A Highly Sensitive Fluorescence and Screen-Printed Electrodes—Electrochemiluminescence Immunosensor for Ricin Detection Based on CdSe/ZnS QDs with Dual Signal

Abstract

A sensitive dual-readout immunosensor for fluorescence and electrochemiluminescence (ECL) detection of ricin was established, which was combined with a streptavidin–biotin signal amplification system. CdSe/ZnS quantum dots with fine fluorescence and ECL properties were used as the dual-signal function probes of the sandwich immunocomplex. Under the optimum experimental conditions, the dual signal intensity increased significantly with the rise in ricin concentration. The fluorescence intensity of the senor exhibited a good liner relationship toward the ricin concentrations with 0.1~100 ng/mL and the limit of detection (LOD) was 81.7 pg/mL; taking ECL as the detection signal, the sensor showed a linear relationship with the ricin concentrations ranging from 0.01 ng/mL to 100 ng/mL and the LOD was 5.5 pg/mL. The constructed sensor with high sensitivity had been successfully applied to the detection of ricin in complex matrices with satisfactory recoveries. The proposed immunosensor model can be extended to the analysis and detection of others target proteins.

Trimetallic Au@Pd@Pt nanozyme-enhanced lateral flow immunoassay for the detection of SARS-CoV-2 nucleocapsid protein

“…The immobilized amount was calculated by: immobilized amount (μg) = Added amount (μg) × [( A 280, before − A 280, after )/ A 280, before ]. 38 The running buffer is important for the delivery of antibody complexes. Appropriate buffer can reduce the nonspecific absorption to the NC membrane and increase the sensitivity of LFIA.…”

Immunosensors for Assay of Toxic Biological Warfare Agents

“…The detection limit for the assay was equal to 0.1 ng/mL for vacuolating cytotoxin A with a linear range of calibration between 0.1 and 12.8 ng/mL and a time per test of 10–15 min. An electrochemiluminescence immunosensor for a ricin assay was developed on a platform of screen-printed electrodes [ 93 ]. The immunosensor contained magnetic beads with antibodies specific for ricin immobilized through streptavidin-biotin.…”