Self-Assembling Behavior of Cysteine-Modified Oligopeptides: An XPS and NEXAFS Study

Achieving rigorous control over the procedures aiming at modifying surfaces by selective and covalent anchoring of bioactive molecules is a mandatory step in view of the realistic applicability of bioengineered materials in the field of tissue engineering, biosensing, and nanomedicine. In this context, we report here a proof-of-concept study carried out on a self-assembling peptide (SAP) functionalized with cysteine (Cys), as to ideally grant molecule grafting to gold surfaces. The effectiveness of the surface functionalization in a monolayer regime and the molecular stability of SAP-Cys were probed by X-ray photoelectron spectroscopy; the highly ordered self-organization attained by the grafting molecules was assessed by means of angular-dependent near edge X-ray absorption spectroscopy studies. This study opens wide perspectives for efficient chemical modification of surfaces with biomolecules to include bioactive motifs and/or to add nanometric fibrous patterns.