Given the potential dangers of organophosphorus pesticides to food safety and human health, the development of a reliable and precise detection platform for pesticides is essential. In this study, we present a novel 'armor-plating' laccase-mimetic catalyst (DNA-Cu@MOFs)-based colorimetric platform, which enables stable and selective pesticide detection. The DNA-Cu@MOFs enhance catalytic stability and overcome pH limitations, enabling effective catalysis under neutral and alkaline physiological conditions, making them well-suited for practical applications in biosensor development. By combining the catalytic properties of DNA-Cu@MOFs with a high-affinity biorecognition element (acetylcholinesterase), the platform achieves a linear detection range of 3.0-90 ng mL-1 for chlorpyrifos, with a detection limit of 0.75 ng mL-1. Notably, this platform demonstrates significant stability in chlorpyrifos detection even in the presence of environmental interferents. This robust colorimetric platform offers new possibilities for pesticide detection and provides a solid foundation for the development of comprehensive and accurate pesticide monitoring systems.

The construction of a nanozyme-enzyme hybrid cascade system is an effective protocol to optimize the performance of biosensors. Yet, the integration has limitations due to the lack of harmonious collaboration between nanozyme and enzyme. Herein, we have constructed an efficient enzymatic cascade system by utilizing the base complementary pairing and the targeting capability of DNA tweezers to combine DNA-regulated copper nanoflowers (CuNFs) with acetylcholinesterase (AChE). The DNA tweezers were immobilized onto the CuNFs undergo regular base complementary pairing, and subsequently employed as aptamer to capture AChE gently, forming CuNFs-Apt-AChE cascade system. This system not only enhanced the spatial proximity of CuNFs and AChE to increase cascade catalytic activity, but also demonstrated excellent stability under harsh conditions. Harnessing the nanoarchitecture and characteristics, the CuNFs-Apt-AChE composites were embedded into the hydrogel to fabricate a sensitive biosensor for on-site detecting carbamate pesticides with a detection limit of 0.19 ng mL-1. The hydrogel sensor exhibited high specificity for carbamate pesticides and had been successfully applied in water and juice samples for pesticide detection with strong anti-interference ability. This method holds great potential for the on-site detection of pesticides, offering a new strategy for constructing nanozyme-enzyme cascade hybrid systems with accuracy and sensitivity.

The biomimetic enzyme cascade system plays a key role in biosensing as a sophisticated signal transduction and amplification strategy. However, constructing a regulated enzyme cascade sensing system remains challenging due to the mismatch of multiple enzyme activities and poor stability. Herein, we design an efficient dual-enhanced enzyme cascade hybrid system (UFD-DEC) containing DNA-controlled nanozymes (Fe-cdDNA) and enzyme (urease) via combining the electrostatic contact effect with the hydrogel-directed confinement effect. Precise modulation of Fe-cdDNA nanozyme by DNA offers a means to control its catalytic efficiency. This regulated UFD-DEC system accelerates the reaction rate and provides remarkable stability compared with the free enzyme system. Benefiting from the plasticity properties of hydrogels, a “lab-in-a-tube” platform was constructed by encapsulating UFD-DEC in a microcentrifuge tube. Such a UFD-DEC-based hydrogel tube exhibits sufficient adaptability to profile urea when used in conjunction with a smartphone-assisted image processing algorithm, which on-site delivers urea information with a detection limit of 0.12 mmol L-1. This customizable and inexpensive miniaturized biosensor platform for monitoring urea may facilitate point-of-care testing applications.

Benefiting from specific target recognition and trans-cleavage capabilities, the CRISPR/Cas12a system has great application prospects in the design of highly sensitive and rapid fluorescence biosensors. The CRISPR/Cas12a-based fluorophore-quencher molecular beacons exhibit single-color emission and are easily exposed to interference from environmental factors. Herein, we design a CRISPR/Cas12a-derived ratiometric fluorescence sensor for Pb2+ detection based on embedded carbon dots@zeolitic imidazolate framework-8 (CDs@ZIF-8) composites and DNAzyme. The functions of ZIF-8 about encapsulating red emissive CDs in the inner cavity and adsorbing DNA on the outer surface are integrated to establish dual fluorescence signals, thereby reducing the possibility of interference and improving sensing accuracy. The presence of Pb2+ is converted into the change of activator by the GR5 DNAzyme to activate the CRISPR/Cas12a system, which provides signal amplification through multiple turnovers of side branch cutting, achieving highly sensitive detection of Pb2+ with a low detection limit of 18 pM. This method has the advantages of simplicity, universality, and excellent quantitative ability, and has broad prospects in sensing applications.

Given the potential dangers of thiram to food safety, constructing a facile sensor is significantly critical. Herein, we presented a colorimetric sensor based on glutathione-iron hybrid (GSH-Fe) nanozyme for specific and stable detection of thiram. The GSH-Fe nanozyme exhibits good peroxidase-mimicking activity with comparable Michaelis constant (Km = 0.551 mM) to the natural enzyme. Thiram pesticides can specifically limit the catalytic activity of GSH-Fe nanozyme via surface passivation, causing the change of colorimetric signal. It is worth mentioning that the platform was used to prepare a portable hydrogel kit for rapid qualitative monitoring of thiram. Coupling with an image-processing algorithm, the colorimetric image of the hydrogel reactor is converted into the data information for accurate quantification of thiram with a detection limit of 0.3 mu g mL-1. The sensing system has good selectivity and high stability, with recovery rates in fruit juice samples ranging from 92.4% to 106.9%.

Entheseal changes are skeletal markers, which are often used in the reconstruction of physical activities. This study investigated patterns of entheseal changes and other activity markers, such as squatting facets and degerative signs at joints in a mortuary population of the Houtaomuga site, Northeast China. Comparisons were conducted between the early period (Neolithic to Early Bronze Age, 8000-2500 BP) and the late period (Late Bronze Age, 2300 BP). Differences between two sexes of the late period were also compared. The results demonstrated that the frequency and severity of entheseal changes and other activity markers differed between early and late populations and between males and females of the late population suggesting subsistence strategies changes and new patterns of sex-based divisions of labor. This is the first attempt to assess activity changes in fisher-hunter-gatherer populations over a long period of time from ancient China. Results reveal that though the Houtaomuga population maintained the primary subsistence modes of fishing, hunting, and gathering, their entheses elucidate gradual shifts along with reduced activity stress due to sedentary life and intensified sex-based divisions of labor and the advent of craft specializations, which was likely influenced by climate changes.

We examined the remains of an individual who was unearthed from the Tuchengzi site and was believed to be from the Warring States period in China. The remains exhibited segmental femoral fracture. We aimed to deduce the cause of fracture, medical interventions, healing process, and motion behavior after fracture healing using several techniques, including macroscopic observation, computed tomography (CT), and finite element analysis. Based on the morphology of the long bones, it appeared that the individual was male. The fractures resulted in an adduction angle of 5.47° and an anterior flexion angle of 21.34° in the proximal femur, while the femoral neck anteversion angle had been replaced by a retroversion angle of 10.74°. Additionally, the distal femur formed an abnormal anterior convex angle of 144.60°. CT revealed mature callus formation and visible trabecular bundles. The finite element analysis indicated that the maximum von Mises stress in the femur was 17.44 MPa during standing and 96.46 MPa during walking. We suggest that medical practitioners in the Warring States period possessed a good knowledge of thigh anatomy, enabling them to perform fracture reduction and fixation. Reasonable medical intervention facilitated fracture healing and load recovery. Satisfactory fracture healing ensured that the individual could engage in normal standing and walking activities after rehabilitation.

"但如果不幸,哪一天我的躯体僵硬了,我想,我还有五脏六腑."这是歌曲《五脏六腑》中的一句歌词,病榻上的李宇春根据自己患上强直性脊柱炎(以下简称"强直")的痛苦经历创作了这首歌曲.李宇春表示自己患病后有时无法平稳躺下,有一种石化的感觉,而MV中也展示了强直患者从最开始身体部分僵直和疼痛,发展到全身僵硬,最终坐在轮椅上扭动脖子无神地看向四周,夜不能寐,行将就木的情况.

Fluorescent aptasensor was developed for acrylamide (AAm) detection by utilizing the adsorption effect of Au nanoparticles (AuNPs) and fluorescence properties of SYBR Green I (SGI) towards double-stranded DNA (dsDNA). Compared to the binding of aptamer with AAm, the higher affinity of aptamer with cDNA may facilitate a structure switching from the aptamer/AAm complex to aptamer/cDNA dsDNA. The free aptamers were adsorbed onto AuNPs and separated by centrifugation. Subsequently, SGI was introduced as a fluorescent reporter for quantitative detection. Compared to conventional AuNPs-based colorimetric detection, the sensitivity of this strategy was improved by 3.18-fold in the range of 0.005–50 mg/L with a low detection limit of 4.68 μg/L. The method has been successfully applied to analyze fried twists and biscuits. Notably, it is a low-cost and general method that provides guidance for the development of rapid screening technology in the field.

Heavy metal pollution can pose a threat to food safety and human health, and accurate quantification of heavy metal ions is a vital requirement. Emerging DNA nanostructures-based biosensors offer attractive tools toward ultra-sensitive or rapid analysis of heavy metal ions. However, the problems including complex design, severe reaction conditions and undesirable reliability are inevitable obstacle in advancing their extension and application. Herein, a ratiometric fluorescent platform was established for monitoring lead ion (Pb2+) in food based on dual Forster resonance energy transfer (FRET) and RNA cleavage-inhibited self-assembly of three-arm branched junction (TBJ). GR-5 DNAzyme was employed for Pb2+ recognition, and enzyme-free amplification technique catalytic hairpin assembly (CHA) served to form FRET probes-carried TBJ. The substrate strand (S) of DNAzyme triggered the generation of CHA-TBJ, and Pb2+-responsive cleavage of S hindered the assembly of CHA-TBJ, causing opposite changes in the FRET states of FAM/BHQ1 and ROX/BHQ2 pairs. The fluorescence responses were recorded through synchronous fluorescence spectrometry to indicate Pb2+ concentration, allowing sensitive and reliable identification of Pb2+ in the linear range of 0.05-5 ng mL(-1) with the detection limit of 0.03 ng mL(-1). The Pb2+ detection can be achieved under conventional reaction conditions, simple mixing procedures and onestep measurement operation. The approach can afford excellent specificity for Pb2+ against competing metal ions, and can be applied to analyze Pb2+ in tea samples with satisfactory results. This facile fluorescence platform shows a capable method for Pb2+ detection, and provides new avenue in the development of ratiometric

免疫分析技术因具有快速、简便和低成本等特点在农药残留监测中发挥着重要的作用.基于纳米材料增敏的荧光免疫传感器因灵敏度高、特异性强等优点,近年来逐渐成为研究热点.本文总结近年来荧光免疫传感器的相关研究进展,针对不同种类荧光纳米探针建立的免疫传感器在农药残留检测中的研究进行综述,重点阐述酶基荧光免疫探针、荧光纳米材料免疫探针、纳米酶基免疫探针和纳米支架型免疫探针的原理、特点及应用现状,并展望荧光免疫传感器在农药检测中的应用前景,旨在为荧光纳米探针在食品农药残留检测中的发展、应用提供参考.

The residues of organophosphorus pesticides have caused the potential risk in environment and human health, arousing worldwidely great concern. Herein, we fabricated a robust gold nanoclusters/MnO2 composites-based hydrogel portable kit for accurate monitoring of paraoxon residues and degradation in Chinese cabbages. With the immobilization of gold nanoclusters/MnO2 composites into a hydrogel, a ratiometric fluorescent signal is generated by catalyzing the oxidation of o-phenylenediamine, which possesses a built-in correction with low background interference. Coupling with acetylcholinesterase catalytic reactions and pesticide inhibition effect, the portable kit can sensitively detect paraoxon residues with a detection limit of 5.0 ng mL-1. For on-site quantification, the fluorescent color variations of portable kit are converted into digital information that exhibits applicative linear range toward pesticide. Notably, the hydrogel portable kit was successfully applied for precisely monitoring the residue and degradation of paraoxon in Chinese cabbage, providing a potential pathway toward practical point-of-care testing in food safety monitoring.