Silvia Tozzi

On the antibacterial activity of roots of Capparis spinosa L.

A decoction of Capparis spinosa L. roots, widely used in the traditional folk medicine of southern Italy, was prepared and submitted to antibacterial activity tests, which showed an interesting bacteriostatic activity on the growth of Deinococcus radiophilus. Heterocyclic compounds were also recovered from the chloroformic extract of the roots.

Interaction between gliadins and anthocyan derivatives

The interaction of gliadins with some anthocyanins (e.g. myrtillin, malvin, keracyanin, callistephin) and anthocyanidins (e.g. delphinidin, pelargonidin, cyanidin) has been analysed in aqueous solution at pH condition of the stomach, in which these compounds are initially metabolized. NMR, FT-IR and UV-Vis spectroscopic methods have been employed to determine the anthocyanin binding mode. The spectroscopic data seem to indicate that anthocyans are located along the polypeptide chains of gliadins in a generical molecular interaction between the two moieties. Our data do not exclude that hydrogen bonding interaction too is operating. Anthocyan-gliadins complexes are very soluble in acidic conditions. The results provide new insights into anthocyan-protein interaction and may have relevance to human health.

Intermolecular interactions between B. mori silk fibroin and poly(l-lactic acid) in electrospun composite nanofibrous scaffolds

In this study, composite nanofibrous scaffolds were obtained by electrospinning a trifluoroacetic acid solution containing B. mori silk fibroin (SF) and poly(l-lactic acid) (PLLA) in a 1:1 weight ratio. SF, PLLA and SF/PLLA nanofibres were prepared with average diameter sizes of 360±90nm, 470±240nm and 580±220nm, respectively, as assessed by SEM analysis. Vibrational and thermal analyses showed that upon blending in the SF/PLLA nanofibres, the crystallisation of PLLA was hindered by the presence of SF, which crystallized preferentially and underwent conformational changes that did not significantly change its prevailing β-sheet structure. The two components were thermodynamically compatible and the intermolecular interactions between them were revealed for the first time. Human keratinocytes were cultured on nanofibres and their viability and proliferation were determined. Preliminary in vitro tests showed that the incorporation of SF into the PLLA component enhanced cell adhesion and proliferation with respect to the unfunctionalised material. SF has been successfully used to modify the biomaterial properties and confirmed to be an efficient bioactive protein to mediate cell-biomaterial interaction.

Study on the interaction between gliadins and a coumarin as molecular model system of the gliadins-anthocyanidins complexes.

To clarify the conformational changes of gliadins (Glia) upon complexation with anthocyanidins (in particular cyanidin, Cya), the interaction of Glia with a coumarin derivative (3-ethoxycarbonylcoumarin, 3-EcC), having a benzocondensed structure similar to that of Cya, has been investigated by NMR, IR, and Raman spectroscopy under acidic and neutral conditions. Raman spectra showed that both molecules produce a similar effect on the Glia structure, i.e. an increase in the α-helix conformation and a decrease in β-sheet and β-turns content. In the presence of both molecules, this effect is more marked; the spectroscopic results showed that both Cya and 3-EcC interact with Glia and 3-EcC favors the complex formation with Glia. The results obtained in this study provide new insights into anthocyanidins-Glia interactions and may have relevance to human health, in the field of the attempts to modify gluten proteins to decrease allergen immunoreactivity.

Ring Closure of Azo Compounds to 1,2-Annulated Benzimidazole Derivatives and Further Evidence of Reversibility of the Azo-Coupling Reaction

The reaction between 1,3,5-tris(N,N-dialkylamino)benzene derivatives and 2 equiv of p-substituted benzenediazonium salts gives dicationic species which collapse to new benzimidazole derivatives with expulsion of p-substituted anilines. The presence of electron-withdrawing groups on the benzenediazo moiety of the dicationic species plays a key role in this unexpected ring closure reaction. The observed chemical behavior has been rationalized in terms of the already reported reversibility of azo coupling reactions and provided further evidence for it.

Combined effect of the body mass index and implant size on the wear of retrieved total knee prostheses

Total Knee Arthroplasty is a well-established surgical procedure performed to relieve pain and to restore function in knee osteoarthritis. A proper choice of the implant size is mandatory in order to guarantee the success of the implant and to respect the bone stock of tibial plateau and femoral condyles. The aim of this study was to investigate the combined effect of Body Mass Index and implant size on the wear damage of retrieved knee implants, a still debated subject. To this purpose, twelve total knee prostheses of the same design (NexGen, Zimmer, Warsaw, Indiana) but with different sizes were investigated. These prostheses were all cemented fixed bearing inserts and posterior stabilised. Roughness analyses were performed on femoral components to assess surface modifications. Micro-Raman spectroscopic characterization was performed on polyethylene inserts to evaluate crystallinity changes. A worsening of the surface and a nonhomogeneous aspect was observed in the prostheses characterized by a high ratio between preoperative Body Mass Index and implant size, which we called Ф factor. Delamination, a good indicator for polyethylene osteolysis, was more pronounced in the inserts having a high Ф than in those with a low Ф. Micro-Raman analyses showed more significant crystallinity changes in the prostheses of lower size, in agreement with the results previously obtained in vitro. The findings of the present study suggested that the Ф factor can be considered a predictor factor of the Total Knee Arthroplasty overall performance. Potentially, it could be used as a discriminating factor to redact Total Knee Arthroplasty outcome and prevent complications.

May the surface roughness of the retrieved femoral head influence the wear behavior of the polyethylene liner

This study was aimed at determining the surface degradation occurred on retrieved ceramic and metallic heads, as well as the influence of the head surface quality on the wear of the polyethylene counterface. To this purpose, 14 ceramic and 14 metallic femoral heads retrieved at revision surgery were examined. Scanning electron microscopic analysis provided visual evidence that some metallic heads presented crescent wear more often than the ceramic ones; the former showed a higher volumetric loss (as determined by Coordinate Measuring Machine) than the latter, but less negative Rsk values. This apparent lack of correlation between volumetric loss (i.e., wear factor) and roughness data may be explained by considering that they are two temporally variant parameters. No significant differences were observed between the Ra values of the two sets of femoral heads. The cups articulating against metal heads were characterized by higher mean wear volumes than those articulating against alumina although this difference was not statistically significant; metal heads displayed significantly higher mean wear volumes than alumina heads. The micro-Raman analysis of the cup articulated against the most worn alumina femoral head showed an orthorhombic into monoclinic phase transformation that was not observed in the cups coupled to metal heads. The obtained results showed that the surface finishing of the femoral head (in terms of Rsk values) determined the morphological changes experienced by the ultra-high-molecular-weight polyethylene crystalline phase at the molecular level.

Structural study on methacrylamide-grafted Tussah silk fibroin fibres

Tussah silk fibroin fibres were modified by grafting with methacrylamide (MAA), with weight gains ranging between 2.6% and 71.4%. Raman and IR spectroscopic analyses showed that upon grafting the fibres underwent slight conformational changes towards a more unordered state, due to the covalent and hydrogen bonds interactions occurring between the polymer (polyMAA) and the amorphous domains of silk fibres. To test the stability towards alkaline hydrolysis, the untreated and MAA-grafted silk fibres (weight gain of 71.4%) were immersed in NaOH 5% at 50°C for different times; the IR and Raman spectroscopic techniques were utilized to elucidate the degradation mechanism as well as the rearrangements of the fibres induced by the treatment. Upon hydrolysis, both the untreated and grafted fibres underwent an enrichment in β-sheet conformation, due to the preferential removal of the unordered domains. As a result of the covalent interactions with silk fibroin, the polymer increased its stability towards alkaline hydrolysis, since its complete solubilization was avoided and the transformation of its CONH2 groups into COO(-) and COOH was delayed. Vibrational spectroscopy proved to be a valid technique to investigate the mechanism and the effects of the hydrolytic attack, which are both fundamental to design new-generation silk-based materials.