Coiled Coil Protein Based Smart Surfaces Implementing Orthogonal Logic Operations

Recently, the gap facilitating the utility of molecular logic systems for application in technological fields was reduced after the implementation of molecular logics on solid surfaces, where molecules functionalizing the surface are designed to respond to specific inputs. Coiled coil protein assemblies are suggested here as new candidates for this task, due to their versatile properties and functionalities.^[1] Here, we present reversible surface attachment-detachment processes involving coiled coil proteins and describing orthogonal logic operations. Coiled coil peptides have been designed, synthesized and characterized in solution by circular dichroism and fluorescence spectroscopies. Several reversible binding and releasing, folding and unfolding processes of heterodimeric coiled coil proteins have been performed on silicon nitride and gold surfaces. The surface layer was characterized by ellipsometry, fluorescence and contact angle after each step. These programmable reactions have been performed demonstrating Boolean logic operation. The coiled coil peptides were labelled with a FRET couple, allowing the parallel implementation of two- and three-input logic gates, NOR-OR and AND-ANH-NAND, following monolayer thickness, donor quenching, and wettability as readout. The experiments accomplished demonstrated the feasibility of this system for reversible protein self-assembly on solid surfaces. Surface properties can be dynamically dictated by functionalization with appropriate designed proteins depending on the targeted device application. This new approach of programmable manipulation of synthetic proteins on solid surface can pave the way to the development of more effective and flexible biosensing devices.

[1] C. Shlizerman, A. Atanassov, I. Berkovich, G. Ashkenasy and N. Ashkenasy, J. Am. Chem. Soc., 2010, 132, 5070-5076.