The sensitive detection of patulin (PAT) is of paramount important for food safety. Here, a novel colorimetric/electrochemical dual-mode sensor was constructed based on an enzyme-triggered nanozyme in situ synthesis strategy for the sensitive and reliable detection of PAT. Iron metal-organic framework (Fe-MOF) was hydrothermal synthesized on an exfoliated graphene paper (EGP) and utilized as the substrate for sensing. Due to the specific recognition between PAT and its aptamer, alkaline phosphatase (ALP) linked DNA chain was replaced. In the presence of ascorbic acid-phosphate (AAP) and K3[Fe(CN)6], Prussian blue nanoparticles (PB NPs) were in situ synthesized based on the ALP-triggered AAP hydrolysis. The produced ascorbic acid (AA) quickly reduced K3[Fe(CN)6] to K4[Fe(CN)6], which subsequently reacted with Fe-MOF on EGP to form PB NPs. The results showed that PB NPs possessed excellent peroxidase-like activity and electrochemical activity, endowing the sensor with good colorimetric and electrochemical dual-mode sensing abilities. In the presence of H2O2, PB NPs catalytically oxidized o-phenylenediamine (OPD) to form the deep yellow-color production with a distinct color change for colorimetric sensing. The electrochemical mode demonstrated high sensitivity with a lower limit of detection (LOD) of
$2.6\times 10^{-{12}}$
g/mL compared to that of the colorimetric mode (
$2.2\times 10^{-{10}}$
g/mL). This portable dual-mode sensor based on ALP-triggered nanozyme in situ synthesis not only offers new insights into sensitive and reliable determination of PAT but also provides an effective way based on visual monitoring and sensitive determination to ensure food safety and health.
Ting Zhang,Lingli Lei,Meiling Tian,Junjie Ren,Zhisong Lu,Yang Liu,Yingshuai Liu
An ultrasensitive lateral flow immunoassay (LFIA) strip has been developed based on a multifunctional photothermal contrast Fe 3 O 4 @Au supraparticle (Fe 3 O 4 @Au SP) for quantitative Ochratoxin A (OTA) detection. The Fe 3 O 4 @Au SP composite not only shows a better photothermal effect over Fe 3 O 4 and gold nanoparticles , but possesses magnetic property and excellent ability to directly adsorb protein (antibody). Under 808 nm irradiation, photothermal images of the test strips are recorded by a portable Infrared thermal camera. A quantitative analysis is easily achieved based on the thermal changes, which are proportional to the concentrations of analytes. Under an optimal condition, a wide linear detection range from 1 pg mL⁻ 1 to 1μgmL⁻ 1 and a limit of detection (LOD) at 0.12 pg mL⁻ 1 have been achieved with OTA as a model analytes. The practical application potential has also been validated by detection of OTA in spiked corn , peanut, and soybean extractives with overall recoveries ranging from 98.6% to 115% and coefficient of variations (CVs) between 6.06% and 12.73%. The photothermal LFIA renders a rapid, sensitive, and quantitative bio-/chemo-sensing platform with only a portable laser source and a thermal camera.
A flower-like gold nanoparticles (FGN)-based immunochromatographic test strip (ICS) was developed and used for the first time for the rapid simultaneous detection of fumonisin B 1 (FB 1 ) and deoxynivalenol (DON) in Chinese traditional medicine. Several experimental conditions affecting the sensitivity of ICS have been investigated, including the type of FGN, the preparation conditions of FGN-monoclonal antibody (MAb) conjugates, and the process parameters of ICS. Under the optimal experimental conditions, the visual limit of detection was 5.0 ng/mL (corresponding to 50 μg/kg in Chinese traditional medicine samples) for both FB 1 and DON, and detection can be completed within 5 min. In addition, the natural samples were analyzed using high-performance liquid chromatography (HPLC) or enzyme-linked immunosorbent assay (ELISA), and the results of these methods showed good correlation with those obtained using ICS. The procedure using FGN-based simultaneous ICS was sensitive, rapid, and convenient for on-site detection of a large number of samples.
危险品化学品经营许可证（带存储）