(19)F-MRI offers unique opportunities to image diseases and track cells and therapeutic agents in vivo. Herein we report a superfluorinated molecular probe, herein called PERFECTA, possessing excellent cellular compatibility, and whose spectral properties, relaxation times, and sensitivity are promising for in vivo (19)F-MRI applications. The molecule, which bears 36 equivalent (19)F atoms and shows a single intense resonance peak, is easily synthesized via a simple one-step reaction and is formulated in water with high stability using trivial reagents and methods.
Although intensively studied, the high‐resolution crystal structure of the peptide DFNKF, the core‐segment of human calcitonin, has never been described. Here we report how the use of iodination as a strategy to promote crystallisation and facilitate phase determination, allowed us to solve, for the first time, the single‐crystal X‐ray structure of a DFNKF derivative. Computational studies suggest that both the iodinated and the wild‐type peptides populate very similar conformations. Furthermore, the conformer found in the solid‐state structure is one of the most populated in solution, making the crystal structure a reliable model for the peptide in solution. The crystal structure of DFNKF(I) confirms the overall features of the amyloid cross‐β spine and highlights how aromatic–aromatic interactions are important structural factors in the self‐assembly of this peptide. A detailed analysis of such interactions is reported.
Perfluorocarbons (PFCs) have proven to be very efficient in building up omniphobic surfaces because of the peculiar properties of fluorine atoms. However, due to their environmental impact and bioaccumulative potential, perfluorinated surfactants with chains longer than six carbon atoms have been banned, and other alternatives had to be found. Herein, we demonstrate the possibility to build omniphobic self-assembled monolayers (SAMs) using a multibranched fluorinated thiol (BRFT) bearing ultrashort fluorinated alkyl groups, surrounding a hydrocarbon polar core. This unique design allows us to multiply the number of fluorine atoms in the molecule (27 F atoms per molecule), affording a high fluorine density on the surface and a low surface free energy. Moreover, the presence of four ether bonds in the core may hasten molecular degradation in the environment because of the cleavage of such bonds in physiological conditions, thus overcoming bioaccumulation issues. BRFT may effectively represent a valuable substitute of long-chain perfluoroalkyl thiols. In fact, BRFT SAMs show the same hydrophobic and oleophobic performances of standard linear perfluoroalkyl thiols (such as 1H,1H,2H,2H-perfluorodecanethiol, PFDT), giving rise to more stable surfaces with a better frictional behavior. Superhydrophobicity was also observed with SAMs grown on nanostructured Cu/Ag surfaces. Our results have proven the ability of short-chain multibranched fluorous molecules to behave as suitable replacements for long-chain perfluoroalkanes in the field of surface coatings. Our molecules may be applied to various surfaces because of the available multiple choice of linker chemistry.
thick fi lm to achieve signifi cant durability and, therefore, requires a relatively large amount of fl uoropolymer. Alternative approaches, such as chemical grafting of fl uoropolymers by radical methods through irradiation, [ 6−8 ] plasma, [ 9−12 ] or direct fl uorination with fl uorine gas, [ 1,2,13 ] require only moderate amounts of fl uorinated surface modifi ers but are much more aggressive and, in some cases, potentially hazardous.Other possibilities involve functionalization with fl uorinated molecules/ polymers consisting of specifi c chemical moieties that are able to bind either covalently or noncovalently to the polymer surface. [ 4,5,14,15 ] However, to achieve sufficiently stable bonding, this general strategy requires the presence of reactive hydrophilic sites, typically OH groups, which are not typically observed on the surfaces of apolar, hydrophobic polymers, such as polyolefi ns, and need to be introduced via oxidizing pretreatments that are usually either energy-intensive or not environmentally friendly. [ 16−19 ] Expanding on this strategy, we present an effi cient, rapid, and more environmentally friendly method to perform the fl uorocarbon coating of hydrophobic polymer surfaces. The method is based on the use of hydrophobins, i.e., amphiphilic surface-active proteins, as a nanosized primer layer that adheres to the hydrophobic polymer surface, making the surface hydrophilic and preparing it for the subsequent binding of a fl uoropolymer containing ionic moieties.Hydrophobins are a class of nontoxic, surface-active, and fi lm-forming proteins that are produced by fi lamentous A new and simple method is presented to fl uorinate the surfaces of poorly reactive hydrophobic polymers in a more environmentally friendly way using the protein hydrophobin (HFBII) as a nanosized primer layer. In particular, HFBII, via electrostatic interactions, enables the otherwise ineffi cient binding of a phosphate-terminated perfl uoropolyether onto polystyrene, polypropylene, and low-density polyethylene surfaces. The binding between HFBII and the perfl uoropolyether depends signifi cantly on the environmental pH, reaching the maximum stability at pH 4. Upon treatment, the polymeric surfaces mostly retain their hydrophobic character but also acquire remarkable oil repellency, which is not observed in the absence of the protein primer. The functionalization proceeds rapidly and spontaneously at room temperature in aqueous solutions without requiring energy-intensive procedures, such as plasma or irradiation treatments.
Dispersing hydrophobin HFBII under air saturated with perfluorohexane gas limits HFBII aggregation to nanometer-sizes. Critical basic findings include an unusual co-adsorption effect caused by the fluorocarbon gas, a strong acceleration of HFBII adsorption at the air/water interface, the incorporation of perfluorohexane into the interfacial film, the suppression of the fluid-to-solid 2D phase transition exhibited by HFBII monolayers under air, and a drastic change in film elasticity of both Gibbs and Langmuir films. As a result, perfluorohexane allows the formation of homogenous populations of spherical, narrowly dispersed, exceptionally stable, and echogenic microbubbles.
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