Semi-quantitative Detection Research Articles

A Turn-On Fluorescence Probe Based on GSH-Protected Silver Nanoclusters for the Selective Detection of Pb2.

Glutathione-protected silver nanoclusters (GSH-AgNCs) with good photostability were successfully synthesized through a one-pot heating process. The resultant GSH-AgNCs with an average diameter of ~1.6 nm exhibit red fluorescence (λem = 650 nm), and the fluorescence is excitation independent. Strong aggregation-induced emission (AIE) effect was observed in GSH-AgNCs, which can be induced by solvent and metal ions. In particular, a specific fluorescence enhancement was detected upon interaction with lead ions (Pb2+). A fluorescent probe was designed for off-on detection of Pb2+ based on as-synthesized GSH-AgNCs. Under the optimum parameters, two linear response intervals were found between the relative fluorescence intensity and the concentration of Pb2+ in the range of 10-250 μM (R2 = 0.9900) and 400-1000 μM (R2 = 0.9930). Significant fluorescence color evolutions observed under UV light, resulting in a semiquantitative visual detection of Pb2+. A possible detection mechanism based on the interaction between GSH-AgNCs and Pb2+ is discussed.

3D-printing and MATLAB assisted ratiometric-sensing platform for visual on-site sensing of tetracycline using color conversion strategy

In this research, a ratiometric-sensing platform (ZIF-8/CDs) that combines non-fluorescence metal–organic frameworks (ZIF-8) with blue-green fluorescent carbon dots (CDs) has been developed for the determination of tetracycline (TC) with high sensitivity and selectivity in real samples. For this purpose, ZIF-8 with polyhedral structure was synthesized, which could form aggregation-induced emission (AIE) effect through electrostatic, hydrogen bonding, π-π stacking, and coordination interactions in the presence of TC, leading to enhanced intensity with a bright yellow fluorescence at 516 nm, acting as a response signal. However, the fluorescence intensity of blue-green fluorescent CDs maintained practically constant at 466 nm, serving as a reference signal. Furthermore, we integrate MATLAB algorithm and 3D-printing technology with the ZIF-8/CDs complex into a ratiometric-sensing platform for semi-quantitative detection of TC, in which 3D-printing technology is responsible for engineering an integrated dark chamber to achieve the fluorescence images of real samples, whereas MATLAB with the image processing functions and data processing capabilities utilizes to develop a mini program for calculating the RGB values of the obtained images. Consequently, the ratiometric-sensing platform in a simple, rapid, and economic way without any complicated process and expensive instruments could be used for visual/onsite detection of TC in real samples.

Rapid dual-modal detection of two types of pesticides in fruits using SERS-based immunoassay

Pesticide residue is a harmful chemical residue produced in agricultural production, posing a threat to human health. To detect mixed pesticide residues in food rapidly and simultaneously, we present a dual-channel dual-modal test strip immunoassay. According to the standard colorimetric bar, the naked-eye test can achieve semi-quantitative detection. By collecting the Raman spectra of the signal probes, surface-enhanced Raman scattering (SERS) detection can achieve accurate quantification of pesticide residues. Specifically, a double-layer 4-mercaptobenzoic acid (4-MBA) molecule-labeled bimetallic core-shell material (AuMBA@AgMBA) was conjugated with target antibodies to obtain signal probes. Here, antibody bonding was achieved by the dehydrated condensation of its amino group with the carboxyl group of the outer 4-MBA. In addition, the Au nanoparticles were connected to rabbit IgG by electrostatic adsorption as indicating probes to ensure the normal operation of the test strips. Under the optimal parameters, the detection ranges of acetamiprid and carbendazim were 0.3 - 2μg/kg and 3 - 30μg/kg, respectively. Furthermore, the recovery experiments showed that the results of the SERS method matched well with the high-performance liquid chromatography method. The SERS immunoassay is characterized by high sensitivity, rapidity and reliability, which has potential to simultaneously detect mixed pesticides in the field.

Research on infrared spectral characteristics and rapid detection technology of industrial hemp

Objective: The aim of this study was to research the infrared spectroscopic features of various industrial hemp samples, establish a rapid infrared detection method for industrial hemp based on cannabidiol (CBD) content, and utilize infrared spectroscopy to differentiate industrial hemp flowers and leaves from different varieties and origins. Methods: Appropriate preprocessing was conducted on the industrial hemp samples based on their inherent characteristics. The samples were then scanned using the FTIR spectrometer, with careful subtraction of the background spectrum. A semi-quantitative rapid detection method for flowers and leaves using infrared spectroscopy was developed through partial least squares discriminant analysis. Data processing software was used to conduct principal component analysis and cluster analysis on the transmittance values of infrared characteristic absorption peaks, aiding in the identification and differentiation of samples from different varieties, origins, and harvest dates. Results: A semi-quantitative rapid detection method for industrial hemp flowers and leaves based on CBD content was successfully developed. Principal component analysis was able to clearly distinguish industrial hemp of different varieties and origins, effectively clustering samples of the same variety. This underscores the significant impact of mid-infrared spectroscopy in the identification and analysis of industrial hemp, providing an innovative approach to quickly identifying different hemp varieties.

Rational integration of fluorogenic and quenching activity of dopamine for reversed ratiometric and semi-quantitative visual detection of tyramine

A facile and efficient reversed ratiometric fluorescence (RF) method has been developed for the sensitive and accurate detection of tyramine (Tyr), an essential marker for food spoilage in fermented or aged foods. This method utilizes an “activation-quenching integration” strategy involving the fluorogenic reactivity and quenching capacity of dopamine (DA), the tyrosinase (TYR) catalyzed products of Tyr. Under alkaline conditions, DA reacts with resorcinol to form azamonardine, exhibiting strong blue emission. Additionally, DA is oxidized to o-dopaquinone by TYR, which quenches the red fluorescence of CdTe quantum dots (QDs). Under optimized conditions, a Tyr-specific RF sensor was established, featuring a linear detection range from 0.1 to 6 mg/mL and a detection limit of 8.50 × 10−3 mg/L. The fabricated reversed RF sensing system was successfully applied for quantitative analysis of Tyr in real samples and semi-quantitative visual detection of Tyr in fermented food samples upon integration with a pseudo-color-assisted approach.

A graphene quantum dots based dual-modal fluorometric and visualized detection of copper ions

In this study, we present a dual-modal fluorometric and visualized detection method for Cu2+ ion, leveraging the synergistic properties of graphene quantum dots (GQDs) and Cu2+ ion catalyzed Fenton-like reaction. The Fenton-like reaction of Cu2+ ions and ascorbate generates highly reactive hydroxyl radical (·OH), which effectively disrupt the structure of GQDs, leading to fluorescence quenching. Under optimized conditions, the fluorescence quenching degree exhibited a linear correlation with Cu2+ concentration within the range of 40 to 2000 nM, enabling the detection of Cu2+ ions as low as 40 nM. Furthermore, we demonstrated the feasibility of semi-quantitative visual detection of Cu2+ ion concentrations in water using a portable ultraviolet instrument. The method achieved a minimum detectable concentration of Cu2+ ion as low as 10 μM, surpassing the maximum contaminant level goals of 20.47 μM set by the EPA and the guideline value of 31.47 μM recommended by the WHO. As such, this approach holds promise as a point-of-care testing (POCT) method for Cu2+ ion detection during copper pollution emergency events in water. Additionally, this method can be adapted for the detection of ascorbic acid. Our findings showcase the potential of this dual-modal detection approach, offering a sensitive, rapid, and efficient means for detecting Cu2+ ion, thereby contributing to environmental monitoring and public health applications.

Fabric-based visualization biosensor for real-time environmental monitoring and food safety

Foodborne and waterborne bacterial infections caused by Escherichia coli (E. coli) pose a serious threat to public health and safety. Therefore, there is an urgent need to develop a fast and accurate diagnostic device for early detection and prevention of bacterial contamination. In this study, we designed a visual cotton fabric-based detection biosensor that can target enzymes produced by E. coli metabolism and induce color changes. In addition, the system can be integrated with the naked eye, smartphones, and small spectrometers to analyze the generated signals for qualitative, semi-quantitative, and quantitative detection. The platform achieved a minimum detection limit of 537 cfu/mL for E. coli, a wide detection range of 102-106 cfu/mL, and a minimum detection time as low as 20 mins. The detection results of complex environmental samples showed that the system has excellent anti-ion interference and anti-pH interference behavior. This visual detection biosensor has great commercial application potential and can be widely used in real-time on-site detection due to its rapid, portable, anti-interference, and low-cost advantages.

DART isotope dilution high resolution mass spectrometry and 19F-NMR detection of fluorotelomeric alcohols in hydrolyzed food contact paper

Fluorotelomer-based acrylate polymers and surfactants used to grease-proof food contact paper (FCP) are potential sources of dietary exposure to perfluoroalkyl substances (PFAS). Food contact substances (FCS) containing polyfluorinated long-chains (≥C8) were voluntarily removed by their manufacturers from the U.S. market in 2011 due to health concerns and largely replaced with FCSs containing short-chain (≤C7) PFAS. In 2020, FDA findings of potential biopersistence of 6:2 FTOH (CF3(CF2)5CH2CH2OH) similarly prompted an additional voluntarily phase-out of FCSs containing 6:2 FTOH by their manufacturers that was completed by the end of 2023. To monitor the phase-out process, a screening method was developed to detect FCPs containing ester-linked polyfluorinated pendant chains. Direct Analysis in Real Time-Isotope Dilution-High Resolution Mass Spectrometry (DART-ID-HRMS) enabled rapid semi-quantitative detection of 6:2 FTOH in FCP saponification reaction headspace without requiring sample concentration or chromatography. 19F-NMR analysis confirmed 6:2 FTOH pendant chain identity and detection dependence on saponification. The speed and specificity of this approach arise from ester saponification in the presence of stable isotopically labeled 6:2 FTOH; high FTOH differential volatility relative to nonfluorinated matrix, and the facile production of FTOH gas-phase anions (e.g., [M + O2]·−, [M-H + CO2]−) under ambient ionization conditions. The efficiency of this simple workflow makes it well-suited for monitoring the phase-out of FCS containing ester-linked polyfluorinated chains from the U.S. marketplace.

N-doped silicon QDs: facile synthesis and application as sensor for discrimination and selective detection of oxytetracycline, tetracycline, and chlortetracycline in foods.

Nitrogen-doped silicon quantum dots (N-SiQDs) with a quantum yield of up to 37.8% were simply synthesized using inexpensive and readily available silica as the silicon source. Based on the internal filter effect (IFE), both oxytetracycline (OTC) and tetracycline (TC) can effectively and rapidly quench the fluorescence of N-SiQDs at 380nm. However, interestingly, the accompanied formation of a new complex of OTC with N-SiQDs could emit fluorescence at 505nm, resulting in a gradualcolor change of the sensor from blue to yellow under the irradiation of 365nm UV lamp. Thus, a visual semi-quantitative detection of OTC was realized. In contrast, based on the aggregation-induced luminescence (AIE) effect, chlortetracycline (CTC) linearly enhanced the fluorescence intensity of N-SiQDs, which can effectively reduce other interfering signals, and can significantly improve the sensitivity and selectivity. Hence, a low limit of detection of 47nM for CTC was obtained. On account of the three distinctly different phenomena and mechanisms of N-SiQDs sensor exhibited towards OTC, TC, and CTC, a novel sensing method for discriminating and selectively measuring OTC, TC, and CTC in food was developed.

Real-Time Visualization of HIV-1 RNA Detection Using Loop-Mediated Isothermal Amplification-Enabled Particle Diffusometry.

Isothermal nucleic acid amplification tests, NAATs, such as reverse transcription-loop-mediated isothermal amplification (RT-LAMP), offer promising capabilities to perform real-time semiquantitative detection of viral pathogens. These tests provide rapid results, utilize simple instrumentation for single-temperature reactions, support efficient user workflows, and are suitable for field use. Herein, we present a novel and robust method for real-time monitoring of HIV-1 RNA RT-LAMP utilizing a novel implementation of particle diffusometry (PD), a diffusivity quantification technique using fluorescent particles, to quantify viral concentration in nuclease-free water. We monitor changes in particle diffusion dynamics of 400 nm fluorescently labeled particles throughout the RT-LAMP of HIV-1 RNA in nuclease-free water, enabling measurement within 20 min and detection of concentrations as low as 25 virus particles per μL. Moreover, in a single-blind study, we demonstrate semiquantitative detection by accurately determining the initial concentration of an unknown HIV-1 RNA within a 10% absolute error margin. These results highlight the potential of real-time PD readout for quantifying HIV-1 RNA via RT-LAMP, offering promise for viral load monitoring of HIV and other chronic infections.

Diagnostic Accuracy of Quantitative, Qualitative and Semi-Quantitative Delayed Post Gadolinium MR Imaging Criteria in Meniere's Disease

Abstract Clinical Relevance The recent detection of endolymphatic hydrops (EH); the pathological hallmark of MD; on the delayed post gadolinium MR hydropic sequences has resulted shift in the diagnostic paradigm. Researchers defined various MRI qualitative, quantitative, and semi-quantitative criteria and grading scales for endolymphatic hydrops however, the best performance and combination of MRI criteria in distinguish MD affected ears is little explored. Establishing the most reliable and highly performing MRI features will improve the ability of the radiologist to diagnose Meniere’s Disease. Objectives To evaluate the diagnostic performance of MRI criteria used for the detection of Menière’s Disease (MD) ears on delayed post-gadolinium MRI. To determine which combination of descriptors should be optimally applied to establish the diagnosis. Materials and Methods This retrospective case-control study evaluated consecutive delayed post-gadolinium MRI of patients with Menièriform symptoms. 7 quantitative and semi-quantitative MR criteria of MD and qualitative perilymphatic enhancement (PLE) in the cochlea were evaluated within the study cohort. Definite MD ears according to the 2015 Barany Society criteria were compared to control ears. Sensitivity and Specificty were calculated for each descriptor to determined which combination of MRI descriptors would best predict MD ears, and the area under the ROC curve for this model was measured. Results 50 patients (30 female, 20 males; age mean 50 ±13 years) with 30 definite MD and 15 control ears were evaluated. Of the defining MRI criteria, the grade 2 cochlear hydrops, the grade 2 vestibular hydrops, saccule as large as utricle and cochlear perilymphatic enhancement were associated with the presence of MD ears (p < 0.05). The highest sensitivity was achieved by severe vestibular hydrops and “saccule, as large as the utricle”. Conclusion The best predictors of MD are the quantitative detection of severe vestibular hydrops together with the Semiquantitative detection of enlarged or confluent saccules which add value to the diagnosis.

Structural Comparisons, Fluorescence Properties, and Glass-to-Crystal Transformations of Heat-Cooled and Melt-Quenched Zeolitic Imidazolate Framework Glass.

As a representative of zeolitic imidazolate framework glass, agZIF-62 has been reported to be synthesized using a melt-quenching method in which the ZIF-62 crystal is heated to a temperature above the melting point. Interestingly, we unexpectedly found that agZIF-62 can also be synthesized by simple heating at temperatures lower than the melting point, which may be assisted by the release of encapsulated solvent molecules. The structural differences between melt-quenched agZIF-62 (MQ-agZIF-62) and heat-cooled agZIF-62 (HC-agZIF-62) were investigated. The results indicated that MQ-agZIF-62 is closer to the liquid state, while HC-agZIF-62 is closer to the crystal state. Interestingly, their luminescent emissions exhibit significant differences. Compared with the ZIF-62 crystal, MQ-agZIF-62 showed a blue-shift of 14 nm, whereas HC-agZIF-62 showed a red-shift of 9 nm. The emission intensity of agZIF-62 is also significantly stronger than that of ZIF-62; thus, rapid semiquantitative detection of the content of the MOF glass in glass and crystal mixtures can be achieved. In addition, HC-agZIF-62 and MQ-agZIF-62 can transform into ZIF-62 crystals via a solvent-media mechanism. This study provides new insights into ZIF-62 glass.

A ratiometric fluorescent sensor based on dual-emitting carbon dots for the rapid detection of sulfite

Sulfur dioxide (SO2) derivatives are typically employed as antioxidants in food and pharmaceutical processing. However, excessive sulfite intake could trigger serious health problems. Hence, it is urgent to establish a rapid and effective system for monitoring SO2. This study adopted a one-step hydrothermal method to synthesize dual-emitting nitrogen-doped carbon quantum dots (CECDs) and developed a ratiometric sensor for sulfite using CECDs-Cr (VI) composites. The emission intensity ratio (I440/I500) of the CECDs-Cr (VI) composites increased considerably with the addition of HSO3−. A method based on the ratiometric sensor was established for SO2 derivatives with advanced efficiency and excellent linearity over a broad concentration range of 0–500 μM (R2 = 0.9946). Four medicine-food homology materials (MFHMs) fumigated with sulfur have been accurately detected using this approach. Furthermore, a portable test tube was prepared to achieve rapid and semi-quantitative detection of SO2 residues and applied to real samples. This work presents an effective approach to develop a rapid on-site detection platform for sulfite residues in food and pharmaceuticals.

Harnessing gold nanomaterials for advanced multicolor colorimetric biosensors in food hazards detection.

Hazards such as pathogenic bacteria, mycotoxins, pesticides, antibiotics, heavy metal ions, etc., cause serious food safety problems worldwide due to their toxicity and frequent contamination. Rapid screening is an effective way for food safety control, which highly relies on the development of sensitive, specific, and convenient detection methods. The multicolor colorimetric biosensors based on gold nanomaterials have evolved into advanced tools for detecting various hazards in food, with intuitive readout. The excellent localized surface plasmon resonance (LSPR) properties of gold nanomaterials enable them to exhibit bright colors when used as chromophores. In addition, the small changes in the morphology of gold nanomaterials can lead to significant changes in the wavelength of the LSPR peak, resulting in vivid color changes. Since the color discrimination ability of the normal human eye is usually superior to the intensity change ability, the way in which different concentrations of targets represent vivid color changes makes it feasible to fabricate sensors with improved accuracy in visual semi-quantitative detection. By combining with various signal amplification strategies, the detection sensitivity of the constructed sensors can be further improved, even reaching the level of pg/mL. In this review, two strategies for changing the morphology of gold nanomaterials in constructing multicolor colorimetric biosensors, namely the etching strategy and the growth strategy were discussed. We also highlight current progress in developing different gold nanomaterial-based multicolor colorimetric biosensors for detecting various hazards in food. The hazards in food samples are classified as pathogens, mycotoxins, indicators of food freshness, pesticides, antibiotics, heavy metal ions, food additives, and hazards from food processing and packaging. The multicolor colorimetric biosensors based on gold nanomaterials represent a promising tool for visual detection of hazardous materials in food.

Dual-mode electrochemical and SERS detection of PFAS using functional porous substrate

Human activity is the cause of the continuous and gradual grooving of environmental contaminants, where some released toxic and dangerous compounds cannot be degraded under natural conditions, resulting in a serious safety issue. Among them are the widely occurring water-soluble perfluoroalkyl and polyfluoroalkyl substances (PFAS), sometimes called “forever chemicals” because of the impossibility of their natural degradation. Hence, a reliable, expressive, and simple method should be developed to monitor and eliminate the risks associated with these compounds. In this study, we propose a simple, express, and portable detection method for water-soluble fluoro-alkyl compounds (PFOA and GenX) using mutually complementary methods: electrochemical impedance spectroscopy (EIS) and surface-enhanced Raman spectroscopy (SERS). To implement our method, we developed special substrates based on porous silicon with a top-deposited plasmon-active Au layer by subsequently grafting –C6H4-NH2 chemical moieties to provide surface affinity toward negatively charged water-soluble PFAS. Subsequent EIS utilization allows us to perform semiquantitative detection of PFOA and GenX up to 10−10 M concentration because surface entrapping of PFAS leads to a significant increase in the electrode–electrolyte charge-transfer resistance. However, distinguishing by EIS whether even PFAS were entrapped was impossible, and thus the substrates were subsequently subjected to SERS measurements (allowed by surface plasmon activity due to the presence of a porous Au layer), clearly indicating the appearance of characteristic C–F vibration bands.

Factors associated with elevated SARS-CoV-2 immune response in children and adolescents.

Understanding the distinct immunologic responses to SARS-CoV-2 infection among pediatric populations is pivotal in navigating the COVID-19 pandemic and informing future public health strategies. This study aimed to identify factors associated with heightened antibody responses in children and adolescents to identify potential unique immune dynamics in this population. Data collected between July and December 2023 from the Texas Coronavirus Antibody REsponse Survey (Texas CARES), a statewide prospective population-based antibody survey among 1-to-19-year-old participants, were analyzed. Each participant had the following data available for analysis: (1) Roche Elecsys® Anti-SARS-CoV-2 Immunoassay for Nucleocapsid protein antibodies (Roche N-test), (2) qualitative and semi-quantitative detection of antibodies to the SARS CoV-2 spike protein receptor binding domain (Roche S-test), and (3) self-reported antigen/PCR COVID-19 test results, vaccination, and health status. Statistical analysis identified associations between participant characteristics and spike antibody quartile group. The analytical sample consisted of 411 participants (mean age 12.2 years, 50.6% female). Spike antibody values ranged from a low of 6.3 U/ml in the lowest quartile to a maximum of 203,132.0 U/ml in the highest quartile in the aggregate sample. Older age at test date (OR = 1.22, 95% CI: 1.12, 1.35, p < .001) and vaccination status (primary series/partially vaccinated, one or multiple boosters) showed significantly higher odds of being in the highest spike antibody quartile compared to younger age and unvaccinated status. Conversely, fewer days since the last immunity challenge showed decreased odds (OR = 0.98, 95% CI: 0.96, 0.99, p = 0.002) of being in the highest spike antibody quartile vs. more days since last immunity challenge. Additionally, one out of every three COVID-19 infections were asymptomatic. Older age, duration since the last immunity challenge (vaccine or infection), and vaccination status were associated with heightened spike antibody responses, highlighting the nuanced immune dynamics in the pediatric population. A significant proportion of children/adolescents continue to have asymptomatic infection, which has important public health implications.

An Fe3O4-Au heterodimer nanoparticle-based lateral flow assay for rapid and simultaneous detection of multiple influenza virus nucleic acids.

Sensitive, convenient and rapid detection and subtyping of influenza viruses are crucial for timely treatment and management of infected people. Compared with antigen detection, nucleic acid detection has higher specificity and can shorten the detection window. Hence, in this work, we improved the lateral flow assay (LFA, one of the most promising user-friendly and on-site methods) to achieve detection and subtyping of H1N1, H3N2 and H9N2 influenza virus nucleic acids. Firstly, the antigen-antibody recognition mode was transformed into a nucleic acid hybridization reaction. Secondly, Fe3O4-Au heterodimer nanoparticles were prepared to replace frequently used Au nanoparticles to obtain better coloration. Thirdly, four lines were arranged on the LFA strip, which were three test (T) lines and one control (C) line. Three T lines were respectively sprayed by the DNA sequences complementary to one end of H1N1, H3N2 and H9N2 influenza virus nucleic acids, while Fe3O4-Au nanoparticles were respectively coupled with the DNA sequences complementary to the other end of H1N1, H3N2 and H9N2 nucleic acids to construct three kinds of probes. The C line was sprayed by the complementary sequences to the DNAs on all three kinds of probes. In the detection, by hybridization reaction, the probes were combined with their target nucleic acids which were captured by the corresponding T lines to form color bands. Finally, according to the position of the color bands and their grey intensity, simultaneous qualitative and semi-quantitative detection of the three influenza virus nucleic acids was realized. The detection results showed that this multi-channel LFA had good specificity, and there was no significant cross reactivity among the three subtypes of influenza viruses. The simultaneous detection achieved comparable detection limits with individual detections. Therefore, this multi-channel LFA had good application potential for sensitive and rapid detection and subtyping of influenza viruses.

Direct Zeptomole Detection of RNA Biomarkers by Ultrabright Fluorescent Nanoparticles on Magnetic Beads.

Nucleic acids are important biomarkers in cancer and viral diseases. However, their ultralow concentration in biological/clinical samples makes direct target detection challenging, because it leads to slow hybridization kinetics with the probe and its insufficient signal-to-noise ratio. Therefore, RNA target detection is done by molecular (target) amplification, notably by RT-PCR, which is a tedious multistep method that includes nucleic acid extraction and reverse transcription. Here, a direct method based on ultrabright dye-loaded polymeric nanoparticles in a sandwich-like hybridization assay with magnetic beads is reported. The ultrabright DNA-functionalized nanoparticle, equivalent to ≈10 000 strongly emissive rhodamine dyes, is hybridized with the magnetic bead to the RNA target, providing the signal amplification for the detection. This concept (magneto-fluorescent sandwich) enables high-throughput detection of DNA and RNA sequences of varied lengths from 48 to 1362nt with the limit of detection down to 0.3 fm using a plate reader (15 zeptomoles), among the best reported for optical sandwich assays. Moreover, it allows semi-quantitative detection of SARS-CoV-2 viral RNA directly in clinical samples without a dedicated RNA extraction step. The developed technology, combining ultrabright nanoparticles with magnetic beads, addresses fundamental challenges in RNA detection; it is expected to accelerate molecular diagnostics of diseases.

Odours in Asphalt: Analysis of the Release of H2S from Bitumen by a Mass Spectrometric Residual Gas Analyser.

During the production and laying phases of hot-mixing asphalt (HMA), various volatile organic compounds (VOCs) and noxious gases such as H2S are released into the atmosphere. These emissions are a serious environmental problem, a risk to human health, and expose workers and residents to unfriendly odours. The aim of this study was the development of a fast and sensitive analytical method to detect the H2S emitted from hot bituminous binder that is generally used in the various stages of asphalt production, processing, handling and during road construction. The method consisted in the analysis of evolved H2S from a flask with molten bitumen, using nitrogen as a carrier gas to lead the volatile compounds into a residual gas analyser equipped with a quadrupole mass spectrometer. The analysis was performed following the H2S-specific signals at m/z 33 (HS+) and at m/z 34 (H2S+) in real time, directly on the sample without laborious and expensive pre-treatments and with short response times (<6 s). Calibration with a standard mixture of 1000 ppm of H2S in nitrogen allows semi-quantitative H2S detection. The sensitivity and rapidity of the method were evaluated by quenching the release of sulphur compounds with commercial odour-suppressing agents. Upon addition of 0.1% of additive in two minutes, the H2S signal drops about 80% in two minutes, confirming the good response of the method, even with a very complex matrix.

Evaluation of dried blood spots for Epstein–Barr virus nucleic acid testing

Epstein–Barr virus (EBV) is a ubiquitous and oncogenic virus that is associated with various malignancies and non-malignant diseases and EBV DNA detection is widely used for the diagnosis and prognosis prediction for these diseases. The dried blood spots (DBS) sampling method holds great potential as an alternative to venous blood samples in geographically remote areas, for individuals with disabilities, or for newborn blood collection. Therefore, the objective of this study was to assess the viability of detecting EBV DNA load from DBS. Matched whole blood and DBS samples were collected for EBV DNA extraction and quantification detection. EBV DNA detection in DBS presented a specificity of 100 %. At different EBV DNA viral load in whole blood, the sensitivity of EBV DNA detection in DBS was 38.78 % (≥1 copies/mL), 43.18 % (≥500 copies/mL), 58.63 % (≥1000 copies/mL), 71.43 % (≥2000 copies/mL), 82.35 % (≥4000 copies/mL), and 92.86 % (≥5000 copies/mL), respectively. These results indicated that the sensitivity of EBV DNA detection in DBS increased with elevating viral load. Moreover, there was good correlation between EBV DNA levels measured in whole blood and DBS, and on average, the viral load measured in whole blood was about 6-fold higher than in DBS. Our research firstly demonstrated the feasibility of using DBS for qualitative and semi-quantitative detection of EBV DNA for diagnosis and surveillance of EBV-related diseases.