Query: electrostatic spinning Wool keratin

title: Silver doped keratin nanofibers preserve a titanium surface from biofilm contamination and favor soft tissue healing.
abstract: Peri implantitis is a severe condition affecting the success of transmucosal dental implants: tissue healing is severely limited by the inflammatory processes that come about to control homeostasis in the surrounding tissues. The main cause of peri implantitis is bacterial biofilm infection; gingival fibroblasts play a pivotal role in regulating the inflammatory cascades. A new technology aimed at preventing bacterial colonization of titanium (Ti) implants, and enhancing the spread of gingival fibroblasts, is presented. Using electro spinning, mirror polished Ti disks were uniformly coated with keratin fibers obtained from discarded wool via sulfitolysis. The keratin coated surfaces were then doped with silver (Ag) to introduce antibacterial properties, using different concentrations of silver nitrate as a precursor (0.01, 0.05 and 0.1 M) The resulting specimens were characterized in terms of morphology and chemical composition by FESEM, FTIR and XPS, revealing silver concentrations between 1.7 and 1.9% Silver release into the medium was evaluated in the presence of cells (a MEM) or bacteria (LB) by ICP; release was 0.2 1.4 mg l 1 for a MEM, and 10 40 mg l 1 for LB. The antibacterial properties of the Ag doped specimens were tested against a multidrug resistant Staphylococcus aureus biofilm through morphology (FESEM) and metabolic assay (XTT) reduction in viability was significant (p 0.05; >80% reduction within 72 h) Lastly, the cytocompatibility of the specimens was confirmed using human primary gingival fibroblasts, whose viability, spread and matrix deposition were found to be comparable to those of untreated Ti polished controls (p 0.05) Thus, Ag surface enrichment was effective in reducing viability and maturation of S. aureus biofilm, without compromising human cell viability. Moreover, cell spread was found to be very sensitive to keratin fiber stimulation. The strategy thus appears to be very promising to introduce surface features in line with the main requirements for transmucosal dental implants.

title: Thermal denaturation of hydrated wool keratin by 1H solid state NMR.
abstract: Thermal denaturation of hydrated keratin in wool was investigated by NMR using 1H wide line spectra to obtain the phase composition and 1H spin diffusion experiments using a double quantum filter to obtain the domain sizes for the wool fibers. The denaturation process detected by DSC takes place for wool fibers in deuterated water in the temperature range 140 144 degreeC. The phase composition measured by 1H wide line NMR spectra reveals a rigid, semirigid and an amorphous phase for temperatures in the range 25 160 degreeC. A dramatic change in the phase composition was detected around 142 degreeC, corresponding to the denaturation temperature. The morphological domain sizes measured by 1H spin diffusion NMR experiments were obtain from the solutions of the spin diffusion equations for two dimensional rectangular and cylindrical morphologies. The keratin mobility gradient in the interfacial region at different denaturation temperatures was measured from the 1H spin diffusion data. A qualitative model describing the denaturation process of hydrated keratin protein was developed that explains the changes in domain thickness, spin diffusivities, phase composition, and thermodynamic parameters.

title: The photodegradation of wool keratin II. Proposed mechanisms involving cystine
abstract: A possible mechanism for the formation of cysteine, cysteic acid and partially oxidized cystine species in keratin following exposure to UVC radiation at 254 nm is proposed. The primary photolysis products are the radical ions RSSR' and RSSR' and it is suggested that partially oxidized cystine species are formed from reactions of the radical cation only. The mechanisms m is supported by Fourier transform IR (FT IR) and optical reflectance spectroscopy of UVC treated wool exposed to air, oxygen and nitrogen atmospheres, and by previous electron spin resonance (ESR) studies on disulphides exposed to both UV and ionizing radiation. The mechanism supports the Symons assignment for the sulphur radical "species X" as [RS(SR)SR] rather than RSS' Exposure of wool to less energetic UV radiation produces different products via a quenching mechanism involving the formation of the radical anion RSSR' only, which precludes the formation of oxidized cystine intermediates. The formation of S sulphonate residues at longer wavelengths suggests that a competing singlet oxygen process may also occur.

title: An Electron Spin Resonance Study of the Copper (II) Interaction with Wool Keratin
abstract: The esr spectrum observed from a wool sample treated in a copper (II) solution in the pH range of 1.5 to 5.0 was inter preted by assuming two paramagnetic species each with an effective spin S=1/2. The interaction giving rise to this esr spectrum was ascribed to the complex formation between Cu(II) and the free carboxyl groups in the wool.

title: An Electron Spin Resonance Study of the Copper (II) Interaction with Wool Keratin
abstract: An examination of the Cu (II)/wool esr signal intensity variations, together with other relevant copper (II) uptake data, have shown that two types of products are formed during the Cu (II)/wool interaction. One of these gives rise to the observed esr signal, while the other is a diamagnetic sulfide of copper. The latter product arises as a result of a reaction of the metal ion and the products of a water/wool interaction. A reaction scheme consistent with the experi mental observations is suggested.

title: Sites for Cu II Stabilization in Wool Keratin
abstract: Light green copper(II) wool samples prepared under conditions of pH 5 have been treated for short periods at about pH 11.5. The color changes and the electron spin resonance spectra of these new samples are described. All observations are con sistent with the metal ion being transferred from the carboxylate binding sites of the light green complex to new ones involving nitrogen donor groups.

title: Aggregation of wool keratin intermediate filament proteins.
abstract: The wool keratin intermediate filament proteins were isolated as their S carboxymethyl derivatives (S carboxymethylkerateine A, SCMKA) and purified by gel filtration to remove residual non helical protein of low molecular weight. The alpha helix content of purified SCMKA was approximately 62% in agreement with that predicted for the alpha helical coiled coil segments from the amino acid sequences of the subunits. In aqueous buffer at pH 11 or in n propanol (20% v/v) at pH 9.2 very large aggregates are dissociated and SCMKA exists largely as a mixture of the dimer (two chain coiled coil of Mr approximately 103,000) and the tetramer. The protein species are not in rapidly reversible equilibrium as judged from gel filtration and sedimentation equilibrium. It is probable that species with a range of association constants are present. The equilibrium is shifted towards the dimer with change of pH from 9.2 to 11 or by the addition of 20% (v/v) n propanol. The tetrameric proteolytic digestion product which is derived from the 1B segment of the alpha helical rod section of the keratin molecule dissociates in a similar way to intact SCMKA with increase of pH and in the presence of n propanol. This indicates the importance of this region of the rod domain in the initial stages of the assembly of the filament. Electrostatic and hydrophobic interactions are implicated in the association of the two chain coiled coil to the tetramer both in intact SCMKA and the 1B segment tetramer. The results are discussed in relation to the intact dimeric and tetrameric complexes obtained from other intermediate filament types.

title: Structural studies and macro performances of hydroxyapatite reinforced keratin thin films for biological applications
abstract: In this work, a series of wool keratin/hydroxyapatite (HA) composite films with different component ratios were fabricated by a modified solution casting technique. During the film forming process, HAs deposited on the keratin matrix and bonded with amino acids of keratin molecules via electrostatic and intermolecular/water bridged hydrogen bond interaction, which can be verified by the different morphologies of HA particles in water and keratin solution from scanning electron microscope and transmission electron microscope images. The microstructural transitions of hybrid films were examined by Fourier transform infrared spectroscopy and X ray diffraction, indicating that HA particles expanded the crystalline area of composites without disrupting the original structures of keratin, and eventually enhanced the macro performance of hybrid film. Nevertheless, excessive HA particles in keratin were liable to agglomerate and accumulate on the surface of films, which led to the weakening of tensile strength to some extent but improved the wettability of films and the biocompatibility and bioactivity compared to the pure keratin film. The composite films with 5 wt% HA granules were taken to be the optimum composition for practical application with good mechanical strength and biocompatibility; moreover, thermo gravimetric analysis was used to confirm the good thermostability of this kind of film.

title: 34 A STUDY OF WOOL KERATIN BY ELECTRON SPIN RESONANCE SPECTROSCOPY
abstract: An account is given of the study by means of electron spin resonance spectroscopy of free radicals induced in wool and chemically modified wool by X rays. 'Cystine' radicals are shown to be formed by only a portion of the total number of residues present, and these are associated with amino end groups. Spectral changes produced by chemical modification of the cystine are explained in terms of superimposed singlet, doublet, and quartet absorptions, and it is proposed that the quartet absorptions originate from free radicals on the alanine side chains. It is shown that X irradiation in air modifies the wool structure so that previously 'inert' disulphide links are capable of radical formation.

title: An Electron Spin Resonance Study of the Copper (II) Interaction with Wool Keratin
abstract: The uptakes of Cu(II) by wool are interpreted with the help of a kinetic model developed on the basis of a previously suggested reaction scheme. The kinetic model may be used to obtain information about the Cu(II)/wool interaction.