Plasmonic Nanosensors for EGFR Detection: Optimizing Aptamer-Based Competitive Displacement Assays

Area of Science:

• Biomedical Engineering
• Nanotechnology
• Biosensing

Background:

• Epidermal growth factor receptor (EGFR) is a key biomarker and therapeutic target in oncology.
• Plasmonic sensing platforms offer potential for sensitive biomarker detection.

Purpose of the Study:

• To comparatively investigate colloidal gold nanoparticle (AuNP) suspensions and gold film over nanosphere (AuFoN) substrates for EGFR detection.
• To evaluate the performance of aptamer-based competitive binding assays for EGFR sensing.

Main Methods:

• Utilized Atto647N-labeled DNA oligomers competitively bound to EGFR-specific aptamers.
• Employed fluorescence emission modulation to detect EGFR-induced displacement.
• Compared sensing performance between AuNP suspensions and AuFoN solid substrates.

Main Results:

• Colloidal AuNPs demonstrated competitive binding, showing fluorescence quenching and recovery upon EGFR interaction.
• AuNP sensor performance was highly sensitive to washing steps, with excessive washing causing signal loss.
• AuFoN substrates exhibited initial fluorescence but failed to retain the aptamer complex, leading to EGFR-independent signal decay.

Conclusions:

• Colloidal AuNPs can function as competitive binding sensors for EGFR, but their reproducibility is limited by colloidal stability and protocol sensitivity.
• AuFoN substrates require enhanced surface functionalization for stable aptamer complex retention in biosensing.
• Optimizing surface chemistry, aptamer-fluorophore affinity, and washing protocols is crucial for robust plasmon-enhanced aptamer-based biosensing.