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Electron donor–acceptor (D–A) molecules are emerging tools for designing sensitive luminogens, attracting significant research attention. However, due to poor quantum yields under certain conditions, current D–A fluorophores often suffer from fluorescence quenching in practical applications. Developing new D–A dyes and functional composites is crucial for expanding their applications. Here, a novel donor–acceptor type flavonoid dye molecule, namely “AFL”, exhibiting both polarity‐dependent fluorescence emission wavelength shift and viscosity‐dependent intensity change, for polarity measurement and temperature sensing is designed and synthesized. Because the intramolecular charge transfer (ICT) can be enhanced by a decrease of excited state energy caused in high‐polarity organic solvents, AFL undergoes fluorescence emission wavelength shift that shows fluorescence color response to solvents of different polarities and hence differentiates between them. Moreover, the actual temperature can be monitored by the as‐designed AFL@tetradecanoic acid (AFL@TA) sensor. By combining with TA, viscosity sensitively changes upon the temperature change of insoluble composites, thus realizing the fluorescence intensity response to temperature. Remarkable recyclable performance and satisfactory mechanical properties are integrated. This study provides a promising approach to developing a new D–A fluorescent probe and furnishes perspectives on the potential of such D–A type flavonoid material in stimuli‐responsive systems with a focus on visualization sensing technology. [ABSTRACT FROM AUTHOR]

Background: Senecavirus A (SVA) is a newly pathogenic virus correlated with the acute death of piglets and vesicular lesions in pigs. The further prevalence of SVA will cause considerable economic damage to the global pig farming industry. Therefore, rapid and accurate diagnostic tools for SVA are crucial for preventing and controlling the disease. Methods: We designed multiple primer pairs targeting the most conserved region of the SVA 3D gene and selected those with the highest specificity. Nfo-probes were subsequently developed based on the highest specificity primer pairs. Subsequently, the recombinase-assisted amplification (RAA) reaction was completed, and the reaction temperature and duration were optimized. The RAA amplicons were detected using a lateral flow device (LFD). Finally, a rapid and intuitive RAA-LFD assay was established against SVA. Results: The SVA RAA-LFD assay can be performed under reaction conditions of 35°C within 17 minutes, with results observable to the naked eye. We then evaluated the performance of this method. It exhibited high specificity and no cross-reaction with the other common swine pathogens. The lowest detectable limits of this method for the plasmid of pMD18-SVA-3D, DNA amplification product, and viral were 3.86×101 copies/µL, 8.76×10-7 ng/µL, and 1×100.25 TCID50/mL, respectively. A total of 44 clinical samples were then tested using the RAA-LFD, PCR, and RT-qPCR methods. The results demonstrated a consistent detection rate between the RAA-LFD and RT-qPCR assays. Conclusion: The SVA RAA-LFD assay developed in our study exhibits excellent specificity, sensitivity, and time-saving attributes, making it ideally suited for utilization in lack-instrumented laboratory and field settings. [ABSTRACT FROM AUTHOR]

With SARS-CoV-2 N protein as a model target, a signal-enhanced LFIA based on Au@Pt nanoparticles (NPs) as labels is proposed. This Au@Pt NPs combined the distinguished localized surface plasma resonance (LSPR) effect of Au NPs and the ultrahigh peroxidase-like catalytic activity of Pt NPs. Au@Pt NPs could trigger substrate chromogenic reaction, generating a color signal orders of magnitude darker than their intrinsic color. In the detection, after the coloration of the strips, 3,3′,5,5′-tetramethylbenzidine (TMB) and H2O2 were added, and a dark blue chelate (OxTMB) was produced soon, enhancing the band color significantly. After the signal amplification, the naked-eye detection limit for N protein reached 40 pg/mL. The detection sensitivity enhanced more than 1000 times than that without signal amplification. Compared with mainstream LFIA requiring complex readout instruments, the Au@Pt-based LFIA achieved a comparable sensitivity using naked eyes detection. This point is crucial, especially for unprofessional users or low-resource areas. Hence, this signal-enhanced LFIA may serve as a sensitive, cost-effective, and user-friendly detection method. It can shorten the testing window period and help identify early infections. [ABSTRACT FROM AUTHOR]

Ascorbic acid (AA) plays an important role in many physiological and biochemical processes. Adequate quantification of AA is required for controlling the intake of AA for health management. In this study, a portable probe was fabricated based on the assembled FePO4@GO nanozyme by homogeneous precipitation. FePO4@GO exhibits excellent peroxidase (POD) activity. As an efficient free radical scavenger, ascorbic acid scavenges 1O2 free radicals produced by hydrogen peroxide catalyzed by peroxidase enzymes and then inhibits the color reaction of 3,3′,5,5′-tetramethylbenzidine (TMB). A good linear relationship between the color of the reaction system and the concentration of AA in the range of 2.5–75 μM was presented, and the detection limit is 1.25 μM. Furthermore, a visual colorimetric detection platform was constructed using a smartphone. The AA content is accurately reflected by intelligent recognition of color changes in the reaction system. It provides an alternative approach for portable and visual rapid detection of Vitamin C (VC) in medicine. Meanwhile, it also provides a reference for the assembly of an intelligent detection platform based on nanozymes. [ABSTRACT FROM AUTHOR]

We lack many quantitative data on the current distributions of several bear species, and hypotheses about the mechanisms underlying those distributions. We raise this point by discussing visual detections of Andean bears (Tremarctos ornatus) in sampling from 14 September 2016 to 24 August 2017 in the Haramba Queros Wachiperi Ecological Reserve Conservation Concession in southeastern Peru, at 811–920 m above sea level, lower in elevation than >90% of known locations for this species on the eastern slope of the Peruvian Andes. Resumo No tenemos muchos datos cuantitativos sobre las distribuciones actuales de varias especies de osos, ni hipótesis sobre los mecanismos detrás de esas distribuciones. Ilustramos esto discutiendo unos registros visuales del oso andino (Tremarctos ornatus) durante foto trampeo del 14 septiembre 2016 al 24 agosto 2017 dentro de la Concesión para la Conservación Reserva Ecológica Haramba Queros Wachiperi, de elevaciones de 820–920 msnm, más bajos que 90% de los lugares conocidos para la especie en las laderas orientales de los Andes peruanos. [ABSTRACT FROM AUTHOR]

Real‐time monitoring of carbon dioxide (CO2) is imperative for medical diagnosis and effective environmental preservation. Despite the formidable challenge posed by the inherent chemical inertness of CO₂ molecules, a pioneering CO2 sensor based on MOF‐804 cofunctionalized with ionic liquid (IL) and m‐cresol purple (mCP) is successfully developed. By ingeniously integrating hydrogen bonding, electrostatic interactions, and hydrophobic properties within the sensitive layer, the sensor achieves a state‐of‐the‐art sensitivity (Δf = 384 Hz), an exceptionally vast detection range spanning 400–80 000 ppm, and remarkable stability with minimal sensitivity drift even at relative humidity (RH) levels exceeding 80%. Furthermore, the inherent gasochromic property, stemming from the zwitterionic mechanism, paves the way for innovative self‐sustaining CO2 test strips and groundbreaking applications, including CO2 tracking and CO2‐encrypted security labeling technology. Collectively, the realization of this ultra‐sensitive and robust CO2 monitoring approach, coupled with its CO2‐triggered visual and multifunctional capabilities, opens up novel avenues for dynamic CO2 detection, advanced military encryption strategies, and enhanced health management systems. [ABSTRACT FROM AUTHOR]

Setophoma terrestris is an important phytopathogenic fungus listed by China as a harmful fungus subject to phytosanitary import control. This pathogen is a threat to a wide range of plants, particularly as the causal agent of onion pink root rot, one of the most severe diseases of onions. In order to provide rapid identification and early warning of S. terrestris and prevent its spread, we have developed a rapid, accurate, and visually intuitive diagnostic assay for this pathogen, by utilizing recombinase polymerase amplification (RPA), coupled with CRISPR/Cas12a cleavage and fluorescence-based detection systems or paper-based lateral flow strips. The developed RPA-CRISPR/Cas12a assay exhibited remarkable specificity for the detection of S. terrestris. Moreover, this protocol can detect the pathogen at a sensitivity level of 0.01 pg/μL, which significantly outperforms the 1 pg/μL sensitivity achieved by the existing qPCR-based detection method. The entire diagnostic procedure, including DNA extraction, the RPA reaction, the Cas12a cleavage, and the result interpretation, can be accomplished in 40 min. Furthermore, the successful application of the assay in infected plant samples highlighted its potential for rapid and accurate pathogen detection in agricultural settings. In summary, this RPA-CRISPR/Cas12a diagnostic method offers a potentially valuable technological solution for quarantine and disease management. [ABSTRACT FROM AUTHOR]

A chemiluminescence (CL) method for determination of glutathione (GSH) was developed with magnetic nanoparticle-decorated metal organic frameworks (Fe3O4 NPs@Cu-TATB). The composite material was synthesized via a hydrothermal method and glutathione (GSH) can be detected by both visual and chemiluminescence (CL) methods. The synthesized Fe3O4 NPs@Cu-TATB exhibited excellent catalytic activity in the luminol-H2O2 CL system. The mechanism revealed that three types of oxygen-containing radicals (ROS) were generated in this system. As GSH can reduce the catalytic effect of generated ROS radicals, the inhibiting CL signal was produced in the Fe3O4 NPs@Cu-TATB-luminol-H2O2 system. Based on the established CL system, the detection limits for GSH using CL and visual methods were found to be 0.3 µM and 0.7 µM, respectively. This low-cost and convenient detection method can be applied to the determination of GSH content in human blood. [ABSTRACT FROM AUTHOR]

Abstract Mycoplasma bovis (M. bovis) is capable of causing a range of diseases in cattle, encompassing calf pneumonia, arthritis, conjunctivitis, meningitis, and mastitis. It is widely recognized as one of the predominant pathogens posing a significant threat to the global cattle industry. Therefore, accurate and sensitive methods are urgently needed to detect M. bovis. This study aims to detect M. bovis by combining colloidal gold with biotin-labeled oligonucleotides to improve detection sensitivity and form a chromogenic detection probe based on signal amplification technology. Here, we developed a sensitive and specific polymerase chain reaction-lateral flow dipstick assay (PCR-LFD) strip for efficient nucleic acid detection of M. bovis. A pair of specific primers with 5’ ends labeled with biotin and digoxigenin probes was designed for PCR experiments. Colloidal gold particles-labeled anti-digoxigenin IgG coated gold-labeled test strip was prepared, streptavidin was used as the detection probe, and nitrocellulose membrane coated goat anti-mouse IgG was used as the control line. Our results showed that the detection limit of the PCR-LFD was 89 fg/µL for the M. bovis DNA. The results from the test strip were highly consistent with those from real-time qPCR. This assay were highly specific for M. bovis, as there were no cross-reactions with other microorganisms tested and the detection sensitivity of the test was also relatively high (97.67%). The novel strips present a promising tool for the cost-effective and sensitive diagnosis of M. bovis.

Abstract Dermatophagoides farina (D. farinae) and Dermatophagoides pteronyssinus (D. pteronyssinus) are the prevalent kinds of house dust mites (HDMs). HDMs are common inhalant allergens that cause a range of allergic diseases, such as rhinitis, atopic dermatitis, and asthma. The epidemiology of these diseases is associated with exposure to mites. Therefore, in the present study, a method named multiplex loop-mediated isothermal amplification (LAMP) was developed to detect environmental dust mites. The multiplex LAMP assay allows amplification within a single tube and has an ITS plasmid detection limit as low as 40 fg/µL for both single dust mites and mixed dust mites (D. pteronyssinus and D. farinae), which is up to ten times more sensitive than classical PCR techniques. Furthermore, the multiplex LAMP method was applied to samples of single dust mites and clinical dust to confirm its validity. The multiplex LAMP assay exhibited higher sensitivity, simpler instrumentation, and visualization of test results, indicating that this method could be used as an alternative to traditional techniques for the detection of HDMs.

Defects such as bubbles and rubber shortages occasionally occur during vehicle tire production. Tiny defects in the crown gradually expand under load, ultimately causing tire failure. However, machine-vision-based crown defect detection faces challenges like limited datasets, varying groove patterns, low colour contrast, and small defect sizes. Therefore, this article integrates principal component analysis (PCA) and deep learning techniques for the visual detection of tire crown defects. A dataset of tire crown defects suitable for deep learning was constructed using an improved-PCA method and composite sampling. We propose the ConvNeXt-Shallow Conv CBAM (ConvNeXt-SCC) model, which includes an improved convolutional block attention module (CBAM) in a shallow stacked structure. And we propose an efficient and accurate method called Improved Selective Search (ISS) to detect and locate tire crown defective regions. The ISS pre-selected box generation method, enhanced with a priori knowledge filtering module, was used alongside a classification model to achieve online inference detection of large-size tire crown images. The experimental results show that the performance indices of the proposed ConvNeXt-Shallow Conv CBAM (ConvNeXt-SCC) model significantly improve compared to the original ConvNeXt-T. The defect detection and localisation method based on ISS meets the online inspection requirements of tire production. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Henan Agricultural Sciences is the property of Editorial Board of Journal of Henan Agricultural Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study represents a visual detection for total biogenic monoamines with naked eye as a simple and rapid semi-quantitative method for biogenic amine monitoring. The equivalent reaction of H2O2 with ascorbic acid resulted in color development by an amine oxidase–peroxidase coupling reaction in the samples containing the biogenic monoamines higher than the subjected ascorbic acid by 10 μM. Upon employing the commercial doenjang extracts as a model food, an additional heating step was requested, and the expected ranges for the biogenic monoamines from 360 to 480 μM covered the real contents of the samples (360.2–407.3 μM). Therefore, this visual detection method makes it possible to decide with naked eye whether the sample contains the biogenic monoamines higher than the ascorbic acid supplemented as much as a control level on manufacturing sites without instrumental analysis. [ABSTRACT FROM AUTHOR]

Mycoplasma bovis (M. bovis) is capable of causing a range of diseases in cattle, encompassing calf pneumonia, arthritis, conjunctivitis, meningitis, and mastitis. It is widely recognized as one of the predominant pathogens posing a significant threat to the global cattle industry. Therefore, accurate and sensitive methods are urgently needed to detect M. bovis. This study aims to detect M. bovis by combining colloidal gold with biotin-labeled oligonucleotides to improve detection sensitivity and form a chromogenic detection probe based on signal amplification technology. Here, we developed a sensitive and specific polymerase chain reaction-lateral flow dipstick assay (PCR-LFD) strip for efficient nucleic acid detection of M. bovis. A pair of specific primers with 5' ends labeled with biotin and digoxigenin probes was designed for PCR experiments. Colloidal gold particles-labeled anti-digoxigenin IgG coated gold-labeled test strip was prepared, streptavidin was used as the detection probe, and nitrocellulose membrane coated goat anti-mouse IgG was used as the control line. Our results showed that the detection limit of the PCR-LFD was 89 fg/µL for the M. bovis DNA. The results from the test strip were highly consistent with those from real-time qPCR. This assay were highly specific for M. bovis, as there were no cross-reactions with other microorganisms tested and the detection sensitivity of the test was also relatively high (97.67%). The novel strips present a promising tool for the cost-effective and sensitive diagnosis of M. bovis. [ABSTRACT FROM AUTHOR]

A low-cost, handheld centrifugal microfluidic system for multiplexed visual detection based on recombinase polymerase amplification (RPA) was developed. A concise centrifugal microfluidic chip featuring four reaction units was developed to run multiplexed RPA amplification in parallel. Additionally, a significantly shrunk-size and cost-effective handheld companion device was developed, incorporating heating, optical, rotation, and sensing modules, to perform multiplexed amplification and visual detection. After one-time sample loading, the metered sample was equally distributed into four separate reactors with high-speed centrifugation. Non-contact heating was adopted for isothermal amplification. A tiny DC motor on top of the chip was used to drive steel beads inside reactors for active mixing. Another small DC motor, which was controlled by an elaborate locking strategy based on magnetic sensing, was adopted for centrifugation and positioning. Visual fluorescence detection was optimized from different sides, including material, surface properties, excitation light, and optical filters. With fluorescence intensity-based visual detection, the detection results could be directly observed through the eyes or with a smartphone. As a proof of concept, the handheld device could detect multiple targets, e.g., different genes of African swine fever virus (ASFV) with the comparable LOD (limit of detection) of 75 copies/test compared to the tube-based RPA. [ABSTRACT FROM AUTHOR]

• Seizure onset zone localization accuracy based on HFO rate was comparable for visual and automated HFO detection. • Optimizing automated HFO detection settings based on visual markings did not increase seizure onset zone localization accuracy. • For many patients, changing detection settings could improve SOZ localization accuracy, but new optimization methods are needed. High frequency oscillations (HFOs) are a biomarker of the seizure onset zone (SOZ) and can be visually or automatically detected. In theory, one can optimize an automated algorithm's parameters to maximize SOZ localization accuracy; however, there is no consensus on whether or how this should be done. Therefore, we optimized an automated detector using visually identified HFOs and evaluated the impact on SOZ localization accuracy. We detected HFOs in intracranial EEG from 20 patients with refractory epilepsy from two centers using (1) unoptimized automated detection, (2) visual identification, and (3) automated detection optimized to match visually detected HFOs. SOZ localization accuracy based on HFO rate was not significantly different between the three methods. Across patients, visually optimized detector settings varied, and no single set of settings produced universally accurate SOZ localization. Exploratory analysis suggests that, for many patients, detection settings exist that would improve SOZ localization. SOZ localization accuracy was similar for all three methods, was not improved by visually optimizing detector settings, and may benefit from patient-specific parameter optimization. Visual HFO marking is laborious, and optimizing automated detection using visual markings does not improve localization accuracy. New patient-specific detector optimization methods are needed. [ABSTRACT FROM AUTHOR]

Pb(II) can accumulate in the body and gradually cause irreversible harm. In this work, a dual-mode colorimetric biosensor based on an aptamer was developed as an effective method for sensitive sensing of Pb(II). The aptamers were immobilized on silver nanoparticles (Ag NPs) by Ag–S bonding to increase the active sites on the electrode surface. Gold–palladium bimetallic nanoparticles (Au@Pd NPs) can not only serve as signal indicators but also play a role as nanozymes. On the one hand, Au@Pd NPs were modified on the aptamer to improve the conductivity of the sensor for the detection of Pb(II) by the electrochemical method of differential pulse voltammetry (DPV). On the other hand, Au@Pd NPs were porous nanomaterials with numerous active sites on their surface that can catalyze the decomposition of hydrogen peroxide (H2O2) in solution to generate O2, so that 3,3′,5,5′-tetramethylbenzidine (TMB) was oxidized to blue oxTMB, enabling the visual prediction of Pb(II). At the same time, with the property that 8–17 deoxyribozyme and metal ions can co-catalyze, it promoted the binding of Au@Pd NPs functionalized aptamer to the electrode in the presence of Pb(II) and enhanced the electrochemical signal. Under optimal conditions, the detection range of Pb(II) was 1—1000 nmol L−1, and the limit of detection (LOD) was 0.4 nmol L−1. The biosensor has been successfully applied to the detection of edible mushroom samples. [ABSTRACT FROM AUTHOR]

A dual-mode fluorescence/visual aptasensor was developed for straightforward and accurate determination of aflatoxin B1 (AFB1) based on an Au/metal–organic framework (Au/MOF) composite. Aptamer-modified Au/Fe3O4 (Apt/Au/Fe3O4) served as the recognition element, and Au/MOF modified with complementary chains and 3,3′,5,5′-tetramethylbenzidine (cDNA/TMB/Au/MOF) acted as the fluorescence and visual probes. These components are integrated to form conjugates (Apt/Au/Fe3O4-cDNA/TMB/Au/MOF). Upon the introduction of AFB1, some cDNA/TMB/Au/MOF dissociated from Apt/Au/Fe3O4, enabling the use of detached probes for visual detection. The undecomposed conjugates were isolated magnetically for use in fluorescence detection. As the AFB1 concentration increases, the visual signal intensifies and fluorescence intensity diminishes. Thus, the proposed aptasensor achieves the simultaneous fluorescence and visual determination of AFB1, obviating the need for material and reagent substitutions. The detection limits were established at 0.07 ng mL−1 for the fluorescence mode and 0.08 ng mL−1 for the visual mode. The effectiveness of the aptasensor was further validated by quantifying AFB1 in real samples. [ABSTRACT FROM AUTHOR]

An ultrasensitive method for the visual detection of microRNAs (miRNAs) in cell lysates using a gold nanorod-based lateral flow nucleic acid biosensor (GN-LFNAB) and exonuclease III (Exo III)-assisted signal amplification. The Exo III-catalyzed target recycling strategy is employed to generate a large number of single-strand DNA products, which can be detected by GN-LFNAB visually. With the implementation of a unique recycling strategy, we have demonstrated that the miRNA in the concentration as low as 0.5 pM can be detected without the need for instrumentation, providing a detection limit that surpasses previous reports. The new biosensor is ultrasensitive and can be applied to the reliable monitoring of miRNAs in cell lysates with high accuracy. The approach offers a simple and rapid tool for cancer diagnosis and clinical biomedicine, thanks to its flexibility, simplicity, cost-effectiveness, and convenience. This new method has the potential to significantly improve the detection and monitoring of cancer biomarkers, ultimately contributing to more effective cancer diagnosis and treatment. [ABSTRACT FROM AUTHOR]

Three phenomena, namely coordination-induced emission (CIE), aggregation-induced emission (AIE), and inner filter effect (IFE), were incorporated into the design of a ratiometric and color tonality-based biosensor. Blue fluorescent Al-based metal–organic frameworks (FMIL-96) were prepared from non-emissive ligand and aluminum ions via CIE. Interestingly, the addition of tetracycline (TC) led to ratiometric detection and color tonality, as the blue emission at 380 nm was quenched (when excited at 350 nm) due to IFE, while the green-yellowish emission at 525 nm was enhanced due to AIE. Based on that, an ultra-sensitive visual-based color tonality mode with smartphone assistance was developed for detection of TC. The sensor exhibited a linear relationship within a broad range of 2.0 to 85.0 μM TC with a detection limit of 68.0 nM. TC in milk samples was quantified with high accuracy and precision. This integration of smartphone and visual fluorescence in solution is accurate, reliable, cost-effective, and time-saving, providing an alternative strategy for the semi-quantitative determination of TC on-site. [ABSTRACT FROM AUTHOR]

An electrochemical biosensor has been developed for detection of Escherichia coli O157 by integrating lateral flow with screen-printed electrodes. The screen-printed electrodes were attached under the lateral flow detection line, and organic–inorganic nanoflowers prepared from E. coli O157-specific antibodies as an organic component were attached to the lateral flow detection line. In the presence of E. coli O157, an organic–inorganic nanoflower-E. coli O157-antimicrobial peptide-labelled ferrocene sandwich structure is formed on the lateral flow detection line. Differential pulse voltammetry is applied using a smartphone-based device to monitor ferrocene on the detection line. The resulting electrochemical biosensor could specifically detect E. coli O157 with a limit of detection of 25 colony-forming units mL−1. Through substitution of antibodies of organic components in organic–inorganic nanoflowers, biosensors have great potential for the detection of other pathogens in biomedical research and clinical diagnosis. [ABSTRACT FROM AUTHOR]

Background: The tcdA gene codes for an important toxin produced by Clostridioides difficile (C. difficile), but there is currently no simple and cost-effective method of detecting it. This article establishes and validates a rapid and visual loop-mediated isothermal amplification (LAMP) assay for the detection of the tcdA gene. Methods: Three sets of primers were designed and optimized to amplify the tcdA gene in C. difficile using a LAMP assay. To evaluate the specificity of the LAMP assay, C. difficile VPI10463 was used as a positive control, while 26 pathogenic bacterial strains lacking the tcdA gene and distilled water were utilized as negative controls. For sensitivity analysis, the LAMP assay was compared to PCR using ten-fold serial dilutions of DNA from C. difficile VPI10463, ranging from 207 ng/µl to 0.000207 pg/µl. The tcdA gene of C.difficile was detected in 164 stool specimens using both LAMP and polymerase chain reaction (PCR). Positive and negative results were distinguished using real-time monitoring of turbidity and chromogenic reaction. Results: At a temperature of 66 °C, the target DNA was successfully amplified with a set of primers designated, and visualized within 60 min. Under the same conditions, the target DNA was not amplified with the tcdA12 primers for 26 pathogenic bacterial strains that do not carry the tcdA gene. The detection limit of LAMP was 20.700 pg/µl, which was 10 times more sensitive than that of conventional PCR. The detection rate of tcdA in 164 stool specimens using the LAMP method was 17% (28/164), significantly higher than the 10% (16/164) detection rate of the PCR method (X2 = 47, p < 0.01). Conclusion: LAMP method is an effective technique for the rapid and visual detection of the tcdA gene of C. difficile, and shows potential advantages over PCR in terms of speed, simplicity, and sensitivity. The tcdA-LAMP assay is particularly suitable for medical diagnostic environments with limited resources and is a promising diagnostic strategy for the screening and detection of C. difficile infection in populations at high risk. [ABSTRACT FROM AUTHOR]

Underwater cleaning work primarily relies on human labor, but applying computer vision technology to Autonomous Underwater Vehicles can enhance cleaning efficiency. Considering that existing vision detection algorithms are difficult to deploy on resource-constrained embedded devices, this paper introduces a lightweight vision detection algorithm based on an improved YOLOv8-GST-YOLO. This algorithm integrates the lightweight Ghost network and prunes the model, overcoming the drawbacks of YOLOv8’s high computational parameters and large size. It also features a GTR module and a bi-directional path aggregated feature pyramid guided by SimAM attention to enhance detection accuracy and global feature extraction capabilities. Experiments on a specially collected underwater trash image dataset show that GST-YOLO, while reducing the model size by 51% and increasing computational efficiency by 54%, improves the accuracy rate to 95.4%, surpassing the YOLOv8 algorithm. This demonstrates its potential as a crucial detection tool for underwater unmanned cleaning tasks, offering broad application prospects. [ABSTRACT FROM AUTHOR]

[Display omitted] Volatile organic compounds (VOCs) have always been a major concern as a global environmental problem. As a low-cost, high-efficiency and visual sensor, photonic crystals (PCs) have been actively studied in VOCs detection. Herein, a one-dimensional PC sensor for visual sensing of highly toxic benzene series VOC vapors is prepared for the first time by integrating a new photo-crosslinked polymer-poly(styrene-benzoylphenyl acrylate) P(St-BPA) and a high specific surface area metal–organic framework (MOF) MIL-101(Cr). The PC can detect VOCs quantitatively and visually, and clearly distinguish 7 benzene series vapors. The detection limit of the benzene series VOCs is as low as 0.06–3.45 g/m3. Meanwhile, owing to the ultra-thin layer and porous structure, the PC can reach a response equilibrium to the VOCs within 1–2.6 s. Moreover, the PC has a good organic vapor tolerance and can maintain stable optical performance after 1000 times of reuse in VOCs. Besides, 4 other PCs assembled with different aryl polymers and MOFs are first fabricated and their sensing performance to benzene series VOCs are studied and compared, which provides a valuable reference for the selection of materials for the preparation of such PC sensors. [ABSTRACT FROM AUTHOR]

Copyright of Food Research & Development is the property of Food Research & Development Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A novel molecularly imprinted ratiometric fluorescent sensor CQDs@MIP/FITC@SiO2 for the detection of p-nitroaniline (p-NA) was constructed through the mixture of CQDs@MIP and FITC@SiO2 in the ratio of 1:1 (VCQDs@MIP:VFITC@SiO₂). The polymers of CQDs@MIP and FITC@SiO2 were prepared by sol-gel method and reversed-phase microemulsion method, respectively. CQDs@MIP was used as the auxiliary response signal and FITC@SiO2 was used as the reference enhancement signal. The signal was measured at excitation/emission wavelengths of 365/438, 512 nm. The sensor showed good linearity in the concentration range 0.14–40.00 µM (R2 = 0.998) with a detection limit of 0.042 µM for p-NA. The color change of "blue-cyan-green" could be observed by the naked eye under 365 nm UV light, thus realizing the visual detection of p-NA. The sensor presented comparable results compared with high-performance liquid chromatography (HPLC) method for the detection of p-NA in hair dye paste and aqueous samples with recoveries of 96.8–103.7% and 95.8–104.4%, respectively. It was demonstrated that the constructed sensor possesses the advantages of simplicity, excellent selectivity, superior sensitivity, and outstanding stability. [ABSTRACT FROM AUTHOR]

Jumping spiders display some of the richest visually mediated behaviours in nature. Vision is indeed the most important sensory modality in these spiders where motion detection and response to visual stimuli allow key behaviours such as hunting, escaping from predators and mating. These spiders have been used in various experiments demonstrating the existence of good associative learning and memory abilities, whose mechanism parallels that found in vertebrates. Here we focused on the habituation and dishabituation (H/DH) paradigm, indicating either a gradual decrease in responsiveness to repeated visual stimuli (H), or a recovery in response wherein the reaction towards a known stimulus is enhanced (DH). H is an elementary form of nonassociative learning and memory, which is expected to vary from individual to individual. The link between personality and H/DH has been shown in many vertebrates, but rarely in invertebrates. The jumping spider Menemerus semilimbatus was used in our study to address the question of whether boldness is related to H/DH. In our protocol, habituation was assessed by repeatedly presenting a visual stimulus on a screen to spiders tethered on a locomotor compensator. In the same individuals, boldness was assessed in a walking arena equipped with a shelter. We found that M. semilimbatus habituated and dishabituated to our visual stimulus and that they differed along a shy–bold axis. However, contrary to our expectations, boldness was not related to learning. In consideration of these results, we speculate that the nature (neutral value) of the stimulus might have played a role in making learning independent from boldness. • We tested boldness and visual habituation in the spider Menemerus semilimbatus. • Spiders showed consistent boldness type in four behavioural parameters. • They reduced their response to the stimulus due to habituation. • They increased rotational movement in response to the first dishabituation stimulus. • Boldness was not related to habituation or dishabituation. [ABSTRACT FROM AUTHOR]

The COVID-19 pandemic has highlighted the urgent need for rapid and accurate diagnostic methods for various infectious diseases, including SARS-CoV-2. Traditional RT-PCR methods, while highly sensitive and specific, require complex equipment and skilled personnel. In response, we developed an integrated RT-LAMP-MS assay, which combines rapid reverse transcription loop-mediated isothermal amplification (RT-LAMP) with microscanning (MS) technology for detecting SARS-CoV-2. The assay uses magnesium pyrophosphate formed during LAMP amplification as a visual marker, allowing direct observation via microscopy without the need for additional chemical indicators or probes. For the SARS-CoV-2/IC RT-LAMP-MS assay, the sample-LAMP reagent mixture was added to a microchip with SARS-CoV-2 primers and internal controls, then incubated at 62 °C for 30 min in a heat block, followed by amplification analysis using a microscanner. In clinical tests, the RT-LAMP-MS assay showed 99% sensitivity and 100% specificity, which is identical to the RT-LAMP results and comparable to the commercial AllplexTM SARS-CoV-2 assay results. Additionally, the limit of detection (LOD) was determined to be 10−1 PFU mL−1 (dynamic range: 103~10−1 PFU mL−1). The assay delivers results in 30 min, uses low-cost equipment, and demonstrates 100% reproducibility in repeated tests, making it suitable for point-of-care use in resource-limited settings. [ABSTRACT FROM AUTHOR]

Accurate detection and localization of fruits in natural environments is a key step for fruit picking robots to achieve precise harvesting. However, existing banana detection and positioning methods have two main limitations in practical applications: a large number of model parameters that make deployment difficult, and a need for performance improvement. To tackle the above issues, a high-precision and lightweight banana bunch recognition and localization method was proposed and deployed on edge devices for application. First, a Slim-Banana model was proposed based on the improvement of YOLOv8l. In order to reduce the model calculation amount and maintain high performance, GSConv was introduced in the Slim-Banana model to replace the standard convolution, and combined with grouped convolution and spatial convolution. At the same time, the cross-stage local network (GSCSP) module was designed to reduce the computational complexity and the complexity of the network structure through a single-stage aggregation method. Then, the RealSense depth sensor is combined with TOF technology to perform image registration and 3D localization of the banana. Finally, the pipeline is deployed on the Nvidia Orin NX edge device and its performance and resource consumption in actual work are deeply analyzed. Experimental results show that the detection precision, recall, mAP and inference time of our method are 0.947, 0.948, 0.98 and 113.6 ms respectively, the network memory size required is 4449MiB, and the average localization errors in the X-axis, Y-axis and Z-axis directions are 13.47 mm, 12.87 mm and 13.87 mm respectively. To our knowledge, this is the first work that implements banana detection and localization on edge devices. Experimental results show that compared with existing methods, our method achieves better performance in complex orchard environments, achieving efficient and lightweight banana recognition and localization.

BackgroundSenecavirus A (SVA) is a newly pathogenic virus correlated with the acute death of piglets and vesicular lesions in pigs. The further prevalence of SVA will cause considerable economic damage to the global pig farming industry. Therefore, rapid and accurate diagnostic tools for SVA are crucial for preventing and controlling the disease.MethodsWe designed multiple primer pairs targeting the most conserved region of the SVA 3D gene and selected those with the highest specificity. Nfo-probes were subsequently developed based on the highest specificity primer pairs. Subsequently, the recombinase-assisted amplification (RAA) reaction was completed, and the reaction temperature and duration were optimized. The RAA amplicons were detected using a lateral flow device (LFD). Finally, a rapid and intuitive RAA-LFD assay was established against SVA.ResultsThe SVA RAA-LFD assay can be performed under reaction conditions of 35°C within 17 minutes, with results observable to the naked eye. We then evaluated the performance of this method. It exhibited high specificity and no cross-reaction with the other common swine pathogens. The lowest detectable limits of this method for the plasmid of pMD18-SVA-3D, DNA amplification product, and viral were 3.86×101 copies/µL, 8.76×10-7 ng/µL, and 1×100.25 TCID50/mL, respectively. A total of 44 clinical samples were then tested using the RAA-LFD, PCR, and RT-qPCR methods. The results demonstrated a consistent detection rate between the RAA-LFD and RT-qPCR assays.ConclusionThe SVA RAA-LFD assay developed in our study exhibits excellent specificity, sensitivity, and time-saving attributes, making it ideally suited for utilization in lack-instrumented laboratory and field settings.

Phytophthora sojae is a devastating plant pathogen that causes soybean Phytophthora root rot worldwide. Early on-site and accurate detection of the causal pathogen is critical for successful management. In this study, we have developed a novel and specific one-pot RPA/PCR-CRISPR/Cas12 assay for onsite detection (Cas-OPRAD) of Phytophthora root rot (P. sojae). Compared to the traditional RPA/PCR detection methods, the Cas-OPRAD assay has significant detection performance. The Cas-OPRAD platform has excellent specificity to distinguish 33 P. sojae from closely related oomycetes or fungal species. The PCR-Cas12a assay had a consistent detection limit of 100 pg. µL-1, while the RPA-Cas12a assay achieved a detection limit of 10 pg. µL-1. Furthermore, the Cas-OPRAD assay was equipped with a lateral flow assay for on-site diagnosis and enabled the visual detection of P. sojae on the infected field soybean samples. This assay provides a simple, efficient, rapid (<1 h), and visual detection platform for diagnosing Phytophthora root rot based on the one-pot CRISPR/Cas12a assay. Our work provides important methods for early and accurate onsite detection of Phytophthora root rot in the field or customs fields. [ABSTRACT FROM AUTHOR]

Southern stem canker (SSC) of soybean, attributable to the fungal pathogen Diaporthe aspalathi, results in considerable losses of soybean in the field and has damaged production in several of the main soybean-producing countries worldwide. Early and precise identification of the causal pathogen is imperative for effective disease management. In this study, we performed an RPA-CRISPR/Cas12a, as well as LAMP, PCR and real-time PCR assays to verify and compare their sensitivity, specificity and simplicity and the practicality of the reactions. We screened crRNAs targeting a specific single-copy gene, and optimized the reagent concentrations, incubation temperatures and times for the conventional PCR, real-time PCR, LAMP, RPA and Cas12a cleavage stages for the detection of D. aspalathi. In comparison with the PCR-based assays, two thermostatic detection technologies, LAMP and RPA-CRISPR/Cas12a, led to higher specificity and sensitivity. The sensitivity of the LAMP assay could reach 0.01 ng μL−1 genomic DNA, and was 10 times more sensitive than real-time PCR (0.1 ng μL−1) and 100 times more sensitive than conventional PCR assay (1.0 ng μL−1); the reaction was completed within 1 h. The sensitivity of the RPA-CRISPR/Cas12a assay reached 0.1 ng μL−1 genomic DNA, and was 10 times more sensitive than conventional PCR (1.0 ng μL−1), with a 30 min reaction time. Furthermore, the feasibility of the two thermostatic methods was validated using infected soybean leaf and seeding samples. The rapid, visual one-pot detection assay developed could be operated by non-expert personnel without specialized equipment. This study provides a valuable diagnostic platform for the on-site detection of SSC or for use in resource-limited areas. [ABSTRACT FROM AUTHOR]

A sensitive and biocompatible N-rich probe for rapid visual uranium detection was constructed by grafting two trianiline groups to 2,6-bis(aminomethyl)pyridine. Possessing excellent aggregation-induced emission (AIE) property and the advantages to form multidentate chelate with U selectively, the probe has been applied successfully to visualize uranium in complex environmental water samples and living cells, demonstrating outstanding anti-interference ability against large equivalent of different ions over a wide effective pH range. A large linear range (1.0 × 10−7–9.0 × 10−7 mol/L) and low detection limit (72.6 nmol/L, 17.28 ppb) were achieved for the visual determination of uranium. The recognition mechanism, photophysical properties, analytical performance and cytotoxicity were systematically investigated, demonstrating high potential for fast risk assessment of uranium pollution in field and in vivo. [ABSTRACT FROM AUTHOR]

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Blastocystis spp. is a ubiquitous protozoon in the intestinal tract of human and many animals. Microscopic examination is the main method of clinical diagnosis for Blastocystis spp., which is prone to false negative. A simple and rapid diagnosis of Blastocystis spp. infection is an important step to prevent and control blastocystosis. Here, a recombinase polymerase amplification-lateral flow dipstick (RPA-LFD) assay was developed for rapid visual detection of Blastocystis spp. DNA amplification could be performed within 18 min at 37°C. The minimum DNA detection limit was 1 µg/mL, and there was no cross-reactivity with 12 other non-target pathogens, which was consistent with the sensitivity of conventional PCR (cPCR). Furthermore, 56 fecal samples from the Third Affiliated Hospital of Xinxiang Medical University were tested using RPA and cPCR methods respectively, and the results were completely consistent. The results show that RPA-LFD method has high accuracy and visual results, which provides a new choice for the differential diagnosis and rapid field detection of Blastocystis spp. [ABSTRACT FROM AUTHOR]

AbstractLabel-free bimetallic CuFe Prussian blue analogue nanocubes (CuFe PBA NCs) were directly employed as colorimetric probes for the visual determination of glutathione (GSH). CuFe PBA NCs produce an absorption peak at 400 nm. In the presence of GSH, the CuFe PBA NCs were transformed into larger hollow nanospheres based on the acid-initiated Kirkendall effect, leading to the appearance of a new peak at 520 nm and a solution color change from yellow to red. Thus, the GSH-induced color changes allowed the establishment of a double-signal colorimetric assay for GSH using the ratio of absorbance at 520 and 400 nm (Δ(A520/A400)). Facile determination of GSH from 0.1 to 8 μM with satisfactory specificity was developed, providing a detection limit as low as 0.08 μM. Additionally, GSH concentrations exceeding 3 μM can be directly identified by the naked eye. The colorimetric assay for GSH has also been demonstrated to have application for serum analysis. Compared with conventional single-signal colorimetric determination, the ratiometric probe was demonstrated to provide good selectivity and high sensitivity. [ABSTRACT FROM AUTHOR]

Avian influenza viruses (AIVs) of the H5 subtype rank among the most serious pathogens, leading to significant economic losses in the global poultry industry and posing risks to human health. Therefore, rapid and accurate virus detection is crucial for the prevention and control of H5 AIVs. In this study, we established a novel detection method for H5 viruses by utilizing the precision of CRISPR/Cas12a and the efficiency of RT-RPA technologies. This assay facilitates the direct visualization of detection results through blue light and lateral flow strips, accurately identifying H5 viruses with high specificity and without cross-reactivity against other AIV subtypes, NDV, IBV, and IBDV. With detection thresholds of 1.9 copies/μL (blue light) and 1.9 × 103 copies/μL (lateral flow strips), our method not only competes with but also slightly surpasses RT-qPCR, demonstrating an 80.70% positive detection rate across 81 clinical samples. The RT-RPA/CRISPR-based detection method is characterized by high sensitivity, specificity, and independence from specialized equipment. The immediate field applicability of the RT-RPA/CRISPR approach underscores its importance as an effective tool for the early detection and management of outbreaks caused by the H5 subtype of AIVs. [ABSTRACT FROM AUTHOR]

Photodynamic therapy (PDT) emerges as a novel approach to treat tumors utilizing "photosensitizers" and "light". This method involves exposing the tumor site to specific wavelengths of light, activating photosensitizers concentrated in the tumor to generate highly oxidizing reactive oxygen species, ultimately dismantling the tumor. In comparison to surgery, chemotherapy, and radiation therapy, PDT boasts simplicity in operation, precise targeting, minimal invasiveness, lack of drug resistance, and the ability to trigger systemic immunity. While PDT has gained widespread adoption in developed nations, its promotion in China is still underway, hampered by a lack of public understanding. In response, we present a popular science experiment elucidating tumor-targeted photodynamic therapy using a laboratory-synthesized selenium-Rhodamine photosensitizer. The experiment encompasses enzyme activation of targeted photosensitizers, visual detection of singlet oxygen, and the photodynamic eradication of cancer cells. This experiment vividly illustrates the scientific principles behind targeted photodynamic therapy, enhancing public awareness of photodynamic cancer treatment. Such efforts are crucial for advancing the adoption of photodynamic therapy in our country, underscoring the pivotal role of chemistry in cancer treatment. The entire popular science experiment is straightforward, visually intuitive, and has demonstrated effective results in science outreach. [ABSTRACT FROM AUTHOR]

Hybrid nanozyme graphene quantum dots (GQDs) deposited TiO2 nanotubes (NTs) on titanium foil (Ti/TiO2 NTs-GQDs) were manufactured by bestowing the hybrid with the advantageous porous morphology, surface valence states, high surface area, and copious active sites. The peroxidase-like activity was investigated through the catalytic oxidation of chromogenic substrate 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H2O2, which can be visualized by the eyes. TiO2 NTs and GQDs comprising oxygen-containing functional groups can oxidize TMB in the presence of H2O2 by mimicking peroxidase enzymes. The peroxidase-mimicking activity of hybrid nanozyme was significantly escalated by introducing light illumination due to the photosensitive features of the hybrid material. The peroxidase-like activity of Ti/TiO2 NTs-GQDs enabled H2O2 determination over the linear range of 7 to 250 μM, with a LOD of 2.1 µM. The satisfying peroxidase activity is possibly due to the unimpeded access of H2O2 to the catalyst's active sites. The porous morphology provides the easy channeling of reactants and products. The periodic structure of the material also gave rise to acceptable reproducibility. Without material functionalization, the Ti/TiO2 NTs-GQDs can be a promising substitute for peroxidases for H2O2 detection. [ABSTRACT FROM AUTHOR]

Pathogen infections including Shigella flexneri have posed a significant threat to human health for numerous years. Although culturing and qPCR were the gold standards for pathogen detection, time-consuming and instrument-dependent restrict their application in rapid diagnosis and economically less-developed regions. Thus, it is urgently needed to develop rapid, simple, sensitive, accurate, and low-cost detection methods for pathogen detection. In this study, an immunomagnetic beads-recombinase polymerase amplification-CRISPR/Cas12a (IMB-RPA-CRISPR/Cas12a) method was built based on a cascaded signal amplification strategy for ultra-specific, ultra-sensitive, and visual detection of S. flexneri in the laboratory. Firstly, S. flexneri was specifically captured and enriched by IMB (Shigella antibody-coated magnetic beads), and the genomic DNA was released and used as the template in the RPA reaction. Then, the RPA products were mixed with the pre-loaded CRISPR/Cas12a for fluorescence visualization. The results were observed by naked eyes under LED blue light, with a sensitivity of 5 CFU/mL in a time of 70 min. With no specialized equipment or complicated technical requirements, the IMB-RPA-CRISPR/Cas12a diagnostic method can be used for visual, rapid, and simple detection of S. flexneri and can be easily adapted to monitoring other pathogens. [ABSTRACT FROM AUTHOR]

This novel nano-adsorbent offers high selectivity and rapid screening of Hg2+ through visual detection. The process involved coating the magnetic nanoparticle (MNP) with alginate, followed by immobilization of a DNA aptamer specific to Hg2+, resulting in the formation of Apt@Alg@MNP. It was utilized as a nano-adsorbent for rapid screening tests to qualitatively detect Hg2+ on the particles by observing the color change in the Hg2+-adsorbed Apt@Alg@MNP dispersion. The nano-adsorbent exhibited high specificity toward Hg2+ and demonstrated strong anti-interference capability. It was successfully employed as a nano-adsorbent for the determination of Hg2+ in various real water samples. [ABSTRACT FROM AUTHOR]

Conveyor belt misalignment is an operational and maintenance issue for many belt conveyor systems and can result in significant downtime and equipment failure. This article presents a visual detection method for belt misalignment detection using real-time instance segmentation. An improved version of the You Only Look At CoeffcienTs (YOLACT) network is discussed, where the feature backbone of the original YOLACT network is optimized. The improved YOLACT network is used to experimentally detect the belt misalignment with different combinations of bulk solid and operating conditions. The results show that the detection precision of the improved YOLACT network achieves 86.05% mean Average Precision (mAP), in which the greatest improvement on the mAP is the FPN modification with an increase of 1.75% compared to the YOLACT network with the ResNeXt-50. In terms of the detection speed, the improved YOLACT network (15.19 Frames Per Second [FPS]) outperforms the Mask R-CNN (3.42 FPS) and the MS R-CNN (3.41 FPS). Moreover, the averaged detection error from the tests is 0.74 mm for a belt loaded with different bulk solids. It can be concluded that the application of the improved YOLACT network is effective for the real-time detection of conveyor belt misalignment. [ABSTRACT FROM AUTHOR]

This novel nano-adsorbent offers high selectivity and rapid screening of Hg2+ through visual detection. The process involved coating the magnetic nanoparticle (MNP) with alginate, followed by immobilization of a DNA aptamer specific to Hg2+, resulting in the formation of Apt@Alg@MNP. It was utilized as a nano-adsorbent for rapid screening tests to qualitatively detect Hg2+ on the particles by observing the color change in the Hg2+-adsorbed Apt@Alg@MNP dispersion. The nano-adsorbent exhibited high specificity toward Hg2+ and demonstrated strong anti-interference capability. It was successfully employed as a nano-adsorbent for the determination of Hg2+ in various real water samples. [ABSTRACT FROM AUTHOR]

Aptamer-based biosensors have been demonstrated to provide real-time physical and chemical signals for biomedicine, food safety, drug identification, and metal ion determination. In this study, cadmium ion (Cd2+) was determined in drinking water by color signaling using the specific binding of the aptamer and target by its regulation of the catalytic capacity of gold nanoparticles (AuNPs). When sodium borohydride (NaBH4) and a probe with a catalytic function were present, the solution containing 4-nitrophenol changed from yellow to colorless. Under optimal conditions, the naked eye was sufficient to determine Cd2+ with a limit of detection (LOD) of 5 μM. The discoloration time showed a positive correlation with Cd2+ concentration up to 30 μM. This method was label-free, efficient, rapid, and selective for Cd2+ in water without expensive instruments, suggesting practical applications. [ABSTRACT FROM AUTHOR]

Giardiasis is a common intestinal infection caused by Giardia duodenalis, which is a major economic and health burden for humans and livestock. Currently, a convenient and effective detection method is urgently needed. CRISPR/Cas12a-based diagnostic methods have been widely used for nucleic acid-based detection of pathogens due to their high efficiency and sensitivity. In this study, a technique combining CRISPR/Cas12a and RPA was established that allows the detection of G. duodenalis in faecal samples by the naked eye with high sensitivity (10−1 copies/μL) and specificity (no cross-reactivity with nine common pathogens). In clinical evaluations, the RPA-CRISPR/Cas12a-based detection assay detected Giardia positivity in 2% (1/50) of human faecal samples and 47% (33/70) of cattle faecal samples, respectively, which was consistent with the results of nested PCR. Our study demonstrated that the RPA-CRISPR/Cas12a technique for G. duodenalis is stable, efficient, sensitive, specific and has low equipment requirements. This technique offers new opportunities for on-site detection in remote and poor areas. [ABSTRACT FROM AUTHOR]

An intelligent fluorescent nanoprobe (lignite-CDs-Eu) was constructed by an effective and facile method based on lignite-derived carbon dots (CDs) and lanthanide europium ions (Eu3+), which exhibited high sensitivity, low detection limit (13.35 nM) and visual color variation (from blue to red) under ultraviolet light towards tetracycline (TC) detection. Significantly, portable and economical sensors were developed using lignite-CDs-Eu immobilized fiber material of filter paper and wearable glove with the aid of color extracting and image processing application (APP) in the smartphone. Facile, fast and real-time visual detection of TC in food samples was realized. Moreover, logic gate circuit was also designed to achieve intelligent and semi-quantitative inspection of TC. To some extent, this study extended the cross-application of intelligent computer software in food analytical science, and provided a certain reference for the development of small portable detection sensors which were suitable for convenience and non-professional use in daily life. [ABSTRACT FROM AUTHOR]

Colloidal crystals are materials self‐assembled from the colloidal nanoparticles. Due to the ordered microstructure, they exhibit significant optical properties and have shown huge potential in the field of biosensing. Besides, the unique macroscopic shapes can also play a critical role in the sensing process. Here, we present a comprehensive discussion on the colloidal crystal‐based biosensors with different topological shapes, including the development strategies of currently reported colloidal crystal particles, films, and fibers, and their recent progress in biosensing. In addition, the faced challenges and the possible solutions are also concluded and discussed. We expect this review can enrich the knowledge and encourage the communication of interdisciplinary researchers, thus promoting the further development and practical applications of colloidal crystal‐based biosensors. [ABSTRACT FROM AUTHOR]

We developed a fluorescent double network hydrogel with ionic responsiveness and high mechanical properties for visual detection. The nanocomposite hydrogel of laponite and polyacrylamide serves as the first network, while the ionic cross-linked hydrogel of terbium ions and sodium alginate serves as the second network. The double-network structure, the introduction of nanoparticles and the reversible ionic cross-linked interactions confer high mechanical properties to the hydrogel. Terbium ions are not only used as the ionic cross-linked points, but also used as green emitters to endow hydrogels with fluorescent properties. On the basis of the "antenna effect" of terbium ions and the ion exchange interaction, the fluorescence of the hydrogels can make selective responses to various ions (such as organic acid radical ions, transition metal ions) in aqueous solutions, which enables a convenient strategy for visual detection toward ions. Consequently, the fluorescent double network hydrogel fabricated in this study is promising for use in the field of visual sensor detection. [ABSTRACT FROM AUTHOR]

Estimating bioavailable heavy metals in seawater is closely related to the indication of ecological risk. This study combined a CadR-regulated vioABE expression module and a MerR-regulated VioC expression module to generate a novel dual-colored bacterial cell-based biosensor. After genetic optimization, the preferred biosensor could detect as low as 9.7 nM Cd(II), 24.4 nM Pb(II), and 0.5 nM Hg(II). Increased grey-green intensities were observed in Cd(II) (4.9 nM to 40 μM) and Pb(II) (24.4 nM to 200 μM) exposure groups. Interestingly, increased purple intensity was observed in the Hg(II) exposure group (3.7 to 468.8 nM) in a dose-dependent manner. A low-cost and mini-equipment biosensing process was established for detecting pollutant heavy metals in seawater, with the added advantage of providing information on the bioavailability and cytotoxicity of heavy metals. High salinity weakly interferes with the biosensing response to Hg(II). This study shows that novel colorimetric biosensors have the potential to simultaneously report various toxic metals in environmental water samples, contributing to protecting marine ecology.