by Keyword: Biotin

Credi, C., De Marco, C., Molena, E., Pla Roca, M., Samitier, J., Marques, J., Fernàndez-Busquets, X., Levi, M., Turri, S., (2016). Heparin micropatterning onto fouling-release perfluoropolyether-based polymers via photobiotin activation Colloids and Surfaces B: Biointerfaces 146, 250-259

A simple method for constructing versatile ordered biotin/avidin arrays on UV-curable perfluoropolyethers (PFPEs) is presented. The goal is the realization of a versatile platform where any biotinylated biological ligands can be further linked to the underlying biotin/avidin array. To this end, microcontact arrayer and microcontact printing technologies were developed for photobiotin direct printing on PFPEs. As attested by fluorescence images, we demonstrate that this photoactive form of biotin is capable of grafting onto PFPEs surfaces during irradiation. Bioaffinity conjugation of the biotin/avidin system was subsequently exploited for further self-assembly avidin family proteins onto photobiotin arrays. The excellent fouling release PFPEs surface properties enable performing avidin assembly step simply by arrays incubation without PFPEs surface passivation or chemical modification to avoid unspecific biomolecule adsorption. Finally, as a proof of principle biotinylated heparin was successfully grafted onto photobiotin/avidin arrays.

JTD Keywords: Antifouling, Heparin, Malaria, Microcontact arrayer, Microcontact printing, Micropatterning, Perfluoropolyether, Photobiotin, Polymers, Soft lithography

Oberhansl, Sabine, Hirtz, Michael, Lagunas, Anna, Eritja, Ramon, Martinez, Elena, Fuchs, Harald, Samitier, Josep, (2012). Facile modification of silica substrates provides a platform for direct-writing surface click chemistry Small 8, (4), 541-545

Lagunas, Anna , Comelles, Jordi, Martínez, Elena, Prats-Alfonso, Elisabet , Acosta, Gerardo A., Albericio, Fernando , Samitier, Josep , (2012). Cell adhesion and focal contact formation on linear RGD molecular gradients: study of non-linear concentration dependence effects Nanomedicine: Nanotechnology, Biology and Medicine , 8, (4), 432-439

Cell adhesion onto bioengineered surfaces is affected by a number of variables, including the former substrate derivatization process. In this investigation, we studied the correlation between cell adhesion and cell–adhesive ligand surface concentration and organization due to substrate modification. For this purpose, Arg-Gly-Asp (RGD) gradient surfaces were created on poly(methyl methacrylate) substrates by continuous hydrolysis and were then grafted with biotin-PEG-RGD molecules. Cell culture showed that adhesion behavior changes in a nonlinear way in the narrow range of RGD surface densities assayed (2.8 to 4.4 pmol/cm2), with a threshold value of 4.0 pmol/cm2 for successful cell attachment and spreading. This nonlinear dependence may be explained by nonhomogeneous RGD surface distribution at the nanometre scale, conditioned by the stochastic nature of the hydrolysis process. Atomic force microscopy analysis of the gradient surface showed an evolution of surface morphology compatible with this hypothesis.

JTD Keywords: RGD gradient, Cell adhesion, Poly(methyl methacrylate), Hydrolysis, Biotin-streptavidin

Hofer, M., Adamsmaier, S., van Zanten, T. S., Chtcheglova, L. A., Manzo, C., Duman, M., Mayer, B., Ebner, A., Moertelmaier, M., Kada, G., Garcia-Parajo, M. F., Hinterdorfer, P., Kienberger, F., (2010). Molecular recognition imaging using tuning fork-based transverse dynamic force microscopy Ultramicroscopy , 110, (6), 605-611

We demonstrate simultaneous transverse dynamic force microscopy and molecular recognition imaging using tuning forks as piezoelectric sensors. Tapered aluminum-coated glass fibers were chemically functionalized with biotin and anti-lysozyme molecules and attached to one of the prongs of a 32 kHz tuning fork. The lateral oscillation amplitude of the tuning fork was used as feedback signal for topographical imaging of avidin aggregates and lysozyme molecules on mica substrate. The phase difference between the excitation and detection signals of the tuning fork provided molecular recognition between avidin/biotin or lysozyme/anti-lysozyme. Aggregates of avidin and lysozyme molecules appeared as features with heights of 1-4 nm in the topographic images, consistent with single molecule atomic force microscopy imaging. Recognition events between avidin/biotin or lysozyme/anti-lysozyme were detected in the phase image at high signal-to-noise ratio with phase shifts of 1-2 degrees. Because tapered glass fibers and shear-force microscopy based on tuning forks are commonly used for near-field scanning optical microscopy (NSOM), these results open the door to the exciting possibility of combining optical, topographic and biochemical recognition at the nanometer scale in a single measurement and in liquid conditions.

JTD Keywords: Tuning fork, Atomic force microscopy, Shear-force microscopy, Molecular recognition, Avidin-biotin