Limited Range Research Articles

American beech mortality in stands recently infected by beech bark disease: implications for partial cutting

Beech bark disease is a major concern for northern hardwood forest management that affects most of the American beech range in North America. In infected stands, mitigating effects of the disease and promoting more resistant beech populations for natural regeneration relies heavily on our ability to identify high-risk trees and adapt tree marking for partial harvesting. We monitored several individual characteristics, including external signs of disease, on 871 beech trees in recently infected northern hardwood stands at the northern range limit of American beech in Canada, to assess their ability to predict mortality over an eight-year period. At the stand level, the mortality rate over the study period was 29.3%, while the uninfected rate was 16.6%. At the tree level, the diameter, the levels of Neonectria perithecia coverage on the stem, crown dieback, and the level of canker coverage on the bark had the greatest capacity to predict individual short-term mortality. Therefore, tree markers should first select trees with a diameter > 20 cm that are affected by any sign or symptom of the disease, followed by smaller trees with > 10% coverage of Neonectria perithecia or crown dieback > 25%, and lastly, trees with > 50% coverage of canker.

Study on automated guided vehicle collision avoidance mechanism with external computer vision

In industrial automation, safely operating Automated Guided Vehicles (AGVs) in dynamic environments is challenging. Traditional collision avoidance methods, which rely on technologies like LiDAR (Light Detection and Ranging), have limitations in detection range, accuracy, and cost. This study introduces a new method called the Collision Avoidance System with External Computer Vision (CAECV). CAECV uses two cameras which are equipped on the wall in the factory to detect obstacles, and AGV don’t need to equip any obstacle detection sensors. The detection algorithm, combining YOLOv8 with an attention mechanism, excels at identifying obstacles. The system then converts image coordinates to global coordinates using inverse perspective mapping for precise obstacle localization. Experimental comparisons with traditional TIM laser scanning radar show that CAECV outperforms in detection range, response time, accuracy, and cost. CAECV offers a broader detection range, quicker response, and lower error rates. As more AGVs are deployed, CAECV becomes significantly more cost-effective than LiDAR-based systems. Moreover, CAECV can be integrated with LiDAR systems to enhance AGV obstacle avoidance. CAECV represents a scalable, accurate, and economical advancement in AGV collision avoidance technology for modern industrial use.

Micro-ring wavelength selective switch device based on contra-DC

This paper presents, to our knowledge, a novel micro-ring wavelength selective switch device based on a contra-directional coupler (contra-DC), which utilizes the transparent window formed by the contra-DC to select the single resonant wavelength of the micro-ring resonator, avoiding the limitation of free spectral range and realizing the function of wavelength selection/switching. The desired wavelength switching function is achieved by changing the crystal state of the Ge2Sb2Te5 (GST) loaded on the micro-ring resonator. When the device is in the on state, the desired wavelength signal is selectively output from the drop port of the bus waveguide; when the device is in the off state, light is output from the through port. By modifying the GST crystal state, selective routing of light can be achieved, which can be used in optical interconnection networks. The simulation is performed using a 3D finite-difference method. The wavelength selection device achieves a 3 dB bandwidthof 1.6 nm with a side lobe suppression ratio of 20 dB at a length of 230 µm; the switching device achieves the extinction ratio of about 14.7 dB and a side lobe suppression ratio of 18.2 dB between the on/off states.

Prohibited Mountains and Forests in Late Imperial China

This essay explores the various types of spaces, primarily montane forested areas, where human access was restricted, either conditionally or entirely, during late imperial times. The range of restrictions always included felling trees, but often also encompassed other forms of extraction from local ecosystems. Based on the motivations for setting up and regulating such zones, it proposes a typology that includes imperial parks and graves, sacred sites, military exclusion zones, and certain forested commons. Based on some commonalities between these types, it concludes by reflecting on the place of notions of sacrality in local policies that directly impacted forested areas.

Impacts of limits to adaptation on population and community persistence in a changing environment.

A key issue in predicting how ecosystems will respond to environmental change is understanding why populations and communities are able to live and reproduce in some parts of ecological and geographical space, but not in others. The limits to adaptation that cause ecological niches to vary in position and width across taxa and environmental contexts determine how communities and ecosystems emerge from selection on phenotypes and genomes. Ecological trade-offs mean that phenotypes can only be optimal in some environments unless these trade-offs can be reshaped through evolution. However, the amount and rate of evolution are limited by genetic architectures, developmental systems (including phenotypic plasticity) and the legacies of recent evolutionary history. Here, we summarize adaptive limits and their ecological consequences in time (evolutionary rescue) and space (species' range limits), relating theoretical predictions to empirical tests. We then highlight key avenues for future research in this area, from better connections between evolution and demography to analysing the genomic architecture of adaptation, the dynamics of plasticity and interactions between the biotic and abiotic environment. Progress on these questions will help us understand when and where evolution and phenotypic plasticity will allow species and communities to persist in the face of rapid environmental change.This article is part of the discussion meeting issue 'Bending the curve towards nature recovery: building on Georgina Mace's legacy for a biodiverse future'.

Development of a Novel Electrochemical Immunosensor for Rapid and Sensitive Detection of Sesame Allergens Ses i 4 and Ses i 5

Due to their lipophilicity and low content, the major sesame oleosin allergens, Ses i 4 and Ses i 5, are challenging to identify using conventional techniques. Then, a novel unlabeled electrochemical immunosensor was developed to detect the potential allergic activity of sesame oleosins. The voltammetric immunosensor was constructed using a composite of gold nanoparticles (AuNPs), polyethyleneimine (PEI), and multi-walled carbon nanotubes (MWCNTs), which was synthesized in a one-pot process and modified onto a glass carbon electrode to enhance the catalytic current of the oxygen reduction reaction. The oleosin antibody was then directed and immobilized onto the surface of the electrode, which had been modified with streptavidin (SPA), through the fragment crystallizable (Fc) region of the antibody. Under optimized conditions, the immunosensor exhibited a linear response within a detection range of 50 to 800 ng/L, with detection limits of 0.616 ng/L for Ses i 4 and 0.307 ng/L for Ses i 5, respectively. The immunosensor demonstrated excellent selectivity and stability, making it suitable for the quantification of sesame oleosins. The comparative analysis of various detection methods for sesame allergens was conducted, revealing that the immunosensor achieved a wide detection range and low limit of detection (LOD). Compared to traditional enzyme-linked immunosorbent assay (ELISA), the immunosensor successfully quantified the allergenicity potential of Ses i 4 and Ses i 5 in roasted sesame seeds at temperatures of 120 °C, 150 °C, and 180 °C. This innovative method offers a new perspective for the rapid quantification of sesame oleosins in foods and real-time monitoring of allergic potential, providing significant advancements in the field of food allergy detection.

Developmental plasticity does not improve performance during a species interaction: Implications for species turnover.

Species interactions can contribute to species turnover when the outcomes of the interactions are context dependent (e.g., change along environmental gradients). Plasticity may change this dynamic by altering the environmental tolerances of the species interacting. Here, we explored how the competitive interaction between two euryhaline fish, Poecilia reticulata and Poecilia picta, is influenced by acute and developmental responses to salinity. In Trinidad, P. reticulata is confined to freshwater despite being tolerant of brackish water. P. reticulata may fail to occupy brackish water because of reduced tolerance to salinity or because P. picta competitively excludes them, and developing in brackish water could alter the dynamics of either scenario. To test this, we compared the salinity tolerances of both species in the absence of competition, reared P. reticulata individuals in freshwater or brackish water, and tested the consequences of developmental plasticity in experiments in which P. reticulata competed against conspecifics or P. picta during acute exposure to freshwater or brackish water. We found that (1) P. reticulata has a weaker salinity tolerance than P. picta; (2) P. reticulata that developed in freshwater perform best when competing against P. picta in freshwater but perform poorly when competing against P. picta in brackish water, suggesting the species interaction is context dependent; and (3) developing in brackish water did not benefit P. reticulata in brackish water. Our results suggest that P. reticulata's freshwater range limit is in part a product of a lower salinity tolerance leading to a decrease in competitive performance in brackish water. Adaptive plasticity has been suggested to be a crucial part of the colonization process, yet nonadaptive plastic responses as found here can limit range expansion and reinforce range limits.

Hydrogen flammability and explosion concentration limits for a wide temperature range

Hydrogen flammability and explosion concentration limits for a wide temperature range

Active site-inspired multicopper laccase-like nanozymes for detection of phenolic and catecholamine compounds.

Phenolic compounds are typical organic pollutants which cause severe human health problems due to their teratogenesis, carcinogenesis, neurotoxicity, immunotoxicity and endocrine disruption. Natural laccase is a multicopper oxidase existing in bacteria, plants, and insects, which can accelerate the transformation of phenolic compounds to their less hazardous oxidized products under mild conditions without harmful byproducts. Despite eco-environmentally friendly property of laccase, it still faces constraints of widespread application attribute to its high cost, complex preparation, and vulnerability. Therefore, exploring laccase mimics with high catalytic activity attracts a lot of attention and endeavors. In this research, copper-based nanozymes were prepared with coordination of copper ions and imidazole for mimicking the active sites of natural laccase via solvothermal method. The obtained Cu-based (Cu-Im) nanozymes exhibited multiple redox valence states of Cu and laccase-mimicking coordination structures, which endow Cu-Im with high laccase-like activity. During the process of catalytic oxidation reactions, singlet oxygen and superoxide anions generated from oxygen. Encouraged by the catalytic property, Cu-Im was utilized in degradation and detection of phenolic and catecholamine compounds. The catalytic degradation of compounds by Cu-Im showed good conversion and substrate versatility, which can be used as a kind of potential materials for phenolic pollutant degradation and remediation. Simultaneously, colorimetric sensors of phenols and catecholamines based on Cu-Im in solution system and POCT pad platform were constructed which indicated wide linear range and low limit of detection for both detection strategies. The Cu-Im-based sensor was a promising method for sensitive, fast, convenient, and qualitative-quantitative colorimetric analysis of phenols and catecholamines. The outcomes of this research elucidate Cu-Im is a satisfactory substitute for natural laccase, which will have broad application prospects in laccase-related fields, such as environmental recovery, pollution monitoring, and diagnosis of neurological diseases etc.

An active-conductive layer stacked sensor platform for real-time detection of heavy metal ions

The development of electrochemical sensors with high sensitivity and accuracy is crucial for the detection of low-concentration heavy metal ions (HMIs) such as Pb(II) and Hg(II), which remains challenging. To address this issue, MgFe-layered double hydroxide (MgFe-LDH) is synthesized as an active layer on the conductive layer SnO2 loaded with nickel foam (NF) with the assistance of oxygen vacancies (OVs) to form an active-conductive layer stacked sensor. The results show that MgFe-LDH@SnO2/NF exhibits superior sensitivity (Pb(II): 417 μA/μM; Hg(II): 986 μA/μM), wider linear range (1.1–2.2 μM) and lower limits of detection (Pb(II): 1.21 nM; Hg(II): 3.7 nM). The high performance of our sensor is attributed to the improved ability to adsorb HMIs via OV reduced binding energy as well as the promoted rapid electron transport via SnO2 reduced charge transfer resistance, as evidenced by density functional theory and electrochemical measurements. Particularly, by combining the newly proposed tiny electrochemical detection network (ECDNet-tiny) and WeChat mini program, we have built a real-time detection platform for Pb(II) and Hg(II) pollution categories and concentrations, which shows high accuracy (0.98) and recovery rate (91.6 %-106.8 %) in the detection of actual water samples. The qualitative and quantitative calculations of electrochemistry is innovatively implemented by deep learning. Besides, smartphones could display detection results transmitted from cloud servers. Thus, this work provides a new sensor platform to improve the sensitivity, accuracy, and intelligence of detecting quintessential HMIs.

Electrochemical Detection and Characterization of Caffeine in Selected Tea Samples using Polyglycine Modified Carbon Paste Electrode

Glycine was electro-polymerized against a carbon paste electrode (CPE) to produce a polymer film via the electro-oxidation process comprising amino (-NH2) and carboxylic (-COOH) groups, by a cyclic voltammetric. The electrochemical oxidation of caffeine was examined in 0.2 M phosphate buffer solution (PBS). The Polyglycine modified Carbon Paste Electrode (PGMCPE) demonstrates greater electrocatalytic activity for caffeine as compared to the unmodified CPE (UNMCPE). This made it suitable for analyzing caffeine owing to its increased electrode surface area and/or improved electron transport at the electrode surface. By varying the concentration range from 0.05 to 0.9 mM, the relationship between peak current and caffeine concentration was studied and this produced a correlation coefficient of R2 = 0.9987. This method was extremely capable of evaluating caffeine concentrations. Square wave voltammetry (SWV) was utilized to assess the caffeine in tea samples. The sample was analyzed with square wave voltammetry and was made easier with an ideal pH of 12.0. Additionally, the caffeine levels in a tea sample were successfully measured using the linear range and detection limit, and the results showed a good limit of detection (LOD) in comparison to previous literature.

Local conditions have greater influence than provenance on sugar maple (Acer saccharum Marsh.) frost hardiness at its northern range limit.

In temperate and boreal ecosystems, trees undergo dormancy to avoid cold temperatures during the unfavorable season. This phase includes changes in frost hardiness, which is minimal during the growing season and reaches its maximum in winter. Quantifying frost hardiness is important to assess the frost risk and shifts of species distribution under a changing climate. We investigate the effect of local conditions and intra-specific variation on frost hardiness in sugar maple (Acer saccharum Marsh.). Seedlings belonging to seven provenances from the northern area of the species' range were planted at two sites in Quebec, Canada. LT50, i.e., the lethal temperature for 50% of the cells, was measured monthly with the Relative Electrolyte Leakage (REL) method on branches and buds from September 2021 to July 2022. LT50 varied between -4°C in summer (July) and-68°C in winter (February). Autumnal acclimation rates (September to early December) and mid-winter frost hardiness (December to early March) were similar in both sites. Samples in the southern site deacclimated faster than in the northern site between March and July, because of a warmer and earlier spring. No difference in frost hardiness was detected between provenances. Our results suggest that the frost hardiness trait is similar within the northern part of the sugar maple distribution, with local weather conditions having a greater influence than provenance. We demonstrate that LT50 in sugar maple can exceed -55°C, far below the minimum temperatures occurring in winter at the northern limit of the species. In order to minimize the risk of damage from extreme frost events exceeding tree frost hardiness, a careful evaluation of site characteristics is more important than provenance selection. Other factors should also be considered within the context of changing climate, in particular the phenology of maple and avoidance of late frost in spring.

Ultrasensitive Protein Aggregate Quantification Assays for Neurodegenerative Diseases on the Simoa Platform.

Nanoscale aggregates play a key role in the pathogenesis of neurodegenerative disorders such as Alzheimer's and Parkinson's disease. However, quantifying these aggregates in complex biological samples, such as biofluids and postmortem brain tissue, has been challenging due to their low concentration and small size, necessitating the development of methods with high sensitivity and specificity. Here, we have developed ultrasensitive assays utilizing the Quanterix Simoa platform to detect α-synuclein, β-amyloid and tau aggregates, including those with common posttranslational modifications such as truncation of α-synuclein and AT8 phosphorylation of tau aggregates. All assays had a detection limit in the low pM range. As a part of this work, we developed silica-nanoparticle calibrators, allowing for the quantification of all aggregates. These assays were validated for aggregate and target specificity through denaturation and cross-reactivity experiments. We then applied these assays to brain homogenate samples from Alzheimer's disease and control samples, demonstrating their applicability to postmortem tissue. Lastly, we explored the potential of these assays for blood-based diagnostics by detecting aggregates in serum samples from early Alzheimer's disease patients.

Evaluating functional outcomes and quality of life in musculoskeletal tumor patients with distal femoral megaprostheses: a case-control study

BackgroundEndoprosthetic knee replacement using megaprostheses has become a common strategy for preserving joint function in patients with distal femur tumors. While existing literature has primarily focused on surgical techniques, complications, and implants, recent improvements in patient survival rates have sparked increased interest in the long-term functional outcomes associated with this treatment.MethodsThis case-control study evaluated functional outcomes—Timed Up and Go (TUG), 6-Minute Walk Test (6MWT), knee flexor and extensor muscle strength, and sagittal knee range of motion—and health-related quality of life (SF-36) between patients with distal femoral megaprostheses (n = 31) and healthy controls (n = 48). Participants performed the TUG and 6MWT equipped with an inertial measurement unit. Additionally, bivariate Spearman correlations were calculated within the patient group to assess relationships between Musculoskeletal Tumour Society (MSTS) scores and functional outcomes.ResultsPatients performed significantly worse than controls in the TUG test, with longer completion times (Mean Difference: -3.3 s; 95% CI: -5.7 to -0.9; p = 0.008), reduced rotational speed during the middle turn (Mean Difference: 16°/s; 95% CI: 7 to 25; p < 0.001) and final turn (Mean Difference: 22°/s; 95% CI: 9 to 34; p < 0.001), and lower vertical acceleration during the Sit-to-Stand phase (Mean Difference: 1.3 m/s²; 95% CI: 0.1 to 2.5; p = 0.032). In the 6MWT, patients walked 86 m less on average than controls (95% CI: 35 to 136; p = 0.002). Knee range of motion was significantly reduced, with median flexion of 90.2° (range: 5–125) in patients versus 136.4° (range: 115–150) in controls (p < 0.001, Z = -7.268). Muscle strength was also markedly lower in patients (p < 0.001). The SF-36 revealed significant differences in the Physical Component Summary (Mean Difference 95% CI: 15.5 [10.0 to 20.9]; p < 0.001), while no significant differences were found in the Mental Component Summary (p > 0.05). In patient group, bivariate Spearman correlations indicated a very strong positive association between MSTS scores and knee extension strength (ρ = 0.710; p < 0.001), and strong positive correlations with sagittal knee range of motion (ρ = 0.472; p = 0.015), total walking distance in 6MWT (ρ = 0.474; p = 0.019), and final turn rotational speed in TUG (ρ = 0.439; p = 0.032).ConclusionOur findings demonstrate a strong association between knee extensor strength and range of motion with overall functional performance, as reflected in MSTS scores. While nearly 75% of patients achieved scores classified as “good” to “excellent,” objective measures from the TUG and 6MWT revealed significant performance deficits compared to healthy controls, likely due to limitations in knee extensor strength and range of motion. These results highlight the need for targeted rehabilitation strategies focused on enhancing muscle strength and range of motion to optimize long-term functional recovery in these patients.

Chitosan/platinum nanocubes/Mn(TPDCA)2-modified glassy carbon electrodes for the electrochemical quantification of amlodipine in unprocessed plasma samples

A novel electrochemical probe is developed to detect amlodipine (AMD) in unprocessed plasma samples. The fabrication process involves the synthesis of platinum nanocubes (Pt NCs) and Mn(TPDCA)2 complexes, which are then immobilized them onto the glassy carbon electrode (GCE) surface. The developed electrochemical probe demonstrates exceptional detection performance, with a wide dynamic range, outstanding selectivity, and commendable reproducibility. The linear range and lower limit of detection of the developed method are 53 nM-3.5 µM and 53 nM, respectively. Electrochemical experiments have been conducted to study the kinetics of electrooxidation on the modified electrode, revealing that the process is diffusion-controlled. Furthermore, method validation studies are performed to assess the accuracy, precision, and selectivity of the sensor, demonstrating excellent performance in all these aspects. Consequently, it can be concluded that the sensor is highly suitable for practical applications in drug analysis.

Quantitative detection of the maize phytocytokine Zip1 utilizing ELISA.

Plant signaling peptides, also known as phytocytokines, play a crucial role in cell-to-cell communication during plant development and immunity. The detection of small peptides in plant tissues is challenging and often relies on time-consuming and cost-intensive approaches. Here, we present an ELISA-based assay as a rapid and cost-effective method for the detection of naturally released peptides in plant tissues. Our ELISA-based method was developed to detect Zip1, a 17-amino-acid phytocytokine derived from Zea mays that elicits salicylic acid signaling in maize leaves. Using a custom peptide-antibody, we designed an experimental pipeline to achieve peptide specificity, selectivity, and sensitivity allowing the detection of the Zip1 peptide in complex biological samples. As a proof of concept, we first overexpressed the precursor molecule PROZIP1 in Nicotiana benthamiana and in transfected maize protoplasts and monitored the release of Zip1-containing peptides. In a second approach we treated maize leaves with salicylic acid to induce native PROZIP1 expression and processing. Using ELISA, we were able to quantify native Zip1 signals with a detection limit in the nanogram range, which allowed us to detect different Zip1-containing peptides in plant material. This method can be adapted for the detection and quantification of a variety of plant signaling peptides.

Effects of Climate Change on the Fish Community, and Rhynchocypris kumgangensis (Cypriniformes: Cyprinidae) Distribution in Deogyusan National Park

Rhynchocypris kumgangensis, endemic to Korea, is limited to the upper Hangang River and Gucheondongcheon Stream. As a key and climate-sensitive biological indicator species in the Deogyusan National Park, it has a southern range limit in the Gucheondong Valley. Due to climate change, notable shifts in the activity, distribution, and population of R. kumgangensis on the Gucheondongcheon Stream are expected. This study examined trends between the 2020 field survey and previous surveys (2014–2018) for fish faunal changes at 13 sites in the Deogyusan National Park and for the population changes of R. kumgangensis at four sites in the Gucheondongcheon Stream. At 13 sites, we identified 996 individuals of 17 fish species in seven families, including 2 endangered (Pseudopungtungia nigra, Hemibarbus mylodon) and 11 Korea-endemic species. The Fish Assessment Index (FAI) of the 13 sites in the Deogyusan National Park was analyzed and found to be of A-grade in both the 2020 and past surveys, with high scores in all M1–M8 categories. Both the results of CCA and field surveys between the entire fish community and pH, DO, and water temperature revealed that the population of R. kumgangensis had a narrower distribution range and was more sensitive to water temperature than the same cold-water fish, R. oxycephalus. Climate change has been identified as causing the annual maximum temperature (°C) in the Deogyusan National Park to increase year on year and the R. kumgangensis population to decline, suggesting that the time for conservation efforts is “now”.

Morphological regulation of platinum nanoflowers with high enzyme loading for glucose biosensing and biofuel cells

Glucose enzymatic biosensors and biofuel cells are particularly important in the development of wearable devices, and the performance of both devices is highly dependent on the rational design of enzyme carrier materials as well as the loading of active enzymes. Herein, we designed highly enzyme-loaded flower-like platinum nanoparticle modified electrodes (GOxEPC/Pt NFs/CC) for glucose sensing and biofuel cells, which were modified with platinum nanoflower carriers on flexible carbon cloth substrate by urea-regulated one-step electrodeposition, followed by loading a large amount of glucose oxidase through enzyme precipitation coating. The biosensor exhibits high sensitivity (64.3 μA mM cm−2), ultra-wide linear range (0.01–31.31 mM) and low detection limit (3.3 μM). In addition, the biosensor also shows good selectivity, reproducibility, long-term stability and accuracy of real blood sample detection. The biofuel cell composed of the GOxEPC/Pt NFs/CC electrode and the laccase-modified electrode displays an open circuit voltage of 0.34 V, a high maximum current density of 289 μA cm−2, and a maximum power density of 19.2 μW cm−2. These results show that the proposed enzymatic electrode construction strategy has great application potential in the field of biosensors and biofuel cells.

Living on the edge – physiological tolerance to frost and drought explains range limits of 35 European tree species

Species distribution models are key to evaluate how climate change threatens European forests and tree species distributions. However, current models struggle to integrate ecophysiological processes. Mechanistic models are complex and have high parameter requirements. Some correlative species distribution models have tried to include traits but so far have struggled to directly connect to ecophysiological processes. Here, we propose a new strategy in which species distributions are based on safety margins which represent species' proximity to their physiological thresholds. We derived frost and drought safety margins for 38 European tree species as the difference between physiological tolerance traits and local maximum stress. We used LT50 and Ψ50 as tolerance traits for frost and drought, respectively, and local minimum temperature and minimum soil water potential as maximum stress. We integrated these safety margins into a species distribution model, which tests if the probability of species presence declines rapidly when the safety margin reaches zero, when physiological stress exceeds the species' tolerance traits. Our results showed thaet 35 of the 38 studied species had their distribution explained by one or both safety margins. We demonstrated that safety‐margins‐based model can be efficiently transferred to species for which occurrence data are not available. The probability of presence dropped dramatically when the frost safety margin reached zero, whereas it was less sensitive to the drought safety margin. This differential sensitivity may be due to the more complex regulation of drought stress, especially as water is a shared resource, whereas frost is not. Our analysis provides a new approach to link species distributions to their physiological limits and shows that, in Europe, frost and drought safety margins are important determinants of species distributions.

Magnetic relaxation switch biosensor for detection of Vibrio parahaemolyticus based on photocleavable hydrogel

BackgroundFoodborne pathogens, particularly Vibrio parahaemolyticus (VP) found in seafood, pose significant health risks, including abdominal pain, nausea, and even death. Rapid, accurate, and sensitive detection of these pathogens is crucial for food safety and public health. However, existing detection methods often require complex sample pretreatment, which limits their practical application. This study aims to overcome these limitations by developing a label-free magnetic relaxation switch (MRS) biosensor for the detection of VP, utilizing a photocleavable sol-gel phase transition system for improved efficiency and accuracy. ResultsIn this work, a tag-free magnetic relaxation switch (MRS) biosensor was designed for the detection of Vibrio parahaemolyticus (VP), based on a photocleavable sol-gel phase transition system. A large amount of lithium acyl hypophosphite (LAP), gold nanoparticles (AuNPs), and single-stranded DNA (ssDNA) loaded on the surface of Ti3C2Tx MXene acted as the signal unit LAP-MXene@AuNPs-ssDNA. The pipette tip served as a reaction vessel, and when VP was present, Apt specifically captured VP and released the signal units. The released signal units were then injected into the low-field nuclear magnetic resonance (LF-NMR) test solution, a gel formed by crosslinking of disulfide bonds. The gel was cleaved by LAPs on the signal units under ultraviolet (UV) irradiation, triggering a gel-sol phase transition, which increased transverse relaxation time (T2), thus enabling the detection of VP. Under the optimal experimental conditions, the linear range and detection limit for VP were 102 ∼ 108 CFU/mL and 10 CFU/mL, respectively. Significance and noveltyThe simplified biometric identification process in the pipette tip reduces errors from multiple sample transfers, enhancing efficiency. The use of photocleavable hydrogel for signal output eliminates issues associated with magnetic material aggregation, significantly improving detection precision. The assay is of good selectivity, stability reproducibility, and convenience, having a broad application prospect in the rapid detection of pathogenic bacteria in the field.