Amino-Modified Magnetic Nanoparticles Magnetophoretic Chromatography Combined with Enzyme-Aptamer Colorimetric Photothermal for the Detection of Escherichia coli O157:H7 in Sea Cucumber Peptides

A Convenient Colorimetric Biosensor Based on Immunomagnetic Separation and G-Quadruplex DNAzyme Signal Amplification for Ultrasensitive Detection of Vibrio parahaemolyticus in Seafood

A Novel Bimetallic Nanozyme-Driven Fluorescence–Colorimetric Dual-Mode Platform for the Rapid Detection of Escherichia coli O157:H7 in Meat Products

Foodborne diseases pose a severe threat to human health. As a critical meat-borne pathogen, Escherichia coli O157:H7 (E. coli O157:H7) can trigger severe illnesses such as hemorrhagic enteritis, threatening public safety and causing a huge economic impact on the meat industry. However, previous detection methods have struggled to strike an optimal balance among accuracy, reliability, and efficiency, with various traditional techniques exhibiting obvious technical shortcomings. To overcome these limitations, this study developed a novel biosensor for the rapid detection of E. coli O157:H7 based on bimetallic carbon-based nanozymes. This sensor leverages the superior peroxidase-like activity and excellent intrinsic fluorescence of bimetallic carbon dots, providing a solid foundation for constructing a dual-modal platform combining colorimetry and fluorescence. Ultimately, this collaborative approach enables the rapid and accurate detection of the pathogen, substantially enhancing the reliability and stability of the results with a limit of detection (LOD) of 10 cfu/mL. This research presents significant practical application value and offers an innovative design strategy for developing advanced diagnostic sensors for E. coli O157:H7 and other meat-borne pathogens.

Mannose-engineered Eu-MOF for ratiometric fluorescent/colorimetric dual-detection and inhibition of E. coli.

Reliable detection and fast inhibition of Escherichia coli (E. coli) are critical for public health and food safety, so the detection-inhibition-integrated strategies become critical. Herein, a mannose-engineered 3,5-dicarboxyphenylboronic acid/curcumin dual-ligand Eu-metal-organic framework (Eu-MOF) was designed as dcMOF@man. Mannose realized the specific identification to E. coli; Eu-MOF exhibited dual-emission at 350 and 633 nm for robust ratiometric fluorescence sensing to E. coli as boronic acid-surface glycan interaction enhanced the emission at 350 nm, while mannose-FimH-mediated interaction attenuates the Eu3+ emission at 633 nm. The intensity ratio of I633/I350 exhibits a good linear relationship to E. coli at the concentration range of 10-107 CFU/mL with a low detection limit of 5 CFU/mL. Concurrently, the dcMOF@man exhibited peroxidase-like activity, enabling E. coli-dependent colorimetric detection based on tetramethylbenzidine oxidation, with the linear range of 10-107 CFU/mL and detection limit of 9 CFU/mL, which was also quantified via smartphone-based RGB analysis for on-site detection. The intrinsic antibacterial activity of curcumin afforded the effective inhibition of E. coli. Moreover, curcumin-mediated antibacterial activity synergizes with mannose targeting, resulting in nearly 100% antibacterial efficiency. Thus, dcMOF@man integrates targeting identification, ratiometric fluorescence sensing, colorimetric detection, and antibacterial functionality within single composite, as a generalizable strategy for on-site bacterial detection and inhibition.

Dual-ligand quantum dot biosensor combining IgY antibodies and DNA aptamers for rapid, on-site detection of staphylococcal enterotoxin A (SEA) in food matrices.

A type of magnetically induced self-assembled electrochemical aptamer nanobiosensor for ultrasensitive detection of hypoxia-inducible factor 1α protein

Hypoxia-inducible factor 1α (HIF-1α) protein has been identified as an aggressive malignant phenotype marker for numerous tumors; therefore, the detection of HIF-1α has become increasingly significant. In this work, we developed a type of magnetically induced self-assembled electrochemical aptamer nanobiosensor for detecting HIF-1α protein. This nanobiosensor utilized the magnetism of hydrothermal-calcination-synthesized α-ferric oxide/ferriferrous oxide (α-Fe 2 O 3 /Fe 3 O 4 , αFO/FFO) magnetic heterogeneous nanorods (MHNRs) to realize magnetically induced self-assembly; further, gold nanoparticles (AuNPs) were used to reinforce the electron transfer capacity and realize secure immobilization of the aptamer via Au–S bonds. Finally, we adopted cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV) for the electrochemical characterization, condition optimization, and performance analysis of the nanobiosensor, respectively. The nanobiosensor revealed a favorable linear relation in the range of 0.1–1,000 ng/mL with a variance R 2 of 0.995 and limit of detection of 0.112 ng/mL, excellent sensitivity, faithful reproducibility with a relative standard deviation (RSD) of 2.28%, reliable 13-d stability with an RSD of 1.71%, and accredited detection capacity for real samples with recoveries of 97.71%–107.47% and RSDs ≤ 3.47%. In this study, we developed a magnetically induced self-assembled electrochemical aptamer nanobiosensor for ultrasensitive detection of HIF-1α protein. The nanosensor delivers outstanding analytical performance with a facile assay strategy suitable for point-of-care testing, suggesting its promising prospects for clinical tests.

A Monolithic, Thiol-Functionalized Au-Based Bio-CMOS Aptasensor for Rapid, Label-Free Detection of Escherichia coli O157:H7 in Patient-Derived and Hospital-Acquired Specimens

Rapid, point-of-care detection of Escherichia coli O157:H7 remains an unmet clinical need, as culture and molecular methods are slow and poorly suited to decentralized or emergency settings. A label-free, monolithic aptasensor biochip was fabricated in a standard 65 nm CMOS process, featuring three aptamer-functionalized gold sensing pads with matched reference pads for differential readout. A 37-mer DNA aptamer targeting the E. coli O157:H7 lipopolysaccharide was immobilized via thiol–gold self-assembled monolayer chemistry. Binding events were transduced into surface-potential shifts, amplified by an on-chip analog front-end (~100 V/V gain, 101.5 µW), and evaluated using calibration standards, patient specimens, and hospital environmental samples, with fluorescence microscopy for validation. The sensor achieved 47.42 mV/decade sensitivity across 1–10,000 CFU/mL, an IUPAC detection limit near 3.74 CFU/mL, and an empirical LOD of about 11 CFU/mL, with outputs tracking bacterial load and ~5.7% matrix-related deviation. Hospital samples were detectable to 28 CFU/mL. Because the patient-derived and hospital-acquired cohorts (n = 10 and n = 6, respectively) were assembled for pilot analytical and matrix-tolerance characterization rather than for diagnostic-accuracy determination, these results establish detectability and matrix robustness in real clinical and environmental specimens rather than clinical diagnostic sensitivity or specificity, which will require a larger, prospectively enrolled cohort in future work. Sensor kinetics followed Langmuir-type adsorption, saturating within 16–25 min for target pathogens versus slower responses for non-target strains. Selectivity tests against six bacterial species showed discrimination, with cross-reactivity decreasing from related E. coli pathotypes to Enterobacteriaceae to Gram-positive species. Inter-pad variability stayed below 1.5 mV, supporting this compact, low-power platform for scalable, enrichment-free point-of-care pathogen detection.