My research can be framed into the broad areas of soft condensed matter and biophysics, with especial focus to biomimetic membranes, based on lipids, block-copolymers and fluorinated amphiphiles, as well as biological membranes in living neurons. My work also encompasses the biophysics of artificial and biological polymers, including proteins and DNA. Our main research lines are the following;
Soft matter physics | Biophysics | Neuroscience | Neurophysics
Last Work at the NBI: Mechanical properties of action potentials in neurons using AFM
The aim of this project is the simultaneous detection of an action potential, electrically and mechanically. The presence of fast volumetric changes (swelling) in the axon during action potential propagation was demonstrated by Tasaki and collaborators in the 80's, by measuring the mechanical displacement of the axonal membrane in different nerve preparations. Most recently Salzberg and collaborators, in 2007, found the same phenomena in synaptic transmission. The presence of these mechanical changes can be explained under the soliton model for action potential propagation suggested by Heimburg and Jackson in 2005. Despite of being known for decades, the nature of those fast mechanical changes during action potential propagation is still a poorly understood phenomena that requires further investigation.
Main Research Interests
Electromechanical signal propagation in neurons
We are interested in investigate the electromechanical properties of action and graded-potentials along the different functional parts of a neuron as well as between neurons through electrotonic and chemical synapses. We focus our research in the effect of geometrical constraints and ion channel distribution on the fundamental properties of the propagating signals; timing and shape, looking at branching points and varicosities in axons as well as dendritic spines in dendrites. Those parameters play a key role on the computational properties of the neuron as well as the neuronal network.
“Penetration of action potentials during collision in the median and lateral giant axons of invertebrates”
Gonzalez-Perez et al. Physical Review X 4 (2014) 031047
Functional Membrane Proteins in Block Copolymer Membranes
We use block copolymer membranes as an alternative support for functional membrane protein reconstitution aiming to get a better understanding of membrane protein functionality in non-biological membranes. It was found recently that some membrane proteins could be reconstituted in a functional form in pure block copolymer membranes with superior mechanical stability than lipid membranes. We focus our research in two membrane protein functional groups; water channels (Aquaporins) and light-driven proton pumps (Rhodopsins), with high potential for separation and sensor applications in the areas of water purification and energy production
"Biomimetic Triblock Copolymer Membranes:
From aqueous solutions to solid supports"
Gonzalez-Perez et al., Soft Matter 7 (2011) 1129-1138
"Biomimetic Triblock Copolymer Membrane Arrays:
A Stable Template for Functional Membrane Proteins"
Gonzalez-Perez et al., Langmuir 5 (18) (2009) 10447-10450
Fluorinated IPA-Based Membranes and Biomedical Applications
Amphiphiles containing fluorocarbon chains display outstanding properties of high chemical and mechanical stability as well as biological inertness. Fluorocarbons are hydrophobic and lypophobic at the same time and can self-assemble in aqueous solutions. In particular they can form membranes with high mechanical and thermal stability. In our research we investigate the membrane properties, based on hybrid hydrocarbon-fluorocarbon ion pair amphiphiles (IPA), in the form of vesicles and free standing membranes. We focus in understanding and controlling the mechanical properties of these membranes as well as their potential used for functional membrane protein reconstitution.
"Fluid Isolated Polyhedral Vesicles"
Gonzalez-Perez et al. JACS 129 (2007) 756-757.
Control DNA conformation using non-biological agents
DNA can exist in the cell in a compact conformation in association with histones and is undergoing partial decompaction when the information contained in it is needed by the cell. However, it is possible to compact and decompact the DNA by using non-biological chemical agents. Our research focus in understanding the biophysical mechanism that ensures the reversibility in the compation process. We aim to develop a reversible switch that could compact and decompact the DNA without altering their basic properties and preserving the information. Our main focus is in the use of inclusion complexes as a fundamental tool for achieving reversible decompation. Additionally we are interested in new techniques for DNA surface immobilization in both extended and compact conformation with potential uses in sensor application
"Reversible DNA compaction"
Gonzalez-Perez, Current Topics in Medicinal Chemistry 14, 6 (2014) 766-773
"A versatile approach towards compaction, decompaction and immobilization of DNA at interfaces using cyclodextrins"
Gonzalez-Perez et al. ChemPhysChem 14, 11 (2013) 2544-2553
"Cycloextrin-Surfactant complex: A new route in DNA decompation"
Gonzalez-Perez et al., Biomacromolecules 9, 3 (2008) 772-775
Other Research Interests
Transitions Between Self-assembled Structures
Self-assembled structures like micelles and lamellar phases undergo transitions towards other structures when we change thermodynamic parameters like concentration or temperature or by adding extra components like ions or other molecules that alter their packing parameter. We are interested in investigate those transitions as well as intermediate phases an model them thermodynamically.
"Temperature dependence of micellar sphere-to-rod transition using adiabatic"
Gonzalez-Perez et al. Colloids and Surfaces A 356 (2010) 48-88
"Sphere-to-rod transition in homologous alkylpyridinium salts: A stauff-Klevens-type equation for the second critical micelle concentration"
Gonzalez-Perez et al. Journal of Colloid Interface Science 293 (2006) 213-221
New protocols for direct imaging and sensor applications
using Electron Microscopy and AFM
Imaging and sensor recording are among the most recurrent techniques used to investigate soft materials. We are interested in develop capabilities of the current imaging techniques to expand the application range of those techniques. Using cryo-fracture protocol the conventional cryo-TEM technique, that is limited to liquid fluid samples, was expanded to investigate viscous samples like different liquid crystals generally inaccessible to this technique. Using a tipless cantilever as a sensor the mechanical part of the action potential (electromechanical pulse) could be detected by using a conventional atomic force microscope recording the z-displacement a 40 KHz on a biomembrane of a living neuron.
”Cryo-Fracture TEM: direct imaging of viscous samples”
Gonzalez-Perez et al. Soft Matter 4 (2008) 1625-1629