Glyphosate (Gly), a widely used organophosphorus pesticide, has raised concern due to its environmental persistence and adverse health effects. Conventional detection methods are often limited by high expenses, complex operations, and insufficient sensitivity, making them unsuitable for on-site application. Herein, we report a colorimetric biosensor based on DNA-encoded copper (DNA/Cu) nanozymes for the sensitive detection of Gly. The DNA/Cu nanozymes were synthesized via a one-step coordination-driven self-assembly at room temperature without additional reagents, and their peroxidase-like activity was modulated by altering the DNA sequence. The nanozyme efficiently catalyzes the H2O2-mediated oxidation of 3,3',5,5'-tetramethylbenzidine (TMB), producing a blue coloration. Mechanistic studies confirm that hydroxyl radicals (·OH) generated from H2O2 decomposition are the dominant reactive intermediates. Gly suppresses this activity by chelating Cu2+ and disrupting the nanozyme structure, thereby blocking the generation of ·OH. Based on this inhibition mechanism, the biosensor exhibits a good linear response to Gly from 0.1 to 5 μg/mL, with a detection limit of 13 ng/mL and excellent specificity. To facilitate on-site monitoring, the biosensor was integrated with a smartphone-based colorimetric reader, enabling quantitative analysis via RGB ratio measurement and achieving a practical LOD of 35 ng/mL. This DNA/Cu nanozyme-based colorimetric platform represents a promising tool for Gly detection in food safety and environmental monitoring.

The global spread of viral infections, particularly highlighted by the COVID-19 pandemic, has underscored the critical demand for rapid, sensitive, and widely accessible diagnostic tools. While polymerase chain reaction (PCR) remains the gold standard for virus detection due to its high sensitivity and specificity, its reliance on complex instrumentation and lengthy processing times makes it unsuitable for point-of-care testing (POCT). In contrast, lateral flow immunoassays (LFIA) are commonly used in POCT for their simplicity and rapid results, yet they often exhibit low sensitivity and limited accuracy, particularly when detecting low concentrations of viral antigens. In this study, we reported an ultrasensitive duplex lateral flow immunoassay (UdLFIA) that integrated hybridization chain reaction (HCR) amplification and dual-functionalized gold nanoparticles (AuNPs) to achieve both high sensitivity and accuracy. To demonstrate its capabilities, we applied the UdLFIA for the simultaneous detection of two SARS-CoV-2 antigens-the nucleocapsid (N) protein and the receptor-binding domain (RBD) of the spike protein. This model confirmed UdLFIA's benefits, enhancing diagnostic accuracy by reducing false negatives when targeting a single antigen. The UdLFIA achieved a limit of detection (LOD) of 0.65 ng/mL for the N protein and 0.99 ng/mL for the RBD protein, representing a 10-20 folds improvement in sensitivity with HCR amplification. The good selectivity of the UdLFIA was demonstrated by comparing the measurement with closely related viruses. Additionally, the 20 min measurement time makes it well-suited for large-scale screening and POCT settings. The UdLFIA platform represents a step toward bridging between high-sensitivity laboratory diagnostics and accessible point-of-care testing. By combining the simplicity and speed of LFIA with enhanced sensitivity and accuracy, UdLFIA may support scalable and cost-effective testing after further validation in clinical and real-world settings for both pandemic response and routine viral screening, addressing the limitations of current POCT technologies.

The formation of Br vacancies is the core factor leading to significant impairment of CsPbBr3 ' s stability. Herein, we ingeniously designed an endogenous bromine species synergistic stabilization strategy by constructing a CsPbBr3/Cs4PbBr6 heterojunction photocatalyst and decabromodiphenyl ether (BDE209) degradation. Via precise control of the Cs2CO3/PbBr2 stoichiometric ratio, the optimal sample (CPB-0.8) exhibited exceptional BDE209 debromination activity with a rate constant of 0.275 min(-1) and nearly complete degradation within 10 min under visible light (lambda > 400 nm). More importantly, it shows significantly enhanced stability compared to pure single-phase CsPbBr3. Structural characterizations confirmed that Cs4PbBr6 in the heterojunction acts as a stabilizing phase. It dissolves in situ to release CsBr, which dynamically passivates Br vacancies on CsPbBr3 surfaces, preventing CsPbBr3 from transforming to inactive Cs2PbBr5. Meanwhile, bromine species released during BDE209 degradation further assist in suppressing the formation of Br vacancies and halide ion loss in CsPbBr3. This work demonstrates the potential synergistic effect between the efficient degradation of halogenated pollutants and the stabilization of halogen vacancies of metal halide perovskites.

CRISPR/Cas12a can activate trans-cleavage activity upon single-stranded DNA binding, making it widely applicable in highly sensitive fluorescent biosensors. Sensors utilizing monochromatic fluorescence output modes are susceptible to interference from multiple factors, resulting in unstable detection methods. To address this, we designed a ratio-based fluorescence sensor for detecting tetracyclines (TCs) based on the synergistic signal amplification of nucleic acid aptamer (42TET) and zirconium-based metal-organic framework (PCN-224) with CRISPR/Cas12a. PCN-224 adsorbs single-stranded DNA, quenching its FAM-labeled fluorescence while simultaneously emitting its own fluorescent signal. This dual-fluorescence output reduces background interference and enhances detection accuracy. By designing an activator as a complementary sequence (cDNA) to the nucleic acid aptamer, the system binds to 42TET in the presence of tetracycline, releasing the cDNA to activate the CRISPR/ Cas12a system. Through this system's signal amplification capability, highly sensitive detection of tetracycline is achieved, with a detection limit reaching 8.7 nM. It possesses the same detection capabilities as traditional HPLC detection methods. This method is simple, rapid, efficient, and highly quantitative, offering broad prospects for future applications.

17β-Estradiol (E2), an endogenous estrogen, can be present in milk and may accumulate during processing, potentially contributing to long-term dietary exposure that raises concerns for consumer health. Regulatory agencies have established intake limits to minimize risk, highlighting the importance of reliable monitoring. In this study, we developed a docking-guided dual-mode aptasensor for sensitive, selective, and practical detection of E2 in complex dairy matrices. Molecular docking analyses revealed critical binding interactions within the aptamer, elucidating the spatial arrangement and chemical environment of the E2 recognition pocket. Van der Waals contacts dominated binding, with residues A41 and A7 serving as key anchoring points that stabilize E2 at the hairpin neck, forming a compact hydrophobic cavity that promotes selective recognition. These structural insights directly guided the rational design of bifunctional hairpin probes, enabling precise control of hairpin switching and hybridization chain reaction amplification, while maintaining recognition fidelity under complex sample conditions such as milk, where matrix effects could perturb aptamer structure. Integrating these docking-informed designs with sequence optimization, the platform simultaneously employs 2-aminopurine fluorescence and gold nanobipyramids-based multicolor plasmonic readouts, achieving low detection limits of 7.71 pM and 88.9 pM with strong specificity and anti-interference capability. The complementary dual-mode signals enhance detection reliability and reduce the risk of false positives by cross-validating fluorescence and colorimetric outputs. Coupled with a semiquantitative visual color chart and a smartphone-assisted interface, this system enables intuitive, on-site, and user-friendly analysis. Application to real milk samples demonstrated reproducible performance, highlighting its potential for routine E2 surveillance, proactive food-safety management, quality assurance, and consumer health protection, while providing a generalizable framework for developing robust nucleic acid sensors targeting diverse small-molecule contaminants in the dairy industry.

Engineered as a molecular switch, the structure-switching aptamer initiates target-induced conformational reorganization from a dsDNA duplex to a DNA/17 beta-estradiol complex. This reorganization activates synergistic enzyme and nanozyme system, generating an intrinsically self-validated dual-mode (colorimetric/fluorometric) output, a critical advantage that is unattainable in single-mode aptasensors. Capitalizing on this mechanism, we develop a dual-mode aptasensor where 17 beta-estradiol binding displaces alkaline phosphatase (ALP)-cDNA from magnetic beads, liberating ALP. The enzyme hydrolyzes ascorbic acid-2-phosphate (AAP) to ascorbic acid (AA), reducing MnO2 NSs to Mn-2(+) and consequently suppressing their oxidase-mimicking activity and fluorescence quenching. The dual-mode aptasensor can be as low as 3.6 nM detection limit. Additionally, the sensor demonstrates high accuracy in milk/tap water samples (97.8-108.95 % recoveries; RSDs < 8.09 %) while enabling smartphone-based instrument-free quantification. The platform's adaptability via aptamer substitution extends its utility to diverse endocrine-disrupting compounds and other small molecules, providing a versatile safety monitoring tool.

Lead ions (Pb2 +) pose a serious threat to ecosystems and human health, and it is urgent to develop reliable and convenient detection methods. In the field of fluorescence biosensors, fluorophore-quencher pairs based on fluorescence resonance energy transfer (FRET) are the most commonly used signal reporters. However, their dependence on a single fluorescence signal poses inherent drawbacks. Herein, DNA-templated silver nanocluster beacons (NCBs) were prepared as the fluorescence signal reporter for the biosensor. The signal response mechanism is due to the transformation process of silver nanoclusters, rather than FRET. When the DNA template is cleaved, a 100 nm emission red shift can be observed, which is in contrast to the traditional fluorophorequencher reporters. By leveraging the unique fluorescence properties of NCBs and the signal amplification capability of CRISPR/Cas12a, a ratiometric fluorescence biosensor was developed for the detection of Pb2+. The detection range of this biosensor is from 0.1 to 20 nM, and the limit of detection (LOD) is 21 pM. Furthermore, by integrating the hydrogels with smartphones, a portable platform has been successfully developed for point-ofcare testing (POCT). This work offers valuable insights for the development of fluorescent biosensors and is significant for on-site environmental monitoring, food safety, and clinical diagnosis.

Enzyme‐based biosensors with rapid and on‐site detection capabilities possess great potential for practical application. However, conventional enzyme immobilization strategies often enhance stability at the expense of substantial enzyme activity loss, thereby limiting the detection performance of enzyme‐based biosensors. Herein, a highly sensitive and robust biosensor is constructed based on defect‐engineered amorphous metal‐organic frameworks, enabling on‐site detection of organophosphate pesticides in complex food matrices. Defective acetylcholinesterase@amorphous metal‐organic frameworks (denoted as AChE@AMOF‐74) can be in situ tailored via a defect‐engineered strategy to provide a suitable microenvironment and obtain high porosity for enzyme encapsulation, while its porous architecture enhances the catalytic activity of immobilized enzyme. Impressively, the catalysis activity and target recognition ability of AChE@AMOF‐74 are 3.4‐fold and 5.6‐fold higher than those of nanoarchitectures with a regular crystalline structure. Benefiting from the structural advantages, a robust AChE@AMOF‐74‐based biosensor is constructed for the sensitive detection of pesticides, enabling quantitative analysis of paraoxon with a detection limit of 0.05 ng·mL −1 using an image processing algorithm. This work demonstrates the significant potential of AMOFs in constructing high‐performance enzyme‐based biosensors and has been successfully applied to detect pesticide in complex food matrices, providing a new protocol for on‐site application.

Antibiotics can accumulate in the body via ingestion, presenting serious health and safety risks to humans, and have garnered extensive international attention in recent years. Meanwhile, aptamers have been applied in the detection of antibiotics, mainly because of their good stability, high specificity, easy synthesis, and low cost. Among various kinds of aptasensors, fluorescent dye-based or nanomaterial-based fluorescent aptasensors serve as highly efficient tools for the rapid quantification of antibiotics owing to their remarkable sensitivity, specificity, and selectivity. In addition, some novel techniques such as aptamer tailoring, signal amplification, and artificial intelligence for aptasensors are also presented. This paper provides a detailed and comprehensive review of fluorescent aptasensors for antibiotic detection. Moreover, it pinpoints the challenges encountered during the development of the aforesaid fluorescent aptasensors and puts forward future research directions.

Nanozymes exhibit huge potential in developing sensors, there are still significant challenges in designing nanozymes and exploring catalytic mechanisms. Inspired by the ligand-environment effect, ligands with differently charged substituents were introduced into a copper metal-organic framework (Cu-BDC-X, X = OH, NH2, COOH, NO2) to study the relationship between ligand structure and laccase-like activity. Attractively, tuning the ligand substituents directly regulates the laccase-like activity of Cu-BDC. In-depth experiments showed that the introduction of electron-withdrawing substituent ligands not only increased the ratio of Cu+ in Cu-BDC but also enlarged the pore diameter of the Cu-BDC. As a concept of the application, a Cu-BDC-NO2 nanozyme-based colorimetric sensor was developed for the detection of glyphosate pesticide. Importantly, Cu-BDC-NO2 nanozyme was embedded in hydrogels to fabricate a portable platform for in situ detection of glyphosate pesticide. This work is expected to provide new ideas for building advanced nanozymes and holds great promise for food safety.

With the increasing demand for aquatic products, assessing their freshness has become increasingly important. Therefore, it is highly urgent to develop various simple, reliable, and portable sensing platforms for aquatic products' freshness assessment. In this work, a kind of bimetal-organic framework nanozyme (MOF Fe-Cu) was synthesized using a one-pot hydrothermal reaction. Attributed to the synergistic action of Fe and Cu, MOF Fe-Cu has enhanced POD-like activity. By combining MOF Fe-Cu with xanthine oxidase (XOD), a self-supplying H2O2 enzymatic cascade catalytic system was proposed, obtaining aquatic products freshness indicator hypoxanthine (Hx)-responsive colorimetric sensing platform. Based on the feasibility analysis for field testing, a portable device was developed by integrating MOF Fe-Cu-based test strips with smartphones to facilitate on-site quantification of Hx. The developed portable device has considerable potential for application in assessing aquatic products' freshness in the field.

Mycotoxins contribute considerably to food losses and pose serious health risks to humans and animals. This study investigated the mechanisms underlying the elimination of mycotoxin zearalenone (ZEN) by a yeast strain, Rhodotorula dairenensis ZDY342B, which was isolated from the feces of ZEN-treated mice. Isotope-labeled 13C18-ZEN was employed for accurately tracking the degradation products of ZEN, and the chemical composition of the yeast cells was characterized before and after ZEN elimination. The results of these analyses confirmed that strain ZDY342B removes ZEN via a combination of degradation and adsorption. Subsequently, the degradation product of ZEN was identified as zearalenol using high-performance liquid chromatography and nuclear magnetic resonance spectroscopy, as opposed to simply inferring the product structure based on the molecular weight of the degradation product. The characterization of the cell structure revealed the role of functional groups such as O-H, N-H, C═O, and C-O in the biosorption of ZEN by yeast ZDY342B. Additionally, an evaluation of the safety of strain ZDY342B revealed it to be a safe and harmless microorganism. Furthermore, the reduced toxicity of the products obtained upon the degradation of ZEN by ZDY342B was ascertained using in vitro and in vivo experiments. In summary, this study demonstrates the effectiveness and safety of ZDY342B, a yeast strain that shows the potential for mitigating ZEN contamination in food and animal feed.

(3-Lactoglobulin (BLG) is considered the main sensitizing protein that causes milk allergy and has become one of the hot spots in food safety research. Here, a simple multicolor visualization sensing strategy was constructed by hemin/G-quadruplex (G4) DNAzyme and 3,3 ',5,5 '-tetramethylbenzidine (TMB)-mediated etching of gold nanorods (GNRs). A dual-functional aptamer enlg2-pl3 was used as the recognition element of BLG and the skeleton of hemin/G4 DNAzyme. Hemin/G4 DNAzyme catalyzed H2O2-mediated oxidation of TMB to produce TMB2+ under acidic conditions. The GNRs were etched by TMB2+ with a change in the aspect ratio, accompanied by a multicolor change. The combination of BLG and enlg2-pl3 reduced the catalytic activity of hemin/G4 DNAzyme, thus inhibiting the etching reaction. The concentration gradient of the BLG can be identified by the difference in the plasmon resonance wavelength signal and the color change generated by the GNRs with different aspect ratios. Compared to previous colorimetric methods for BLG determination, multiple colors corresponding to the concentration of BLG was the most attractive virtue of our approach. This aptasensor can easily detect BLG within 50 min. Combined with the smartphone detection platform, it can realize convenient quantitative analysis without instruments and meet the requirements of point-of-care testing (POCT).

Lead ions (Pb2+) are a widely prevalent toxic heavy metal posing a serious threat to environmental safety and public health. Therefore, there is an urgent need to develop simple, sensitive, and cost-effective alternative solutions. In this study, cobalt oxyhydroxide nanosheets (CoOOH NSs) and manganese dioxide nanosheets (MnO2 NSs) were prepared by facile, efficient, and labor-saving methods, and the properties of these two twodimensional layered nanosheets were compared, especially their adsorption capacities for single-strand DNA (ssDNA). It was found that CoOOH NSs were more likely to adsorb short ssDNA, while MnO2 NSs were the opposite. To achieve the signal-on analysis strategy, MnO2 NSs were selected as the nucleic acid adsorbent and the fluorescence quencher. Combined with the specific activation of Pb2+ on GR5 DNAzyme, a simple and fast fluorescence biosensor for Pb2+ detection was constructed. At the excitation wavelength of 495 nm, the fluorescence intensity at 520 nm increases with rising Pb2+ concentration. This biosensor had a broad linear range of 1-100 nM and a low detection limit of 0.1 nM. Meanwhile, this method has been applied to real samples, including river water and fish, yielding good recovery rates with no significant difference compared to ICP-MS. Furthermore, with smartphone support, quantitative detection of Pb2+ in the 1-100 nm range has been achieved. The prepared color chart can also be used for portable detection. This study deepens fundamental understanding of DNA adsorption by nanomaterials and contributes to further rational design of biosensors.

Designable morphology and predictable properties of Metal-organic frameworks (MOFs) are important problems in material engineering. Herein, we report a simple preparation method of ZIF-67 nanoflower (ZIF-67 NF) without high temperature calcination and external metal doping. ZIF-67 NF was successfully synthesized by optimizing the molar ratio of precursors of Co2+ and 2-methylimidazole (2-MI) based on the synthesis conditions of ZIF-67 dodecahedra. Besides the peroxidase-like activity common to both ZIF-67 dodecahedron and ZIF-67 NF, ZIF-67 NF also exhibits oxidase-like activity owing to the elevated Co3+ content and the presence of oxygen vacancies, revealing more active sites and unsaturated coordination of the Co active center. Using ZIF-67 NF as a catalyst, which can catalyze the oxidation of three color developing substrates (TMB, ABTS, OPD), and realize multi-component identification detection of eight antioxidants as low as 0.1 mu M, providing a new strategy for the synthesis, design, and development of MOFs.

The development of a suitable mimetic scaffolds for maintaining high activity and stability of co-immobilized multi-enzymes is a key challenge in biotechnology. Herein, we achieved the regular distribution of cascade enzymes through spatially controlled hierarchical loading into protein-inorganic hybrid nanoflowers using a mild biomineralization technique. The comprehensive understanding of sequential regulation in constructing controlled nanoarchitecture enables to combine a continuous reaction and achieve tailoring catalysis for biomimetic application. The ordered-assembled cascade enzymes showed stronger bioactivity in comparison with the disordered format or inappropriate loading format. The stability of the enzyme is incrementally improved by an efficient dual-enhanced mode of immobilizing the free enzyme into hybrid nanoflowers and encapsulating it in a hydrogel system, addressing the inherent fragility of natural enzymes. Benefiting from the structural integration, a protein-inorganic hybrid nanoflowers-embedded hydrogel sensor is constructed for on-site detecting NO2- with a detection limit of 5.08 mu M. This work showcases a convenient approach for the efficient design of the ideal cascade biocatalysts, and supports the development of portable devices for practical application.

beta-Lactoglobulin (BLG) is a major allergen in milk and has proven to be a valuable biomarker for the assessment of milk quality. Herein, a colorimetric and fluorometric dual-mode biosensor was first constructed for detecting BLG based on the G-quadruplex/hemin DNAzyme and orange-emitting carbon dots (O-CDs). The BLG aptamer was employed to generate G-quadruplex/hemin DNAzyme, which exhibits peroxidase-like (POD-like) activity and serves as a specific recognition probe. The DNAzyme efficiently catalyzes the conversion of 3,3 ',5,5 '-Tetra-methylbenzidine (TMB) into its blue oxidation product (oxTMB) and simultaneously quenches the fluorescence of O-CDs through the internal filter effect (IFE). Upon the presence of BLG, the aptamer specifically binds to BLG, thereby destroying the structure of the DNAzyme. Consequently, the POD-like activity of the DNAzyme is decreased, leading to an inhibition of oxTMB production and a restoration of the fluorescence of O-CDs. The BLG can be accurately measured by observing the changes in the colorimetric signal of oxTMB at 370 nm and the fluorescence signal of O-CDs at 580 nm. The developed biosensor demonstrates excellent linearity over a concentration range spanning from 1 mu g center dot mL-1 to 500 mu g center dot mL-1. Integrated with the smartphone platform, it could realize convenient quantitative analysis without instruments and meet the requirements of point-of-care testing (POCT). This study holds significant potential for ensuring food security.

Accurate and rapid detection of lead ions in food and environment is urgently needed for human health. Herein, we have developed a ratiometric fluorescence system grounded in GR5 DNAzyme and carbon dots-embedded ZIF-8 nanocomposite (CDs@ZIF-8) to achieve the self-calibration detection of lead ions (Pb2+). GR5 DNAzyme, which acts as a molecular recognition element, is adsorbed onto the surface belonging to CDs@ZIF-8. Pb2+-induced cleavage of DNAzyme results in the desorption of short FAM-labeled single-stranded DNA, which triggers a detectable change in the FAM fluorescence. Meanwhile, CDs@ZIF-8 provides an unchanging reference signal through the self-luminescence of encapsulated blue-emitting CDs. The ratiometric fluorescence signal blocks the environmental interference. This method achieves a hypersensitized and specific monitoring method of Pb2+ in 60 min through a simple mixing process, with a minimum detectable limit of 0.1 nM. The use of self-calibrating multifunctional nanomaterials is expected to enable the development of more reliable and accurate sensors compared to single-functional nanomaterials, with the resulting sensors having broader application prospects.

Polybrominated diphenyl ethers (PBDEs) have raised increasing concerns due to their biotoxicity and persistence. Herein, the visible-light photodegradation of decabromodiphenyl ether (BDE209) is achieved on diethylenetriamine (DETA) intercalated wide band gap ZnS, mediated by a photosensitized complex formed via a N & ctdot;Br halogen bond. By regulating the amount of DETA, ZnS(DETA)1/2n, referred to as ZD, exhibit tunable photocatalytic activity towards BDE209. The most rapid degradation is observed on ZD-4, with 98% removal achieved within 6 hours. Density functional theory (DFT) calculations reveal that the halogen bond is preferentially formed between the amino N and para-Br atom in BDE209 with a bond length of 2.7548 & Aring;. A novel degradation pathway for BDE209 is proposed, in which the DETA & ctdot;BDE209 complex functions as a visible light photosensitizer, providing photoelectrons to the conduction band of ZnS, thereby participating in the degradation of BDE209 adsorbed on the ZnS surface. This process is significantly more effective than the indirect photolysis of BDE209 by DETA solely. Notably, this degradation phenomenon is also observed in other organic amine coordinated ZnS, suggesting a universal mechanism for BDE209 degradation by photosensitized halogen bond-based complexes. This work provides a novel strategy to utilize weak interfacial halogen bonding for visible-light photosensitized degradation of brominated persistent organic pollutants by wide band gap inorganic semiconductors.