Bead-Based Competitive Fluorescence Immunoassay for Sensitive and Rapid Diagnosis of Cyanotoxin Risk in Drinking Water

Abstract

Due to the increased occurrence of cyanobacterial blooms and their toxins in drinking water sources, effective management based on a sensitive and rapid analytical method is in high demand for security of safe water sources and environmental human health. Here, a competitive fluorescence immunoassay of microcystin-LR (MCYST-LR) is developed in an attempt to improve the sensitivity, analysis time, and ease-of-manipulation of analysis. To serve this aim, a bead-based suspension assay was introduced based on two major sensing elements: an antibody-conjugated quantum dot (QD) detection probe and an antigen-immobilized magnetic bead (MB) competitor. The assay was composed of three steps: the competitive immunological reaction of QD detection probes against analytes and MB competitors, magnetic separation and washing, and the optical signal generation of QDs. The fluorescence intensity was found to be inversely proportional to the MCYST-LR concentration. Under optimized conditions, the proposed assay performed well for the identification and quantitative analysis of MCYST-LR (within 30 min in the range of 0.42-25 μg/L, with a limit of detection of 0.03 μg/L). It is thus expected that this enhanced assay can contribute both to the sensitive and rapid diagnosis of cyanotoxin risk in drinking water and effective management procedures.

Manganese modified CdTe/CdS quantum dots as an immunoassay biosensor for the detection of Golgi protein-73

“…Hepatocellular carcinoma (HCC) is a leading cause of cancer-related death 29 worldwide and its incidence has been rising for decades. According to the American 30 Cancer Society, more than 700,000 people are diagnosed with this cancer each year 31 throughout the world, which is the most common type of cancer in sub-Saharan Africa 32 and Southeast Asia, accounting for more than 600,000 deaths each year [1].…”

Magnetic Bead-Based Colorimetric Immunoassay for Aflatoxin B1 Using Gold Nanoparticles

“…Iron oxide particles, for instance, have been widely used in immunoassay [ 10 , 11 ], protein and enzyme immobilization [ 12 , 13 ], cell separation [ 14 ], DNA hybridization [ 15 , 16 ] and drug delivery [ 17 ]. MB-based assays have been developed by combining MBs with recognition elements such as enzymes [ 18 ], noble metal nanoparticles [ 19 , 20 ], fluorescent nanoparticles [ 21 , 22 ] and carbon nanotubes [ 23 ]. Since the particles have a large surface area, diffuse freely in the reaction mixture and can be easily separated after reaction [ 24 ], these assays are usually fast and simple to operate, which offers a promising platform for the detection of various analytes such as proteins [ 25 ], DNA [ 26 ] and small molecules [ 27 ].…”

“…Since the particles have a large surface area, diffuse freely in the reaction mixture and can be easily separated after reaction [ 24 ], these assays are usually fast and simple to operate, which offers a promising platform for the detection of various analytes such as proteins [ 25 ], DNA [ 26 ] and small molecules [ 27 ]. Different analytical methods have been employed in MB-based assays, including colorimetry [ 28 ], fluorescence [ 22 , 29 ], light scattering [ 30 , 31 ], electrochemistry [ 32 ], and chemiluminescence [ 10 , 33 ].…”

A high-sensitivity fiber-optic evanescent wave sensor with a three-layer structure composed of Canada balsam doped with GeO2

“…Furthermore, the figure shows that the low limit of detection (LOD) of the CBX-coated FOEW sensor was 0.2 ng/l over the detection range of 0-200 μg/l (the sensitivity was À 0.0613/ng/l, the uncertainty was less than 9.57% and the maximum RSD was 16.7% over the IgG concentration range of 0-0.2 ng/l). The LOD of the CBX-coated FOEW sensor is highly comparable with that of other bioassay methods, including a capillary biosensor with a LOD of 0.3-0.8 ng/l in immunoassays (mouse IgG and staphylococcal enterotoxin B) (Ligler et al, 2002), a surface plasmon resonance biosensor for the detection of microcystins in drinking water with a LOD of 0.7 μg/l (Herranzet et al, 2010), a competitive fluorescence immunoassay of microcystin-LR for the rapid diagnosis of cyanotoxin risk in drinking water with a LOD of 0.03 μg/l (Yu et al, 2011), evanescent wave-based optical fiber biosensors consisting of LPG-based biosensors for measuring goat anti-mouse IgG analyte with a LOD of 25 μg/l (Chiavaioli et al, 2015), and a sandwich-like immunoassay strategy based on a quantum dot immunoprobe (QD-labeled antimouse IgG antibody) for the detection of small molecules with a DOL of 3 ng/l (Zhou et al, 2016). However, compared with the given sensors, the proposed CBX-coated FOEW sensor is remarkably simpler, easily customizable, and more cost-effective.…”