Multifunctional Yolk-Shell Nanostructure as a Superquencher for Fluorescent Analysis of Potassium Ion Using Guanine-Rich Oligonucleotides.

The excellent performance of a biosensor generally depends on the high signal-to-noise ratio, and the superquencher plays a dominant role in fluorescent sensors. Novel nanoquenchers exhibited high quenching efficiency in various fluorescent assays of biological/chemical molecules. Here, we developed a novel nano-biosensor using Fe3O4@C yolk-shell nanoparticles (YSNPs) and studied their quenching effect. We found Fe3O4@C YSNP was a superquencher and exhibited an ultrastrong quenching ability, up to almost 100% quenching efficiency, toward fluorophores. Also, Fe3O4@C YSNPs possessed the most superior fluorescence restoration efficiency, due to biomolecular recognition event, compared to the other nanoquenchers, including bare Fe3O4 NPs, graphene oxide (GO), and single-wall carbon nanotubes (SWCNTs). On the basis of that, a fluorescent sensing platform for potassium-ion (K+) analysis with guanine (G)-rich oligonucleotides was designed. As a result, Fe3O4@C YSNP-based fluorescent sensors demonstrated excellent performance, with an ultrahigh sensitivity of a detection limit as low as 1.3 µM, as well as a wide dynamic range from 50 µM to 10 mM. The proposed method is fast, simple, and cost-effective, suggesting the great potential for practical applications in biomedical detection and clinical diagnosis.

Nanomaterials as analytical tools for genosensors.

Nanomaterials are being increasingly used for the development of electrochemical DNA biosensors, due to the unique electrocatalytic properties found in nanoscale materials. They offer excellent prospects for interfacing biological recognition events with electronic signal transduction and for designing a new generation of bioelectronic devices exhibiting novel functions. In particular, nanomaterials such as noble metal nanoparticles (Au, Pt), carbon nanotubes (CNTs), magnetic nanoparticles, quantum dots and metal oxide nanoparticles have been actively investigated for their applications in DNA biosensors, which have become a new interdisciplinary frontier between biological detection and material science. In this article, we address some of the main advances in this field over the past few years, discussing the issues and challenges with the aim of stimulating a broader interest in developing nanomaterial-based biosensors and improving their applications in disease diagnosis and food safety examination.