Confirmation of Bioinformatics Predictions of the Structural Domains in Honeybee Silk.

Honeybee larvae produce a silk made up of proteins in predominantly a coiled coil molecular structure. These proteins can be produced in recombinant systems, making them desirable templates for the design of advanced materials. However, the atomic level structure of these proteins is proving difficult to determine: firstly, because coiled coils are difficult to crystalize; and secondly, fibrous proteins crystalize as fibres rather than as discrete protein units.

On the detection of carbon fibre storage contamination and its effect on the fibre-matrix interface.

Contamination caused by inappropriate carbon fibre (CF) storage may have an impact on their end use in reinforced composite materials. Due to the chemical complexity of CFs it is not easy to detect potential contaminants, especially at the early stage during manufacturing and handling. In this paper, X-ray Photoelectron Spectroscopy (XPS), Fourier Transform Infrared (FTIR) spectroscopy and Surface Energy Analysis (IGC-SEA) were used to assess the surfaces of CFs stored in polyolefin zip-lock bags for possible contamination.

Graphene based room temperature flexible nanocomposites from permanently cross-linked networks.

Graphene based room temperature flexible nanocomposites were prepared using epoxy thermosets for the first time. Flexible behavior was induced into the epoxy thermosets by introducing charge transfer complexes between functional groups within cross linked epoxy and room temperature ionic liquid ions. The graphene nanoplatelets were found to be highly dispersed in the epoxy matrix due to ionic liquid cation-π interactions.

Design of silk proteins with increased heme binding capacity and fabrication of silk-heme materials.

In our previous studies, heme was bound into honeybee silk to generate materials that could function as nitric oxide sensors or as recoverable heterogeneous biocatalysts. In this study, we sought to increase the heme-binding capacity of the silk protein by firstly redesigning the heme binding site to contain histidine as the coordinating residue and secondly, by adding multiple histidine residues within the core of the coiled coil core region of the modified silk protein. We used detergent and a protein denaturant to confirm the importance of the helical structure of the silk for heme coordination.

Recombinant Structural Proteins and Their Use in Future Materials.

Recombinant proteins are polymers that offer the materials engineer absolute control over chain length and composition: key attributes required for design of advanced polymeric materials. Through this control, these polymers can be encoded to contain information that enables them to respond as the environment changes. However, despite their promise, protein-based materials are under-represented in materials science.

Structural Analysis of Hand Drawn Bumblebee Bombus terrestris Silk.

Bombus terrestris, commonly known as the buff-tailed bumblebee, is native to Europe, parts of Africa and Asia. It is commercially bred for use as a pollinator of greenhouse crops. Larvae pupate within a silken cocoon that they construct from proteins produced in modified salivary glands.

De Novo Engineering of Solid-State Metalloproteins Using Recombinant Coiled-Coil Silk.

To achieve the sophisticated chemistry required for life, nature uses metal containing proteins (metalloproteins). However, despite intensive research efforts, very few of these metalloproteins have been exploited for biotechnological applications. One major limiting factor is the poor stability of these proteins when they are removed from their cellular environment.

The purple coloration of four late 19th century silk dresses: A spectroscopic investigation.

Prior to the 19th century the use of purple dyes for textile coloration was expensive and usually limited to royalty. The discovery of several synthetic purple dyes during the 19th century made the production of purple textiles more affordable and thus more readily available. The identification of the source of the purple coloration is of historical interest.

Click chemistry modification of natural keratin fibers for sustained shrink-resist performance.

This paper introduces a novel chemical treatment for achieving sustained shrink-resist performance on natural keratin fibers. The new treatment involves the controlled reduction of keratin in the cuticle region of the fiber, and the application of a water soluble diacrylate, namely glycerol 1,3-diglycerolate diacrylate (GDA), on the reduced keratin substrate. The acrylate groups of the GDA react with cysteine residues in the reduced keratin through thiol-ene click reactions at room temperature, leading to GDA grafting and the formation of GDA crosslinks in the keratin structure.

The effects of physical and chemical treatments on Na2S produced feather keratin films.

The industrial utilisation of feather keratin as a biopolymer has proven difficult due to the lack of a viable extraction technique and the poor mechanical properties of the regenerated products. Here, pure keratin films were produced from chicken feathers using sodium sulphide as sole extraction reagent in a scheme that allows films to be formed without residual chemicals. In a comparison to other films, those produced using Na2S extraction were found to be superior to other regenerated protein films and were similar to un-oriented commercial polymers.

Stabilization of viruses by encapsulation in silk proteins.

Viruses are important for a range of modern day applications. However, their utility is limited by their susceptibility to temperature degradation. In this study, we report a simple system to compare the ability of different dried protein films to stabilize viruses against exposure to elevated temperatures.

Micromolar biosensing of nitric oxide using myoglobin immobilized in a synthetic silk film.

In this work we investigate the use of coiled-coil silk proteins, produced in recombinant Escherichia coli, as a new material for immobilizing biosensors. Myoglobin was embedded in transparent honeybee silk protein films. Immobilized myoglobin maintained a high affinity for nitric oxide (KD NO=52 µM) and good sensitivity with a limit of detection of 5 µM.

Novel immobilization of a quaternary ammonium moiety on keratin fibers for medical applications.

This paper introduces a new approach for immobilizing a quaternary ammonium moiety on a keratinous substrate for enhanced medical applications. The method involves the generation of thiols by controlled reduction of cystine disulfide bonds in the keratin, followed by reaction with [2-(acryloyloxy)ethyl]trimethylammonium chloride through thiol-ene click chemistry. The modified substrate was characterized with Raman and infrared spectroscopy, and assessed for its antibacterial efficacy and other performance changes.

Infrared and Raman spectroscopic studies of tris-[3-(trimethoxysilyl)propyl] isocyanurate, its sol-gel process, and coating on aluminum and copper.

Tris-[3-(trimethoxysilyl)propyl] isocyanurate (TTPI) has been used as a precursor to prepare a sol using ethanol as the solvent under acidic conditions. The sol-gel was applied for the surface treatment of aluminum and copper. Infrared and Raman spectra have been recorded for pure TTPI and the TTPI sol, xerogel and TTPI sol-gel coated metals.

Raman spectroscopy in the analysis of food and pharmaceutical nanomaterials.

Raman scattering is an inelastic phenomenon. Although its cross section is very small, recent advances in electronics, lasers, optics, and nanotechnology have made Raman spectroscopy suitable in many areas of application. The present article reviews the applications of Raman spectroscopy in food and drug analysis and inspection, including those associated with nanomaterials.

Convergently-evolved structural anomalies in the coiled coil domains of insect silk proteins.

The use of coiled coil proteins as the basis of silk materials is an engineering solution that has evolved convergently in at least five insect lineages-the stinging hymenopterans (ants, bees, hornets), argid sawflies, fleas, lacewings, and praying mantises-and persisted throughout large radiations of these insect families. These coiled coil silk proteins share a characteristic distinct from other coiled coil proteins, in that they are fabricated into solid materials after accumulating as highly concentrated solutions within dedicated glands. Here, we relate the amino acid sequences of these proteins to the secondary and tertiary structural information available from biophysical methods such as X-ray scattering, nuclear magnetic resonance and Raman spectroscopy.

Modifying surface resistivity and liquid moisture management property of keratin fibers through thiol-ene click reactions.

This paper reports on a new method for improving the antistatic and liquid moisture management properties of keratinous materials. The method involves the generation of thiols by controlled reduction of cystine disulfide bonds in keratin with tris(2-carboxyethyl) phosphine hydrochloride and subsequent grafting of hydrophilic groups onto the reduced keratin by reaction with an acrylate sulfonate or acrylamide sulfonate through thiol-ene click chemistry. The modified substrates were characterized with Raman spectroscopy and scanning electron microscopy and evaluated for their performance changes in liquid moisture management, surface resistivity, and wet burst strength.

A comparison of convergently evolved insect silks that share β-sheet molecular structure.

Raspy crickets produce silk webs that are used to build shelters. These webs have been found to consist of both fiber and film components. Raman spectra obtained from both components were found to be very similar for a given species.

Thermal annealing effects on multi-walled carbon nanotube yarns probed by Raman spectroscopy.

The realized mechanical properties of CNT macrostructures such as webs and yarns remain significantly lower than those of the individual CNTs. Structural changes induced by thermal annealing under inert atmosphere were assessed using Raman spectroscopy. Annealing above 1000 °C resulted in a marked decrease in the D/G ratio which can be attributed to an increase in the crystallite size or the distance between defects.

Continuous production of flexible fibers from transgenically produced honeybee silk proteins.

Flexible and solvent stable fibers are produced after concentrated recombinant honeybee protein solutions are extruded into a methanol bath, dried, drawn in aqueous methanol, then covalently cross-linked using dry heat. Proteins in solution are predominantly coiled coil. Significant levels of non-orientated ß-sheets form during drying or after coagulation in aqueous methanol.

Temperature variations at nano-scale level in phase transformed nanocrystalline NiTi shape memory alloys adjacent to graphene layers.

The detection and control of the temperature variation at the nano-scale level of thermo-mechanical materials during a compression process have been challenging issues. In this paper, an empirical method is proposed to predict the temperature at the nano-scale level during the solid-state phase transition phenomenon in NiTi shape memory alloys. Isothermal data was used as a reference to determine the temperature change at different loading rates.

Silverfish silk is formed by entanglement of randomly coiled protein chains.

Silks are semi-crystalline solids in which protein chains are associated by intermolecular hydrogen bonding within ordered crystallites, and by entanglement within unordered regions. By varying the type of protein secondary structure within crystallites and the overall degree of molecular order within fibers, arthropods produce fibers with a variety of physical properties suited to many purposes. We characterized silk produced as a tactile stimulus during mating by the grey silverfish (Ctenolepisma longicaudata) using Fourier transform infrared spectroscopy, polarized Raman spectroscopy, gel electrophoresis and amino acid analysis.

Controlling the molecular structure and physical properties of artificial honeybee silk by heating or by immersion in solvents.

Honeybee larvae produce silken cocoons that provide mechanical stability to the hive. The silk proteins are small and non-repetitive and therefore can be produced at large scale by fermentation in E. coli.

Silk from crickets: a new twist on spinning.

Raspy crickets (Orthoptera: Gryllacrididae) are unique among the orthopterans in producing silk, which is used to build shelters. This work studied the material composition and the fabrication of cricket silk for the first time. We examined silk-webs produced in captivity, which comprised cylindrical fibers and flat films.

Effects of thermal denaturation on the solid-state structure and molecular mobility of glycinin.

The effects of moisture and thermal denaturation on the solid-state structure and molecular mobility of soy glycinin powder were investigated using multiple techniques that probe over a range of length and time scales. In native glycinin, increased moisture resulted in a decrease in both the glass transition temperature and the denaturation temperature. The sensitivity of the glass transition temperature to moisture is shown to follow the Gordon-Taylor equation, while the sensitivity of the denaturation temperature to moisture is modeled using Flory's melting point depression theory.