30 July 2014 Beyond super-resolution with photonic antennas

Dual color imaging of individual molecules using a hybrid nano-antenna

Single molecule nanoimaging with angstrom localization precision using hybrid photonic antennas. A recent study carried out by Mathieu Mivelle and Thomas van Zanten of the Single Molecule Biophotonics group led by ICREA Professor at ICFO Maria Garcia-Parajo, demonstrated simultaneous dual-color single molecule nanoimaging with 20 nm resolution and angstrom localization precision using a novel design of hybrid photonic antennas engineered at the apex of tapered optical fibers. The work, supported by EU project NanoVista, was published in Nano Letters.

Photonic antennas amplify and confine optical fields at the nanoscale offering excellent perspectives for nanoimaging and nanospectroscopy. Increased resolution beyond the diffraction limit has been already demonstrated using a variety of photonic antennas, but multicolor nanoscale imaging was precluded until now by the resonance behavior of the previous designs. Now, Mivelle at al have conceived a clever hybrid nano-antenna probe based on a monopole antenna engineered on a bowtie nanoaperture. The entire device combines broadband enhanced emission, extreme field conferment down to a few nanometers, and zero-background illumination. Using these devices, ICFO researchers reached 20nm true optical resolution together with unprecedented angstrom localization accuracy on the coordinates position of individual fluorescent molecules.

Compared to far-field super-resolution approaches, hybrid antennas reach the molecular scale using a single image and requiring only a modest photon budget. Moreover, the excitation powers and labeled dyes used are fully compatible with live cell research. Therefore, the researchers predict that a large number of biologically relevant processes could be investigated using hybrid antennas, including unraveling the stoichiometry of multimolecular complexes in living cells at molecular resolution level.