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Purpose Biochar production from biowastes (e.g. digestate) is currently one of the more innovative and unexplored fields of research. A complete characterization of these materials, also according to the production temperature, would be a key tool to assess their potential use as soil amendments. Material and methods For this purpose, five feedstocks (sewage sludge, municipal organic waste, cattle manure and silage digestates, poultry litter and vineyard pruning residues) were pyrolyzed at different temperatures. Structural and morphological transformations of biomasses during heating were followed by using FT-IR, scanning electron microscopy (SEM) and hyperspectral enhanced dark-field microscopy, a novel technique that provides both spectral and spatial information in one measurement. In addition, biochar microstructure (i.e. surface area and pore size distribution) using CO 2 and N 2 adsorption isotherms was investigated. Specific density was also analysed by a helium pycnometer. Results and discussion Biochars exhibited considerable chemical, structural and morphological differences depending on temperature and feedstock type. Moreover, specific density and surface area increased with the temperature. In particular, heating was able to produce a sharp increase of mesopore and micropore volume especially at 450 and 550 °C, but with different intensities for each feedstock. Thanks to the hyperspectral analysis, distinctive spectral patterns depending on the biochar chemical composition as well as the spatial distribution of the components were found. Conclusions The results demonstrated that, from a physical–chemical point of view, it is not possible to identify an “ideal” biochar able to improve both soil nutrient content and structure. On the contrary, depending on feedstocks and temperature, each biochar exhibits specific features that would make it suitable for a specific purpose.

In recent years there has been a growing interest in the use of proteins as biocompatible and environmentally friendly biomolecules for the design of wound healing and drug delivery systems. Keratin is a fascinating protein, obtainable from several keratinous biomasses such as wool, hair or nails, with intrinsic bioactive properties including stimulatory effects on wound repair and excellent carrier capability. In this work keratin/poly(butylene succinate) blend solutions with functional properties tunable by manipulating the polymer blending ratios were prepared by using 1,1,1,3,3,3-hexafluoroisopropanol as common solvent. Afterwards, these solutions doped with rhodamine B (RhB), were electrospun into blend mats and the drug release mechanism and kinetics as a function of blend composition was studied, in order to understand the potential of such membranes as drug delivery systems. The electrophoresis analysis carried out on keratin revealed that the solvent used does not degrade the protein. Moreover, all the blend solutions showed a non-Newtonian behavior, among which the Keratin/PBS 70/30 and 30/70 ones showed an amplified orientation ability of the polymer chains when subjected to a shear stress. Therefore, the resulting nanofibers showed thinner mean diameters and narrower diameter distributions compared to the Keratin/PBS 50/50 blend solution. The thermal stability and the mechanical properties of the blend electrospun mats improved by increasing the PBS content. Finally, the RhB release rate increased by increasing the keratin content of the mats and the drug diffused as drug-protein complex.

In this work, keratin sponges were prepared by freeze-drying method and tested for adsorption of Azure A and Methyl Orange dyes. The obtained materials showed a porosity of 99.92% and a mean pore size dimension of about 91 μm. The use of oxidized sucrose with a heating treatment at 150°C was demonstrated to be a useful crosslinking procedure alternative to the conventional glutaraldehyde. Keratin sponges showed a maximum adsorption capacity of 0.063 and of 0.037 mmol/g for Azure A and Methyl Orange, respectively. The absorption of the cationic dye Azure A onto keratin sponges was better described by Freundlich model while the isotherm adsorption of the anionic Methyl Orange was found to correlate with both Langmuir and Freundlich models. The mean free energies evaluated by using the D-R model indicated a physisorption of Methyl Orange and a chemisorptions of Azure A onto keratin sponges. Finally, the functionalization of keratin sponges with Zn Al hydrotalcites nanoparticles did not affect the adsorption performances of the adsorbent toward the cationic dye Azure A, while it improved those toward the anionic Methyl Orange, increasing the related removal efficiencies from 43 to 96%. Collectively, the reported data indicates that the combination of keratin with hydrotalcites nanoparticles is a good strategy to obtain more functional adsorbent materials of potential interest for water treatment and purification.

The surface-enhanced Raman scattering (SERS) spectra of three amphiphilic oligopeptides derived from EAK16 (AEAEAKAK)2 were examined to study systematic amino acid substitution effects on the corresponding interaction with Ag colloidal nanoparticles. Such self-assembling molecular systems, known as “molecular Lego”, are of particular interest for their uses in tissue engineering and as biomimetic coatings for medical devices because they can form insoluble macroscopic membranes under physiological conditions. Spectra were collected for both native and gamma-irradiated samples. Quantum mechanical data on two of the examined oligopeptides were also obtained to clarify the assignment of the prominent significative bands observed in the spectra. In general, the peptide–nanoparticles interaction occurs through the COO− groups, with the amide bond and the aliphatic chain close to the colloid surface. After gamma irradiation, mimicking a free oxidative radical attack, the SERS spectra of the biomaterials show that COO− groups still provide the main peptide–nanoparticle interactions. However, the spatial arrangement of the peptides is different, exhibiting a systematic decrease in the distance between aliphatic chains and colloid nanoparticles.

Substance P (SP) is one of the most studied peptide hormones and knowing the relationship between its structure and function may have important therapeutic applications in the treatment of a variety of stress-related illnesses. In order to obtain a deeper insight into its folding, the effects of different factors, such as pH changes, the presence of Ca2+ ions, and the substitution of the Met-NH2 moiety in the SP structure, was studied by Raman and infrared spectroscopies. SP has a pH-dependent structure. Under acidic–neutral conditions, SP possesses a prevalent β-sheet structure although also other secondary structure elements are present. By increasing pH, a higher orderliness in the SP secondary structure is induced, as well as the formation of strongly bound intermolecular β-strands with a parallel alignment, which favour the self-assembly of SP in β-aggregates. The substitution of the Met-NH2 moiety with the acidic functional group in the SP sequence, giving rise to a not biologically active SP analogue, results in a more disordered folding, where the predominant contribution comes from a random coil. Conversely, the presence of Ca2+ ions affects slightly but sensitively the folding of the polypeptide chain, by favouring the α-helical content and a different alignment of β-strands; these are structural elements, which may favour the SP biological activity. In addition, the capability of SERS spectroscopy to detect SP in its biologically active form was also tested by using different metal nanoparticles. Thanks to the use of silver NPs prepared by reduction of silver nitrate with hydroxylamine hydrochloride, SP can be detected at very low peptide concentration (~ 90 nM). However, the SERS spectra cannot be obtained under alkaline conditions since both the formation of SP aggregates and the lack of ion pairs do not allow a strong enough interaction of SP with silver NPs.

Model systems constituted by proteins and unsaturated lipid vesicles were used to gain more insight into the effects of the propagation of an initial radical damage on protein to the lipid compartment. The latter is based on liposome technology and allows measuring the trans unsaturated fatty acid content as a result of free radical stress on proteins. Two kinds of sulfur-containing proteins were chosen to connect their chemical reactivity with membrane lipid transformation, serum albumins and metallothioneins. Biomimetic systems based on radiation chemistry were used to mimic the protein exposure to different kinds of free radical stress and Raman spectroscopy to shed light on protein structural changes caused by the free radical attack. Among the amino acid residues, Cys is one of the most sensitive residues towards the attack of free radicals, thus suggesting that metal-Cys clusters are good interceptors of reactive species in metallothioneins, together with disulfides moieties in serum albumins. Met is another important site of the attack, in particular under reductive conditions. Tyr and Phe are sensitive to radical stress too, leading to electron transfer reactions or radical-induced modifications of their structures. Finally, modifications in protein folding take place depending on reactive species attacking the protein.

The effects of a high energy sterilization treatment on poly-ε-caprolactone/carbonated hydroxyapatite composites have been investigated. Poly-ε-caprolactone is a biodegradable polymer used as long-term bioresorbable scaffold for bone tissue engineering and carbonated hydroxyapatite is a bioactive material able to promote bone growth. The composites were gamma-irradiated in air or under nitrogen atmosphere with doses ranging from 10 to 50 kGy (i.e. to a value higher than that recommended for sterilization). The effects of the irradiation treatment were evaluated by vibrational spectroscopy (IR and Raman spectroscopies) coupled to thermal analysis (Differential Scanning Calorimetry and Thermogravimetry) and Electron Paramagnetic Resonance spectroscopy. Irradiation with the doses required for sterilization induced acceptable structural changes and damaging effects: only a very slight fragmentation of the polymeric chains and some defects in the inorganic component were observed. Moreover, the radiation sensitivity of the composites proved almost the same under the two different atmospheres.

Self-assembling peptides are a category of peptides which undergo spontaneous assembling into ordered nanostructures. These designed peptides have attracted huge interest in the field of nanotechnology for its potential application in areas such as biomedical nanotechnology, cell culturing, molecular electronics, and more. In the emerging field of tissue engineering, the development of synthetic materials promoting cell growth has led to the study of regularly alternating polar/non-polar amphiphilic oligopeptides, such as EAK16 (AEAEAKAK)^sub 2^, also called LEGO peptides, which have been considered particularly promising. Self-assembling LEGO peptides have a preferential b-sheet structure, are resistant to proteolytic cleavage, and are able to form an insoluble macroscopic membrane under physiological conditions. Their ability to create such stable structures derive from the hydrophobic interactions between the aliphatic groups of non-ionic residues and the complementary ionic bonds between acidic and basic amino acids. This stability can be enhanced by the pH regulation and the presence of monovalent ions. This chapter will be focused on some approaches useful for elucidating the influence of the sequence modifications and the interactions with a surface on the self-assembly capability of differently synthesised peptides. Eight different oligopeptides (from 16 to 19 residues), derived from EAK16, have been analysed by IR and Raman spectroscopies that are particularly useful for obtaining qualitative and quantitative information on the secondary structure of these peptides. Several modifications in the primary structure of peptides have been considered, namely acidic and/or basic substitutions (Glu [arrow right] Asp; Lys [arrow right] Orn), changes in the length of the aliphatic side chain of the spacer residues (Ala [arrow right] Abu or Ala [arrow right] Tyr), the addition of RGD (known to promote osteoblast adhesion), or scrambling of the sequence. As these peptides are widely used as biocompatible coatings of metallic implants, the peptide folding after adsorption on different surfaces, in particular on titanium oxide, will be also discussed. Finally, it will be shown that not all the oligopeptides examined can self-assemble into a homogeneous multilayer on metallic surfaces; however, most of the peptides take a prevailing b-sheet structure which guarantees the best peptide-surface interaction. In particular, the interactions of polar, ionic and aromatic residues with surfaces will be discussed more in detail.