4,708 research outputs found
Bioactive supramolecular peptide nanofibers for regenerative medicine
Cataloged from PDF version of article.Recent advances in understanding of cell-matrix interactions and the role of the extracellular matrix (ECM) in regulation of cellular behavior have created new perspectives for regenerative medicine. Supramolecular peptide nanofiber systems have been used as synthetic scaffolds in regenerative medicine applications due to their tailorable properties and ability to mimic ECM proteins. Through designed bioactive epitopes, peptide nanofiber systems provide biomolecular recognition sites that can trigger specific interactions with cell surface receptors. The present Review covers structural and biochemical properties of the self-assembled peptide nanofibers for tissue regeneration, and highlights studies that investigate the ability of ECM mimetic peptides to alter cellular behavior including cell adhesion, proliferation, and/or differentiation. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Encapsulation of a zinc phthalocyanine derivative in self-assembled peptide nanofibers
Cataloged from PDF version of article.In this article, we demonstrate encapsulation of octakis(hexylthio) zinc phthalocyanine molecules by non-covalent supramolecular organization within self-assembled peptide nanofibers. Peptide nanofibers containing octakis(hexylthio) zinc phthalocyanine molecules were obtained via a straight-forward one-step self-assembly process under aqueous conditions. Nanofiber formation results in the encapsulation and organization of the phthalocyanine molecules, promoting ultrafast intermolecular energy transfer. The morphological, mechanical, spectroscopic and non-linear optical properties of phthalocyanine containing peptide nanofibers were characterized by TEM, SEM, oscillatory rheology, UV-Vis, fluorescence, ultrafast pump-probe and circular dichroism spectroscopy techniques. The ultrafast pump-probe experiments of octakis(hexylthio) zinc phthalocyanine molecules indicated pH controlled non-linear optical characteristics of the encapsulated molecules within self-assembled peptide nanofibers. This method can provide a versatile approach for bottom-up fabrication of supramolecular organic electronic devices. © 2012 The Royal Society of Chemistry
Thalassemia mutations in Gaziantep, Turkey
Ninety-eight postnatal and six prenatal cases of thalassemia were studied by the reverse dot-blot hybridization technique in the city of Gaziantep, Turkey. We found the following mutations: IVS 1.110 (G>A) in 29.1%, IVS 2.1 (G>A) in 12.3%, IVS 1.1 (G>A) in 7.7%, Codon 8 (-AA) in 5.6%, -30 (T>A) in 4.6%, IVS 1.6 (T>C) in 4.6%, Codon 39 (C>T) in 3.6%, Codon 44 (-C) in 3.1%, IVS 2.745 (C>G) in 1.5%, Codon 8/9 (+G) in 2.1%, Codon 36/37 (-T) in 2.1%, IVS 1.5 (G>C) in 2.1%, Codon 22 (7pb del) in 0.5%, Codon 5 (-CT) in 0.5% while 20.9% were undetermined. 54 of the thalassemia patients were homozygotes, 12 were compound heterozygous and 31 were heterozygotes. In one allele of 5 thalassemia patients, - thalassemia mutation (3.7 single gene deletions in 1 patient, anti-3.7 gene triplication in 4 patients) wasdetermined at the same time. Finally, this is the first comprehensive study in this region and percentage of and - globin genes mutation is 2.6 and 79.4%, respectively
Amyloid Inspired Self-Assembled Peptide Nanofibers
Cataloged from PDF version of article.Amyloid peptides are important components in many degenerative
diseases as well as in maintaining cellular metabolism. Their unique stable structure
provides new insights in developing new materials. Designing bioinspired selfassembling
peptides is essential to generate new forms of hierarchical nanostructures.
Here we present oppositely charged amyloid inspired peptides (AIPs),
which rapidly self-assemble into nanofibers at pH 7 upon mixing in water caused
by noncovalent interactions. Mechanical properties of the gels formed by selfassembled
AIP nanofibers were analyzed with oscillatory rheology. AIP gels
exhibited strong mechanical characteristics superior to gels formed by self-assembly
of previously reported synthetic short peptides. Rheological studies of gels
composed of oppositely charged mixed AIP molecules (AIP-1 + 2) revealed superior mechanical stability compared to individual
peptide networks (AIP-1 and AIP-2) formed by neutralization of net charges through pH change. Adhesion and elasticity
properties of AIP mixed nanofibers and charge neutralized AIP-1, AIP-2 nanofibers were analyzed by high resolution force−
distance mapping using atomic force microscopy (AFM). Nanomechanical characterization of self-assembled AIP-1 + 2, AIP-1,
and AIP-2 nanofibers also confirmed macroscopic rheology results, and mechanical stability of AIP mixed nanofibers was higher
compared to individual AIP-1 and AIP-2 nanofibers self-assembled at acidic and basic pH, respectively. Experimental results were
supported with molecular dynamics simulations by considering potential noncovalent interactions between the amino acid
residues and possible aggregate forms. In addition, HUVEC cells were cultured on AIP mixed nanofibers at pH 7 and biocompatibility
and collagen mimetic scaffold properties of the nanofibrous system were observed. Encapsulation of a zwitterionic
dye (rhodamine B) within AIP nanofiber network was accomplished at physiological conditions to demonstrate that this network
can be utilized for inclusion of soluble factors as a scaffold for cell culture studies. Copyright © 2012 American Chemical Societ
Alkaline phosphatase-mimicking peptide nanofibers for osteogenic differentiation
Recognition of molecules and regulation of extracellular matrix synthesis are some of the functions of enzymes in addition to their catalytic activity. While a diverse array of enzyme-like materials have been developed, these efforts have largely been confined to the imitation of the chemical structure and catalytic activity of the enzymes, and it is unclear whether enzyme-mimetic molecules can also be used to replicate the matrix-regulatory roles ordinarily performed by natural enzymes. Self-assembled peptide nanofibers can provide multifunctional enzyme-mimetic properties, as the active sequences of the target enzymes can be directly incorporated into the peptides. Here, we report enhanced bone regeneration efficiency through peptide nanofibers carrying both catalytic and matrix-regulatory functions of alkaline phosphatase, a versatile enzyme that plays a critical role in bone formation by regulating phosphate homeostasis and calcifiable bone matrix formation. Histidine presenting peptide nanostructures were developed to function as phosphatases. These molecules are able to catalyze phosphate hydrolysis and serve as bone-like nodule inducing scaffolds. Alkaline phosphatase-like peptide nanofibers enabled osteogenesis for both osteoblast-like and mesenchymal cell lines. © 2015 American Chemical Society
Noncovalent functionalization of a nanofibrous network with a bio-inspired heavy metal binding peptide
Peptide-polymer nanofibrous networks can be developed to obtain hybrid systems providing both functionalities of peptides and stability and processability of the polymers. In this work, a bio-inspired heavy metal binding peptide was synthesized and noncovalently immobilized on water-insoluble electrospun hydroxypropyl-beta-cyclodextrin nanofibers (CDNF). The peptide functionalized hybrid nanofibers were able to bind to heavy metal ions and facilitated removal of metal ions from water. The peptide-polymer scavenging system has potential for development of further molecular recognition systems with various peptide sequences or host-guest inclusion complexes. © 2013 The Royal Society of Chemistry
Improving pancreatic islet in vitro functionality and transplantation efficiency by using heparin mimetic peptide nanofiber gels
Pancreatic islet transplantation is a promising treatment for type 1 diabetes. However, viability and functionality of the islets after transplantation are limited due to loss of integrity and destruction of blood vessel networks. Thus, it is important to provide a proper mechanically and biologically supportive environment for enhancing both in vitro islet culture and transplantation efficiency. Here, we demonstrate that heparin mimetic peptide amphiphile (HM-PA) nanofibrous network is a promising platform for these purposes. The islets cultured with peptide nanofiber gel containing growth factors exhibited a similar glucose stimulation index as that of the freshly isolated islets even after 7 days. After transplantation of islets to STZ-induced diabetic rats, 28 day-long monitoring displayed that islets that were transplanted in HM-PA nanofiber gels maintained better blood glucose levels at normal levels compared to the only islet transplantation group. In addition, intraperitoneal glucose tolerance test revealed that animals that were transplanted with islets within peptide gels showed a similar pattern with the healthy control group. Histological assessment showed that islets transplanted within peptide nanofiber gels demonstrated better islet integrity due to increased blood vessel density. This work demonstrates that using the HM-PA nanofiber gel platform enhances the islets function and islet transplantation efficiency both in vitro and in vivo. © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved
Vitamin D3/vitamin K2/magnesium-loaded polylactic acid/tricalcium phosphate/polycaprolactone composite nanofibers demonstrated osteoinductive effect by increasing Runx2 via Wnt/β-catenin pathway
Vitamin D3, vitamin K2, and Mg (10%, 1.25%, and 5%, w/w, respectively)-loaded PLA (12%, w/v) (TCP (5%, w/v))/PCL (12%, w/v) 1:1 (v/v) composite nanofibers (DKMF) were produced by electrospinning method (ES) and their osteoinductive effects were investigated in cell culture test. Neither pure nanofibers nor DKMF caused a significant cytotoxic effect in fibroblasts. The induction of the stem cell differentiation into osteogenic cells was observed in the cell culture with both DKMF and pure nanofibers, separately. Vitamin D3, vitamin K2, and magnesium demonstrated to support the osteogenic differentiation of mesenchymal stem cells by expressing Runx2, BMP2, and osteopontin and suppressing PPAR-γ and Sox9. Therefore, the Wnt/β-catenin signaling pathway was activated by DKMF. DKMF promoted large axonal sprouting and needle-like elongation of osteoblast cells and enhanced cellular functions such as migration, infiltration, proliferation, and differentiation after seven days of incubation using confocal laser scanning microscopy. The results showed that DKMF demonstrated sustained drug release for 144 h, tougher and stronger structure, higher tensile strength, increased water up-take capacity, decreased degradation ratio, and slightly lower Tm and Tg values compared to pure nanofibers. Consequently, DKMF is a promising treatment approach in bone tissue engineering due to its osteoinductive effects
G Electronics and Data Acquisition (Forward-Angle Measurements)
The G parity-violation experiment at Jefferson Lab (Newport News, VA) is
designed to determine the contribution of strange/anti-strange quark pairs to
the intrinsic properties of the proton. In the forward-angle part of the
experiment, the asymmetry in the cross section was measured for
elastic scattering by counting the recoil protons corresponding to the two
beam-helicity states. Due to the high accuracy required on the asymmetry, the
G experiment was based on a custom experimental setup with its own
associated electronics and data acquisition (DAQ) system. Highly specialized
time-encoding electronics provided time-of-flight spectra for each detector for
each helicity state. More conventional electronics was used for monitoring
(mainly FastBus). The time-encoding electronics and the DAQ system have been
designed to handle events at a mean rate of 2 MHz per detector with low
deadtime and to minimize helicity-correlated systematic errors. In this paper,
we outline the general architecture and the main features of the electronics
and the DAQ system dedicated to G forward-angle measurements.Comment: 35 pages. 17 figures. This article is to be submitted to NIM section
A. It has been written with Latex using \documentclass{elsart}. Nuclear
Instruments and Methods in Physics Research Section A: Accelerators,
Spectrometers, Detectors and Associated Equipment In Press (2007
Label-Free Nanometer-Resolution Imaging of Biological Architectures through Surface Enhanced Raman Scattering
Label free imaging of the chemical environment of biological specimens would readily bridge the supramolecular and the cellular scales, if a chemical fingerprint technique such as Raman scattering can be coupled with super resolution imaging. We demonst
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