Sensitive Detection of ssDNA Using an LRET-Based Upconverting Nanohybrid Material

Abstract

Water-dispersible, optical hybrid nanoparticles are preferred materials for DNA biosensing due to their biocompatibility. Upconverting nanoparticles are highly desirable optical probes in sensors and bioimaging owing to their sharp emission intensity in the visible region. We herein report a highly sensitive ss-DNA detection based on an energy transfer system that uses a nanohybrid material synthesized by doping NaYF₄:Tm³⁺/Yb³⁺ upconverting nanoparticles (UCNPs) on silica coated polystyrene-<i>co</i>-acrylic acid (PSA) nanoparticles (PSA/SiO₂) as the donor, and gold nanoparticles (AuNPs) decorated with Ir­(III) complex as the acceptor. UCNPs tagged on PSA/SiO₂ and the cyclometalated Ir­(III)/AuNP conjugates were then linked through the ss-DNA sequence. Sequential addition of the target DNA to the probe molecular beacon complex resulted in the separation of the optical nanohybrid material and the quencher, leading to a measurable increase in the blue fluorescence emission intensity. Our results have shown a linear relationship between the fluorescence intensity and target DNA concentration down to the picomolar