Biofunctional organic nanocrystals for quantitative detection of pathogen deoxyribonucleic acid

Advances in nanotechnology have had significant impacts in the field of biodiagnostics. In this study, we describe the novel application of dissolvable, organic and biofunctional nanocrystals for the quantitative detection of a PCR product. Fluorescein diacetate (FDA), a fluorogenic precursor of fluorescein, was milled in a solution of a polymeric surfactant to create a stable, nanosized colloid with an interface for coupling streptavidin molecules. The application of these particulate labels for the quantitative detection of biotinylated human papillomavirus (HPV) DNA, amplified in a standard PCR procedure, was demonstrated. After the affinity reaction, the FDA molecules were dissolved and concomitantly converted into fluorescein. This approach resulted in a high selectivity, short incubation times and a sensitivity up to 147 times greater than obtained from state-of-the-art, directly fluorescent-labeled streptavidins. This innovative method offers rapid detection of small amounts of nucleic acids because less target material and thus fewer PCR cycles are required. © 2006 Elsevier B.V. All rights reserved.