A Multiparameter pH-Sensitive Nanodevice Based on Plasmonic Nanopores

With controllable mass transfer and special optical properties, plasmonic nanopores may be applied as a nanodevice and possibly create a new generation of single molecule detection technique based on plasmon-enhanced spectra. In the present study, gold nanoparticles self-assemble into a gold porous sphere (GPS) on the tip of a glass nanopipette with the help of i-motif DNA thiolated by both ends as linker molecules. The gaps among neighboring gold nanoparticles are considered as plasmonic nanopores. The size of the formed nanopores can be tuned by the folded–unfolded conformational change of i-motif DNA upon pH adjustment from 4.5 to 7.0. Based on its tunable structural property, the GPS shows reversible changes in ionic current, potential, and surface-enhanced Raman scattering signal. The GPS is further used to probe regional pH in single cells. The successful application of GPS in multiparameter pH probing and single cell analysis suggests that the new physical properties of the self-assembled plasmonic nanopores can be used for fabricating multiple types of nanodevices and nanosensors.