SurfLab at Institute of Physics UC:

We design and adapt experimental equipment for our needs in study of Surfaces and Interfaces. Beside the study of dip-coated, spin-coated and sputtered thin films, monolayers, bilayers, and multilayers, we focus on growth of phospholipid bilayers on diverse substrates. In the latter context we developed a solvent free, dry process for deposition of stable lipid bi-layers in high vacuum. We focus on processes to obtain homogeneous layers. Protein insertion by conventional wet processes and the development of dry, long term storable and stable systems as platforms for biosensors is one of our objectives.

Experimentos en el SurfLab UC

Sobre el Laboratorio de Superficies Surflab UC

Bionanotechnology is an emerging field that combines nanoscale technologies with biological systems in order to create functional devices with applications in drug delivery, biosensors, carriers of small molecules and templates for pharmaceutical design. A cornerstone material in the semiconductor industry and nanotechnology is silicon. An important goal for bionanotechnology is to create a silicon-based chips that biomimics the cell membrane, i.e. a bio-silica interface. Such a bio-silica interface could be used to study the insertion of proteins within membranes. A first step to mimic the cell membrane over a solid surface is to form the phospholipid bilayers, which are referred to as a supported lipid bilayers (SLB). One method to form a SLB is by using small vesicles, which are suspended in water or buffer solution and set to interact with a silicon surface. Once the vesicles interact with the hydrophilic silicon surface, they self-assemble into a SLB. There have been many studies reporting different methods to form SLBs from vesicles, such as polymer cushioned lipid bilayers, hybrid bilayers supported over alkane-thiol self-assembled monolayers (SAM), tethered lipid bilayers and freely suspended bilayers. Another method to form SLBs, without starting from a vesicle, is using the Langmuir-Blodgett trough method, where a solid substrate is successively immersed within a compressed layer of lipids, that assemble at a liquid-air interface. Furthermore, a recent solvent-assisted method using isopropanol has been reported to form SLB, where lipid molecules are dissolved in isopropanol and flowed through a liquid reaction chamber, generating a bilayer over a glass slide. All the aforementioned methods involve the use of solvents to dissolve lipid molecules, transport small vesicles or assemble a transfer monolayer over liquid-air interfaces. A main disadvantage of liquid-based methods is that they are dependent on specific phospholipid and solvent type, concentration and surface tension between the liquid-solid interface. 

One branch of our research focuses on the creation of solvent-free bio-silica interfaces. We have shown that supported bilayers of Dipalmitoylphosphatidylcholine (DPPC) can be evaporated from their vapor phase over a porous polymer cushion, which is also previously evaporated onto the substrate. The task of the porous polymer cushion is to hydrate the phospholipid bilayer. In addition, we experimented with the fabrication of nanoporous silicon as a substrate for supported lipid bilayers. Again, the pores shall hydrate the phospholipid bilayer for a prolonged stability. 

Recently we studied the solvent free formation of supported lipid bilayers in air directly on solid surfaces, without further hydration with very promising results. This would be an important step for the development of functional interface components of biosensors and other microengineering materials. 

Actually,we are investigating the thermodynamic parameters to produce nearly perfect 2D membranes with long time stability and without the need of further hydration.