Label-Free Electrical Immunosensor for Highly Sensitive and Specific Detection of Microcystin-LR in Water Samples

Abstract

Microcystin-LR (MCLR) is one of the most commonly detected and toxic cyclic heptapeptide cyanotoxins released by cyanobacterial blooms in surface waters, for which sensitive and specific detection methods are necessary to carry out its recognition and quantification. Here, we present a single-walled carbon nanotube (SWCNTs)-based label-free chemiresistive immunosensor for highly sensitive and specific detection of MCLR in different source waters. MCLR was initially immobilized on SWCNTs modified interdigitated electrode, followed by incubation with monoclonal anti-MCLR antibody. The competitive binding of MCLR in sample solutions induced departure of the antibody from the antibody-antigen complexes formed on SWCNTs, resulting in change in the conductivity between source and drain of the sensor. The displacement assay greatly improved the sensitivity of the sensor compared with direct immunoassay on the same device. The immunosensor exhibited a wide linear response to log value of MCLR concentration ranging from 1 to 1000 ng/L, with a detection limit of 0.6 ng/L. This method showed good reproducibility, stability and recovery. The proposed method provides a powerful tool for rapid and sensitive monitoring of MCLR in environmental samples.

Carbon nanotubes and graphene nano field-effect transistor-based biosensors

“…Nevertheless, a novel strategy for overcoming these challenges was demonstrated in several studies using SWCNT-based FET biosensors [74]- [76]. This strategy applies the principle of competitive [74].…”

Recent Trends in Field-Effect Transistors-Based Immunosensors

“…Table 2 also depicts the application of immunoFET devices for detecting environmental contaminants such as pesticides [74], herbicides [75], toxins [76], and phytopathogens [77]. Alzheimer biomarker, amyloid-β SWCNT 10 −12 -10 −9 g·mL −1 1 pg·mL −1 in human serum [63] Chondroitin sulfate proteoglycan 4, multiple cancer types biomarker Graphene 0.01 fM-10 pM 0.01 fM [85] Pancreatic cancer biomarker, carbohydrate antigen 19-9 (CA 19-9) Graphene 0.01 unit·mL −1 -1000 unit·mL −1 0.01 unit·mL −1 [56] Prostate specific antigen/α1-antichymotrypsin (PSA-ACT) complex Graphene 100 fg·mL −1 -1 µg·mL −1 100 fg·mL −1 [49] Breast cancer biomarkers human epidermal growth factor receptor 2 (HER2) and epidermal growth factor receptor (EGFR) SiO 2 /graphene 100 pM-1 µM 1 pM for HER2 and 100 pM for EGFR [52] Human immunodeficiency virus (HIV) 2,4-Dichlorophenoxyacetic acid herbicides SWCNT 5 fM-500 µM 500 fM in soil sample and 50 pM in buffer [75] 2,4,6-Trinitrotoluene (TNT) contamination SWCNT 0.5 ppb-5000 ppb 0.5 ppb [76] Microcystin-LR (cyanotoxin in surface waters) SWCNT 1-1000 ng·L −1 0.6 ng·L −1 [91] Citrus tristeza virus and Xylella fastidiosa phytopathogens InP 60-340 ng·mL −1 for Citrus tristeza virus and 34-250 ng·mL −1 for Xylella fastidiosa 2 nM for both phytopathogens [77] 3.1. Silicon Nanowires…”

“…This chemiresistive biosensor was able to detect small size and uncharged cortisol molecules because the antibody bound to the SWCNT functionalized with cortisol analog was stripped/displaced, provoking a large change of the device resistance/conductance and a LOD of 1 pg·mL −1 [82]. Tan et al also fabricated a label-free immunoFET based on SWCNT by the displacement assay of the immobilized antibodies [91]. The immunosensors were able to detect the small molecular mass microcystin-LR (MCRL), a toxin released by cyanobacteria in surface waters, with high sensitivity and specificity along with a detection limit of 0.6 ng·L −1 .…”

Integrated optical waveguide-based fluorescent immunosensor for fast and sensitive detection of microcystin-LR in lakes: Optimization and Analysis

“…Microcystin-LR (MC-LR) is one of the most toxic cyclic heptapeptide cyanotoxins released by cyanobacterial blooms in surface waters, for which sensitive and specific detection methods are necessary to carry out recognition and quantification 7 . Although several analytical techniques for microcystin detection such as ELISA, HPLC and LC-MS/MS etc.…”