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.

 

Electrical potential distribution corresponding to the electric interaction between a biased nanometric sharp conducting tip of radius 5 nm and a polystyrene dielectric nanoparticle of radius 20 nm. The electric polarization force acting on the tip is below a picoNewton, and sensitivity depends on the size, dielectric constant and non-sphericity of the nanoparticle.

 

During 2013 we demonstrated for the first time the possibility to measure with high accuracy the electric polarization properties (dielectric constant) of biomembranes in liquid environment revealing a direct contribution coming from membrane hydration effects. Moreover, we have deepened our theoretical understanding of quantitative electrostatic force microscopy applied to single dielectric nanoparticles and applied in liquid media. Finally, we have completed the study of the electric polarization properties of single bacteria. In addition, we have also completed the study of the mechanical properties of natural nanovesicles containing olfactory receptors for biosensor applications.

 

Dielectric image of a 5 nm thick DPPC lipid bilayer on a highly doped silicon substrate measured in a 1mM salt concentration aqueous solution. The image has been obtained with an applied ac voltage of 0.25 V and frequency 80 MHz and using a solid platinum tip of radius 45 nm. Quantification of the dielectric image gives a lipid bilayer relative dielectric constant of εr,DPPC= 3.2. This value is higher than the one obtained in dry air conditions and reveals a contribution of the hydration of the polar region of the lipid bilayer.