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      • Highlights:

        How water wets and self-hydrophilizes nanopatterns of physisorbed hydrocarbons. Our experiments evidence that water molecules can very effectively hydrophilize initially hydrophobic surfaces that consist of weakly bound hydrocarbon carpets. Published in Journal of Colloid and Interface Science (2022):

         

        Dry Two-Step Self-Assembly of Stable Supported Lipid Bilayers on Silicon Substrates. We analyze a cleanroom-compatible method for dry fabrication of stable SLBs directly on silicon surfaces, which self-assemble without hydration. Published in International Journal of Molecular Sciences (2020):


        Study of nitrogen implantation in Ti surface using plasma immersion ion implantation & deposition technique as biocompatible substrate for artificial membranes. The formation of artificial membranes was confirmed by AFM, measuring the topography at different temperatures and performing force curves. Published in Materials Science and Engineering: C (2020):

        AFM image for the DPPC at 24 °C (a), 38 °C (b), 47 °C (c) and 56 °C (d) at the same scanning area.

        Wetting properties of hydrothermally synthesized crystalline CuFeO2 delafossite porous surfaces. After annealing treatment at relatively low temperatures T > 300 C (Tmelt $ 1100 C), the CuFeO2 surface displayed superhydrophilicity and a rapid absorption of H2O droplets via its intergranular porosity. Published in Materials Letters (2019).

        (A) XRD spectra of powder sample, (B) Raman spectra of powder sample. Inset: pellet annealed 500 C. (C) XRD spectra of pellet annealed 500 C in air. (D) As (C) under N2 flow. (E–G) Visualized characteristic wetting properties.

        Surface Morphology of Vapor-Deposited Chitosan: Evidence of Solid- State Dewetting during the Formation of Biopolymer Films. Our work shows that ultrathin biopolymer films can undergo dewetting during film formation, even in the absence of solvents and thermal annealing. Published in ACS BioMacromolecules (2016):

         

        Towards bio-silicon interfaces: Formation of an ultra-thin self-hydrated artificial membrane composed of dipalmitoylphosphatidylcholine (DPPC) and chitosan deposited in high vacuum from the gas-phase (pdf), published in the Journal of Chemical Physics - see also the press release of the American Institute of Physics.

         

         

        Organic and inorganic materials grouped together to bridge the gap between biology and physics.

        Credit: S.E.Gutierrez-Maldonado/FCV

        Study on the Spontaneous Formation of Nanopatterns in Velocity-Dependent Dip-Coated Organic Films: From Dragonflies to Stripes, published in ACS Nano.

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.