Application of photonic crystal enhanced fluorescence to detection of low serum concentrations of human IgE antibodies specific for a purified cat allergen (Fel D1)

We demonstrate the detection of low concentrations of allergen-specific Immunoglobulin E (IgE) in human sera using a Photonic Crystal Enhanced Fluorescence (PCEF) microarray platform. The Photonic Crystal (PC) surface, designed to provide optical resonances for the excitation wavelength and emission wavelength of Cy5, was used to amplify the fluorescence signal intensity measured from a multiplexed allergen microarray. Surface-based sandwich immunoassays were used to detect and quantify specific IgE antibodies against a highly purified cat allergen (Fel d1). A comparison of the lowest detectable concentration of IgE measured by the PC microarray system and a commercially available clinical analyzer demonstrated that the PCEF microarray system provides higher sensitivity. The PCEF system was able to detect low concentrations of specific IgE (~0.02. kU/L), which is 5-17-fold more sensitive than the commercially available FDA-approved analyzers. In preliminary experiments using multi-allergen arrays, we demonstrate selective simultaneous detection of IgE antibodies to multiple allergens.