Citrinin detection by intensified fluorescence signal of a FRET-based immunosensor using magnetic/silica core–shell

Abstract

The specific immune-reaction between the anti-citrinin antibody immobilized on the surface of magnetic/silica core-shell (MSCS) and the citrinin-Rho123-BSA conjugate brings the Rho123 fluorophore as an acceptor and the QDs as a donor in close spatial proximity and causes FRET for occurring upon photo-excitation of the QDs. The novelties of this study include: (1) immobilization of the MSCS; (2) large amount of the immobilized QDs, and (3) immobilization of a large amount of Rho123 on the BSA macromolecule. Cd/Te QDs were synthesized by the simultaneous reduction of cadmium chloride and tellurium in the presence of sodium borohydride. Magnetic nanoparticles were synthesized using FeSO and FeCl. The prepared magnetic nanoparticles shelled by silica using tetraethoxysilane in the presence of ammonia. Transmission electron microscopy (TEM) analysis was used for investigating shape and monodispersity of the nanoparticles. EDC/NHS was used as a cross linking agent for immobilization of the QDs, conjugation of citrinin to amino groups of BSA, labeling of BSA with Rho123 and also for immobilization of the amino-functionalized MSCS on the immobilized QDs. Immobilization of the anti-citrinin antibody on the surface of the amino-functionalized MSCS was performed by Schiff-base mechanism. By using these three effective strategies, sensitivity of the designed nanobiosensor was incredibly enhanced as a very low limit of detection (up to 0.1 pM). The feasibility of this technique was tested by the detection of citrinin in the spiked human serum. Results showed that there was a linear correlation between the decreased fluorescence intensity of the Rho123 and increased fluorescence intensity of the QDs with increasing concentration of citrinin in the spiked samples in the range of 1-6 pM. According to obtained results, we conclude that this highly sensitive detection scheme is a easy, quick and impressive method that can be used in optical-based nanosensors.

Development of Real-Time Immuno-PCR Based on Phage Displayed an Anti-Idiotypic Nanobody for Quantitative Determination of Citrinin in Monascus

“…Biosensors are mainly composed of biological components and signal converters, which can amplify and convert biological signals of target molecules into electrical signals or other signals for analysis and detection purposes. This method can also be applied to quantitative determination of CIT [11,23,24,25]. These methods produce sensitive and reliable results but they are laborious, costly, and conducted in a sequential manner, making them unsuitable for routine analysis of a large scale of samples [26,27].…”

Application of biosensors in aflatoxins detection in food: a review

“…These biosensors are favorable in screening several samples at the same time, whereas they are not potent to miniaturize for bloodstream insertion easily (Bueno et al , 2016). Many optical transduction sensors still need a spectrophotometer to discover the changes in signal (Shojaee Sadi et al , 2018; Al-Jawdah et al , 2019). Some optical transducers are able to form the base of biosensors, concluding fluorescence, surface resonance and spectroscope for foodborne pathogens’ detection (Zongfu and Jang, 2018; Khan et al , 2018).…”