Fluorescence Amplification Using Biospecific Nanoparticle Conjugates as Labels in Microfluidic Heterogeneous Immunoassays

In microfluidic sensing systems, it is challenging to achieve desirable sensitivity for detecting reduced number of analytes in a small volume (pL–nL). 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.