Nanozyme and bifunctional nanobody-based colorimetric-SERS dual-mode Immunosensor for microcystin-LR detection
Long Wu, Luyao Jiao, Danni Xue, Yueqing Li, Yu Han, Wei Ouyang, Qi Chen
Abstract
Microcystin-LR (MC-LR), a potent cyanotoxin in freshwater , poses a risk of severe liver damage and other health issues, making its detection vital. However, the detection capabilities of conventional antibodies are constrained, which limited their use in immunoassays . In this work, we designed a new bifunctional nanobody , named A2.3-SBP (comprised of nanobody and streptavidin binding peptide), capable of binding with MC-LR and streptavidin . Based on A2.3-SBP and Fe 3 O 4 @Au-Pt nanozyme , we introduced an enzyme-free immunosensor that operated in microplate with colorimetric and surface-enhanced Raman scattering (SERS) detection modes. The dual-mode assay showed color changes and SERS intensity directly correlating to MC-LR concentrations with a range from 1.0 to 500 ng/mL and a limit of detection of 0.26 and 0.032 ng/mL, respectively. This strategy eliminated the need for complex enzymatic reactions and realized dual-signal detection of MC-LR in 96 water samples (0.03 μg/kg) within 30 min, suggesting its potential in drinking water detection.