Nanofabrication of bioinspired architectures with light harvesting proteins

In this research we used diverse nanofabrication techniques in order to direct the assembly on micro- and nanostructured surfaces of purified units from the photosynthetic unit of purple bacteria. This allowed us to explore the unique energy transfer properties of light harvesting complexes by producing biomolecular photonic wires. We developed an approach based on the combination of site-directed mutagenesis, nanoimprint lithography and multivalent host-guest interactions for the realization of engineered ordered functional arrays of purified components of the photosynthetic system, the membrane-bound LH2 complex. In addition to micrometer-scale patterned structures, we demonstrated the use of nanometer-scale hard NIL stamps to generate functional protein arrays approaching molecular dimensions. We also report the first observation of long-range transport of excitation energy within a bio-mimetic molecular light-guide constructed from LH2 antenna complexes organized vectorially into functional nanoarrays. Fluorescence microscopy of the emission of light after local excitation with a diffractionlimited light beam reveals long-range transport of excitation energy over micrometer distances, which is much larger than required in the parent bacterial system. Other biological systems used were visible fluorescent proteins and α-synuclein, an intrinsically unfolded protein associated with Parkinson’s disease. We report for the first time the directed assembly and characterization of FRET pairs on micrometer dimension patterned surfaces. In order to characterize the biological assemblies on the surfaces AFM imaging in combination with optical imaging (spectral fluorescence microscopy and lifetime measurements) were performed in liquid conditions.