In this study, an ultrasensitive, and glyceraldehyde-3-phosphate dehydrogenase (GTP)-modified gold nanoparticles (AuNPs)-based localized surface plasmon resonance (LSPR) sensor for detection of chlorothalonil (CTL) in environmental and food safety applications. As a widely used fungicide, CTL plays an important role in agricultural production. However, its residues pose a potential threat to environmental ecology and human health. Therefore, it is particularly urgent and significant to develop an efficient and sensitive detection method for CTL. In this study, an innovative detection method of CTL is proposed based on LSPR sensor. A highly sensitive LSPR sensor was successfully constructed by carefully synthesizing AuNPs and modifying them with GTP. The sensor demonstrates high sensitivity, evidenced by its low limit of detection (LoD) for CTL and exhibits excellent selectivity and stability. More importantly, the recovery rate of the detection method in actual samples reached more than 90 %, which fully proved its broad application prospects in the field of environmental monitoring and food safety. The linear range of the sensor is 0-1000 μM, and the LoD is 75.41 μM. The sensitivity is as high as 0.0037 nm/(μM), which verifies that the sensor provides an indispensable technology and a cost-effective and portable solution for CTL-specific detection.
All fiber Michaelson interferometer cascaded fiber Bragg grating (FBG) sensor for simultaneous measurement of trace dimethyl methyl phosphate and temperature is proposed. One end of the four-core fiber (FCF) is spliced with a multimode fiber (MMF), the other end is flattened and evaporated with silver film to enhance reflection, and the Michelson interference structure is formed. The grating is engraved in the single-mode fiber (SMF) core and spliced with MMF, then the Michelson interference cascaded FBG, FBG-MMF-FCF sensor is obtained. The sensing film, MnCo2O4 is coated on the surface of FCF, and the structure, elemental composition and morphology of MnCo2O4 were analyzed by X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. The sensitivity and the detection limit of DMMP are 86.44 dB/ppm and 0.1767 ppb, respectively. The response/recovery time is about 14/10 s. the temperature sensitivity can be compensated and calculated as 0.069 nm/°C. The sensor has good selectivity and stability, and has a good application prospect in high sensitivity detection of trace DMMP vapor.
Aflatoxins are a kind of fungal toxin that causes great damage to humans and animals due to its wide distribution, secretive nature, and high toxicity. For the purpose of achieving qualitative and quantitative detection of aflatoxin B1 (AFB1), a novel tri-taper-in-taper fiber-optic structure based on core mismatch of four-core fiber with a multimode fiber-based WaveFlex biosensor is developed and tested. The sensor probe's surface is coated with gold nanoparticles (AuNPs). Multi-walled carbon nanotubes and zinc oxide nanoparticles are sequentially immobilized on the sensing probe surface to enhance the sensor's sensing capabilities. Then, the AFB1 antibody is utilized to functionalize the sensor to possess specific selectivity. After the modification of nanomaterials and the corresponding bioreceptors, the final sensor structure is formed. By stimulating the localized surface plasmon resonance phenomenon of AuNPs, different concentrations of AFB1 can be detected. The sensor demonstrates high sensitivity (38.29 nm/μM) as well as low LOD (7.12 nM) within the range of 0-100 nM for detection. The sensor is also found to be stable and reproducible in repeated measurements, indicating its potential for practical application. Additionally, it exhibits satisfactory specific recognition of AFB1. These results show that AFB1 can be detected in food and agricultural products using LSPR-based optical fiber sensors, which could have significant ramifications for public health and food safety.
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