Evolutionary screening and adsorption behavior of engineered M13 bacteriophage and derived dodecapeptide for selective decoration of gold interfaces.

There is a growing interest in identifying biomacromolecules such as proteins and peptides to functionalize metallic surfaces through noncovalent binding. One method for functionalizing materials without fundamentally changing their inherent structure is using biorecognition moieties. Here, we proved a general route to select a biomolecule adhesive motif for surface functionalization by comprehensively screening phage displayed peptides. In particular, we selected a genetically engineered M13 bacteriophage and a linear dodecapeptide derived from its pIII domain for recognizing gold surfaces in a specific and selective manner. In the phage context, we demonstrated the adhesive motif was capable to adsorb on gold in a preferential way with a morphological and viscoelastic signature of the adsorbed layer as evidenced by QCM-D and AFM investigations. Out of the phage context, the linear dodecapeptide is reproducibly found to adhere to the gold surface, and by quantitative SPR measurements, high affinity constants (K(eq)~10(6)M(-1), binding energy ~-8 kcal/mol) were determined. We proved that the interactions occurring at gold interface were mainly hydrophobic as a consequence of high frequency of hydrophobic residues in the peptide sequence. Moreover, by CD, molecular dynamics and steered molecular dynamics, we demonstrated that the molecular flexibility only played a minor role in the peptide adsorption. Such noncovalent but specific modification of inorganic surfaces through high affinity biomolecule adsorption represents a general strategy to modulate the functionality of multipurpose metallic surfaces.

Three-dimensional poly(ε-caprolactone) bioactive scaffolds with controlled structural and surface properties.

The requirement of a multifunctional scaffold for tissue engineering capable to offer at the same time tunable structural properties and bioactive interface is still unpaired. Here we present three-dimensional (3D) biodegradable polymeric (PCL) scaffolds with controlled morphology, macro-, micro-, and nano-mechanical performances endowed with bioactive moieties (RGD peptides) at the surface. Such result was obtained by a combination of rapid prototyping (e.g., 3D fiber deposition) and surface treatment approach (aminolysis followed by peptide coupling). By properly designing process conditions, a control over the mechanical and biological performances of the structure was achieved with a capability to tune the value of compressive modulus (in the range of 60-90 MPa, depending on the specific lay-down pattern). The macromechanical behavior of the proposed scaffolds was not affected by surface treatment preserving bulk properties, while a reduction of hardness from 0.50-0.27 GPa to 0.1-0.03 GPa was obtained. The penetration depth of the chemical treatment was determined by nanoindentation measurements and confocal microscopy. The efficacy of both functionalization and the following bioactivation was monitored by analytically quantifying functional groups and/or peptides at the interface. NIH3T3 fibroblast adhesion studies evidenced that cell attachment was improved, suggesting a correct presentation of the peptide. Accordingly, the present work mainly focuses on the effect of the surface modification on the mechanical and functional performances of the scaffolds, also showing a morphological and analytical approach to study the functionalization/bioactivation treatment, the distribution of immobilized ligands, and the biological features.