Color Signals Research Articles

Portable paper-based microfluidic devices with Cu1-xAgxS NPs modification for multiplex intelligent visualized detection of adrenaline and glucose simultaneously

BackgroundAdrenaline and glucose are essential biomarkers in human body for maintaining metabolic balance. Abnormal levels of adrenaline and glucose are associated with various diseases. Therefore, it is important to design portable, on-site devices for rapid adrenaline and glucose analysis to safeguard health. Traditional paper-based analytical devices (μPADs) for multiplexed detection typically required multiple recognized probes, increasing the cost and complexity. Moreover, non-uniform color distribution, caused by lateral chromatographic elution effect, reduced results accuracy. Hence, it is necessary to construct visualized μPADs with controlled flow capability using single sensing probe for simultaneous adrenaline and glucose analysis in point-of-care testing (POCT). ResultsThe portable multiplexed 3D-folded μPADs have been developed for the visualized, accurate and simultaneous detection of adrenaline and glucose, employing Ag-doped copper sulfide nanoparticles (Cu1-xAgxS NPs) as multifunctional sensing probe. The μPADs integrated the sampling entrance layer, buffer layer and test layer into a single device through wax printing, allowing the analyte solution to flow vertically from buffer zones to detection zones, thereby minimizing lateral chromatographic elution effect. Cu1-xAgxS NPs, exhibiting laccase-like and peroxidase-like multi-enzyme activities, were modified on various detection zones of μPADs for multiplex colorimetric analysis of adrenaline and glucose. Based on Cu1-xAgxS-induced colorimetric reactions, the orange-red and blue colors were generated in adrenaline and glucose detection zones, respectively. Subsequently, color signals were converted into RGB values via smartphone application (APP) for rapid and intelligent results analysis. The Cu1-xAgxS-incorporated μPADs exhibited colorimetric uniformity and accuracy with limit of detection (LOD) of 10.2 nM and 11.5 μM, respectively. SignificanceThe adjustable laccase-like and peroxidase-like activities of Cu1-xAgxS NPs induced by Ag doping provide a new perspective for multiple biomarkers analysis. Benefiting from the excellent multienzyme activity of Cu1-xAgxS NPs, μPADs can perform on-site, visual and multiplex analysis using a single probe, demonstrating their potential for POCT in personal healthcare. The 3D folded Cu1-xAgxS-incorporated μPADs with integrated horizontal and vertical flows exhibit uniform color signals for obtaining accurate detection results.

Colour guided ground-to-UAV fire segmentation

Leveraging ground-annotated data for scene analysis on unmanned aerial vehicles (UAVs) can lead to valuable real-world applications. However, existing unsupervised domain adaptive (UDA) methods primarily focus on domain confusion, which raises conflicts among training data if there is a huge domain shift caused by variations in observation perspectives or locations. To illustrate this problem, we present a ground-to-UAV fire segmentation method as a novel benchmark to verify typical UDA methods, and propose an effective framework, Colour-Mix, to boost the performance of the segmentation method equivalent to the fully supervised level. First, we identify domain-invariant fire features by deriving fire-discriminating components (u*VS) defined in colour spaces Lu*v*, YUV, and HSV. Notably, we devise criteria to combine components that are beneficial for integrating colour signals into deep-learning training, thus significantly improving the generalisation abilities of the framework without resorting to UDA techniques. Second, we perform class-specific mixing to eliminate irrelevant background content on the ground scenario and enrich annotated fire samples for the UAV imagery. Third, we propose to disentangle the feature encoding for different domains and use class-specific mixing as robust training signals for the target domain. The framework is validated on the drone-captured dataset, Flame, by using the combined ground-level source datasets, Street Fire and Corsica Wildfires. The code is available at https://github.com/Rui-Zhou-2/Colour-Mix.

Rapid reagent-free anaemia screening using plant-derived “HemoQR” paper-strips and smartphone: A study on 200 human subjects

Detecting anaemia in resource-limited settings is challenging due to limited access to diagnostic tools, healthcare infrastructure, and trained personnel, often resulting in underdiagnosis and delayed treatment. This study aims to evaluate HemoQR, a novel point-of-care (POC) diagnostic method for haemoglobin (Hb) level detection using a smartphone-based system integrated with a paper strip without needing any reagent or additional auxiliary device. The goal is to assess the efficacy of this portable, user-friendly, rapid and accurate alternative for Hb measurement in large-scale intervention programmes such as Anaemia-mukt Bharat (AMB), which is crucial for diagnosing anaemia and monitoring various health conditions. The method involves the transfer of one drop of the blood sample to a paper strip that is made indigenously using plant based cellulosic sources for optimal functionality. The colour signal around the test spot is quantitatively analysed using a smartphone camera equipped with a custom application. The application processes the images through a machine learning algorithm to determine the Hb concentration. The system was evaluated in a clinical trial involving 200 participants, comparing its performance with the gold-standard laboratory Hb assay using automated haematology analyser. The smartphone-based method demonstrated high sensitivity (87.09 %) and specificity (96.11 %) for anaemia screening, as compared with laboratory results. The average detection time was significantly reduced to under q minute, and the system showed excellent user-friendliness and portability with no auxiliary device needed beyond the smartphone. Clinical trial results indicated that the device was accurate and reliable across different Hb levels. Summarily, HemoQR evidenced to be a promising tool for POC diagnostics. Its high accuracy, rapid results, and ease of use make it suitable for both clinical settings and remote areas with limited access to laboratory facilities. Future research will prioritize further validation and integration of the anaemia screening outcome with electronic health records from a large population cohort. This will help identify early indicators and signals of numerous emerging disease burdens that could escalate into secondary and tertiary health crises if not addressed in time.

A dual-mode colorimetric and surface-enhanced Raman strategy for chloramphenicol detection based on the Au@Pt nanozyme and EXPAR

The misuse of chloramphenicol (CAP) has resulted in an escalation of antibiotic-resistant bacterial strains, posing a significant threat to human health. Through the fabrication of magnetic multi-“hotspot” nanoflower particles as SERS substrates and combine bimetallic peroxidase Au@Pt, dual-mode detection of CAP was achieved. The preparation of magnetic nanoparticles Fe3O4@Au facilitated rapid aggregation, enriching a SERS signal. Integrated with the exponential amplification reaction (EXPAR) strategy, under isothermal conditions, a highly rate increase of amplicon production was achieved, thereby binding more nanozyme Au@Pt. In the presence of the target CAP, due to specific binding with the aptamer, the EXPAR was activated, generating a substantial amount of amplicons that formed a stable “Y-shaped” structure with magnetic nanoparticle probes and nanozyme probes. With the addition of TMB, the excellent peroxidase-like activity of the nanozyme oxidized it to oxTMB, resulting in changes in both color and Raman signals. This strategy achieved dual-mode ultra-trace detection of CAP. The SERS detection ranged from 1.0 × 10-12 M to 1.0 × 10-6 M, with a detection limit of 4.96 × 10-13 M; the colorimetric method ranged from 2.5 × 10-7 M to 1.0 × 10-8 M, with a detection limit of 9.23 × 10-9 M. This method offers a new approach and insights for the ultra-trace detection of antibiotics.

Highly sensitive multiplexed colorimetric lateral flow immunoassay by plasmon-controlled metal-silica isoform nanocomposites: PINs.

Lateral flow assay (LFA) systems use metal nanoparticles for rapid and convenient target detection and are extensively studied for the diagnostics of various diseases. Gold nanoparticles (AuNPs) are often used as probes in LFAs, displaying a single red color. However, there is a high demand for colorimetric LFAs to detect multiple biomarkers, requiring the use of multicolored NPs. Here, we present a highly sensitive multiplexed colorimetric lateral flow immunoassay by multicolored Plasmon-controlled metal-silica Isoform Nanocomposites (PINs). We utilized the localized surface plasmon resonance effect to create multi-colored PINs by precisely adjusting the distance between the NPs on the surface of PINs through the controlled addition of reduced gold and silver precursors. Through simulations, we also confirmed that the distance between nanoparticles on the surface of PINs significantly affects the color and colorimetric signal intensity of the PINs. We achieved multicolored PINs that exhibit stronger colorimetric signals, offering a new solution for LFA detection with high sensitivity and a 33 times reduced limit of detection (LOD) while maintaining consistent size deviations within 5%. We expect that our PINs-based colorimetric LFA will facilitate the sensitive and simultaneous detection of multiple biomarkers in point-of-care testing.

Ultrasensitive on-site colorimetric detection of Campylobacter in oyster with a portable biosensing platform based on hydroxamate/Fe3+–violurate chromogenic reaction and smartphone

The contamination of Campylobacter in shellfish poses a health risk for its pathogenicity associated with campylobacteriosis. However, an efficient method to detect this risk is unavailable. Herein, we introduce a portable colorimetric biosensing platform that comprises three modules: an enrichment module 1, a binding and transduction module 2, and a smartphone-based module 3. Module 1 is an aptamer-modified 96-well plate for the specific capture of Campylobacter in a simple and high-throughput manner. Module 2 features a bifunctional biopolymer of L-glutamic acid γ-hydroxamate–alginate–Fe3+ coordinating fusarinine C, which can bind the captured Campylobacter cells and transduce them into amplified color signals upon reaction with Fe3+–violurate complexes. Module 1 achieves a capture efficiency of 97.24 %, and the subsequent addition of module 2 renders colorimetric indication of Campylobacter ranging from 101 to 106 CFU/mL, achieving an actual limit of detection of 8 CFU/mL validated by Campylobacter single-cells. Moreover, the generated colors can be recognized and converted into cell densities by module 3 with ultrasensitivity. Notably, this biosensor–smartphone platform accomplishe reliable high-throughput colorimetric detection of Campylobacter in real samples with an accuracy of 80 %. This work showcases a proof of principle for efficient on-site detection of Campylobacter contamination regarding shellfish farming.

Ensemble percepts of colored targets among distractors are influenced by hue similarity, not categorical identity.

Color can be used to group similar elements, and ensemble percepts of color can be formed for such groups. In real-life settings, however, elements of similar color are often spatially interspersed among other elements and seen against a background. Forming an ensemble percept of these elements would require the segmentation of the correct color signals for integration. Can the human visual system do this? We examined whether observers can extract the ensemble mean hue from a target hue distribution among distractors and whether a color category boundary between target and distractor hues facilitates ensemble hue formation. Observers were able to selectively judge the target ensemble mean hue, but the presence of distractor hues added noise to the ensemble estimates and caused perceptual biases. The more similar the distractor hues were to the target hues, the noisier the estimates became, possibly reflecting incomplete or inaccurate segmentation of the two hue ensembles. Asymmetries between nominally equidistant distractors and substantial individual variability, however, point to additional factors beyond simple mixing of target and distractor distributions. Finally, we found no evidence for categorical facilitation in selective ensemble hue formation.

Development of a Spot Test (ST) Based on the Nucleic Acid Amplification Test (NAAT) for Ginseng Species Authentication

It is very challenging to distinguish between Panax ginseng (P. ginseng) and Panax quinquefolius (P. quinquefolius) based on their physical appearances. Therefore, a molecular test that can be performed in commercial settings is needed to address this challenge. We have selected a locus containing a single nucleotide polymorphism (SNP) site in the Dammarendiol-II Synthase (DS) gene to differentiate between P. ginseng and P. quinquefolius. An isothermal nucleic acid amplification test (NAAT) developed previously was adapted and used on a spot test (ST) format consisting of a sample pad, a nitrocellulose membrane, and an adsorbent pad. An ST with a colorimetric detection method has been developed with visual detection based on 20-nm gold nanoparticles. The presence of the target DNA will generate a red color signal, which is visible to the naked eye. The assay comprises the capture probes, constructed based on the DS gene of ginseng, and the ends of the probe sequences sit on the SNP site for the P. ginseng and P. quinquefolius sequences; the detection probe employed in the assay is tagged with gold. The NAAT amplifies the extracted plant genomic samples and enhances the detection of specific SNPs. This NAAT technique was used to authenticate two ginseng root samples, showing greater specificity ratios than our previous work.

Flash behaviors protect prey from avian predators

Abstract It has been proposed that flash behaviors, defined as the transient display of conspicuous color patches during escape, serve as an anti-predator defense in camouflaged prey. While recent studies in humans have demonstrated the effectiveness of flash behaviors in improving the survival of artificial prey, it remains unclear whether these benefits also arise in more natural systems involving non-human predators. This study investigated the adaptive significance of flash behaviors using chicks (Gallus gallus domesticus) as predators and virtual prey. Our experiments revealed that prey employing flash behaviors consistently enhanced their survival rate compared to non-flashing prey. Additionally, prey with non-conspicuous escape colors, though distinct from their resting colors, also showed a higher survival rate than non-flashing prey, challenging the conventional belief that conspicuous colors are required for search interference. An interplay between prey size and flash behaviors in enhancing survival was evident, with larger prey benefiting more than smaller prey. We found no evidence to suggest that being hidden before initiating an escape confers a survival advantage to flashing prey compared to being visible before escape. This study sheds light on the adaptive benefits of flash behaviors against natural predators and contributes to our understanding of the widespread occurrence of hidden color signals in camouflaged prey. We encourage further studies to explore the effectiveness of remaining hidden in flashing prey when confronted with natural predators, as well as how predators might learn to overcome the deception of flash behaviors.

How life became colourful: colour vision, aposematism, sexual selection, flowers, and fruits.

Plants and animals are often adorned with potentially conspicuous colours (e.g. red, yellow, orange, blue, purple). These include the dazzling colours of fruits and flowers, the brilliant warning colours of frogs, snakes, and invertebrates, and the spectacular sexually selected colours of insects, fish, birds, and lizards. Such signals are often thought to utilize pre-existing sensitivities in the receiver's visual systems. This raises the question: what was the initial function of conspicuous colouration and colour vision? Here, we review the origins of colour vision, fruit, flowers, and aposematic and sexually selected colouration. We find that aposematic colouration is widely distributed across animals but relatively young, evolving only in the last ~150 million years (Myr). Sexually selected colouration in animals appears confined to arthropods and chordates, and is also relatively young (generally <100 Myr). Colourful flowers likely evolved ~200 million years ago (Mya), whereas colourful fruits/seeds likely evolved ~300 Mya. Colour vision (sensu lato) appears to be substantially older, and likely originated ~400-500 Mya in both arthropods and chordates. Thus, colour vision may have evolved long before extant lineages with fruit, flowers, aposematism, and sexual colour signals. We also find that there appears to have been an explosion of colour within the last ~100 Myr, including >200 origins of aposematic colouration across nine animal phyla and >100 origins of sexually selected colouration among arthropods and chordates.

Performance-complementary colorimetric/electrochemical bimodal detection of Hg2+ based on analyte-accelerated peroxidase-mimicking activity of GO-AuNPs

As a highly toxic heavy metal pollutant, mercury ions cause substantial risks to the environment and human health, and developing high-performance and convenient analytical approaches becomes quite important. Here we propose a performance-complementary colorimetric/electrochemical dual-mode Hg2+ sensing method based on the analyte accelerating the peroxidase-mimetic activity of gold nanoparticles (AuNPs) loaded on graphene oxide (GO). The GO-AuNPs composite was readily fabricated via mechanically mixing AuNPs and GO with controllable proportions, exhibiting a weak peroxidase-like activity in catalyzing the oxidation reaction of 3,3′,5,5′-tetramethylbenzidine (TMB). Upon the introduction of Hg2+, it combined with AuNPs rapidly, significantly enhancing the peroxidase-mimicking activity of GO-AuNPs. By capturing the color signal of the generated blue oxTMB and the electro-oxidation response of residual TMB, a “turn-on” colorimetric and “turn-off” electrochemical bimodal method was established for Hg2+ measurement, providing a linear range of 10–60 μg/L in colorimetric detection and 0.001–20 μg/L in electrochemical analysis. Different from common bimodal assays mainly improving detecting reliability due to their cross-validation ability, our dual-mode sensor exhibits the unique feature of complementary sensitivity and detection range, thus enabling its flexible use in analyzing different levels of the target in a broad scope with no requirement for sample enrichment and dilution.

Cu2O nanoparticles with morphology-dependent peroxidase mimic activity: a novel colorimetric biosensor for deoxynivalenol detection.

Different morphological Cu2O nanoparticles including cube, truncated cube, and octahedron were successfully prepared by a selective surface stabilization strategy. The prepared cube Cu2O exhibited superior peroxidase-like activity over the other two morphological Cu2O nanoparticles, which can readily oxidize 3,3',5,5'-tetramethylbenzidine (TMB) to form visually recognizable color signals. Consequently, a sensitive and simple colorimetric biosensor was proposed for deoxynivalenol (DON) detection. In this biosensor, the uniform cube Cu2O was employed as the vehicle to label the antibody for the recognition of immunoreaction. The sensing strategy showed a detection limit as low as 0.01ng/mL, and a wide linear range from 2 to 100ng/mL. Concurrently, the approximate DON concentration can be immediately and conveniently observed by the vivid color changes. Benefiting from the high sensitivity and selectivity of the designed biosensor, the detection of DON in wheat, corn, and tap water samples was achieved, suggesting the bright prospect of the biosensor for the convenient and intuitive detection of DON in actual samples.

Unveiling the potential of the capillary-driven microfluidic paper-based device integrated with smartphone-based for simultaneously colorimetric salivary ethanol and △9-tetrahydrocannabinol analysis

Monitoring various biomarkers in saliva samples emerges as a dynamic and non-invasive method. However, the high viscosity of saliva presents a distinct challenge when integrating paper-based platforms for on-site analysis. In addressing this challenge, we introduced the capillary-driven microfluidic paper-based analytical devices (μCD-PAD) designed for user-friendly and simultaneous detection of ethanol and tetrahydrocannabinol (THC) in saliva without a sample preparation step. Employing a colorimetric approach, we quantified both analytes. Synthetic salivas of varying viscosity flowed seamlessly to the detection zone without needing a sample preparation step, and no impact on colorimetric detection due to viscosity was observed (RSD <5 %). Within 10 min after the solution reached the detection zone, the device produced a homogeneous color signal, easily analyzed by a smartphone camera. To extend the application for determination to cover a legal limit concentration of ethanol and concentration of salivary THC even 24 h after marijuana consumption, the detection time of 30 min was optimized. Moreover, a saliva sample containing both analytes was used to demonstrate the capability of the developed device to detect ethanol and THC simultaneously. No cross-talk between ethanol and THC occurred and showed recovery in the 98–102 % for ethanol and 95–105 % for THC with acceptable accuracy. This developed device exhibits excellent potential for forensic applications, providing a user-friendly, cost-effective, and real-time screening tool for detecting ethanol and THC in saliva.

Application of a dual-modality colorimetric analysis methodto inkjet printing lateral flow detection of Salmonella typhimurium.

Lateral flow assay (LFA) color signal quantification methods were developed by utilizing both International Commission on Illumination (CIE) LAB (CIELAB) color space and grayscale intensity differences. The CIELAB image processing procedure included calibration, test, control band detection, and color difference calculation, which can minimize the noise from the background. The LFA platform showcases its ability to accurately discern relevant colorimetric signals. The rising occurrence of infectious outbreaks from foodborne pathogens like Salmonella typhimurium presents significant economic, healthcare, and public health risks. The study introduces an aptamer-based lateral flow (ABLF) platform by using inkjet printing for specially detecting S. typhimurium. The ABLF utilized gold-decorated polystyrene microparticles, functionalized with specific S. typhimurium aptamers (Ps-AuNPs-ssDNA). The platform demonstrates a detection limit of 102 CFU mL-1 in buffer solutions and 103 CFU mL-1 in romaine lettuce tests. Furthermore, it sustained performance for over 8 weeks at room temperature. The ABLF platform and analysis methods are expected to effectively resolve the low-sensitivity problems of the former LFA systems and to bridge the gap between lab-scale platforms to market-ready solutions by offering a simple, cost-effective, and consistent approach to detecting foodborne pathogens in real samples.

Cooling Condition Effect on Spectral Properties and Smartphone-Based Anticounterfeiting Application of Zn3Ga2Ge2O10/Cr3+ Phosphors.

The influence of cooling history for the Zn3Ga2Ge2O10/Cr3+ phosphors prepared by solid state reaction on the spectral properties was discovered, and an anticounterfeiting scheme based on the identification with smartphone was proposed and experimentally demonstrated using the studied phosphors. A combination of color-tunable visible fluorescence emission and near-infrared (NIR) afterglow emission in Zn3Ga2Ge2O10/x mol % Cr3+(x = 0, 0.05, 1, 2, 3, and 4) phosphors to achieve multimode anticounterfeiting was reported. It is found that with the increasing Cr3+ concentrations, the visible emission can be tuned from green, light pink, and light red to deep red under 254 nm ultraviolet (UV) excitation. This phenomenon is related to the formation of oxygen vacancies in the host during the process of natural cooling and the characteristic emission of Cr3+. In addition, the persistent time of the Cr3+ emission centered at 700 nm can be also tuned by various Cr3+ concentrations. A possible mechanism was deduced to explain the afterglow phenomenon. Lastly, a flower pattern applied in anticounterfeiting was fabricated using the Zn3Ga2Ge2O10/x mol % Cr3+ (x = 0, 0.05, 1, 2, 3, and 4) phosphors to present tunable color and NIR afterglow signals at different excitation modes, and the camera of smartphone was chosen as a detection tool to take the NIR images. The results obtained above suggest that the prepared phosphors at natural cooling condition have great potential in affording advanced optical anticounterfeiting.

Jellyfish-Inspired Visual and Sensory Bubbling Robots with Automatic 3D Morphable Films for Underwater Environmental Interactions.

Coelenterates, such as Atolla jellyfish, are capable of integrating color, communication, and motion in a sophisticated manner, thereby enabling them to function as intelligent biological systems that can adapt to the challenges of the underwater environment. Extensive efforts have been dedicated to exploiting underwater visual, sensory, actuating, or combined systems. However, current biomimetic soft systems are still limited by the lack of comprehensive, integrated functional skins that can automatically deform, dynamically sense, and further send color signals when diving into underwater conditions. Here, we propose the synthetic soft skins composed of assembled entangled carbon nanotube networks and fluorescent unit-embedded elastomers which can be applied in a suspended form to allow autonomic 3D deformation, real-time perception, and dynamic fluorescence color transformation. The capabilities of the sensory and color display thresholds were controlled through the entanglement density of carbon nanotubes and the suspended area. As a demonstration, the soft thin skin was integrated into an artificial jellyfish robot, enabling the realization of a closed-loop feedback system for dynamic sensory processing, signal processing, and further 3D morphing-induced fluorescent color change, demonstrating significant potentials in underwater visual display, danger warning, and environmental exploration.

Imprinted membrane-covalent organic framework platform for efficient label-free visual detection of Listeria monocytogenes and Salmonella typhimurium in food samples

BackgroundRapid and sensitive detection of foodborne pathogens in food plays a crucial role in controlling outbreaks of foodborne diseases, of which Listeria monocytogenes and Salmonella typhimurium are representative and notable pathogens. Thus, it's of great importance to achieve the effective detection of these pathogens. However, the most common detection methods (culture-based technique, Polymerase Chain Reaction and immunological methods) have disadvantages that cannot be ignored, such as time-consuming, laborious, complex sample preparation process, and the possibility of cross-reaction. Hence, it is essential to develop a facile detection method for the pathogens with high sensitivity and specificity to avoid the above-mentioned disadvantages. ResultsWe report a label-free visual platform for the simultaneous capture and detection of Listeria monocytogenes and Salmonella typhimurium. For the first time, we have prepared polydimethylsiloxane-Chromotrope 2R membrane which serves as the substrate for bacterial capture and enrichment through the formation of specific recognition sites. The positively charged Pt-covalent organic framework combines with the pathogens through surface charge interaction, thereby the label-free sandwich platform is formed. Remarkable peroxidase activity of Pt-covalent organic framework converts the conversion of bacterial quantity into amplified color signal by catalyzing 3,3′,5,5′-Tetramethylbenzidine to oxidized 3,3′,5,5′-Tetramethylbenzidine. The platform demonstrates the capability to identify two representative food-borne pathogens within a time frame of 100 min, exhibiting high sensitivity and excellent specificity without the interference from non-target bacteria. The limit of detection of the visual platform toward Listeria monocytogenes and Salmonella typhimurium was 1.61 CFU mL−1 and 1.31 CFU mL−1, respectively. And the limit of quantification toward Listeria monocytogenes and Salmonella typhimurium was 4.94 CFU mL−1 and 2.47 CFU mL−1, respectively. The relative standard derivations of the visual platform for both bacteria were lower than 4.9 %. Furthermore, our proposed platform has obtained reliable and satisfactory results on analyzing diverse food samples. SignificanceThis research expands the application of a label-free platform combined with unlabeled nanocomponents in the rapid isolation and detection of diverse of food-borne pathogens. The platform possesses the advantages of simple operation and real-time monitoring, without complicated sample pretreatment process. The whole detection process can realize the simultaneous monitoring of Listeria monocytogenes and Salmonella typhimurium within 100 min. Furthermore, it is also of reference significance for the detection of other common pathogens.

A label-free fluorescence sensing strategy based on gold nanoparticles assisted copper nanoclusters for the detection of aflatoxin B1 in cereals and peanuts

To effectively monitor the degree of aflatoxin B1 (AFB1) contamination in food and mitigate potential health risks to consumers eating food contaminated with AFB1, a label-free fluorescence aptamer-sensing strategy utilizing gold nanoparticles (AuNPs) was developed. Polyvinylpyrrolidone-copper nanoclusters (PVP-CuNCs) and AuNPs were selected as donor/acceptor pairs to convert the color signal change of AuNPs into fluorescence signal changes in PVP-CuNCs via the inner filter effect (IFE). In the presence of AFB1, the aptamer preferentially adsorbed with AFB1, and the AuNPs without aptamer protection changed color from red to blue under NaCl-induced aggregation. The green fluorescence of PVP-CuNCs recovered gradually. The developed strategy offers high sensitivity for the detection of AFB1, with a linear range of 0.02–20 μg L−1, and a low detection limit of 0.69 μg L−1. In addition, the strategy was successfully applied to real samples such as corn, rice, oats and peanuts, and the recovery rate was 93.4–106.2 %, which verified the reliability and applicability of this strategy. This strategy has the advantages of cost-effectiveness, high sensitivity, low detection limit and easy operation, providing a reference for sensitive and selective detection of mycotoxins contamination in food.

Multiple plumage color signals associated with courtship displays may represent body quality in male golden pheasants (Chrysolophus pictus)

Many animals display numerous colors that can range from red, green, blue, and orange to ultraviolet, whereas others are dull or have a uniform coloration. The reason for this variation in coloration remains unknown. It has been hypothesized that different colors represent multiple signals that either reflect different components, redundant information, or simply no longer provide reliable information regarding body quality. Here, we analyzed the highly diverse coloration of male golden pheasants ( Chrysolophus pictus) using an avian visual model from the avian visual system and related the different components of coloration to several phenotypic traits of body quality. We found that different components of plumage color correlated with the length of the body, tail, spur, and beak, suggesting that the multiple colors in male golden pheasants signal different components of body quality. In particular, tail length was correlated with many aspects of coloration, especially the green and orange colors of neck plumage, which are particularly important because male golden pheasants spread their neck plumage and show it to females during their courtship display. Therefore, these findings reveal that the plumage colors of male golden pheasants encode multiple signals that reflect their body condition during courtship displays.

Expression patterns of melanin-related genes are linked to crypsis and conspicuousness in a pumpkin toadlet.

Colour signals play pivotal roles in different communication systems, and the evolution of these characters has been associated with behavioural ecology, integumentary production processes and perceptual mechanisms of the species involved. Here, we present the first insight into the molecular and histological basis of skin colour polymorphism within a miniaturized species of pumpkin toadlet, potentially representing the lowest size threshold for colour polytypism in tetrapods. Brachycephalus actaeus exhibits a coloration ranging from cryptic green to conspicuous orange skin, and our findings suggest that colour morphs differ in their capability to be detected by potential predators. We also found that the distribution and abundance of chromatophores are variable in the different colour morphs. The expression pattern of coloration related genes was predominantly associated with melanin synthesis (including dct, edn1, mlana, oca2, pmel, slc24a5, tyrp1 and wnt9a). Up-regulation of melanin genes in grey, green and brown skin was associated with higher melanophore abundance than in orange skin, where xanthophores predominate. Our findings provide a significant foundation for comparing and understanding the diverse pathways that contribute to the evolution of pigment production in the skin of amphibians.