Nanobiotechnology

Nanoscale bioelectrical characterization

Dr. Gomila, Gabriel
Group Leader


Ed. Hèlix | Baldiri Reixac, 15-21 | 08028 | Barcelona
Email : ggomilaibecbarcelona.eu

Research Topics

Direct and Alterning Current sensing Atomic Force Microscopy in air and liquids / Conducting probes and sample holders for electrical characterization in liquid environment / Single receptor ligand-binding processes in olfactory receptors and bacteriorhodopsin / Supramolecular organization of native biological membranes


The main goal of our research group is to develop new experimental setups based on atomic force microscopy and theoretical frameworks enabling the measurement of the electrical properties of biological samples at the nanoscale (for example, biomembranes, single viruses or single bacteria). Our main objective is to contribute to develop new label-free biological characterization methods and new electronic biosensors.

 

Left: Topography (left column) and dielectric (right column) images of polystyrene (PS), silicon dioxide (SiO2) and aluminum oxide (Al2O3) nanoparticles of 20 nm radius measured on different graphite substrates and with different tips, with radii between 5 nm and 7 nm. By matching the maximum dielectric signal measured at the centre of the nanoparticles with theoretical calculations, which include the nanoparticle and tip geometries, we obtained the dielectric constant of each nanoparticle material, εr=2.69, 4.47 and 8.75, respectively, in good agreement with the corresponding bulk materials. Right: Dielectric image of an unknown mixture of nanoparticles. By obtaining the dielectric constant of each nanoparticle we could identify the material composition of the nanoparticles in a label-free way.

 

During 2012 we demonstrated for the first time the possibility to measure with high accuracy the dielectric properties of small scale objects down to 10 nm in radius by means of electrostatic force microscopy. The high accuracy and spatial resolution achieved enabled us the material identification of single dielectric nanoparticles and of single viruses without the use of any labeling molecule. Moreover, we have extended this methodology to the liquid environment reaching a spatial resolution down to 100 nm. Finally, we have completed the study of natural nanovesicles containing olfactory receptors and its absorption onto solid supports for biosensor applications, and the preparation and mechanical characterization of multicomponent-multiphase supported lipid bilayers stable in air for use as lipid raft model systems in dry air conditions.

 

(Upper image) Topography and (lower image) dielectric images of 20 nm thin and 2.5 μm wide SiO2 microstripes on a doped Silicon substrate obtained in electrolyte solutions. Dielectric images were obtained at constant height at 100 nm from the Silicon baseline with an electrolyte with ion concentration of 1mM and with 0.5 V applied. The applied frequency in the dielectric image was changed from 20 MHz to 0.1MHz every ten lines to show how the image contrast depends strongly on the frequency of the applied voltages and disappears at low frequencies.