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End-to-end self-assembly of RADA 16-I nanofibrils in aqueous solutions.

ABSTRACT: RADARADARADARADA (RADA 16-I) is a synthetic amphiphilic peptide designed to self-assemble in a controlled way into fibrils and higher ordered structures depending on pH. In this work, we use various techniques to investigate the state of the peptide dispersed in water under dilute conditions at different pH and in the presence of trifluoroacetic acid or hydrochloric acid. We have identified stable RADA 16-I fibrils at pH 2.0-4.5, which have a length of ?200-400 nm and diameter of 10 nm. The fibrils have the characteristic antiparallel ?-sheet structure of amyloid fibrils, as measured by circular dichroism and Fourier transform infrared spectrometry. During incubation at pH 2.0-4.5, the fibrils elongate very slowly via an end-to-end fibril-fibril aggregation mechanism, without changing their diameter, and the kinetics of such aggregation depends on pH and anion type. At pH 2.0, we also observed a substantial amount of monomers in the system, which do not participate in the fibril elongation and degrade to fragments. The fibril-fibril elongation kinetics has been simulated using the Smoluchowski kinetic model, population balance equations, and the simulation results are in good agreement with the experimental data. It is also found that the aggregation process is not limited by diffusion but rather is an activated process with energy barrier in the order of 20 kcal/mol.

SUBMITTER: Arosio P

PROVIDER: S-EPMC3318125 | biostudies-literature | 2012 Apr

REPOSITORIES: biostudies-literature

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End-to-end self-assembly of RADA 16-I nanofibrils in aqueous solutions.

Arosio Paolo P Owczarz Marta M Wu Hua H Butté Alessandro A Morbidelli Massimo M

Biophysical journal 20120403 7

RADARADARADARADA (RADA 16-I) is a synthetic amphiphilic peptide designed to self-assemble in a controlled way into fibrils and higher ordered structures depending on pH. In this work, we use various techniques to investigate the state of the peptide dispersed in water under dilute conditions at different pH and in the presence of trifluoroacetic acid or hydrochloric acid. We have identified stable RADA 16-I fibrils at pH 2.0-4.5, which have a length of ∼200-400 nm and diameter of 10 nm. The fibr ...[more]

PMID: 22500762

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Project description:BackgroundSafe and effective hemostatic materials are important for reducing mortality resulting from excessive hemorrhage. In this work, new biomaterials with hemostatic effects were created by fusing the gene coding for RADA-16, a self-assembling peptide with the sequence RADARADARADARADA, to the 3'-end of the open reading frame (ORF) encoding elastin-like polypeptides through gene recombination.ResultsThe fusion proteins, termed 36R, 60R and 96R, were solubly over-expressed in Escherichia coli BL21 (DE3) based on genetic manipulation of the high-efficiency prokaryotic expression vector pET28a (+) and bacterial transformation. Western Blot analysis showed that the over-expressed proteins were the target fusion proteins. The target proteins 36R with 94.72% purity, 60R with 96.91% purity and 96R with 96.37% purity were prepared using an inverse phase transition cycle at 65 °C followed by His-tag affinity chromatography. The proliferation results of the mouse fibroblast cell line L929 and hippocampus neuron cell line HT22 indicated that the fusion proteins did not cause obvious cell toxicity. The lyophilized spongy film of the purified 36R, 60R and 96R could stop the hemorrhage of a 2?×?2 mm bleeding wound in the mouse liver after 27.21?±?1.92 s, 18.65?±?1.97 s and 15.85?±?1.21 s, respectively. The hemostasis time was 21.23?±?1.84 s for rat-tail collagen and 14.44?±?1.33 s for RADA-16 lyophilized on gauze. The hemostatic time of three treated groups were all significantly superior to that of the negative control without any hemostasis treatment, which spontaneously stopped bleeding after 37.64?±?1.34 s. Statistical analysis showed that the spongy film with purified 96R exhibited an exciting hemostatic effect that was superior to rat-tail collagen and close to that of RADA-16 lyophilized on gauze.ConclusionsThese results revealed that the fusion proteins achieved by gene recombination technology could serve as a promising hemostatic material.

Project description:The development of electrochemical multisensor systems is driven by the need for fast, miniature, inexpensive, analytical devices, and advanced interdisciplinary based on both chemometric and (nano)material approaches. A multicomponent analysis of complex mixtures in environmental and technological monitoring, biological samples, and cell culture requires chip-based multisensor systems with high-stability sensors. In this paper, we describe the development, characterization, and applications of chip-based nanoelectrochemical sensor arrays prepared by the directed electrochemical nanowire assembly (DENA) of noble metals and metal alloys to analyze aqueous solutions. A synergic action of the electrode transducer function and electrocatalytic activity of the nanostructured surface toward analytes is achieved in the assembled metal nanowire (NW) sensors. Various sensor nanomaterials (Pd, Ni, Au, and their multicomponent compositions) can be electrochemically assembled on a single chip without employing multiple cycles of photolithography process to realize multi-analyte sensing applications as well as spatial resolution of sensor analysis by this single-chip multisensor system. For multi-analyte electrochemical sensing, individual amperometric signals of two or more nanowires can be acquired, making use of the specific electrocatalytic surface properties of the individual nanowire sensors of the array toward analytes. To demonstrate the application of a new electrochemical multisensor platform, Pd-Au, Pd-Ni, Pd, and Au NW electrode arrays on a single chip were employed for the non-enzymatic analysis of hydrogen peroxide, glucose, and ethanol. The analytes are determined at low absolute values of the detection potentials with linear concentration ranges of 1.0 × 10-6 - 1.0 × 10-3 M (H2O2), 1.5 × 10-7 - 2.0 × 10-3 M (glucose), and 0.7 × 10-3 - 3.0 × 10-2 M (ethanol), detection limits of 2 × 10-7 M (H2O2), 4 × 10-8 M (glucose), and 5.2 × 10-4 M (ethanol), and sensitivities of 18 ?A M-1 (H2O2), 178 ?A M-1 (glucose), and 28 ?A M-1 (ethanol), respectively. The sensors demonstrate a high level of stability due to the non-enzymatic detection mode. Based on the DENA-assembled nanowire electrodes of a compositional diversity, we propose a novel single-chip electrochemical multisensor platform, which is promising for acquiring complex analytical signals for advanced data processing with chemometric techniques aimed at the development of electronic tongue-type multisensor systems for flexible multi-analyte monitoring and healthcare applications.

Dataset Information

End-to-end self-assembly of RADA 16-I nanofibrils in aqueous solutions.

Publications

End-to-end self-assembly of RADA 16-I nanofibrils in aqueous solutions.

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