Nanoparticle-Based Visual Detection of HPV DNA and LSD1 Activity

Abstract

Functionalized nanoparticles (dye-doped silica nanoparticles, gold nanoparticles and dots quantum) have been extensively explored and applied for assay of various biomolecules, such as DNA, protein, and enzyme. With the advantages of high sensitivity, high stability, and easy surface modification, the functionalized nanoparticles have gradually become an alternative to traditional fluorescent molecular probes in current bioassay protocols. In addition, with the development of genomics and proteomics, the nanoparticle-based detection system has drawn great interests in recent years in development of a simple, rapid, and low cost strategy for point-of-care use in clinical diagnostics. In this dissertation, a detection system for human papillomavirus (HPV) DNA based on the light scattering of aggregated silica nanoparticle probes on a HPV DNA chip is presented. In the assay, a target HPV DNA is sandwiched between the capture DNA immobilized on the chip and the probe DNA immobilized on a plain silica nanoparticle. The spot where the sandwich reaction occurs appears bright white and is readily distinguishable to the naked eye. The demonstrated capability to detect a disease related target DNA with direct visualization without using a complex detection instrument provides the prerequisite for the development of portable testing kits for genotyping. In addition, a simple and rapid colorimetric strategy was developed for detecting LSD1 enzyme using avidin functionalized gold nanoparticles. The strategy was based on the vivid color changes from red to purple by adding a biotinylated peptide (dimethyl-H3K4, substrate of LSD1) solution to an avidin functionalized gold nanoparticle solution, while no color changes if the dimethyl-H3K4 peptide is complexed with its antibody. Thus, the presence of LSD1 enzyme in a sample containing the biotinylated dimethyl-H3K4 can be determined by simple visual inspection of the color changes with naked eye upon mixing with the avidin functionalized gold nanoparticle solution.