FLUORESCENCE AMPLIFICATION USING BIOSPECIFIC NANOPARTICLE CONJUGATES AS LABELS IN MICROFLUIDIC HETEROGENEOUS IMMUNOASSAYS

摘要

In microfluidic sensing systems, it is challenging to achieve desirable sensitivity for detecting reduced number of analytes in a small volume (pL-nL).1 Many efforts have been made in order to improve the sensitivity of microfluidic fluorescence detection systems. Some prevalent methods (e.g., optical components integration and analyte enrichment) either increase cost or require extra operational steps. Fluorescence amplification using dye-doped silica nanoparticles has proved to be an inexpensive and efficient approach; however, this technique is still far from perfect. For instance, dye molecules physically entrapped in the silica nanoparticles occasionally leak and can cause false-negative results. In addition, the nonspecific adsorption of nanoparticles has not been resolved.2rnIn this article, we present an inexpensive, simple, leak-free and highly biospecific fluorescence amplification method by using bioconjugated polystyrene nanoparticles. The fluorescence amplification is achieved by attaching many fluorophore labeled detection antibodies to each streptavidin-coated polystyrene nanoparticle via the streptavidin-biotin binding. These antibody-conjugated nanoparticles are then used as fluorescent labels for detecting antigens captured on the functionalized walls of the microchannels in a microfluidic chip. Experimental results showed that this method greatly enhanced the sensitivity of the assay since the fluorescent signal is a function of the average number of detection antibodies attached to each nanoparticle.