Highly sensitive biosensors using photonic crystal enhanced fluorescence
|Institution:||University of Illinois – Urbana-Champaign|
|Keywords:||Photonic Crystal Enhanced Fluorescence (PCEF)|
|Full text PDF:||http://hdl.handle.net/2142/73064|
Due to the importance of fluorescence assays in clinics, life science and genomic research, many nanostructures have been proposed to enhance the weak fluorescence signals from low abundance analytes. Among these structures, photonic crystal (PC) has attracted particular attentions because of its capability to produce high electric fields without quenching fluorescence emission. Properly designed PC surface can efficiently couple laser illumination to fluorescent dye molecules (enhanced excitation) and meanwhile effectively collects fluorescence emission (enhanced extraction). In this dissertation, photonic crystal enhanced fluorescence (PCEF) was used for disease biomarker dissertation. We applied PCEF to multiplexed microspot immunoassays for detection of allergen-specific antibodies. The PCEF system was able to detect low concentrations of Fel d1 specific IgE ~0.02 kU/L, which is 5-fold to 17-fold more sensitive than the commercially available FDA-approved analyzers. We also aimed to improve the current platform by incorporating a PC surface with a microfluidic chip in order to enable a rapid and automatic biomarker analysis at microliter sample consumption. We fabricated a plastic microfluidic device for holding the PC using a low-cost and flexible process and developed a leak-free automation system to introduce the correct sequence of fluids through the microfluidic device. The PCEF platform was successfully automated to enable more rapid, high sensitivity detection and a simplified output that will be readily usable by a clinician. Besides microarray immunoassays, the PCEF platform was also adapted to a molecular beacon assay for miRNA detection, where the PC surface was incorporated with a submicron-height fluid channel. The use of the PCEF platform results in a reduction of the detection limits and an increase in the signal-to-noise ratio (SNR) with a small, inexpensive detection instrument.