Spontaneous deposition of polylysine on surfaces: Role of the secondary structure to optimize noncovalent coating strategies

Understanding the factors that governs spontaneous molecular transfer from solution to solid surface is fundamental to control noncovalent surface functionalization strategies, both in term of robustness and reproducibility. The comprehension of the nature of interaction involved in the mechanism of spontaneous adsorption will allow for a fine modulation of the deposition process. Herein, we provide experimental evidences to demonstrate that poly-lysine secondary structure represents a crucial factor profoundly influencing the outcome of its spontaneous deposition on quartz surfaces. In particular, random coil to alpha-helix transition is required to drive an effective transfer of the poly-L-lysine at the liquid-solid interface. beta-sheet deposition requires longer times to be accomplished, while random-coil deposition is highly unfavored. Accordingly, polylysine deposition on quartz and silicon is effective when alpha-helix is formed in solution (pH > 10). This surface noncovalent functionalization represents a simple strategy to fabricate hybrid organic-inorganic or biocompatible materials. In fact, the proposed methodology is proven robust and repeatable and compatible for combination with solution or vapor phases (i.e. MOCVD) nanomaterial deposition approaches. (c) 2014 Elsevier Inc. All rights reserved.