Single-Molecule Detection on Nanoparticles-on-Nanoposts

Advancements in nanotechnology and biology have led to the development of planar surfaces for biosensing and diagnostics, with gold nanoparticles being the adsorption support material of choice. However, controlling the number of biomolecules on the surface of gold nanoparticles and the fast assembly of biomolecules on the surface is challenging. To address this, a kelp root system-inspired 7-ARM PEG-holdfast was developed for the precise mounting of biomolecules onto the gold nanoparticles. These smartly designed holdfasts have a single post for the covalent attachment of biomolecules and are tunable providing control of a defined number of biomolecules per nanoparticle and efficient fluorescence detection on the nanoparticle surface. This study demonstrated fluorescence readout enhancement on the surface of the gold nanoparticle at a mounting resolution of one holdfast per nanoparticle. As a proof of concept, a single avidin-bound holdfast mounted on the gold nanoparticle was recognized by fluorescently labelled biotin molecules. This approach has potential applications in biosensors, tissue engineering scaffolds, and microfluidic devices operated at single molecule scales.