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The two-dimensional (2D) homogeneous assembly of nanoparticle monolayer arrays onto a broad range of substrates constitutes an important challenge for chemistry, nanotechnology, and material science. α-Synuclein (αS) is an intrinsically disordered protein associated with neuronal protein complexes and has a high degree of structural plasticity and chaperone activity. The C-terminal domain of αS has been linked to the noncovalent interactions of this protein with biological targets and the activity of αS in presynaptic connections. Herein, we have systematically studied peptide fragments of the chaperone-active C-terminal sequence of αS and identified a 17-residue peptide that preserves the versatile binding nature of αS. Attachment of this short peptide to gold nanoparticles afforded colloidally stable nanoparticle suspensions that allowed the homogeneous 2D adhesion of the conjugates onto a wide variety of surfaces, including the formation of crystalline nanoparticle superlattices. The peptide sequence and the strategy reported here describe a new adhesive molecule for the controlled monolayer adhesion of metal nanoparticles and sets a stepping-stone toward the potential application of the adhesive properties of αS This work was partially supported by the Spanish Agencia Estatal de Investigación (AEI) [BIO2015-70092-R, SAF2017-89890-R], the Xunta de Galicia (ED431C 2017/25, 2016-AD031, AGAUR (2017 SGR 324), and Centro Singular de Investigación de Galicia accreditation 2016–2019, ED431G/09), the ISCIII (COV20/00297), and the European Union (European Regional Development Fund – ERDF). X.S. acknowledges funding from the ERC (CONCERT-648201). IRB Barcelona is the recipient of a Severo Ochoa Award (Government of Spain). J.M. received a Ramón y Cajal (RYC-2013-13784), an ERC Starting Grant (DYNAP-677786), and a Young Investigator Grant from the HFSP (RGY0066/2017) SI

The effect of the distance between a β-cyclodextrin (βCD) host core and a conductive substrate on the electron-transfer rate of complexed guests as well as of free-diffusing electrochemically active probes has been studied. First we have evaluated a set of short-tethered βCD adsorbates bearing different anchoring groups in order to get a reliable platform for the study of short-distance electron transfer. An electrochemically active trivalent guest was immobilized on these host monolayers in a selective and reversible manner, providing information about the packing density. Iodine- and nitrile-functionalized βCD monolayers gave coverages close to maximum packing. Electron transfer in the presence of Fe(CN)6 3-/4- studied by impedance spectroscopy revealed that the electron transfer of the diffusing probe was 3 orders of magnitude faster than when the βCD cores were separated from the surface by undecyl chains. When an electrochemically active guest was immobilized on the surface, electron-transfer rate measurements by cyclic voltammetry and capacitance spectroscopy showed differences of up to a factor of 8 for different βCD monolayers. These results suggest that increasing the distance between the βCD core and the underlying conductive substrate leads to a diminishing of the electron-transfer rate.