 235 and uranium 236 while minimizing the elemental fractionation between neptunium and plutonium. Moreover, plutonium 242 can be used as a tracer for neptunium 237 isotopic dilution-based quantification. After an optimization of the measurement parameters, excellent figures of merit were obtained. Indeed, this protocol allows an accurate direct measurement of neptunium 237 in various nuclear effluent samples containing up to 2 mg L-1 (2.4 Bq L-1) of uranium 236 and up to 20 mg L-1 (250 Bq L-1) of uranium 238 with excellent accuracy and uncertainties lower than 15%, for samples containing 10-5 to 10-1 mg L-1 (10-3 to 13 Bq L-1), and a limit of detection for 237Np as low as 4 pg L-1 (10-4 Bq L-1). [ABSTRACT FROM AUTHOR]

The determination of formaldehyde (HCHO) concentration in human exhaled breath can be used as an effective means for the early diagnosis of lung cancer. Lanthanide metal–organic frameworks (LnMOFs) have shown great potential in formaldehyde fluorescence sensing, yet challenges persist in achieving high sensitivity and selectivity. In this work, we report new hydrazine-functionalized LnMOFs (Ln = Eu3+, Gd3+, Tb3+, H2BDC–NH–NH2 = 2-hydrazine-terephthalic acid), having an fcu topology for the sensitive and selective detection of formaldehyde gas. The ligands with hydrazine groups not only act as an "antenna effect" between the ligands and Eu3+ ions, but also act as formaldehyde recognition sites, enabling Eu-BDC–NH–NH2 to be used for fluorescence enhanced sensing of formaldehyde gas in gaseous environments. Eu-BDC–NH–NH2 thus exhibits low detection limit (41.7 ppb), high selectivity, and fast (3 minutes) formaldehyde gas response, showing great potential to be practically applied in the field of early diagnosis of lung cancer. [ABSTRACT FROM AUTHOR]

Carbohydrate antigen 24-2 (CA242) as a biomarker played critical roles in the early diagnosis of colorectal cancer. Herein, a quenching-typed electrochemiluminescence immunosensor based on resonance energy transfer strategy was proposed for ultrasensitive CA242 detection. CdS NCs exhibited good electrochemiluminescence performance, which was used as an ECL energy donor, while COFs with a porous structure presenting UV-vis light absorption was used as an energy acceptor, which could significantly quench the ECL signal of CdS NCs. The sandwich-type immunosensor was constructed with thiolated CdS NCs as substrates for primary antibody (Ab1) immobilization and functionalized COFs as the carrier to immobilize secondary antibody (Ab2). With CA242 antigen captured, the distance between CdS NCs and COFs was closed and the electron transfer path shortened, leading to the quenching of the ECL signal of CdS NCs. Under optimal conditions, the proposed immunosensor represented wide linearity, and the detection limit was in the range from 0.001 U mL−1 to 1000 U mL−1. At the same time, the detection limit of CA242 antigen was 0.000183 U mL−1 (S/N = 3). The immunosensor exhibited its feasibility for the detection of CA242 and lays a good foundation for the high sensitivity sensing of other disease biomarkers in clinical diagnosis in the future. [ABSTRACT FROM AUTHOR]