Gold nanoparticle-based localized surface plasmon immunosensor for staphylococcal enterotoxin A (SEA) detection.

Area of Science:

• Nanotechnology
• Biosensing
• Immunotechnology

Background:

• Staphylococcal enterotoxin A (SEA) is a potent toxin requiring sensitive detection methods.
• Gold nanoparticles (AuNPs) offer unique optical properties for biosensing applications.
• Localized surface plasmon resonance (LSPR) is a sensitive detection technique based on changes in nanoparticle optical properties.

Purpose of the Study:

• To engineer stable gold nanoparticle (AuNP) bioconjugates for SEA detection.
• To develop and validate a localized surface plasmon resonance (LSPR) based biosensor for SEA.
• To assess the stability and performance of the AuNP bioconjugates and biosensor.

Main Methods:

• Covalent attachment of anti-SEA antibodies or SEA to AuNPs using Traut's reagent.
• Characterization of bioconjugates using absorption spectroscopy, cryo-TEM, DLS, and zeta potential.
• Development of homogeneous LSPR binding assays (direct and competitive formats).
• Stability assessment of bioconjugates after one year of storage at 4°C.

Main Results:

• Stable AuNP bioconjugates (anti-SEA Ab and SEA) were successfully prepared and characterized.
• A direct LSPR assay demonstrated high specificity and sensitivity for SEA detection (LOD of 5 ng/mL).
• The analytical performance of the AuNP-Ab bioconjugates remained stable after one year of storage.
• The LSPR biosensor successfully detected SEA in milk samples.

Conclusions:

• Stable AuNP bioconjugates can be effectively used for SEA detection via LSPR.
• The direct LSPR assay format offers a simple, sensitive, and reliable method for SEA quantification.
• This nanoplasmonic immunosensor is a promising tool for rapid and sensitive biotoxin detection in various matrices.