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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]

We reported a colorimetric paper-based device by integrating the modified acid RNA-cleaving DNAzymes (MaRCD-EC1) for highly sensitive (detection limit = 102 CFU mL−1), and rapid (within 30 min) detection of E. coli without amplification. This device exhibited a clinical sensitivity of 100% and a specificity of 100% in identifying E. coli-associated urinary tract infections (UTIs) using the clinical urine samples. [ABSTRACT FROM AUTHOR]

Gossypol, a phytotoxicant in cotton-seed oil, has been found to sensitize Tb(III)-luminescence in a supramolecular hydrogel. Based on this observation, a paper-based sensor has been developed to detect gossypol with a limit of detection (LOD) of 2.9 nM. This is the first report of water-based detection with the highest sensitivity involving turn-on time-gated luminescence. This method was also able to sense gossypol in commercial crude cotton-seed oil. [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 paper, Tesla coil discharge (TCD) was combined with laser-induced breakdown spectroscopy (LIBS). The TCD successfully enhanced the emission of Al atomic lines and AlO molecular bands in Al LIBS, and improved the sensitivity of quantitative analysis of Cr and Pb elements detected by LIBS in water. Firstly, the paper explored the effect of the distance from the TCD tip to the sample surface on the emission of Al atomic lines and AlO molecular bands, finding that 5 mm was the optimal distance. Secondly, the paper investigated the effect of laser energy on the emission of Al atomic lines and AlO molecular bands, finding that 25.1 mJ was the optimal laser energy. Finally, the paper constructed the calibration curves of Cr and Pb elements in water and calculated the limit of detection (LoD), finding that compared with surface enhanced LIBS (SELIBS), TCD–SELIBS reduced the LoDs of Cr and Pb elements from 16.7 ng mL−1 and 12.2 ng mL−1 to 7.3 ng mL−1 and 5.5 ng mL−1, respectively. It indicated that the combination of TCD and SELIBS can achieve high-sensitivity detection of Cr and Pb elements in the water. The combination of TCD and LIBS is a simple, low-cost, easy-to-operate, industrialized and commercialized technology, and has a promising application prospect in the high-sensitivity analysis of heavy metals in water. [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]

A europium-functionalized, dual-emissive, metal–organic framework-based fluorescence sensor (EuUCNDA) was constructed via post-synthetic modification of an UiO-66-type precursor through coordination interactions. EuUCNDA exhibited extremely high selectivity and sensitivity for malachite green (MG) with a low detection limit of 13.01 nM, a wide linear concentration range (0.05–50 μM), excellent anti-interference properties, a rapid response (<1 min), and the possibility of recycling. The good sensing performance of EuUCNDA enables the practical detection of MG in fish pond water and grass carp with good recoveries. Moreover, EuUCNDA can be reused for sensing MG and over 90% of fluorescence intensity can be restored after 7 cycles. Furthermore, EuUCNDA-embedded paper-based sensors combined with smartphone imaging afford portable and visual monitoring of MG in real samples. Notably, besides good sensing performance, EuUCNDA could efficiently remove MG from water. Hence, this work provides a recyclable and sensitive fluorescence sensor for portable, visual, rapid detection and efficient removal of MG. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) have unique potential in the field of gas sensing due to their ultra-high specific surface area and abundant mesoporous structure. In this paper, a mesoporous Co3O4 hollow polyhedron structure with high specific surface area (141.6 m2 g−1) was synthesized by annealing at the optimum temperature. The gas response of the mesoporous Co3O4 hollow polyhedron structure to volatile organic compounds such as xylene, ethanol, methanol and acetone was systematically tested. The experimental results show that the mesoporous Co3O4 hollow polyhedron structure has the highest sensitivity (21.33) and excellent stability for xylene gas, and the detection limit is low (1 ppm). The excellent sensing performance benefits from large surface area, high oxygen defect concentration and mesoporous structure. [ABSTRACT FROM AUTHOR]

In this paper, we report on the development of an 'off–on' fluorescent probe for the detection of hydrogen peroxide (H2O2) and mercury ions (Hg2+) using an in situ synthesized carbon quantum dot and gum Arabic silver nanoparticle composite (CQDs@GA-Ag NPs). Electron microscopy measurement clearly shows that CQDs are attached to the surface of the GA-Ag NPs. The fluorescence intensity of the CQDs was dramatically quenched in the synthesized nanocomposite via the inner filter effect (IFE) mechanism. After adding H2O2 to the nanocomposite system, the Ag NPs got oxidized leading to the formation of Ag+ ions, and the CQDs regained their photoluminescence (PL) property. This facilitates the detection of H2O2 with an extremely low detection limit of 1.02 μM. Furthermore, the as-developed nanocomposite was also tested for the detection of Hg2+ ions, obtaining a remarkably low detection limit of 1.82 μM. The developed probe was extremely selective over a wide range of interfering ions and substances. [ABSTRACT FROM AUTHOR]

A volumetric bar-chart chip (V-chip) is a microfluidic device based on distance-based quantitative measurement that visualizes analyte concentration without the need for apparatus or data processing. This typically utilizes special receptors and catalysis parts that generate oxygen, so ink can be moved inside the channels, and enables instant visual quantitation of the analyte. However, the low stability of some macromolecules, the use of expensive catalysts, and difficulty in controlling the process cause inaccurate readings, and therefore, limit further development and the use of these systems. In this article, we introduced a novel approach that eliminates the use of catalysts in V-chips and provides an efficient and simple path in the design of biosensors. The product of the enzymatic reaction of urease with urea is bicarbonate, which turns into CO2 gas in an acidic environment. Therefore, the amount of gas produced is proportional to the amount of urea in the sample, and it can be quantitatively measured by visual detection from the amount of ink movement caused by CO2 gas pressure. This biosensor has a linear response range of 0 to 1000 µg ml-1 and a detection limit of 3.6 µg ml-1 in raw milk. The recovery of urea in raw milk at 100 and 400 µg ml-1 concentrations was 96.5% and 98.9%, respectively. This volumetric chip shows potential for determining urea levels in real samples without requiring additional equipment. The combination of the sensitivity and specificity of enzymatic reactions, inherent gas-generating reactions, and the processability of microchips discussed in this paper can be the basis for the comprehensive development of volumetric chips, which can create a new path for the development of efficient and cheap biosensors. [ABSTRACT FROM AUTHOR]

In recent years, the development of new scintillation materials with red and near-infrared light emission has had significant advantages based on the development of an avalanche photodiode with high quantum yield. This study used a hydrothermal method to synthesize rare-earth-doped Cs2NaScCl6 crystals, in which a red emission of Cs2NaScCl6:Sm was investigated with high X-ray sensitivity and low detection limit. In addition, a tunable wavelength range of radioluminescence can be achieved, in which a near-white light emission can be generated by precisely controlling the proportion of Sm3+ and Tb3+ doping concentrations. Meanwhile, a Cs2NaScCl6:7%Sm scintillation film has been successfully prepared by direct coating with a thickness of 150 μm, which achieves a spatial resolution of 11.9 lp mm−1 based on X-ray imaging experiments. Therefore, this perovskite material has shown potential application as an eco-friendly multifunctional imaging material. [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]

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]

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]

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]

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]

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]

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]

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]

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]

Developing a facile and effective assay method is crucial due to the potential harm of metronidazole (MNZ) antibiotics to both human health and the environment. Herein, snowflake-shaped poly(3-thiophenemalonic acid, 3-TPA) combined with a carbonized core–shell-type ZIF-8@ZIF-67 (C-ZIF-8@ZIF-67) hollow polyhedra modified glassy carbon electrode (GCE), denoted as C-ZIF-8@ZIF-67/P3TPA/GCE, was fabricated by electropolymerization followed by the electrodeposition strategy. The resulting sensor demonstrates a significant electrocatalysis effect for the reduction reaction of MNZ, exhibiting a broad linear range (0.1–20, 20–800 μM) with a low limit of detection (LOD, 3S/N) of 0.024 μM. Furthermore, it has been successfully applied to determine MNZ in tablets and lake water. A synergistic effect between P3TPA and C-ZIF-8@ZIF-67 is elucidated through density functional theory (DFT) calculations. Consequently, this research introduces a sensitive and effective method for monitoring MNZ in real samples. [ABSTRACT FROM AUTHOR]

Early-stage diagnosis of prostatic carcinoma is essential for successful treatment and, thus, significant prognosis improvement. In laboratory practice, the standard non-invasive diagnostic approach is the immunochemical detection of the associated biomarker, prostate-specific antigen (PSA). Ultrasensitive detection of PSA is essential for both diagnostic and recurrence monitoring purposes. To achieve exceptional sensitivity, we have developed a microfluidic device with a flow-through cell for single-molecule analysis using photon-upconversion nanoparticles (UCNPs) as a detection label. For this purpose, magnetic microparticles (MBs) were first optimized for the capture and preconcentration of PSA and then used to implement a bead-based upconversion-linked immunoassay (ULISA) in the microfluidic device. The digital readout based on counting single nanoparticle-labeled PSA molecules on MBs enabled a detection limit of 1.04 pg mL−1 (36 fM) in 50% fetal bovine serum, which is an 11-fold improvement over the respective analog MB-based ULISA. The microfluidic technique conferred several other advantages, such as easy implementation and the potential for achieving high-throughput analysis. Finally, it was proven that the microfluidic setup is suitable for clinical sample analysis, showing a good correlation with a reference electrochemiluminescence assay (recovery rates between 97% and 105%). [ABSTRACT FROM AUTHOR]

Aflatoxin B1 (AFB1), classified as a class I carcinogen, is a widespread mycotoxin that poses a serious threat to public health and economic development, and the food safety problems caused by AFB1 have aroused worldwide concern. The development of accurate and sensitive methods for the detection of AFB1 is significant for food safety monitoring. In this work, a sandwich-type photoelectrochemical (PEC) biosensor for AFB1 detection was constructed on the basis of an aptamer–antibody structure. A good photocurrent response was obtained due to the sensitization of In2S3 by Ru(bpy)32+. In addition, this sandwich-type sensor constructed by modification with the antibody, target detector, and aptamer layer by layer attenuated the migration hindering effect of photogenerated carriers caused by the double antibody structure. The aptamer and antibody synergistically recognized and captured the target analyte, resulting in more reliable PEC response signals. CdSe@CdS QDs-Apt were modified as a signal-off probe onto the sensor platform to quantitatively detect AFB1 with a "signal-off" response, which enhanced the sensitivity of the sensor. The PEC biosensor showed a linear response range from 10−12 to 10−6 g mL−1 with a detection limit of 0.023 pg mL−1, providing a feasible approach for the quantitative detection of AFB1 in food samples. [ABSTRACT FROM AUTHOR]

Alpha-synuclein (α-syn) is closely related to the pathological process of Parkinson's disease (PD). Sensitive detection of α-syn is important for the early diagnosis and disease progression monitoring of PD. Herein, we report a binding-triggered hybridization chain reaction (HCR) cascade multi-site activated CRISPR/Cas12a signal amplification strategy for sensitive detection of α-syn. In this method, antibody–DNA capture probes recognized α-syn and bound with it to increase the local effective concentrations of two DNA strands, promoting their hybridization to form a split HCR trigger. Then the trigger initiated an HCR to generate a long double-stranded structure which contained abundant periodically repeated Cas12a/crRNA target sequences. Finally, the Cas12a/crRNA recognized the target sequence in HCR products and then the cleavage activity toward fluorescent reporters was activated, leading to the recovery of appreciable fluorescence signals. Our method provided a detection limit as low as 9.33 pM and exhibited satisfactory applicability in human serum samples. In summary, this study provides a homogeneous strategy for convenient, sensitive, and accurate detection of α-syn, showing great potential in the early diagnosis of PD. [ABSTRACT FROM AUTHOR]

Herein, we synthesized three new LMOFs, [Cd(TPPE)0.5(oba)(H2O)]n (LMOF-1), [Cd2(TPPE)(bpdc)2]n (LMOF-2), and [Cd2(TPPE)(sdc)2]n (LMOF-3) (TPPE = 1,1,2,2-tetra[4-(pyridin-4-yl)phenyl]ethylene, oba = 4,4′-diphenyl ether dicarboxylic acid, bpdc = 4,4′-biphenyl dicarboxylic acid, sdc = 4,4′-styrene dicarboxylic acid), with high quantum yields of 43.74%, 36.68% and 45.89%, respectively, exceeding those reported for most Cd-based LMOFs. All three LMOFs have good detection sensitivity for Fe3+, CrO42− and Cr2O72−. Surprisingly, Na+ can rarely but significantly enhance the fluorescence intensity of LMOF-3, and the detection limit is 1.90 × 10−5 M. This is the first reported LMOF material that can quantitatively analyze Na+ among references. All results indicate that the three MOFs can be developed into phosphor materials and fluorescent chemical sensors for detecting ions in water. [ABSTRACT FROM AUTHOR]

Monitoring methods for beta-lactam (β-lactam) antibiotics, especially for ampicillin (AMP), with simple operation and sensitivity for realtime applications are highly required. To address this need, antioxidant carbon dots (E-CDs) with excellent fluorescence properties were synthesized using citric acid and ethylenediamine as raw materials. With a quantum yield of 81.97%, E-CDs exhibited a specific and sensitive response to ˙OH. The quenched fluorescence of E-CDs by the formed ˙OH could be restored through a competition reaction with AMP. Leveraging the signal-quenching strategy of E-CDs, H2O2, and Fe2+, a fluorescence signal-on strategy was developed using AMP as the fluorescence recovery agent for the sensitive detection of AMP. The mechanism of the quenching of E-CDs by ˙OH was attributed to the damaging effect of ˙OH on E-CDs. Under optimal conditions, the detection limit of this method for AMP was determined to be 0.38 μg mL−1. This method was successful in drug quality control and the spiked detection of AMP in lake water, milk, and sea cucumber, presenting a viable option for convenient and rapid antibiotic monitoring methods. [ABSTRACT FROM AUTHOR]

Bioinspired nanochannel-based sensors have elicited significant interest because of their excellent sensing performance, and robust mechanical and tunable chemical properties. However, the existing designs face limitations due to material constraints, which hamper broader application possibilities. Herein, a heteromembrane system composed of a periodic mesoporous organosilica (PMO) layer with three-dimensional (3D) network nanochannels is constructed for glutathione (GSH) detection. The unique hierarchical pore architecture provides a large surface area, abundant reaction sites and plentiful interconnected pathways for rapid ionic transport, contributing to efficient and sensitive detection. Moreover, the thioether groups in nanochannels can be selectively cleaved by GSH to generate hydrophilic thiol groups. Benefiting from the increased hydrophilic surface, the proposed sensor achieves efficient GSH detection with a detection limit of 1.2 μM by monitoring the transmembrane ionic current and shows good recovery ranges in fetal bovine serum sample detection. This work paves an avenue for designing and fabricating nanofluidic sensing systems for practical and biosensing applications. [ABSTRACT FROM AUTHOR]

Single nucleotide variants (SNVs) play a crucial role in understanding genetic diseases, cancer development, and personalized medicine. However, existing ligase-based amplification and detection techniques, such as Rolling Circle Amplification and Ligase Detection Reaction, suffer from low efficiency and difficulties in product detection. To address these limitations, we propose a novel approach that combines Ligase Chain Reaction (LCR) with acoustic detection using highly dissipative liposomes. In our study, we are using LCR combined with biotin- and cholesterol-tagged primers to produce amplicons also modified at each end with a biotin and cholesterol molecule. We then apply the LCR mix without any purification directly on a neutravidin modified QCM device Au-surface, where the produced amplicons can bind specifically through the biotin end. To improve sensitivity, we finally introduce liposomes as signal enhancers. For demonstration, we used the detection of the BRAF V600E point mutation versus the wild-type allele, achieving an impressive detection limit of 220 aM of the mutant target in the presence of the same amount of the wild type. Finally, we combined the assay with a microfluidic fluidized bed DNA extraction technology, offering the potential for semi-automated detection of SNVs in patients' crude samples. Overall, our LCR/acoustic method outperforms other LCR-based approaches and surface ligation biosensing techniques in terms of detection efficiency and time. It effectively overcomes challenges related to DNA detection, making it applicable in diverse fields, including genetic disease and pathogen detection. [ABSTRACT FROM AUTHOR]

Rare earth elements are greatly valued for their crucial role in many high-tech fields. Highly sensitive and precise determination technology of these elements in aqueous solution is essential for the extraction and recycling processes of these elements. Currently, conventional measurement methods for rare earth elements, such as ICP-MS and ICP-OES, often suffer from issues related to complex operations, lengthy procedures, and low economic efficiency. While laser-induced breakdown spectroscopy (LIBS) provides fast and convenient detection capability, due to the matrix effect of the water LIBS technology itself, the reported sensitivities of these elements have not met the application requirements for detection capabilities. In this work, we propose a method that utilizes a micro-hole array sprayer to rapidly prepare rare earth aqueous solution samples into densely and uniformly adhered particles on an Al substrate, combined with a computer-controlled three-dimensional displacement platform to facilitate fully automated LIBS detection. Through optimization of system parameters, the detection limits for La, Pr, Nd, and Sm reach 8.6, 22.3, 13.6, and 6 μg L−1, respectively, with a stable repeatability of 4.96%, within a total sample preparation and detection time of no more than 15 minutes. Compared to existing LIBS-based detection methods, the average detection limits have been reduced by two orders of magnitude, essentially meeting the ppb-level requirements for practical production. This demonstrates the potential of our system to develop into a fast, low-cost, standardized detection technology in the field of rare earth element exploration, mining, and recovery. [ABSTRACT FROM AUTHOR]

In this work, 2(3),9(10),16(17),23(24)-octamethoxyphthalocyanine (Pc(OH)8) was first used to modify Cu/CuFe2O4(Cu/CFO) nanospheres, and Pc(OH)8–Cu/CFO nanocomposites with enhanced peroxidase mimetic enzyme activity was obtained compared to the performance of Cu/CFO alone. SEM, XRD, and XPS were used to study the surface morphology, phase composition and elemental analysis of the newly synthesized Pc(OH)8–Cu/CFO. Using TMB as the chromogenic substrate, Pc(OH)8–Cu/CFO accelerate the oxidation process of chromogenic substrate 3,3′,5,5′- tetramethylbenzidine (TMB) by hydrogen peroxide in three minutes. The catalytic oxidation mechanism of Pc(OH)8–Cu/CFO on TMB was comprehensively investigated through free radical and fluorescence probe experiments. Based on the excellent catalytic performance of the composite materials, a simple and fast colorimetric sensing platform for the colorimetric detection of H2O2 and glutathione (GSH) was constructed in the range of 0.6–5 mM and 2–10 μM with detection limits (LODs) of 0.35 mM and 0.55 μM, respectively. In addition, using Pc(OH)8–Cu/CFO colorimetric detection for GSH has a lower detection limit, good selectivity and high sensitivity, which is expected to become an ideal material for GSH colorimetric detection. [ABSTRACT FROM AUTHOR]

The ruthenium (Ru)-based functional structure has been well understood in catalytic performance due to its special particularity in structural fabrication. In this work, the controllable synthesis of core–shell Ru nanomaterials is first reported, which were not only realized via ice bath conditions with amorphous characterization but also showed a flexible design in the controllable synthesis of crystalline Ru after high intensity focused ultrasound (HIFU) treatment. The achieved amorphous Ru particles (∼115 ± 3 nm) and crystalline Ru (∼5 ± 0.5 nm) exhibit hydrogen peroxide catalytic performance and can be considered as an electrochemical sensing platform. The Km value of core–shell Ru for 3,3′,5,5′-tetramethylbenzidine (TMB) was 0.221 mM, which exhibits higher affinity for TMB and prominent catalytic performance than horseradish peroxidase (HRP). For selectivity and sensitivity towards the detection of H2O2 molecules, it expressed a wide linear range from 0.5 to 100 mM with an H2O2 detection limit of 1.45 μM (S/N = 3) and a sensitivity of 2.07 μA μM−1. After HIFU treatment, the diameter of the achieved crystalline Ru was about one-twentieth that of the core–shell Ru structure. An enhancement in catalytic performance was observed as a sensor platform for detecting H2O2, its detection range was wider, from 0.5 to 110 mM, its limit of detection was 0.007 μM (S/N = 3), and it exhibited a higher sensitivity of 443 μA μM−1. Hence, this flexible design in the synthesis of Ru NMs (amorphous and crystalline in status) could provide a novel synthetic strategy and make achievements in catalytic performance. [ABSTRACT FROM AUTHOR]

In this work, a gold-supported cerium-based organic framework hybrid structure (Au@Ce-MOF@COF) and gold@molybdenum disulfide@graphene oxide (Au@MoS2@rGO) were successfully prepared, and used for constructing an electrochemical aptasensor to detect carcinoembryonic antigen (CEA). Au@MoS2@rGO has a large surface area and good electron transfer rate, so it was used as the substrate to immobilize more aptamers (Apt1). The prepared Ce-MOF@COF was also used as a substrate for the immobilization of aptamers (Apt2) and horseradish peroxidase (HRP). When CEA exists, CEA binds to Au@Ce-MOF@COF-HRP-Apt2. In the presence of H2O2, it can effectively promote the oxidation of hydroquinone (HQ) to benzoquinone (BQ), and the electrochemical reduction signal of BQ was significantly amplified. So, the highly sensitive and selective detection of CEA was achieved. The linear range of the aptasensor is 0.1 pg mL−1–100 ng mL−1, and the detection limit is 0.019 pg mL−1, which shows excellent selectivity, reproducibility and stability. Finally, the aptasensor was applied to detect CEA in serum. [ABSTRACT FROM AUTHOR]

Digital PCR is a powerful method for absolute nucleic acid quantification and is widely used in the absolute quantification of viral copy numbers, tumor marker detection, and prenatal diagnosis. However, for most of the existing droplet-based dPCR systems, the droplet generation, PCR reaction, and droplet detection are performed separately using different instruments. Making digital PCR both easy to use and practical by integrating the qPCR workflow into a superior all-in-one walkaway solution is one of the core ideas. A new innovative and integrated digital droplet PCR platform was developed that utilizes cutting-edge microfluidics to integrate dPCR workflows onto a single consumable chip. This makes previously complex workflows fast and simple; the whole process of droplet generation, PCR amplification, and droplet detection is completed on one chip, which meets the clinical requirement of "sample in, result out". It provides high multiplexing capabilities and strong sensitivity while all measurements were within the 95% confidence interval. This study is the first validation of the DropXpert S6 system and focuses primarily on verifying its reliability, repeatability, and consistency. In addition, the accuracy, detection limit, linearity, and precision of the system were evaluated after sample collection. Among them, the accuracy assessment by calculating the absolute bias of each target gene yielded a range from -0.1 to 0.08, all within ±0.5 logarithmic orders of magnitude; the LOB for the assay was set at 0, and the LoD value calculated using probit curves is MR4.7 (0.002%); the linearity evaluation showed that the R2 value of the BCR-ABL was 0.9996, and the R2 value of the ABL metrics calculated using the ERM standard was 0.9999; and the precision evaluation showed that all samples had a CV of less than 4% for intra-day, inter-day, and interinstrument variation. The CV of inter-batch variation was less than 7%. The total CV was less than 5%. The results of the study demonstrate that dd-PCR can be applied to molecular detection and the clinical evaluation of CML patients and provide more precise personal treatment guidance, and its reproducibility predicts the future development of a wide range of clinical applications. [ABSTRACT FROM AUTHOR]

In this work, a new d10-configuration based Cd(II) coordination polymer (CP) with the formula [Cd2(CH3COO)2(bimb)2]·2ClO4 (1) have been synthesized using 4,4′-bis(imidazolyl)biphenyl (bimb) ligand and characterized. Single-crystal X-ray analysis reveals that the CP forms a 2D layer connected to a 3D supramolecular framework with weak packing interactions between benzyl and imidazolyl rings. CP 1 has been used as a photoluminescent sensor and a photocatalyst for the photodegradation of antibiotics, in particular nitrofurantoin (NFT). Sensing experiments indicate that 1 can selectively detect nitrofurantoin with a limit of detection of 0.025 μM, whereas when employed as a photocatalyst, CP 1 can photodecompose NFT up to 91.83% in a time span of 20 min. The decline in the photoluminescence intensity of CP 1 in the presence of NFT and the photocatalytic mechanism are addressed using theoretical calculations. [ABSTRACT FROM AUTHOR]

Visually colorimetric sensing of hazardous metallic ions based on gold nanoparticles (AuNPs) has been considered a facile, on-site, and reliable monitoring route, yet the improvement of detection limit, as well as environmental pH tolerance, is still needed. Herein, we present an integrated probe design based on functionalizing AuNP cores with carbon quantum dots (CQD) as colorimetric probes for tracing Cu2+ ions with a limit of detection as low as 18.7 nM. Improved detection selectivity was elucidated with the reduction in thiol groups bound between CQD decorations and AuNP probes initiated by oxidation of Cu2+ ion analytes, thus separating crossly connected probes, depending on tracing Cu2+ concentrations. Moreover, distributed CQDs with negative potentials allowed the stabilization of dispersed AuNPs against re-aggregation, which caused the gradual morphological transition from aggregated features to dispersed states in microscopic view, and eventually, reflected the gradual color change from red to purple-red. The correlated practicality of colorimetric detection of the Cu2+ ion was further validated with sound-sensing selectivity, environmental pH resistance and tests on real samples. [ABSTRACT FROM AUTHOR]

The effective assembly of hollow nanomaterials is of great importance for the rapid advancement of electroanalytical platforms. Herein, the hollow tubular zeolite imidazolium framework-8 (HTZIF-8) was carefully constructed via the precursor conversion pathway. Subsequently, the predictable assembly of HTZIF-8 with carbon nanotubes (CNTs) occurred to form a unique hollow dual-tube MOF hybrid material (HTZIF-8@CNTs). Meanwhile, the HTZIF-8@CNTs electroanalytical platform was established with dopamine (DA) as the objective biomolecule. In the electrochemical evaluation, the linear intervals of 0.06–600 μmol L−1 and detection limit of 0.02 μmol L−1 (S/N = 3) were determined, which were mainly ascribed to nano-synergistic engineering of HTZIF-8 and CNTs. The HTZIF-8@CNTs hybrid material exhibited superior electrocatalytic performance for DA compared to the solid rod-like MOF composite (SRZIF-8@CNTs), which was majorly based on the faster mass transfer characteristics of hollow MOFs. Additionally, the HTZIF-8@CNTs electrochemical sensor presented outstanding anti-interference capabilities as well as stability and could be utilized for the detection of DA in real samples. The employment of F and t statistics were employed to ensure the reliability of the results. This study will offer novel thoughts toward the application of hollow MOF composites in the area of electroanalytical platforms. [ABSTRACT FROM AUTHOR]

The development of a facile and reliable assay for arsenic (As) detection is crucial for its pollution control, which is a well-known heavy-metal pollutant in the environment. In this work, an efficient colorimetric method was established for As(V) detection based on a novel cuboid-shape Mn-Urea nanozyme (UMnzyme) with arsenic-enhanced oxidase-like activity. The UMnzyme was prepared through the coordination of Mn ions and carbonyl groups in urea, which possesses outstanding oxidase-like activity that can generate the superoxide anion free radical (O2˙−) by catalyzing the dissolved O2, triggering the 3,3′,5,5′-tetramethylbenzidine (TMB) chromogenic reaction. Furthermore, the free oxygen atoms in UMnzyme provide potential sites to bind with As, in which the formation of As–O will not destroy the morphology and structure of UMnzyme. The capture of As by UMnzyme results in the improvement of its oxidase-like activity; therefore, a colorimetric method for As(V) detection was developed with a linear range of 12.5–250 μg L−1. The limit of detection was determined to be 2.4 μg L−1 (S/N = 3), which is lower than the threshold (10 ppb) recommended by the World Health Organization. Moreover, the developed method was applied in the detection of As(V) in environmental water, and the recoveries are 89.5–103.6%. In short, this study provides an efficient and reliable strategy for As(V) detection based on a novel Mn-based nanozyme and a new idea for the reasonable design of Mn-based nanozymes with enhanced catalytic performance. [ABSTRACT FROM AUTHOR]

Herein, we introduce a novel method for tryptophan detection via a reduction reaction facilitated by its interaction with a copper(II) phthalocyanine (CuPc) electrocatalytic electrode. This method addresses challenges associated with the susceptibility of the oxidation response to interference from various species when measuring tryptophan in bodily fluids. The reduction currents exhibit a linear increase with tryptophan concentrations in two ranges: 0.0013–0.10 mM and 0.10–1.20 mM, with the sensitivities of 14.7 ± 0.5 μA mM−1 and 3.5 ± 0.1 μA mM−1, respectively. The limit of detection (LOD, 3SB/m) is determined to be 0.39 μM. The sensor exhibits excellent reproducibility, with the relative standard deviation of <5%. Application of the sensor to authentic urine samples yields a % recovery of 101 ± 4%. [ABSTRACT FROM AUTHOR]

Tumor necrosis factor-alpha (TNF-α) serves as a crucial biomarker in various diseases, necessitating sensitive detection methodologies. This study introduces an innovative approach utilizing an aptamer-functionalized surface plasmon resonance (SPR) substrate together with an ultrasensitive measure, the Goos–Hänchen (GH) shift, to achieve sensitive detection of TNF-α. The developed GH-aptasensing platform has shown a commendable figure-of-merit of 1.5 × 104 μm per RIU, showcasing a maximum detectable lateral position shift of 184.7 ± 1.2 μm, as characterized by the glycerol measurement. Employing aptamers as the recognition unit, the system exhibits remarkable biomolecule detection capabilities, including the experimentally obtained detection limit of 1 aM for the model protein bovine serum albumin (BSA), spanning wide dynamic ranges. Furthermore, the system successfully detects TNF-α, a small cytokine, with an experimental detection limit of 1 fM, comparable to conventional SPR immunoassays. This achievement represents one of the lowest experimentally derived detection limits for cytokines in aptamer-based SPR sensing. Additionally, the application of the GH shift marks a ground breaking advancement in aptamer-based biosensing, holding significant promise for pushing detection limits further, especially for small cytokine targets. [ABSTRACT FROM AUTHOR]

Dissolved lead is a serious but common health hazard in drinking water, yet there is still no practical way to monitor its levels continuously in the distribution system or at the point of use. Here we propose using a lead-selective membrane on top of a chemiresistive device to continuously measure Pb2+ ion concentrations in real time. The detection limit was lowered by stabilizing the surface of the resistive film with sodium hydroxide and 15-crown-5 ether and optimizing the sensor geometry to maximize the effective surface area. The detection mechanism is based on the complexation of the Pb2+ ions by the lead ionophores within the membrane, thus modulating the interactions between the ionophores and the chemiresistive film. The limit of detection of the fabricated devices was reliably below 2 μg L−1, with concentrations up to 3 mg L−1 routinely quantifiable over several measurement cycles. The chemiresistive sensors can thus achieve lower detection limits than potentiometric devices while being more robust and simpler to fabricate by omitting the reference electrode. Ion-selective membrane-covered chemiresistors can therefore be deployed to continuously monitor drinking water sources and detect harmful levels of lead in real time. [ABSTRACT FROM AUTHOR]

A new strategy for doping selenium and phosphide in hollow N-doped carbon nanobox (N-CNB)-based porous electrospun N-doped carbon nanofibers (CNFs) was developed. First, lightweight N-CNBs were produced. Then, a hybrid of N-CNBs and CNFs (CNBs/CNFs) was prepared using electrospinning/carbonization techniques. Eventually, P and Se atoms were doped into CNBs/CNFs using a thermal treatment approach to prepare Se/P@CNBs/CNFs. The electrocatalytic capability of the Se/P@CNBs/CNFs composite toward H2O2 oxidation was investigated for H2O2 sensing, which showed performance in a linear range from 200 μM to 1800 μM with a high sensitivity of 171 μA mM−1 cm−2 and a limit of detection (LOD) of 58 μM (S/N = 3). In addition, the ability of Se/P@CNBs/CNFs toward H2O2 sensing in human serum was studied. These results indicated the excellent electrocatalytic performance of the as-prepared Se/P@CNBs/CNFs, which could be related to the unique hollow CNBs/CNFs doped with P and Se elements with a mesoporous structure, the open channels for effective H2O2 diffusion, fast mass/electron transport, and synergistic effect between the P and Se and CNBs/CNFs. [ABSTRACT FROM AUTHOR]

Coordination polymers (CPs) with a d10-configuration containing metal cations offer interesting photoluminescent properties and hence can be employed as sensors to detect various classes of analytes. Moreover, due to their tuneable pore size they can be employed as adsorbents for various species. Herein, a new d10-configuration Cd(II)-based CP with composition {[Cd(bip)4(H2O)2]n·2NO3} (1) (bip = 3,5-bis(1-imidazol)pyridine) has been synthesized and characterized. Single-crystal X-ray analysis reveals that the Cd(II) center adopts octahedral geometry that is satisfied by four N atoms from the four bip linkers and two aqua ligands, and the resultant CP displays sql topology with the point symbol of (44·62). The CP offers prospective application as a photoluminescent sensor for dichromate anions with a limit of detection of 1.28 ppm and a Stern–Volmer constant (KSV) of 1.51 × 105. Furthermore, CP 1 was employed as an efficient adsorbent for dichromate ions, reaching an equilibrium adsorption capacity of 389.82 mg g−1 within 80 min. The effects of temperature, pH and concentration of dichromate were further investigated, which revealed that CP 1 displays the best adsorption at 30 °C and pH 4 with a dichromate concentration of 200 mg L−1. The possible adsorption mechanism has been proposed with the aid of Hirshfeld surface analysis. [ABSTRACT FROM AUTHOR]

Detection of pathogens is one of the key concerns for hospitals, the food industry, water suppliers, or other environmental engineering practices because pathogens can cause a wide range of infectious risks. Staphylococcus aureus (S. aureus) is one of the most common pathogens that are hazardous to human health and its existence is an important index to the safety of food, environmental sanitation, or medical products. In this study, we prepared an electrode with designed surface multilevel 3D micro/nano protrusions for facile and efficient S. aureus detection. The existence of these multilevel protrusions enhanced the adsorption of S. aureus. Hence, the detection limit could be as low as 10 CFU mL−1. Furthermore, the electrode was also successfully used to detect S. aureus in actual samples, such as milk and artificial human tissue fluid. It was found that the recovery of the reported approach showed no significant difference from that of the traditional plate count method. However, compared with the plate count method, the detection process of our approach is much more time-saving and easy-operating. These advantages of the approach we report, such as high sensitivity, reliability, quickness, and user-friendliness, make it a potential platform for detecting S. aureus in relation to the food industry and clinical diagnosis. [ABSTRACT FROM AUTHOR]