Repeat protein scaffolds: Ordering photo- and electroactive molecules in solution and solid state

The precise control over the organization of photoactive components at the nanoscale is one of the main challenges for the generation of new and sophisticated macroscopically ordered materials with enhanced properties. In this work we present a novel bioinspired approach using protein-based building blocks for the arrangement of photo- and electroactive porphyrin derivatives. We used a designed repeat protein scaffold with demonstrated unique features that allow for the control of their structure, functionality, and assembly. Our designed domains act as exact biomolecular templates to organize porphyrin molecules at the required distance. The hybrid conjugates retain the structure and assembly properties of the protein scaffold and display the spectroscopic features of orderly aggregated porphyrins along the protein structure. Finally, we achieved a solid ordered bio-organic hybrid thin film with anisotropic photoconductivity. ¸ 2016 The Royal Society of Chemistry.This work has been supported by the European Commission IRG-246688 Bionanotools (ALC), the Spanish Ministry of Economy and Competitiveness (MINECO) BIO2012-34835 (ALC) and CTQ2014-520456-R (NM) and the European Research Council ERC-320441-Chirallcarbon (NM), and ERC-2014-CoG-648071 (ProNANO) (ALC). C. A. thanks to the Ramón y Cajal granted and J. L.-A. thanks to Spanish Ministry of Education for FPU granted. SHM thanks the Basque Government for financial support through a PhD fellowship. KPE gives thanks for financial support from the MIT–Spain internship program

Toward Bioelectronic Nanomaterials: Photoconductivity in Protein–Porphyrin Hybrids Wrapped around SWCNT

The development of sophisticated ordered functional materials is one of the important challenges in current science. One of the keys to enhance the properties of these materials is the control of the organization and morphology at different scales. This work presents a novel bioinspired methodology to achieve highly ordered donor/acceptor bio‐nanohybrids using a designed repeat protein as scaffold, endowed with photoactive and electron donating porphyrin (P) units, to efficiently wrap around electron accepting single wall carbon nanotubes (SWCNT). A systematic experimental and theoretical study to evaluate the effect of the length of the protein reveals that longer proteins wrap around the SWCNT in a more efficient manner due to the stronger supramolecular interaction existing between the inner concave surface of the protein (namely Trp and His residues) and the convex surface of the (7,6)‐SWCNT. Interestingly, spectroscopy and X‐ray diffraction data further confirm that the so‐called protein‐P–SWCNT donor–acceptor bio‐nanohybrids retain the original protein structure. Finally, the new bio‐nanohybrids show a remarkable enhancement on the photoconductivity values by flash‐photolysis microwave conductivity (FP‐TRMC technique) demonstrating that the major charge carriers of electrons are injected into the SWCNTs and move along the 1D‐structures.This work has been supported by the European Commission IRG-246688 Bionanotools (ALC), the Spanish Ministry of Economy and Competitiveness (MINECO) BIO2012-34835 and BIO2016-77367-C2-1-R (ALC) and CTQ2014-520456-R (NM) and the European Research Council ERC-320441-Chirallcarbon (NM), and ERC-2014-CoG-648071-ProNANO (ALC). NM thanks to Community of Madrid Government (Photocarbon project. S2013/MIT-2841). CA thanks to the Ramón y Cajal granted and JL-A thanks to Spanish Ministry of Education for FPU granted. SHM thanks the Basque Government for financial support through a PhD fellowship. F.F. thanks the European Community for MSCA-IF-2014-EF-661160-MetAccembly grant. S.O. thanks the Spanish MINECO CTQ2014-59212-P, Ramón y Cajal contract (RYC-2014-16846), the European Community for CIG project (PCIG14-GA-2013-630978), and the funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (ERC-2015-StG-679001-NetMoDEzyme)

Transverse and longitudinal components of the propagating and evanescent waves associated to radially-polarized nonparaxial fields

A comparison is established between the contributions of transverse and longitudinal components of both the propagating and the evanescent waves associated to freely propagating radially polarized nonparaxial beams. Attention is focused on those fields that remain radially polarized upon propagation. In terms of the plane-wave angular spectrum of these fields, analytical expressions are given for determining both the spatial shape of the above components and their relative weight integrated over the whole transverse plane. The results are applied to two kinds of doughnut-like beams with radial polarization, and we compare the behavior of such fields at two transverse planes