One-pot process: Microwave-assisted keratin extraction and direct electrospinning to obtain keratin-based bioplastic

Poultry feathers are among the most abundant and polluting keratin-rich waste bio-masses. In this work, we developed a one-pot microwave-assisted process for eco-friendly keratin extraction from poultry feathers followed by a direct electrospinning (ES) of the raw extract, without further purification, to obtain keratin-based bioplastics. This microwave-assisted keratin extraction (MAE) was conducted in acetic acid 70% v/v. The effects of extraction time, solvent/feathers ratio, and heating mode (MAE vs conventional heating) on the extraction yield were investigated. The highest keratin yield (26 ± 1% w/w with respect to initial feathers) was obtained after 5 h of MAE. Waste-derived keratin were blended with gelatin to fabricate keratin-based biodegradable and bio-compatible bioplastics via ES, using 3-(Glycidyloxypropyl)trimethoxysilane (GPTMS) as a cross-linking agent. A full characterization of their thermal, mechanical, and barrier properties was performed by differential scanning calorimetry, thermogravimetric analysis, uniaxial tensile tests, and water permeability measurements. Their morphology and protein structure were investigated using scanning electron microscopy and attenuated total reflection-infrared spectroscopy. All these characterizations highlighted that the properties of the keratin-based bioplastics can be modulated by changing keratin and GPTMS concentrations. These bioplastics could be applied in areas such as bio-packaging and filtration/purification membranes

Study of retention, efficiency and selectivity in Chiral Ligand-Exchange Chromatography with a dynamically coated stationary phase

A Bakerbond ODS column was dynamically coated with the chiral selector N-decyl-L-histidine, and then loaded with copper(II) ions. A number of racemic mixtures of underivatized amino acids were resolved on such a column via Chiral Ligand-Exchange Chromatography. The most important experimental parameters influencing column efficiency, retention and selectivity (eluent flow rate, analyte concentration, temperature and mobile phase composition) were exten-sively investigated. Results are discussed in light of CLEC theory and thermodynamic data on mod-el systems in aqueous solution. The most likely structures for the stationary ternary complex are suggested

HPTLC separation of aromatic a-amino acid enantiomers on a new histidine-based stationary phase using ligand-exchange

A new chiral ligand exchange selector for hydrophobic stationary phase modification has been synthesized by selective alkylation of L-histidine at the pyrrolic nitrogen atom in its imidazolic ring. Its performance was then tested on RP-HPTLC plates treated with copper acetate. Significant selectivity towards aromatic amino acid enantiomers, was observed. Chromatographic retention data were compared to available thermodynamic complex formation parameters for the relevant model systems in aqueous solution. Stationary and mobile phase effects on retention were studied by using different RP-HPTLC plates and various binary aqueous solvent mixtures. Optimized separation conditions for aromatic amino acid sample class are given

HPTLC Separation of Aromatic a-Amino-Acid Enantiomers on a New Histidine-Based Stationary Phase Using Ligand Exchange

A new chiral ligand exchange selector for hydrophobic stationary phase modification has been synthesized by selective alkylation of L-histidine at the pyrrolic nitrogen atom in its imidazolic ring. Its performance was then tested on RP-HPTLC plates treated with copper acetate. Significant selectivity towards aromatic amino acid enantiomers, was observed. Chromatographic retention data were compared to available thermodynamic complex formation parameters for the relevant model systems in aqueous solution. Stationary and mobile phase effects on retention were studied by using different RP-HPTLC plates and various binary aqueous solvent mixtures. Optimized separation conditions for aromatic amino acid sample class are given

Binary and ternary Cu(II) complexes of L-spinacine in aqueous solution

Complexation of L-spinacine with the Cu(II) ion in aqueous solution, even in the presence of L/D-phenylalanine, L/D-tryptophane or L/D-histidine, is thoroughly investigated by means of potentiometry and UV-VIS spectrophotometry. The synthesis of L-spinacine by reaction of L-histidine with formaldehyde is also described in detail

Synthesis of glycil-L-spinacine and study of its protonation and Cu(II) complex-formation equilibria, in aqueous solution

A new dipeptide, glycil-L-spinacine, has been synthesised and fully characterised. Protonation constants have been determined and binary Cu(II) complex formation equilibria investigated in an aqueous solution (25 °C, I = 0.1 mol dm-3, KNO3) using the potentiometric and spectrophotometric techniques. Mononuclear and binuclear complex species have been found to form. Binding sites and structure hypotheses are discussed on the basis of available experimental and literature data

Synthesis of spinacine and spinacine derivatives: crystal and molecular structures of N-pi-hydroxymethyl spinacine and N-alpha-methyl spinaceamine

The natural amino acid L-Spinacine (4,5,6,7-tetrahydro-IH-imidazo[4,5-c]pyridine-6-carboxylic acid) has been synthesized following a new pathway which gives a chemically and optically pure product with an excellent yield. The crystal structures of a synthetic intermediate, N-hydroxymethyl-spinacine, and a spinacine derivative, N-methyl-spinaceamine, have been investigated through X-ray diffraction. Spi(MeOH) crystallizes with a water molecule and displays a zwitterionic character. The carboxylate group is in equatorial position and forms a short electrostatic interaction of 2.618(2) A, between one of its oxygens and the protonated nitrogen of the tetrahydropyridine ring. The crystal packing is assured by strong O-H- - -O, O-H-- -N, N-H- - -N intermolecular hydrogen bonds and C-H---O close contacts. The biprotonated compounds Spm(alpha-Me) crystallizes with two Cl- anions and a water molecule. The positive charge on the imidazole ring is delocalized on the conjugated moiety N=C-N. The crystal is built up by clusters formed by two biprotonated Spm(aMe) molecules, tour Cl- anions and two water molecules linked together by hydrogen bonds

Enthalpies of dilution of bifunctional alcohols in concentrated aqueous solutions of urea at 298.15 K

none5The enthalpies of dilution of aliphatic bifunctional alcohols were measured in 7 m urea aqueous solutions at 298.15 K by flow microcalorimetry. The excess enthalpies were expressed as a power expansion series in the molality of the alcohol, referred to 1 kg of the mixed urea-water solvent. The values of the second and the third coefficients were all found to be positive and lower than the corresponding values in water. They show an approximately linear dependence on the square of the number of methylene groups. This fact suggests that in the presence of a large amount of urea excess enthalpies are determined primarily by methylene-methylene interactions. This is quite surprising and of remarkable interest on account of its obvious biological implications, since a kind of “lipophobic” or some modified hydrophobic effect seems still to be effective in concentrated urea solutions.noneG. BARONE; G. BORGHESANI; C. GIANCOLA; F. PULIDORI; M. REMELLIG., Barone; G., Borghesani; C., Giancola; F., Pulidori; Remelli, Maurizi