Cytometric Microbead Magnetic Suspension Array for High-Throughput Ultrasensitive Detection of Aflatoxin B₁

Abstract

High-throughput and low-cost detection of mycotoxins in complex matrices is becoming increasingly urgent but it is still challenging to perform ultrasensitive analyses. Here we report a green and practical cytometric microbead magnetic suspension array (CBMSA) strategy for rapid and economical detection of aflatoxin B1 (AFB1) in multiple batches of lotus seed samples. The protocol included (1) fabrication of suspension array chips by immobilizing biotin-modified bovine serum albumin–AFB1 (antigen) onto the surface of streptavidin-coated magnetic microbeads in a multiwell array, (2) indirect immunocompetition of antigen and target of AFB1 in lotus seed samples with the specific antibodies, (3) rapid magnetic separation regardless of complex pretreatment steps, and (4) ultrasensitive fluorescence detection of fluorescein isothiocyanate-labeled goat anti-mouse immunoglobulin G (FITC-IgG) probes. After systematic optimization of some crucial parameters, the developed CBMSA assay allowed for ultrasensitive detection of AFB1 with limit of detection as low as 7.8125 pg·kg–1. For high-throughput analysis, the CBMSA technique was capable of on-site co-instantaneous detection of 50–100 samples in one operation within 30 s, only needing a small amount (50 μL) of solution, which is much cheaper, greener, and more user-friendly than conventional techniques. Moreover, CBMSA with magnetic separation is free of multiple centrifugation and cleanup steps to avoid unpredictable loss of targets. Since various capture and fluorescent probes can be randomly constructed and bound onto the surface of magnetic microbeads to establish an ultrasensitive detection system, the CBMSA technique is very promising for more trace analytes in complex matrices and for broad point-of-need applications, such as drug screening and real-time high-throughput analysis.

Simulation of the Electro-Superconducting System Based on the H Equation

“…According to its working principle and technical characteristics, traditional maglev trains can be divided into electromagnetic attraction type (EMS) and electrodynamic repulsion type (EDS) [3]. Electromagnetic attraction (EMS) maglev trains mainly use electromagnets installed on the bogies on both sides of the train and magnets laid on the rails of the line; the attractive force generated under the action of a magnetic eld attracts the long stator core under the guide rails to make the train levitate; the magnets on both sides of the guide rail and the magnets on both sides of the train generate attractive force to achieve guiding and braking functions [4,5]. At present, conventional gravimeters mainly use mechanical springs to achieve the suspension of inspection quality.…”

Superparamagnetic Nanostructures for Split-Type and Competitive-Mode Photoelectrochemical Aptasensing

“…Superparamagnetic nanomaterials have been shown to be promising in biological systems as they disperse well when the applied magnetic field is removed. , With superparamagnetic behavior and high magnetization strength, water-dispersed Fe 3 O 4 colloidal nanoclusters are most attractive because they have good biocompatibility and stability in organisms. , The integration of bioseparation and recognition has been applied in various biosensors. − Inspired by these designs, to overcome the shortcomings of the PEC biosensors above, we reported the significantly important bioprobe functionalized magnetic-optical composite for PEC aptasensing . However, this is a direct-mode and signal-off type PEC aptasensor based on the conformational change of progesterone aptamer and then the decreased photoelectric responses.…”

Breaking Through Bead-Supported Assay: Integration of Optical Tweezers Assisted Fluorescence Imaging and Luminescence Confined Upconversion Nanoparticles Triggered Luminescent Resonance Energy Transfer (LRET)

“…Bead-supported assay, due to its superiorities of fast binding kinetics and good flexibility in target selection, has been a fascinating high-throughput and high-density analytical technique efficiently applied in various fields such as drug discovery and disease diagnosis. − Unlike the traditional planar based enriching strategy, this approach is usually conducted by capturing large numbers of targets (e.g., nucleic acids and proteins) on suspended microscale beads (e.g., polystyrene and silica beads) with extremely large surface areas and tiny differences in liquid phases, allowing for distinctly improving sensitivity and offering high-quality results in a quantity as low as a microliter and nanoliter. , In practice, the core concept of this excellent analysis system is the introduction of signal encoding, i.e., graphical, electronic, magnetic, and optical means, to make an easy way for identifying and detecting the biomolecular binding events. Among the available candidates, optical recognition is the commonly effective manner because of its unique features relating to speed, intuitiveness, and controllability.…”