Sample Recovery Research Articles

Green electrochemical sensor based on ZnO@α-Fe2O3 NPs modified carbon paste electrode for sensitive voltammetric determination of the FDA-approved Anti-COVID-19 medication baricitinib

In this study, we developed an electrochemical sensor for the sensitive voltammetric determination of Baricitinib (BCT), a recently FDA-approved medication for curing COVID-19. Voltammetric measurements were employed using a carbon paste electrode modified with zinc oxide and iron oxide nanoparticles (ZnO/α-Fe2O3-NPs/CPE). The composition of the fabricated electrode was optimized, and the best sensitivity was achieved by utilizing 5% of ZnO/α-Fe2O3-NPs, which maximized the electroactive surface area. The final optimized electrode was electrochemically and physicochemically characterized by exploiting the following techniques: X-ray diffraction (XRD) patterns, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), and X-ray photoelectron spectroscopy (XPS). All experimental parameters, including the pH and scan rate, have been studied and optimized. The proposed sensor was successfully employed for BCT analysis by square wave voltammetry (SWV), and the attained linear dynamic range was (8.0 × 10−8 – 1.0 × 10−6 mol L−1), and the estimated limit of detection (LOD) and limit of quantitation (LOQ) were 1.799 × 10−8 mol L−1 and 5.453 × 10−8 mol L−1, respectively. The suggested electrochemical methodology was effectively utilized to determine BCT with satisfactory percentage recoveries in pharmaceutical preparation (99.69% ± 0.73) and human plasma samples. The developed approach underwent validation and was determined to be reproducible (RSD = 0.75%) and accurate (99.68% ± 0.76) following the ICH recommendations. The greenness of the established electrochemical protocol was assessed utilizing the Analytical Eco-Scale and Analytical GREEnness Metric Approach (AGREE).

Location and function of TDP-43 in platelets, alterations in neurodegenerative diseases and arising considerations for current plasma biobank protocols

The TAR DNA Binding Protein 43 (TDP-43) has been implicated in the pathogenesis of human neurodegenerative diseases and exhibits hallmark neuropathology in amyotrophic lateral sclerosis (ALS). Here, we explore its tractability as a plasma biomarker of disease and describe its localization and possible functions in the cytosol of platelets. Novel TDP-43 immunoassays were developed on three different technical platforms and qualified for specificity, signal-to-noise ratio, detection range, variation, spike recovery and dilution linearity in human plasma samples. Surprisingly, implementation of these assays demonstrated that biobank-archived plasma samples yielded considerable heterogeneity in TDP-43 levels. Importantly, subsequent investigation attributed these differences to variable platelet recovery. Fractionations of fresh blood revealed that ≥ 95% of the TDP-43 in platelet-containing plasma was compartmentalized within the platelet cytosol. We reasoned that this highly concentrated source of TDP-43 comprised an interesting substrate for biochemical analyses. Additional characterization of platelets revealed the presence of the disease-associated phosphoserine 409/410 TDP-43 proteoform and many neuron- and astrocyte-expressed TDP-43 mRNA targets. Considering these striking similarities, we propose that TDP-43 may serve analogous functional roles in platelets and synapses, and that the study of platelet TDP-43 might provide a window into disease-related TDP-43 dyshomeostasis in the central nervous system.

Chemiluminescence detection of kanamycin by DNA aptamer regulating peroxidase-like activity of Co3O4 nanoparticles.

Kanamycin (KAN) is widely used as a growth hormone analog and an antibacterial agent. However, abuse of this substance has resulted in the accumulation of excessive residue levels in foods of animal origin, which presents a significant risk to human health. A chemiluminescent aptasensor was constructed for the rapid quantitative detection of KAN by combining the properties of Co3O4 nanoparticles (Co3O4 NPs) nanozyme activity and DNA aptamer with high specificity. The DNA aptamer/Co3O4 NPs nanozyme regulated the chemiluminescence signal by exploiting the chemiluminescent properties of luminol oxidation by H2O2. Specific binding of KAN to the aptamer led to the formation of a steric hindrance block in the solution, which inhibited the activity of nanozyme and reduced signal intensity. The degree of signal reduction is related to the concentration of KAN. Under optimal conditions, there was good linearity between KAN concentration and chemiluminescence signal intensity in the range of 0.5-8.0 μΜ, with a detection limit of 0.26 μΜ. The detection system performed well in the presence of competing antibiotics and was virtually unaffected. The method was also suitable for the detection of KAN in milk samples with sample recoveries of 97.8%-99.1%. The chemiluminescence sensor has the advantages of low cost, specificity, and sensitivity, and does not require an external light source or modification of the nucleic acid aptamer which makes it a promising candidate for applications in the field of food detection.

The Role of Addiction Treatment in Building Recovery Capital: Findings From 2022 Life in Recovery Survey in Flanders, Belgium

Introduction: This paper examines life experiences before and during addiction recovery in a large sample of treated and untreated persons in Flanders (Belgium). Methods: A total of 343 participants in recovery from alcohol and/or illicit drug problems (≥3 months) completed the 2022 ‘Life in Recovery’ survey online. Participants were categorized into four groups based on their engagement with treatment services: (1) unassisted recovery, (2) mutual aid support only, (3) formal treatment only, and (4) formal treatment and mutual aid support. The questionnaire was supplemented with open-ended questions about facilitators and barriers to recovery. Findings: Group comparisons revealed significant differences in the severity of dependence and living conditions (recovery strengths and barriers, SABRS) during addiction between those in recovery without treatment and the treatment groups. However, similarities in strengths, barriers, and quality of life during recovery were observed across all groups. Differences in barriers during recovery were attributed to variations in initial conditions rather than treatment engagement. The complementary qualitative analysis revealed that the four clusters experienced similar factors as facilitating and hindering recovery. Discussion: These findings suggest that while various pathways can lead to recovery, those involving formal treatment and mutual aid support may be particularly valuable for individuals facing greater initial barriers and fewer strengths during addiction, highlighting treatment as an important but not universally necessary source of recovery capital.

Surface-Initiated Reversible Addition-Fragmentation Chain Transfer Polymerization (SI-RAFT) to Produce Molecularly Imprinted Polymers on Graphene Oxide for Electrochemical Sensing of Methylparathion.

A nonenzymatic redox-responsive sensor was put forward for the detection of methylparathion (MP) by designing globular nanostructures of molecularly imprinted polymers on graphene oxide (GO@MIPs) via surface-initiated reversible addition-fragmentation chain transfer polymerization (SI-RAFT). Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), and small-angle X-ray scattering (SAXS) studies have confirmed the successful formation of receptor layers of MIPs on RAFT agent-functionalized GO sheets. The electrochemical signal with an amplified current response was attained because of the enhanced diffusion rate of ions at the interface provided by widening the pore size of the MIP film. The analytical response of GO@MIPs, validated by recording square-wave anodic stripping voltammetry (SWASV) at varying MP concentrations, followed the linear response between 0.2 and 200 ng/mL. Under optimized conditions, the sensor exhibited a limit of detection of 4.25 ng/mL with high selectivity over other interfering ions or molecules. The anti-interfering ability and good recovery (%) in food samples directed the use of the proposed sensor toward real-time monitoring and also toward future mimicking of surfaces.

Rhodamine-benzothiazole-thiophene: A triangular molecular tool for simultaneous detection of Hg2+ and Cu2+

A novel rhodamine-benzothiazole fluorescent chemosensor, bridged with a thiophene unit, is designed for the turn-on detection of Hg2+ and Cu2+. Noteworthy findings include impressively low limits of detection (0.007 μM for Hg2+ and 0.013 μM for Cu2+), a determined sensing mechanism involving spirolactam ring opening and hydrolytic cleavage, consistent 1:1 binding stoichiometry for both metal ions and an optimal pH of around 6. The sensor’s practical applicability is demonstrated through successful implementation in HeLa cells and zebrafish, along with effective analyte recovery in various water samples. This work advances the field by providing a highly sensitive and versatile chemosensor for environmental and biological applications.

Visual fluorescence detection of Listeria monocytogenes with CRISPR-Cas12a aptasensor.

Listeria monocytogenes (L. monocytogenes) is a prevalent food-borne pathogen that can cause listeriosis, which manifests as meningitis and other symptoms, potentially leading to fatal outcomes in severe cases. In this study, we developed an aptasensor utilizing carboxylated magnetic beads and Cas12a to detect L. monocytogenes. In the absence of L. monocytogenes, the aptamer maintains its spatial configuration, keeping the double-stranded DNA attached and preventing the release of a startup template and activation of Cas12a's trans-cleavage capability. Conversely, in the presence of L. monocytogenes, the aptamer undergoes a conformational change, releasing the double-stranded DNA to serve as a startup template, thereby activating the trans-cleavage capability of Cas12a. Consequently, as the concentration of L. monocytogenes increases, the observable brightness in a blue light gel cutter intensifies, leading to a rise in fluorescence intensity difference compared to the control. This Cas12a aptasensor demonstrates excellent sensitivity towards L. monocytogenes, with a lowest detection limit (LOD) of 57.15CFU/mL and a linear range of 4×102 to 4×107 CFU/mL (R2=0.9858). Notably, the proposed Cas12a aptasensor exhibited outstanding selectivity and recovery in beef samples, and could be employed for precise monitoring. This Cas12a aptasensor not only provides a novel fluorescent and visual rapid detection method for L. monocytogenes but also offers simplicity, speed, and stability compared to previous detection methods. Furthermore, it is suitable for on-site detection of beef samples.

Lessons learned from a one-year study of Legionella spp. cultivation from activated sludge samples

Risk assessment and management of Legionella spp. contamination in activated sludge in wastewater treatment plants is carried out using the culture method. Underestimation of Legionella spp. is frequently reported in the literature, but a comprehensive long-term study of the performance of the method under comparable conditions is still lacking. The aim of this study is to evaluate the recovery rate and limit of detection of the culture method for Legionella spp. from activated sludge samples collected during the different seasons of the year. Activated sludge samples spiked with Legionella pneumophila subsp. pneumophila strain Philadelphia-1 (mean concentration 5.2 ± 0.35 logCFU/mL) were analysed monthly for one year using the culture method. Three different sample pre-treatments were compared, namely filtration, acid treatment and thermal treatment, and the recovery rate and limit of detection were assessed for each. The recovery rate of the culture method for Legionella spp. depended on the type of sample pre-treatment and the season of activated sludge sampling, while the limit of detection depended only on the sample pre-treatment. The best performance of the culture method, defined as the combination of the highest recovery rate and lowest limit of detection, was obtained for the filtered acid pre-treated samples (recovery rate: 89 ± 4 %; limit of detection: 1.3 logCFU/mL in 83 % of the samples). The lowest limit of detection was observed for the filtered thermally pre-treated samples (1.0 logCFU/mL in 93 % of the samples). Simultaneously, both thermally pre-treated samples showed up to a third lower recovery rates than the other pre-treatments in winter, while untreated and acid pre-treated samples showed consistently high recovery rates (>80%, logCFU/mL). The recovery rates of the unfiltered and filtered thermally pre-treated samples showed significant weak to strong positive correlations with the organic and phosphorus load in the influent as well as with the water and atmospheric temperatures, indicating that the recovery rate depends on the seasonal variation of the wastewater composition. This study presents new insights into the detection and quantification of Legionella spp. in activated sludge samples and considers seasonal dependencies in analytical results.

Guide DNA dephosphorylation-modulated Pyrococcus furiosus Argonaute fluorescence biosensor for the detection of alkaline phosphatase and aflatoxins B1

Foodborne hazardous factors pose a significant risk to public health, emphasizing the need for the development of sensitive and user-friendly detection strategies to effectively manage and control these risks in the food supply chain. Pyrococcus furiosus argonaute (PfAgo)-based biosensing approaches have been extensively explored due to its built-in signal amplification. However, the property that PfAgo is a DNA-guided DNA endonuclease has enabled almost all the existing PfAgo-based reports to be used for the detection of nucleic acids. To lend PfAgo toolbox to extended non-nucleic acid detection, we systematically investigated the mechanism characteristic of PfAgo′ preference for guide DNA (gDNA) and proposed a gDNA dephosphorylation-modulated PfAgo sensor for the detection of non-nucleic acid targets. Our results indicated that PfAgo exhibits preference for 5′-phosphorylated gDNA at a specific ratio of PfAgo to gDNA concentration. Leveraging this PfAgo′ preference and the dephosphorylation activity of alkaline phosphatase (ALP), ALP could be detected as low as 2.7 U/L. Furthermore, the PfAgo was coupled with immunolabelled ALP to develop a PfAgo-based fluorescence immunosensor, which achieves aflatoxins B1 detection with a detection limit of 29.89 pg/mL and exhibits satisfactory recoveries in wheat and maize samples. The developed method broadens the application scope of PfAgo toolbox, and provides a simple, sensitive, and universal detection platform for a variety targets.

Centrifugated lateral flow assay strips based on dual-emission carbon dots modified with europium ions for ratiometric determination and on-site discrimination of tetracyclines in environment

Due to the serious detrimental impact on human health, antibiotic pollution particularly tetracyclines residues has become a serious problem. Herein, a multiple response fluorescent probe consisted of dual-emission carbon dots and Eu3+ (D-CDs@Eu3+) is designed for the determination and discrimination of tetracyclines (TCs). Specifically, the carboxyl and amidogen group of dual-emission carbon dots (D-CDs) can coordinate with Eu3+ to form the D-CDs@Eu3+. Upon adding TCs, the fluorescence intensities of D-CDs at 405 nm and 495 nm are quenched due to inner filter effect (IFE) and the localization of fluorescence resonance energy transfer (L-FRET) between the D-CDs@Eu3+ and TC. Simultaneously, the D-CDs@Eu3+ may chelate with TCs to enhance the occurrence of antenna effect, while the characteristic peaks of Eu3+ at 590 nm and 615 nm are enhanced. On these bases, the TCs detection is achieved with low detection limits from 46.7 to 72.0 nM. Additionally, through the distinct efficiencies of L-FRET, the discrimination of TCs is achieved. Moreover, a novel centrifugated lateral flow assay strips (CLFASs) device is developed by integrating the D-CDs@Eu3+, lateral flow assay strips and smartphone using RGB variations for TCs detection, achieving remarkable recoveries (98.6–103.7 %) in real samples. Therefore, this CLFASs device provides a reliable approach for the TCs detection, demonstrating potential applications.

Coupling Microdroplet-Based Sample Preparation, Multiplexed Isobaric Labeling, and Nanoflow Peptide Fractionation for Deep Proteome Profiling of the Tissue Microenvironment.

There is increasing interest in developing in-depth proteomic approaches for mapping tissue heterogeneity in a cell-type-specific manner to better understand and predict the function of complex biological systems such as human organs. Existing spatially resolved proteomics technologies cannot provide deep proteome coverage due to limited sensitivity and poor sample recovery. Herein, we seamlessly combined laser capture microdissection with a low-volume sample processing technology that includes a microfluidic device named microPOTS (microdroplet processing in one pot for trace samples), multiplexed isobaric labeling, and a nanoflow peptide fractionation approach. The integrated workflow allowed us to maximize proteome coverage of laser-isolated tissue samples containing nanogram levels of proteins. We demonstrated that the deep spatial proteomics platform can quantify more than 5000 unique proteins from a small-sized human pancreatic tissue pixel (∼60,000 μm2) and differentiate unique protein abundance patterns in pancreas. Furthermore, the use of the microPOTS chip eliminated the requirement for advanced microfabrication capabilities and specialized nanoliter liquid handling equipment, making it more accessible to proteomic laboratories.

A highly sensitive dual-mode lateral flow immunoassay based on plasmonic hollow Ag/Au nanostars enhancing light absorption

The conventional lateral flow immunoassay (LFIA) based on gold nanoparticles (Au NPs) is limited by low sensitivity due to the insufficient brightness of Au NPs. To address this problem, noble metal nanomaterials with localized surface plasmon resonance (LSPR) and synthetic tunability are potential signal outputs for LFIA, which can achieve better optical properties by adjusting the preparation conditions. Herein, this study prepared the hollow silver/gold nano-stars (HAg/Au NSts) as LFIA signal output via the galvanic replacement method. HAg/Au NSts with anisotropic hollow alloy nanostructures exhibit a wide visible light absorption band and great NIR thermal conversion efficiency (η = 37.32 %), which endows them with enhanced colorimetric and photothermal signals. Further, we constructed a colorimetric-photothermal (CM-PT) dual-signal HAg/Au NSts-LFIA and chose staphylococcal enterotoxin B as the target analyte. The linear range of HAg/Au NSts-LFIA is 0.19–100 ng mL−1, and the limit of detection (LOD) is up to 0.29 ng mL−1 and 0.09 ng mL−1 in the colorimetric and photothermal modes respectively. Compared with the conventional Au NPs-LFIA, HAg/Au NSts-CM/PT-LFIA effectively improved the detection performance of LFIA. In addition, HAg/Au NSts-LFIA also showed satisfactory sensitivity (vLOD = 0.78 ng mL−1) and recovery (89.06–114.74 %) in milk and pork samples. Therefore, this work provides a new shape design idea for noble metal nanomaterials in biosensor applications.

A high-throughput, turbulent-mixing, condensation aerosol concentrator for direct aerosol collection as a liquid suspension

Trace measurement of aerosol chemical composition in workplace atmospheres requires the development of high-throughput aerosol collectors that are compact, hand-portable, and can be operated using personal pumps. We describe the design and characterization of a compact, high flow, Turbulent-mixing Condensation Aerosol-in-Liquid Concentrator (TCALC) that allows direct collection of aerosols as liquid suspensions, for off-line chemical, biological, or microscopy analysis. The TCALC unit, measuring approximately 12 × 16 × 18 cm, operates at an aerosol sample flowrate of up to 10 L min−1, using rapid mixing of a hot flow saturated with water vapor and a cold aerosol sample flow, thereby promoting condensational growth of aerosol particles. We investigated the effect of operating parameters such as vapor temperature, growth tube wall temperature, and aerosol sample flowrate, along with the effect of particle diameter, inlet humidity, aerosol concentration, and operation time on TCALC performance. Nanoparticles with an initial aerodynamic diameter ≥25 nm could grow to droplet diameters >1400 nm with an efficiency ≥80%. Good droplet growth efficiency was achieved for sampled aerosol relative humidity ≥9%. We measured complete aerosol collection for concentrations of ≤3 × 105 cm−3. The results showed good agreement between the particulate mass collected through the liquid collector and direct filter collection. The TCALC eliminates the need for sample preparation and filter digestion during chemical analysis, thereby increasing sample recovery and substantially improving the limit of detection and sensitivity of off-line trace analysis of collected liquid samples.

Construction of PCN-222@PCN-134 as sorbent of dispersive solid-phase extraction for extraction and enrichment of sulphonamides

A MOF-on-MOF composite (PCN-222@PCN-134) was synthesized by seed epitaxial growth method and applied as sorbent to extract sulfonamides (SAs) in different sample matrices. Using PCN-222@PCN-134 as sorbent, a dispersive solid-phase extraction was developed to clean-up and preconcentration of SAs prior to HPLC-DAD analysis. The linear range of the method are achieved between 0.1 and 200 ng/mL, and the limits of detection are in the range of 0.03–0.27 ng/mL. Comparison with pristine MOFs, the performance of PCN-222@PCN-134 composite is significantly improved. The enrichment factors are obtained in the range of 254–333. The adsorption kinetics and adsorption isotherms are in accordance with pseudo-second-order and Langmuir models, respectively. The spiked recovery of real samples including egg and urine are between 76.4 and 120.1 % with relative standard deviation not higher than 12.1 %. After 14 times of use, the recovery rate of sorbent to SAs is still above 80 %. This work demonstrates that PCN-222@PCN-134 possesses excellent extraction performance to SAs, which can be used to clean-up and preconcentration of trace SAs in different sample matrices, such as egg and urine.

Synthesis and properties of a visual fluorescence-enhanced HClO/ClO- probe

Hypochlorite ion (ClO-/HClO) is a reactive oxygen species that plays a vital role in biological systems and daily life. The accurate detection of ClO- is critical for disease prevention and environmental monitoring. Therefore, it is necessary to develop highly sensitive probes. In this study, we report a visual fluorescence-enhanced HClO/ClO- probe CN-TPE-PEG1900, which was obtained by grafting poly (ethylene glycol) monomethyl ether 1900 with tetraphenylethylene (TPE) as the fluorescent parent. The fluorescence intensity of a solution containing CH3OH/H2O (30 μM, v/v, 1/4, PBS, pH = 7.4) and the probe CN-TPE-PEG1900 was increased by 9 times at 525 nm due to the presence of ClO-. The color of the probe CN-TPE-PEG1900 solution changed from yellow to colorless after reaction with ClO-. The limit of detection (LOD) of the probe CN-TPE-PEG1900 was 5.48 × 10–8 mol/L. In addition, it had a high fluorescence quantum yield of 51.27 %, a large Stokes shift of 165 nm, good water solubility, and high water sample recovery rates. The calculated data, 1H NMR, mass spectrometry, DLS, and SEM results were combined to deduce the recognition mechanism of the probe CN-TPE-PEG1900 for ClO-. Thus, the presence of ClO- facilitated the cleavage of the double bond in CN-TPE-PEG1900, thereby separating the water-soluble poly (ethylene glycol) chain from TPE through oxidative cleavage. Moreover, this led to the formation of TPE-CHO, which was less water-soluble and more prone to aggregation, resulting in fluorescence enhancement at 525 nm. Meanwhile, the process also caused a blue shift in the emission wavelength and a change in the color of the probe solution.

Integrating colorimetry with surface sensitive transducers: Advancing molecular diagnostics in biofluids

Colorimetric sensors are preferred for visually detecting target analytes, but achieving ultra-low detection capabilities for food analysis, environmental samples, and molecular diagnostics is challenging. In this study, we interfaced a purpald-based formaldehyde color sensor (as a model probe reaction) with a surface plasmon gold microarray imaging chip. Such hyphenated surface-sensitive signal-amplifying techniques enabled ultra-low detection in biofluids with a linear range of 10−5 – 0.5 ppm compared to the spectrophotometric narrower linear range of 0.01–1 ppm. The detection limit of 86×10−6 ppm from the hyphenated sensing is 140-fold lower than the detection limit from the spectrophotometric method alone (12×10−3 ppm). The absorbance maximum of the purpald-formaldehyde adduct was 553 nm, with no notable tail overlap between the adduct absorbance band beyond 700 nm and the fixed angle source incident wavelength of 800 nm from the surface plasmon instrument. Hence, the possible adduct thiol-surface plasmon gold surface interaction, affinity, and the higher mass and refractive index changes of the adduct are likely causes of the observed signal amplification. We achieved a formaldehyde sample recovery of 92 % from a diluted serum (a minimally invasive assay method), which was comparable to the results in a buffer solution. Further, we extended to demonstrate in diluted urine sample matrices to be noninvasive bioanalysis and determined the interference from urea that could also form a purpald adduct like formaldehyde. In conclusion, coupling a surface-sensitive transducer with less sensitive colorimetric reactions is promising for molecular diagnostics in real samples and can be broadly extended to any other desired molecular targets and sample matrices.

Fluorescent covalent organic framework as an ultrasensitive fluorescent probe for tyrosinase activity monitoring and inhibitor screening

BackgroundAs a significant biomarker of melanocytic lesions, tyrosinase (TYR) plays an essential role in the clinical diagnosis and treatment of melanin-related diseases. Thus, it is important to develop robust methods for assessing TYR activity. Covalent organic frameworks (COFs) have garnered considerable attention owing to their unique properties, including high chemical stability, good biocompatibility, and large surface area compared with organic dyes, noble metal nanoclusters, and semiconductor quantum dots. However, most COFs are insoluble in water and exhibit weak or no fluorescence emission. Therefore, the development of a water-soluble fluorescent COF for detecting TYR activity in biological samples remains highly desired. ResultsIn this work, a sensitive and facile fluorometric method based on fluorescent COF was constructed for the detection of TYR activity in human serum samples. The water-soluble COF was fabricated through the condensation polymerization of 4′,4‴,4′′′′′,4′′′′′′′-(1,2-ethene-diylidene) tetrakis [1,1′-biphenyl]-4-carboxaldehyde and 2,4,6-tris-(4-aminophenyl)-triazine. The resulting COF displayed yellow-green fluorescence with a maximum emission peak at 560 nm. Tyrosine was catalyzed by TYR to produce melanin-like polymers which formed a coating on the surface of COF and effectively quenched its fluorescence due to fluorescence resonance energy transfer. The proposed approach demonstrated a strong linear correlation in the range of 0.5–80 U/L with a low detection limit of 0.09 U/L. Additionally, the limit of detection for kojic acid, serving as a representative TYR inhibitor, was determined to be 0.0004 μg/mL. SignificanceOur proposed fluorometric sensing platform exhibited exceptional selectivity, sensitivity, and satisfactory recoveries in human serum samples, which is of paramount importance for the clinical diagnostics of melanin-related diseases. Furthermore, the proposed approach was further employed for the screening of TYR inhibitors, suggesting the potential applications in clinical treatment and pharmaceutical research.

Detection of foodborne methicillin-resistant Staphylococcus aureus via fluorescence-encoded microsphere and Argonaute-mediated decoding

Molecular diagnosis of foodborne methicillin-resistant Staphylococcus aureus (MRSA) is crucial for controlling its dissemination and ensuring food safety. However, existing genetic methods are limited by susceptibility to aerosol contamination and restricted to single-gene detection. Herein, a fluorescent biosensor employing fluorescence-encoded microspheres and Argonaute-mediated decoding is developed, enabling ultrasensitive, accurate, and duplex detection of MRSA genes. This assay utilizes a target-triggered polymerization/nicking reaction to cyclically produce specific guide DNA, guiding Argonaute protein to site-specifically cleave the molecular beacon on the microsphere, thereby decoding a fluorescent signal. Notably, the fluorescence-encoded microsphere, designed via on-tetrahedron rolling circle amplification, achieves high fluorescence loadings in a unit area. This biosensor demonstrates simultaneous detection of two unamplified MRSA genes, mecA and femA, at concentrations as low as 0.63 fM and 0.48 fM, respectively. Moreover, the method exhibited excellent recoveries in milk, egg, and pork samples ranging from 73% to 112%, highlighting its practicability in real scenarios.

A Zwitterionic Detergent and Catalyst-Based Single-Cell Proteomics Using a Loss-Free Microhole-Collection Disc.

Recent advances in single-cell proteomics have solved many bottlenecks, such as throughput, sample recovery, and scalability via nanoscale sample handling. In this study, we aimed for a sensitive mass spectrometry (MS) analysis capable of handling single cells with a conventional mass spectrometry workflow without additional equipment. We achieved seamless cell lysis and TMT labeling in a micro-HOLe Disc (microHOLD) by developing a mass-compatible single solution based on a zwitterionic detergent and a catalyst for single-cell lysis and tandem mass tag labeling without a heat incubation step. This method was developed to avoid peptide loss by surface adsorption and buffer or tube changes by collecting tandem mass tag-labeled peptide through microholes placed in the liquid chromatography injection vials in a single solution. We successfully applied the microHOLD single-cell proteomics method for the analysis of proteome reprogramming in hormone-sensitive prostate cells to develop castration-resistant prostate cancer cells. This novel single-cell proteomics method is not limited by cutting-edge nanovolume handling equipment and achieves high throughput and ultrasensitive proteomics analysis of limited samples, such as single cells.

Ionic liquid-functionalized covalent organic frameworks on the surface of silica for online solid-phase extraction

A covalent organic framework (COF) was gown on porous silica with 1,3,5-tri(4-aminophenyl)benzene and 2,5-divinyl-1,4-phenyldiformaldehyde as monomers, and two ionic liquids were grafted to COF by a click reaction. The materials before and after the modification of ionic liquids were separately packed into solid-phase extraction columns (10 × 4.6 mm, i.d.), which were coupled with liquid chromatography to construct online analysis systems. The extraction mechanisms of polycyclic aromatic hydrocarbons, bisphenols, diphenylalkanes and benzoic acids were investigated on these materials. There were π-π, hydrogen-bond and electrostatic interactions on ionic liquid-functionalized sorbents. After the comparison among these materials, the best sorbent was used, and the analytical method was established and successfully applied to the detection of some estrogens from actual samples. For the analytical method, the detection limit was as low as 0.005 μg L−1, linear range was as wide as 0.017–10.0 μg L−1, and enrichment ratio was as high as 3635. The recoveries in actual samples were 70 %-129 %.