Aptamer biosensor for lable-free detection of human immunoglobulin E based on surface plasmon resonance

Aptasensor, an aptamer-based sensor for non-labeled detection of human immunoglobulin E (IgE), was developed using surface plasmon resonance (SPR). Various oligo(ethylene glycol) mixtures of different molar ratios of EG6-COOH and EG3-OH were used for the construction of self-assembled monolayers (SAM). Direct assays and modified sandwich assays over a 1.0 nM anti-IgE, aptamer-immobilized, gold chip, consisting of a 1:3 molar ratio of EG6-COOH:EG3-OH SAM, were investigated for real-time IgE detection. The linear ranges for both were 1.0–1000 ng/mL and the lowest amounts of detectable analytes in the samples were 3.44 and 2.07 ng/mL for direct and modified sandwich assays, respectively. These results for IgE detection suggest that the aptamer offers the possibility of a simple and realistic biosensor platform based on a SAM-fabricated SPR system. Furthermore, as an optic-biosensor, an SPR aptasensor could be used for the diagnosis of allergies.