Izhar Medalsy

SP1 protein-based nanostructures and arrays.

Controlled formation of complex nanostructures is one of the main goals of nanoscience and nanotechnology. Stable Protein 1 (SP1) is a boiling-stable ring protein complex, 11 nm in diameter, which self-assembles from 12 identical monomers. SP1 can be utilized to form large ordered arrays; it can be easily modified by genetic engineering to produce various mutants; it is also capable of binding gold nanoparticles (GNPs) and thus forming protein-GNP chains made of alternating SP1s and GNPs. We report the formation and the protocols leading to the formation of those nanostructures and their characterization by transmission electron microscopy, atomic force microscopy, and electrostatic force microscopy. Further control over the GNP interdistances within the protein-GNP chains may lead to the formation of nanowires and structures that may be useful for nanoelectronics.

Logic implementations using a single nanoparticle–protein hybrid

A Set-Reset machine is the simplest logic circuit with a built-in memory. Its output is a (nonlinear) function of the input and of the state stored in the machines memory. Here, we report a nanoscale Set-Reset machine operating at room temperature that is based on a 5-nm silicon nanoparticle attached to the inner pore of a stable circular protein. The nanoparticle-protein hybrid can also function as a balanced ternary multiplier. Conductive atomic force microscopy is used to implement the logic input and output operations, and the processing of the logic Set and Reset operations relies on the finite capacitance of the nanoparticle provided by the good electrical isolation given by the protein, thus enabling stability of the logic device states. We show that the machine can be cycled, such that in every successive cycle, the previous state in the memory is retained as the present state. The energy cost of one cycle of computation is minimized to the cost of charging this state.

Wiring of Redox Enzymes on Three Dimensional Self-Assembled Molecular Scaffold

The integration of biological molecules and nanoscale components provides a fertile basis for the construction of hybrid materials of synergic properties and functions. Stable protein 1 (SP1), a highly stable ring shaped protein, was recently used to display different functional domains, to bind nanoparticles (NPs), and to spontaneously form two and three-dimensional structures. Here we show an approach to wire redox enzymes on this self-assembled protein-nanoparticle hybrid. Those hybrids are genetically engineered SP1s, displaying glucose oxidase (GOx) enzymes tethered to the protein inner pore. Moreover, the Au-NP-protein hybrids self-assembled to multiple enzymatic layers on the surface. By wiring the redox enzymes to the electrode, we present an active structure for the bioelectrocatalytic oxidation of glucose. This system demonstrates for the first time a three-dimensional assembly of multiple catalytic modules on a protein scaffold with an efficient electrical wiring of the enzyme units on an electrode surface, thus implementing a hybrid electrically active unit for nanobioelectronic applications.

Float and Compress : Honeycomb-like Array of a Highly Stable Protein Scaffold

Organizing nano-objects, proteins in particular, on surfaces is one of the primary goals of bio/chemical nanotechnology. A highly stable protein scaffold (6His-SP1) was organized into a hexagonal 2D array by a new, versatile method. The protein was expelled from solution into the air/water interface and compressed in a Langmuir trough into a closely packed monolayer without the use of phospholipids or other surfactants at the interface. The 2D arrays formed at the air/water interface were characterized by transmission electron microscopy (TEM) and atomic force microscopy (AFM).