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Background Fentanyl test strips (FTS) are a harm reduction tool used by individuals seeking to avoid unintentional fentanyl exposure while consuming other illicit substances (e.g., heroin, cocaine). While evidence speaks to the efficacy and acceptability of FTS, there are currently no standardized instructions for the use of FTS as a drug checking tool, and little is known about potential variability across instructions. Methods We sought to investigate variability in content across FTS instructions ( N  = 16) through conducting a thematic content analysis of instructions listed in the first three pages of a Google search. The search was conducted in May of 2024, with “fentanyl test strip instructions” entered as the search term. To be included in the present analysis, the information listed in the search result must have contained explicit instructions for how to use FTS and have been printed in English. Results Thematic content analysis of FTS instructions yielded 26 codes and 4 themes. Themes included (1) Information about FTS (2) Testing Methods (3) Test Results and (4) Additional Resources. Overall, results indicated considerable variability across the 16 instructions examined, with the greatest variability observed within the testing methods theme. Conclusion Inconsistencies in online FTS instructions, such as those identified in the current study, could lead to distrust among people who use drugs and disengagement with this drug checking practice. Standardized and accessible instructions are critical to optimizing the efficacy of FTS as a harm reduction tool and reducing accidental fentanyl exposure.

Cancer is one of the major public health challenges in the world, which is characterized by rapid progression and high mortality. Immunotherapy, represented by PD-1 monoclonal antibody, has significantly improved the efficacy of malignant tumors and has become one of the most popular immunotherapy methods at present. Therefore, there is an increasing demand for novel detection methods for PD-1 monoclonal antibodies. The aim of this work was to establish a rapid, simple, and sensitive immunochromatographic test strip (ICTS) based on the AuNPs enlargement for both visual and instrumental detection of the PD-1 monoclonal antibody concentration. The mixed solution of NH2OH·HCl and HAuCl4 was used as an enhancement solution to lower the detection limit and achieve higher sensitivity. A test strip reader was used to construct a visualized quantitative detection standard curve for the PD-1 monoclonal antibody concentration. The LOD was 1.58 ng/mL through a triple signal-to-noise ratio. The detection time was within 10 min. The constructed test strips can rapidly, accurately, and efficiently detect the concentration of PD-1 monoclonal antibody in real samples.

Quantum dots-labeled urea-enzyme antibody-based rapid immunochromatographic test strips have been developed as quantitative fluorescence point-of-care tests (POCTs) to detect helicobacter pylori. Presented in this study is a new test strip reader designed to run on tablet personal computers (PCs), which is portable for outdoor detection even without an alternating current (AC) power supply. A Wi-Fi module was integrated into the reader to improve its portability. Patient information was loaded by a barcode scanner, and an application designed to run on tablet PCs was developed to handle the acquired images. A vision algorithm called Kmeans was used for picture processing. Different concentrations of various human blood samples were tested to evaluate the stability and accuracy of the fabricated device. Results demonstrate that the reader can provide an easy, rapid, simultaneous, quantitative detection for helicobacter pylori. The proposed test strip reader has a lighter weight than existing detection readers, and it can run for long durations without an AC power supply, thus verifying that it possesses advantages for outdoor detection. Given its fast detection speed and high accuracy, the proposed reader combined with quantum dots-labeled test strips is suitable for POCTs and owns great potential in applications such as screening patients with infection of helicobacter pylori, etc. in near future.

Adult-onset immunodeficiency syndrome (AOID) patients with autoantibodies (autoAbs) against interferon-gamma (IFN-γ) generally suffer from recurrent and recalcitrant disseminated non-tuberculous mycobacterial diseases. Since the early stages of AOID do not present specific symptoms, diagnosis and treatment of the condition are not practical. A simplified diagnostic method for differentiating AOID from other immunodeficiencies, such as HIV infection, was created. Anti-IFN-γ is generally identified using enzyme-linked immunosorbent assay (ELISA), which involves an instrument and a cumbersome process. Recombinant IFN-γ indirectly conjugated to colloidal gold was used in the modified immunochromatographic (IC) strips. The biotinylated-IFN-γ was incorporated with colloidal-gold-labeled 6HIS-maltose binding protein-monomeric streptavidin (6HISMBP-mSA) and absorbed at the conjugate pad. The efficacy of the IC strip upon applying an anti-IFN-γ autoAb cut-off ELISA titer of 2500, the sensitivity and specificity were 84% and 90.24%, respectively. When a cut-off ELISA titer of 500 was applied, the sensitivity and specificity were 73.52% and 100%, respectively.

The Lateral Flow Immunoassay (LFIA) is by far one of the most successful analytical platforms to perform the on-site detection of target substances. LFIA can be considered as a sort of lab-in-a-hand and, together with other point-of-need tests, has represented a paradigm shift from sample-to-lab to lab-to-sample aiming to improve decision making and turnaround time. The features of LFIAs made them a very attractive tool in clinical diagnostic where they can improve patient care by enabling more prompt diagnosis and treatment decisions. The rapidity, simplicity, relative cost-effectiveness, and the possibility to be used by nonskilled personnel contributed to the wide acceptance of LFIAs. As a consequence, from the detection of molecules, organisms, and (bio)markers for clinical purposes, the LFIA application has been rapidly extended to other fields, including food and feed safety, veterinary medicine, environmental control, and many others. This review aims to provide readers with a 10-years overview of applications, outlining the trends for the main application fields and the relative compounded annual growth rates. Moreover, future perspectives and challenges are discussed.

A series of dual-emission fluorescent probes was prepared from copper nanoclusters (Cu NCs) and carbon dots (CDs). They show two emission peaks (blue at 469 nm and red at 622 nm) when photoexcited at 365 nm. Upon exposure to sulfide, the Cu NCs will be deteriorated because they react with sulfide to form CuS. This results in the quenching of the red fluorescence of the Cu NCs, while the blue fluorescence of the CDs remains constant. Thus, the color of the nanocomposite changes from red to blue. The ratio of the fluorescences at the two wavelengths decreases linearly in the 2-10 ppb (26-128 nM) sulfide concentration range, and the limit of detection is 0.33 ppb (4.3 nM). The nanocomposite also was placed in an agar gel and then incorporated into a paper strip for fluorometric monitoring of gaseous hydrogen sulfide. Graphical abstract Schematic presentation of the synthesis of Cu NCs (copper nanoclusters)-CDs (carbon dots) dual-emission nano-assembly, Cu NCs-CDs-agar fluorescent film and their application for the detection of sulfide and H S.

To produce, purify, and characterize a polyclonal antibody against acrylamide (anti-AA) for an application to immunochromatographic strip tests for AA. Polyclonal anti-AA was prepared by injecting N-acryloxysuccinimideconjugated bovine serum albumin hapten-antigen into New Zealand white rabbits. The antibody was purified using protein A, characterized using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and conjugated with gold nanoparticles (AuNP). The conjugated antibody was then characterized using UV-Vis and FTIR spectroscopy and transmission electron microscopy (TEM). Immunochromatographic strip tests were performed using sample pads, conjugated pads, test zones, control zones, and absorbent pads. Strip tests were finally validated using standard AA solutions followed by the application of various concentrations of coffee samples. Using SDS-PAGE, the purified anti-AA antibody was resolved at 50 and 25 kDa, indicating the presence of heavy and light chains, respectively. The conjugation of anti-AA with AuNP was confirmed using wavelength shifts in UV-Vis and FTIR spectra, and TEM analyses revealed increased diameters of AuNPs after conjugation. The immunochromatographic strip test was sensitive to 1 mgml standard AA. Various concentrations of coffee samples resulted in red color differences in the test zone. High and low coffee concentrations produced thick and thin red lines, respectively. Purified anti-AA can be conjugated with AuNP to produce strip tests for detecting AA in coffee samples. The present immunochromatographic strip tests quantitatively showed increasing intensities of red lines with increasing AA concentrations.

Mycotoxins are toxic secondary metabolites produced by certain filamentous fungi (molds). These low molecular weight compounds (usually less than 1000 Daltons) are naturally occurring and practically unavoidable. They can enter our food chain either directly from plant-based food components contaminated with mycotoxins or by indirect contamination from the growth of toxigenic fungi on food. Mycotoxins can accumulate in maturing corn, cereals, soybeans, sorghum, peanuts, and other food and feed crops in the field and in grain during transportation. Consumption of mycotoxin-contaminated food or feed can cause acute or chronic toxicity in human and animals. In addition to concerns over adverse effects from direct consumption of mycotoxin-contaminated foods and feeds, there is also public health concern over the potential ingestion of animal-derived food products, such as meat, milk, or eggs, containing residues or metabolites of mycotoxins. Members of three fungal genera, Aspergillus, Fusarium, and Penicillium, are the major mycotoxin producers. While over 300 mycotoxins have been identified, six (aflatoxins, trichothecenes, zearalenone, fumonisins, ochratoxins, and patulin) are regularly found in food, posing unpredictable and ongoing food safety problems worldwide. This review summarizes the toxicity of the six mycotoxins, foods commonly contaminated by one or more of them, and the current methods for detection and analysis of these mycotoxins.

Deoxynivalenol (DON) and zearalenone (ZEN) are mycotoxins that contaminate a wide range of grains and crops. In this study, a one-step time-resolved single-channel immunochromatographic test strip based on europium ion polystyrene fluorescence microspheres was first developed for sensitive and quantitative detection of DON and ZEN. The concentration of the artificial antigen and the mass ratio of the monoclonal antibody to fluorescent microspheres for conjugation were optimized to simplify the sample addition process during immunochromatographic assay and improve the on-site detection efficiency. The limits of detection (LOD) of the single-channel immunochromatographic test strip for DON and ZEN detection were 0.17 and 0.54 μg/L, respectively. Meanwhile, the dual-channel immunochromatographic test strip was designed to simultaneously detect DON and ZEN, with LODs of 0.24 and 0.69 μg/L achieved for DON and ZEN, respectively. The developed test strips also yielded recovery results consistent with that obtained by LC-MS/MS for DON and ZEN detection in real samples of wheat and corn flour, confirming the practicability and reliability of the test strip. The developed immunochromatographic test strips realize quick and sensitive detection of DON and ZEN, exhibiting potential for broad applications in the point-of-care testing platform of multiple mycotoxins in agricultural products.

Excessive molybdenum (VI) (Mo (VI)) in water threatens environmental safety and human health, yet rapid on-site methods for Mo (VI) determination remain limited. Here, we propose a rapid method for Mo (VI) determination using phenylfluorone (PF)-modified test strips with dual readouts: visual colorimetry and image-based analysis in the CIELAB (Lab*) color space, and demonstrate its applicability using urban park water samples. Based on visual colorimetry, a standard color card was established, providing a screening range of 0.08 to 0.8 mg L−1 (A blank (0 mg L−1) was used as the baseline reference). Moreover, by the LAB color space, the linear relationship between the color development results of the PF-modified test strip and the A channel conforms to y = 21.08 + 8.82x (R2 = 0.992), with a detection range of 0–0.8 mg L−1. The total detection time was reduced to 2.5 min. To evaluate accuracy in real matrices, influent, midstream, and effluent samples from Chengdu Living Water Park were analyzed, with UV-vis spectrophotometry used as the reference method. The test-strip results agreed well with UV-vis spectrophotometry, with relative errors below 5%. Overall, this study provides a portable, rapid, and accurate method for the detection of Mo (VI) in water, and has potential application prospects in the field of water environment detection in the future.