DNA-assembled bimetallic plasmonic nanosensors

Abstract

Plasmonic hybrid nanomaterials are highly desirable in advanced sensing applications. Different components in these materials undertake distinct roles and work collectively. One material component may act as an efficient light concentrator and optical probe, whereas another provides specific chemical or biological functionality. In this work, we present DNA-assembled bimetallic plasmonic nanostructures and demonstrate their application for the all-optical detection of hydrogen. Gold (Au) nanorods are functionalized with DNA strands, which serve both as linkers and seeding sites for the growth of palladium (Pd) nanocrystals and facilitate reliable positioning of Pd satellites around an Au nanorod at an ultrashort spacing in the nanometer range. Dark-field scattering spectra of single Au–DNA–Pd nanorods were recorded during controlled cycles of hydrogen gas exposure, and an unambiguous concentration-dependent optical response was observed. Our method enables, for the first time, the all-optical detection of hydrogen-induced phase-change processes in sub-5-nm Pd nanocrystals at the single-antenna level. By substituting the Pd satellites with other functional materials, our sensor platform can be extended to plasmonic sensing of a multitude of chemical and biological reagents, both in liquid and gaseous phases. A nanoscale all-optical scheme for the real-time detection of hydrogen at room temperature has been demonstrated by researchers. They fabricated miniature sensors that are based on gold nanorods functionalized with DNA and palladium nanocrystals. When the researchers exposed these sensors to hydrogen gas, they observed an unambiguous concentration-dependent optical scattering response. These nanoscale probes were developed by Na Li and co-workers from the National Center for Nanoscience and Technology in Beijing, China, and the University of Stuttgart and the Max Planck Institute for Intelligent Systems in Stuttgart, Germany. The researchers say that by replacing the palladium nanocrystals with other functional materials, the sensing approach can be extended to a wide variety of other chemical and biological agents of interest in both liquid and gaseous phases.