Tuning Protein Orientation for Bioactive Surfaces
Grazia M. L. Messina1, Nunzio Tuccitto1, Giovanni Li Destri1, Claudia Mazzuca2, Antonio Palleschi1 and Giovanni Marletta1
1 Laboratory for Molecular Surfaces and Nanotechnology (LAMSUN), Department of Chemical Sciences, University of Catania and CSGI, Viale Andrea Doria 6, 95125, Catania, Italy
2 Department of Chemical Sciences and Technologies, University of Roma Tor Vergata, Via della Ricerca Scientifica, 00133 Roma, Italy
Tissue engineering technologies must take into account the dramatic effect of the surface features on their interaction with the biological medium, with particular attention to the achievement of proper exposure of the relevant biomolecule epitopes. In this contribution we report two strategies of surface functionalization to obtain preferred orientation and/or conformation of adsorbed proteins.
In the first case, we report on the dependence upon nanocurvature of Laminin adsorption onto silica-based nanocurved surfaces, prepared as ordered hexagonally packed arrays of hemispheres of diﬀerent diameters (147 nm, 235 nm and 403 nm). Nanostructuring has been achieved by embedding the nanoparticles in ultrathin poly(hydroxymethylsiloxane) ﬁlms and modifying them by means of UV-O 3 treatments, to obtain chemically uniform surfaces. Laminin molecules are shown to adsorb at nanostructures in two limiting arrangements, i.e., with the molecule main axis orthogonal or parallel to the nanostructured surface. This behavior is explained by the interplay of molecular size and charge distribution vs. the spatial arrangement of adsorbed molecules and adsorbent nanostructures.
In the second case, we describe the preparation of protein-orienting surfaces, based on the exposure of well-defined protein chelating sites for specific metal ion. A mercaptoundecanoic acid monolayer was used to bind GHK tripeptide, containing a selective site to chelate copper ions. The GHK-Cu(II) chelated surfaces resulted able to immobilize a model globular protein, human serum albumin (HSA), significantly reducing (about 50%) its unfolding by adsorption, i.e., prompting its adsorption in native-like state.
In situ quartz crystal microbalance with dissipation monitoring (QCM-D), dynamic force spectroscopy (DFS), Fourier transform infrared reflection-absorption spectroscopy
(FTIR-RAS) and Montecarlo calculations have been used for both studies.