Browsing by Subject "Self-assembled peptides"

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Open Access
Catalytic supramolecular self-assembled peptide nanostructures for ester hydrolysis
(Royal Society of Chemistry, 2016) Gulseren, G.; Khalily, M. A.; Tekinay, A. B.; Güler, Mustafa O.
Essential amino acids in catalytic sites of native enzymes are important in nature inspired catalyst designs. Active sites of enzymes contain the coordinated assembly of multiple amino acids, and catalytic action is generated by the dynamic interactions among multiple residues. However, catalysis studies are limited by the complex and dynamic structure of the enzyme; and it is difficult to exclusively attribute a given function to a specific residue. Minimalistic approaches involving artificial catalytic sites are promising for the investigation of the enzyme function in the absence of non-essential protein components, and self-assembling peptide nanostructures are especially advantageous in this context. Here we demonstrate the design and characterization of an enzyme-mimetic catalytic nanosystem presenting essential residues (Ser, His, Asp). The function of each residue and its combinations on the nanostructures in hydrolysis reaction was studied. The catalytic self-assembled nanostructures were used for efficient ester hydrolysis such as a model substrate (pNPA) and a natural substrate (acetylcholine) highlighting the key role of self-assembly in catalytic domain formation to test the efficiency of the de novo designed catalyst as a catalytic triad model.
Open Access
Facile Synthesis of Three-Dimensional Pt-TiO2Nano-networks: A Highly Active Catalyst for the Hydrolytic Dehydrogenation of Ammonia–Borane
(Wiley, 2016) Khalily, M. A.; Eren, H.; Akbayrak, S.; Susapto, H. H.; Bıyıklı, Necmi; Özkar, S.; Güler, Mustafa O.
Three‐dimensional (3D) porous metal and metal oxide nanostructures have received considerable interest because organization of inorganic materials into 3D nanomaterials holds extraordinary properties such as low density, high porosity, and high surface area. Supramolecular self‐assembled peptide nanostructures were exploited as an organic template for catalytic 3D Pt‐TiO2 nano‐network fabrication. A 3D peptide nanofiber aerogel was conformally coated with TiO2 by atomic layer deposition (ALD) with angstrom‐level thickness precision. The 3D peptide‐TiO2 nano‐network was further decorated with highly monodisperse Pt nanoparticles by using ozone‐assisted ALD. The 3D TiO2 nano‐network decorated with Pt nanoparticles shows superior catalytic activity in hydrolysis of ammonia–borane, generating three equivalents of H2.
Open Access
Inhibition of VEGF mediated corneal neovascularization by anti-angiogenic peptide nanofibers
(Elsevier, 2016-11) Senturk, B.; Cubuk, M. O.; Ozmen, M. C.; Aydin B.; Güler, Mustafa O.; Tekinay, A. B.
Atypical angiogenesis is one of the major symptoms of severe eye diseases, including corneal neovascularization, and the complex nature of abnormal vascularization requires targeted methods with high biocompatibility. The targeting of VEGF is the most common approach for preventing angiogenesis, and the LPPR peptide sequence is known to strongly inhibit VEGF activity by binding to the VEGF receptor neuropilin-1. Here, the LPPR epitope is presented on a peptide amphiphile nanofiber system to benefit from multivalency and increase the anti-angiogenic function of the epitope. Peptide amphiphile nanofibers are especially useful for ocular delivery applications due to their ability to remain on the site of interest for extended periods of time, facilitating the long-term presentation of bioactive sequences. Consequently, the LPPR sequence was integrated into a self-assembled peptide amphiphile network to increase its efficiency in the prevention of neovascularization. Anti-angiogenic effects of the peptide nanofibers were investigated by using both in vitro and in vivo models. LPPR-PA nanofibers inhibited endothelial cell proliferation, tube formation, and migration to a greater extent than the soluble LPPR peptide in vitro. In addition, the LPPR-PA nanofiber system led to the prevention of vascular maturation and the regression of angiogenesis in a suture-induced corneal angiogenesis model. These results show that the anti-angiogenic activity exhibited by LPPR peptide nanofibers may be utilized as a promising approach for the treatment of corneal angiogenesis.
Open Access
Self-assembled peptide nanofiber templated ALD growth of TiO2 and ZnO semiconductor nanonetworks
(Wiley - V C H Verlag GmbH & Co. KGaA, 2016) Garifullin, R.; Eren, H.; Ulusoy, T. G.; Okyay, Ali Kemal; Bıyıklı, Necmi; Güler, Mustafa O.
Here peptide amphiphile (PA) nanofiber network is exploited as a three‐dimensional soft template to construct anatase TiO2 and wurtzite ZnO nanonetworks. Atomic layer deposition (ALD) technique is used to coat the organic nanonetwork template with TiO2and ZnO. ALD method enables uniform and conformal coatings with precisely controlled TiO2 and ZnO thickness. The resulting semiconducting metal oxide nanonetworks are utilized as anodic materials in dye‐sensitized solar cells. Effect of metal oxide layer thickness on device performance is studied. The devices based on thin TiO2 coatings (<10 nm) demonstrate considerable dependence on material thickness, whereas thicker (>17 nm) ZnO‐based devices do not show an explicit correlation.
Open Access
Self-assembled peptide nanostructures for functional materials
(Institute of Physics Publishing, 2016) Ekiz, M. S.; Cinar, G.; Khalily, M. A.; Güler, Mustafa O.
Nature is an important inspirational source for scientists, and presents complex and elegant examples of adaptive and intelligent systems created by self-assembly. Significant effort has been devoted to understanding these sophisticated systems. The self-assembly process enables us to create supramolecular nanostructures with high order and complexity, and peptide-based self-assembling building blocks can serve as suitable platforms to construct nanostructures showing diverse features and applications. In this review, peptide-based supramolecular assemblies will be discussed in terms of their synthesis, design, characterization and application. Peptide nanostructures are categorized based on their chemical and physical properties and will be examined by rationalizing the influence of peptide design on the resulting morphology and the methods employed to characterize these high order complex systems. Moreover, the application of self-assembled peptide nanomaterials as functional materials in information technologies and environmental sciences will be reviewed by providing examples from recently published high-impact studies.