Surface Plasmon Resonance Biosensors for Detection of Allergen-Specific Immunoglobulin E

This study focuses on optical-based surface plasmon resonance (SPR) biosensors developed for the detection of allergen-specific serum immunoglobulin E (IgE). The SPR gold chip surface was functionalized with 3-mercaptopropionic acid (3-MPA) and then covalently bon- ded using N-ethyl-N’-(3-diethylaminopropyl) carbodiimide (EDC)/N-hydroxysulfosuccinimide (NHS) to activate the carboxylic acid. Antibodies containing anti-immunoglobulin E (anti-IgE) were then immobilized on the chip surface with terminal amine groups as biotransport sites. The modified SPR chip surface was realized the characterization studies by atomic force microscopy (AFM), contact angle measurements, and ellipsometry. Three different contact angle values were determined, emphasizing the hydrophilicity of the surface: unmodified gold surface 60.5°, 3-MPA modified surface 28.13°, and EDC-NHS/anti-IgE modified surface 36.38°. The morphological analysis using AFM revealed that the unmodified SPR chip surface had a depth of 0.28 nm, while the EDC-NHS/anti-IgE modified SPR biosensor chip surface had a depth of 8.36 nm. The experiments conducted for IgE detection exhibited high selectivity within the range of 1.0–1000 ng/mL. Selectivity studies were performed with bovine serum albumin, immunoglobulin G (IgG), and myoglobin as similar proteins. The limit of detection and quantification values were obtained as 0.051 and 0.153 ng/mL, respectively. This study highlights the potential of SPR biosensors to provide high sensitivity and specificity for detecting allergen-specific IgE, indicating promising future applications in allergy diagnosis. The results underscore the importance of highly sensitive detection of allergen-specific IgE in accurately diagnosing and effectively treating allergic diseases.