CB[7]-mediated signal amplification approach for sensitive surface plasmon resonance spectroscopy

Area of Science:

• Biomolecular Engineering
• Nanotechnology
• Analytical Chemistry

Background:

• Cucurbit[7]uril (CB[7]) possesses unique recognition properties valuable for biosensing.
• Surface plasmon resonance (SPR) biosensors require enhanced sensitivity for detecting low-abundance analytes.
• Caspase-3 is a key enzyme implicated in various biological processes and diseases.

Purpose of the Study:

• To develop a novel strategy for improving the sensitivity of SPR biosensors.
• To utilize CB[7]-modified gold nanoparticles (AuNPs) as an intermediate for enhanced analyte capture.
• To establish a highly sensitive SPR method for the detection of caspase-3.

Main Methods:

• Designed CB[7]-modified AuNPs (CB[7]-AuNPs) for specific caspase-3 recognition.
• Utilized the cleavage of substrate peptides by caspase-3 to expose N-terminal Phenylalanine (Phe).
• Facilitated CB[7]-AuNPs binding to Phe on a gold chip, followed by layer-by-layer assembly with peptide-modified AuNPs to amplify SPR signals.

Main Results:

• Achieved specific binding of CB[7]-AuNPs to the N-terminal Phe residue exposed by caspase-3 activity.
• Demonstrated significant signal amplification through the layer-by-layer assembly of AuNPs.
• Established a linear detection range for caspase-3 from 10 fg/mL to 10^3 fg/mL.
• Reported a low detection limit of 2.2 fg/mL for caspase-3.

Conclusions:

• The CB[7]-assisted SPR method provides high specificity and sensitivity for caspase-3 detection.
• This approach offers a promising tool for future caspase-3 assays.
• The developed model can be applied to enhance SPR biosensor performance for other protein detection and disease diagnosis applications.