Evidence of single-nanoparticle translocation through a solid-state nanopore by plasmon resonance energy transfer

This work proposes a gold nanoparticle (AuNP) based probe to study the single-nanoparticle translocation behavior through a silicon nitride (SiNx) solid-state nanopore. The AuNP probe is functionalized with a rhodamine derivative molecule, termed Rhod-DPA, whose fluorescence can be activated in the presence of Cu(2+) due to the binding between Rhod-DPA and Cu(2+). The Cu(2+) triggered configuration change of Rhod-DPA on the probe surface can induce the plasmon resonance energy transfer (PRET) from single AuNPs to the transformed fluorescent molecules, which can be detected by the color change of AuNP probes under dark-field microscopy (DFM) and their scattering spectra recorded on a spectrometer. By analyzing the peak shifts before and after the addition of Cu(2+), evidence of single nanoparticle translocation through the nanopore has been obtained, proving the successful establishment of the tracking strategy.