Novel drug‐eluting soy‐protein structures for wound healing applications

Naturally derived materials are becoming widely used in the biomedical field. Soy protein has advantages over the various types of natural proteins employed for biomedical applications due to its low price, nonanimal origin, and relatively long storage time and stability. In the current study, novel drug‐eluting soy‐protein films for wound healing applications were developed and studied. The films were prepared using the solvent casting technique. The analgesic drug bupivacaine and two types of wide range antibiotics (gentamicin and clindamycin) were incorporated into the soy‐protein films. The effect of drug incorporation and plasticizers content on the films' mechanical properties, drug release profiles, and cell viability was studied. Drug incorporation had a softening effect of the films, lowering mechanical strength and increasing ductility. Release profiles of bupivacaine and clindamycin exhibited high burst release of 80% to 90% of encapsulated drug within 6 hours, followed by continuous release in a decreasing rate for a period of 2 to 4 days. Gentamicin release was prolonged, probably due to interaction between the gentamicin and the polymer chains. Hybrid soy‐protein/poly (Dl‐lactic‐co‐glycolic acid) (PDLGA) microspheres structure showed potential for long and sustained release of bupivacaine. Films with no drugs and films loaded with gentamicin were found to be noncytotoxic for human fibroblasts, while bupivacaine and clindamycin were found to have some effect on cell growth. In conclusion, our new drug‐loaded soy‐protein films combine good mechanical properties and biocompatibility, with desired drug release profiles, and can therefore be potentially very useful as burn and ulcer dressings.     

Nanoscopic Porous Iridium/Iridium Dioxide Superstructures (15 nm): Synthesis and Thermal Conversion by In Situ Transmission Electron Microscopy

Porous particle superstructures of about 15 nm diameter, consisting of ultrasmall nanoparticles of iridium and iridium dioxide, are prepared through the reduction of sodium hexachloridoiridate(+IV) with sodium citrate/sodium borohydride in water. The water-dispersible porous particles contain about 20 wt % poly(N-vinylpyrrolidone) (PVP), which was added for colloidal stabilization. High-resolution transmission electron microscopy confirms the presence of both iridium and iridium dioxide primary particles (1–2 nm) in each porous superstructure. The internal porosity (≈58 vol%) is demonstrated by electron tomography. In situ transmission electron microscopy up to 1000 °C under oxygen, nitrogen, argon/hydrogen (all at 1 bar), and vacuum shows that the porous particles undergo sintering and subsequent compaction upon heating, a process that starts at around 250 °C and is completed at around 800 °C. Finally, well-crystalline iridium dioxide is obtained under all four environments. The catalytic activity of the as-prepared porous superstructures in electrochemical water splitting (oxygen evolution reaction; OER) is reduced considerably upon heating owing to sintering of the pores and loss of internal surface area.     

Thermal and chemical stability of diphenylalanine peptide nanotubes: implications for nanotechnological applications

The diphenylalanine peptide, the core recognition motif of the beta-amyloid polypeptide, efficiently self-assembles into discrete, well-ordered nanotubes. Here, we describe the notable thermal and chemical stability of these tubular structures both in aqueous solution and under dry conditions. Scanning and transmission electron microscopy (SEM and TEM) as well as atomic force microscopy (AFM) revealed the stability of the nanotubes in aqueous solution at temperatures above the boiling point of water upon autoclave treatment. The nanotubes preserved their secondary structure at temperatures up to 90 degrees C, as shown by circular dichroism (CD) spectra. Cold field emission gun (CFEG) high-resolution scanning electron microscope (HRSEM) and thermogravimetric analysis (TGA) of the peptide nanotubes after dry heat revealed durability at higher temperature. It was shown that the thermal stability of diphenylalanine peptide nanotubes is significantly higher than that of a nonassembling dipeptide, dialanine. In addition to thermal stability, the peptide nanotubes were chemically stable in organic solvents such as ethanol, methanol, 2-propanol, acetone, and acetonitrile, as shown by SEM analysis. Moreover, the acetone environment enabled AFM imaging of the nanotubes in solution. The significant thermal and chemical stability of the peptide nanotubes demonstrated here points toward their possible use in conventional microelectronic and microelectromechanics processes and fabrication into functional nanotechnological devices.     

Parking garages with optimal dynamics

We construct generalized polygons (??parking garages??) in which the billiard flow satisfies the Veech dichotomy, although the associated translation surface obtained from the Zemlyakov?CKatok unfolding is not a lattice surface. We also explain the difficulties in constructing a genuine polygon with these properties.     

The Facile Deposition of Pt Nanoparticles on Reduced Graphite Oxide in Tunable Aryl Alkyl Ionic Liquids for ORR Catalysts

In this study, we present the facile formation of platinum nanoparticles (Pt-NPs) on reduced graphite oxide (rGO) (Pt-NP@rGO) by microwave-induced heating of the organometallic precursor ((MeCp)PtMe₃ in different tunable aryl alkyl ionic liquids (TAAIL). In the absence of rGO, transmission electron microscopy (TEM) reveals the formation of dense aggregates of Pt-NPs, with primary particle sizes of 2 to 6 nm. In contrast, in the Pt-NP@rGO samples, Pt-NPs are homogeneously distributed on the rGO, without any aggregation. Pt-NP@rGO samples are used as electrode materials for oxygen reduction reaction (ORR), which was assessed by cyclic voltammetry (CV) and linear sweep voltammetry (LSV). The electrochemical surface area (ECSA) and mass-specific activity (MA) increase up to twofold, compared with standard Pt/C 60%, making Pt-NP@rGO a competitive material for ORR.     

Plant-Based Seafood Analogs

There is a growing global need to shift from animal- towards plant-based diets. The main motivations are environmental/sustainability-, human health- and animal welfare concerns. The aim is to replace traditional animal-based food with various alternatives, predominantly plant-based analogs. The elevated consumption of fish and seafood, leads to negative impacts on the ecosystem, due to dwindling biodiversity, environmental damage and fish diseases related to large-scale marine farming, and increased intake of toxic substances, particularly heavy metals, which accumulate in fish due to water pollution. While these facts lead to increased awareness and rising dietary shifts towards vegetarian and vegan lifestyles, still the majority of seafood consumers seek traditional products. This encourages the development of plant-based analogs for fish and seafood, mimicking the texture and sensorial properties of fish-meat, seafood, or processed fish products. Mimicking the internal structure and texture of fish or seafood requires simulating their nanometric fibrous-gel structure. Common techniques of structuring plant-based proteins into such textures include hydrospinning, electrospinning, extrusion, and 3D printing. The conditions required in each technique, the physicochemical and functional properties of the proteins, along with the use of other non-protein functional ingredients are reviewed. Trends and possible future developments are discussed.     

Enzyme-Driven,Switchable Catalysis Based on Dynamic Self-Assembly of Peptides

Covalent regulatory systems of enzymes are widely used to modulate biological enzyme activities. Inspired by the regulation of reactive-site phosphorylation in organisms, we developed peptide-based catecholase mimetics with switchable catalytic activity and high selectivity through the co-assembly of nanofibers comprising peptides and copper ions (Cu²⁺). Through careful design and modification of the peptide backbone structure based on the change in the free energy of the system, we identified the peptide with the most effective reversible catalytic activity. Kinase/phosphatase switches were used to control the reversible transition of nanofiber formation and depolymerization, as well as to modulate the active-site microenvironment. Notably, the self-assembly and disassembly processes of nanofibers were simulated using coarse-grained molecular dynamics. Furthermore, theoretical calculations confirmed the coordination of the peptide and Cu²⁺, forming a zipper-like four-ligand structure at the catalytically active center of the nanofibers. Additionally, we conducted a comprehensive analysis of the catalytic mechanism. This study opens novel avenues for designing biomimetic enzymes with ordered structures and dynamic catalytic activities.     

Simulation of novel soy protein‐based systems for tissue regeneration applications

In the present research, molecular modeling methods were used to study novel porous soy protein conjugates with gelatin or alginate, which were recently developed as potential scaffolds for tissue engineering applications. Gelatin (protein) and alginate (polysaccharides) were chemically crosslinked to soy protein isolates (SPI) in order to obtain a porous 3D network. Computational tools were applied to estimate the crosslinking degree and compare the degradation rate of soy–gelatin or soy–alginate conjugates. Soy protein 3D structure was obtained from the Protein Data Bank (PDB). Alginate and gelatin structures were built and subjected to dynamic simulation using the molecular modeling package Material Studio 7.0. The crosslinking degree was estimated by the miscibility of the two reactants and the interaction with the crosslinking agents 1‐ethyl‐3‐(3‐dimethylaminopropyl) carbodiimide (EDC) or glyoxal. The calculations revealed that soy protein mixes well with gelatin but not with alginate. Radial distribution function (RDF) calculations showed that the interaction distance between alginate and EDC is significantly shorter than between gelatin and EDC, probably because of ionic attraction between the ammonium groups of EDC and the carboxylate groups in alginate, which facilitates the crosslinking reaction. The degradation rate of soy protein conjugates was related to their interaction with water. It was found that the solubility of soy–gelatin in water is higher than soy–alginate and that water molecules form more hydrogen bonds with soy–gelatin than with soy–alginate. These findings might be the reason for the observed difference in degradation rate of the two conjugates; the soy–gelatin degrades faster than soy–alginate. Copyright © 2016 John Wiley & Sons, Ltd.