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A new method is proposed for detecting typical melamine dopants in food using surface-enhanced Raman scattering (SERS) biosensing technology. Melamine specific aptamer was used as the identification probe, and gold magnets (AuNPs@MNPs) and small gold nanoparticles (AuNPs@MBA) were used as the basis for Raman detection. The Raman signal of the detection system can directly detect melamine quantitatively. Under optimized conditions, the detection of melamine was carried out in the low concentration range of 0.001–500 mg/kg, the enhancement factor (EF) was 2.3 × 107, and the detection limit was 0.001 mg/kg. The method is sensitive and rapid, and can be used for the rapid detection of melamine in the field environment. [ABSTRACT FROM AUTHOR]

To reduce the crop losses associated with biotic and abiotic stresses, novel sensor technologies that can monitor plant health and predict and track plant diseases in real time are required. Plant sensors based on wearable technologies are placed directly on the plant leaf or stem. The health status of the plant is reflected by various biomarkers and microenvironmental parameters, which are converted into electric readouts by the sensors for convenient analysis. Herein, the latest research progress in the field of wearable plant sensors is evaluated, and the sensors are classified according to their individual functions. Moreover, the design principles and working mechanisms of previously reported wearable sensors are analyzed, and the design features adopted to overcome the difficulties associated with precision agriculture are explored. Finally, the challenges and future development prospects in this field are outlined. This review contributes to the growing body of literature on wearable plant sensors, underscoring their critical role in mitigating crop losses through real-time plant health monitoring and disease prediction. Advancements in wearable plant sensors could ultimately revolutionize crop production and sustainability by enabling more precise, efficient, and proactive farming practices. [ABSTRACT FROM AUTHOR]

We designed and synthesised a magnetic adsorbent (Fe3O4@Si–OH@CS-Glu) combining chitosan-silanol groups with glutaraldehyde as a cross-linking agent, which has improved physicochemical properties and can be used to remove multiple heavy metals and bacteria from polluted water. The adsorbent was characterised with SEM, XRD, FTIR, BET, VSM, and zeta potential. Under optimum conditions, the adsorption efficiencies of Fe3O4@Si–OH@CS-Glu for Cr6+, As5+, Hg2+, and Se6+ were as high as 90.5%, 73.5%, 91.6%, and 100% respectively. In addition, Escherichia coli (gram-negative) and Staphylococcus aureus (gram-positive) can be removed after 2–4 adsorption cycles with 2.5 mg Fe3O4@Si–OH@CS-Glu. The main adsorption mechanism of the adsorbent for heavy metals and bacteria is electrostatic adsorption. Overall, the synthesised Fe3O4@Si–OH@CS-Glu adsorbent showed high removal efficiency and adsorption capacity with a stable structure and easy separation. It has promising applications for the removal of heavy metals and bacteria from water. [ABSTRACT FROM AUTHOR]

Bisphenol A (BPA) is one of the endocrine-disrupting chemicals which might cause reproductive and endocrine system diseases, and poses a serious threat to the ecosystem and human health. This paper reports an ultrasensitive sensor for trace BPA detection employing fluorescence resonance energy transfer (FRET) between modified upconversion nanoparticles (UCNPs) and tetramethylrhodamine. To circumvent the problems of low luminous efficiency of FRET and low sensitivity of sensor, the upconversion nanoparticles with very strong fluorescence efficiency were prepared and quantitatively modified. Results showed that the concentrations of amino groups and streptavidin were 43 nmol/mg and 6.12 μg/mg on the surface of the UCNPs, respectively. Under the optimal detection conditions, the peak intensity of UCNPs at 547 nm was linear with the logarithm of the BPA concentration with the detection limit of 0.05 ng/mL. Without complicated pre-processing, the recoveries were in general between 91.0 and 115.0% in tap water, river water, and disposable paper cup water. Therefore, the proposed sensor is suitable for effective sensing of trace BPA in water samples.ᅟ [ABSTRACT FROM AUTHOR]

This study describes an upconversion fluorescent aptasensor based on black phosphorus nanohybrids and self-assembled DNA tetrahedrons dual-amplification strategy for rapid detection of the environmental estrogens bisphenol A (BPA) and 17β-estradiol (E2). Tetrahedron complementary DNAs (T-cDNAs) were self-assembled in an oriented fashion on a 2D nanohybrid composed of black phosphorus (BP) and gold to give a materials of architecture BP-Au@T-cDNAs. In parallel, core-shell upconversion nanoparticles were modified with aptamers (UCNPs@apts) and used as capture probes. On complementary pairing, the BP-Au@T-cDNA quench the fluorescence of UCNPs@apts (measured at an excitation wavelength 808 nm and at main emission peaks at 545 nm and 805 nm.) Compared with single-stranded probes based on black phosphorus and gold, the dual-amplification strategy increases quenching efficiency by nearly 25%-30% and reduces capture time to 10 min. This is due to the higher optical absorption of 2D nanohybrid and the reduction of steric hindrance by T-cDNAs. Exposure to BPA or E2 cause the release of UCNPs@apts from the BP-Au@T-cDNAs due to stronger binding between aptamer and analyte. Hence, fluorescence recovers at 545 nm for BPA and 805 nm for E2. Based on these findings, a dually amplified aptamer assay was constructed that covers the 0.01 to 100 ng mL−1 BPA concentration range, and the 0.1 to 100 ng mL−1 E2 concentration range. The detection limits are 7.8 pg mL−1 and 92 pg mL−1, respectively. This method was applied to the simultaneous determination of BPA and E2 in spiked samples of water, food, serum and urine.Schematic presentation of novel quenching probes designed by tetrahedron complementary DNAs oriented self-assembled on the surface of black phosphorus/gold nanohybrids. Combined with aptamer-modified upconversion nanoparticles, a dual-amplification self-assembled fluorescence nanoprobe was constructed for simultaneous detection of BPA and E2. [ABSTRACT FROM AUTHOR]