Gap-Tethered Au@AgAu Raman Tags for the Ratiometric Detection of MC-LR

Area of Science:

• Environmental Science
• Analytical Chemistry
• Materials Science

Background:

• Microcystin-LR (MC-LR) poses risks to environmental and human health, necessitating accurate detection methods.
• Existing assays for MC-LR detection often lack simplicity, accuracy, or reproducibility.
• Development of novel sensing platforms is crucial for effective MC-LR monitoring.

Purpose of the Study:

• To develop a simple, accurate, and reproducible ratiometric surface-enhanced Raman scattering (SERS) aptasensor for quantitative MC-LR detection.
• To utilize gap-tunable SERS-active nanoparticles and an internal standard for enhanced analytical performance.
• To demonstrate the potential of the developed assay for detecting MC-LR in complex environmental samples.

Main Methods:

• Fabrication of gap-tethered SERS-active Au@AgAu nanoparticles with adjustable gap sizes.
• Preparation of graphene oxide (GO)/Fe3O4 nanoparticles as a stable internal standard (IS) for Raman analysis.
• Assembly of Au@gap@AgAu nanoparticles with GO/Fe3O4 nanoparticles via π-π stacking interactions and aptamer binding.
• Detection of MC-LR based on the changes in Raman intensity of SERS tags upon aptamer-analyte interaction.

Main Results:

• Successfully synthesized gap-tunable Au@AgAu nanoparticles with amplified SERS activity.
• Demonstrated the utility of GO/Fe3O4 nanoparticles as an effective IS for quantitative Raman analysis.
• Achieved a low limit of detection (LOD) of 9.82 pM for MC-LR after IS correction.
• The developed aptasensor showed high sensitivity and reproducibility in quantitative MC-LR detection.

Conclusions:

• The developed ratiometric SERS aptasensor provides a simple, rapid, and sensitive method for MC-LR detection.
• The internal standard approach enhances the accuracy and reproducibility of the quantitative analysis.
• This assay shows significant promise for practical applications in monitoring MC-LR in complex environmental systems.