1,721,100 research outputs found
Adsorption of bovine serum albumin onto synthetic Fe-doped geomimetic chrysotile
No full textSynthetic stoichiometric and Fe-doped geomimetic chrysotile nanocrystals represent a reference standard to investigate the health hazard associated with mineral asbestos fibres. Experimental evidence suggests that the generation of reactive oxygen species and other radicals, catalysed by iron ions at the fibre surface, plays an important role in asbestos-induced cytotoxicity and genotoxicity. In this study, structural modification of bovine serum albumin (BSA) adsorbed onto synthetic chrysotile doped with different amounts of Fe has been investigated by Fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analysis (TGA) and analytical pyrolysis coupled with gas chromatography-mass spectrometry. FT-IR data evidenced a marked increase in disordered structures like random coil and β-turn of BSA-nanocrystal adduct with 0.52 wt% of Fe doped. The TGA profile of the BSA revealed that its interaction with the synthetic chrysotile surface was strongly affected by the substitution of Fe into the chrysotile structure. The 2,5-diketopiperazine yields, formed upon thermal degradation of the polypeptide chain ( pyrolysis-gas chromatography), changed when the BSA was adsorbed on the nanofibres. In general, results suggested that minute amount (less than 1 wt%) of Fe doping in chrysotile affected the protein-nanofibre interactions, supporting the role that this element may play in asbestos toxicity. The catalytic role of iron and the consequent unfolding of protein due to the structural surface modification of nanofibres were also evaluated
Biologically inspired synthesis of nanocomposites for bone tissue regeneration
No full textRecently the replacement of bone tissue by graft materials and products of tissue engineering with composition, structure and biological features very similar to natural tissue is the main topic of research in biomaterials. A biomimetic synthesis has been performed to prepare new bone like composites constituted of hydroxyapatite nanocrystals and self-assembled type 1 collagen fibers. We have used a biological inspired approach which proves that the biological systems store and process information at the molecular level. Direct nucleation of hydroxyapatite (HA) into reconstituted collagen fibers during their assembling was employed. The new preparation technique was experimented then the composites thoroughly characterized and compared : composites showed an intimated interaction of the inorganic and proteic components which modified the apatitic phase and made its composition, morphology and structure similar to the mineral component of natural bone
PROCESSO PER IL TRATTAMENTO DI UN MATERIALE CONTENENTE AMIANTO
No full textIl brevetto descrive il processo biotecnologico in grado di denaturare le fibre di amianto presenti in manufatti cementizi, utilizzando siero di latte esausto
Simultaneous refinement of structure and microstructure of layered materials
No full textThe recursive description of stacking in layered crystals, originally developed by Treacy et al. [Proc. R. Soc. London Ser. A (1991), 433, 499-520] and implemented in the DIFFaX code, is enclosed in a non-linear least-squares minimization routine and combined with additional models (of specimen-related broadening and instrumental broadening) to allow the simultaneous refinement of both structural and microstructural parameters of a layered crystal. This implementation is named DIFFaX+. As examples, the refinements both of a simulated pattern of diamond, showing fault clustering, and of the observed powder pattern of a synthetic stoichiometric nanocrystalline chrysotile are reported
ELETTRODEPOSIZIONE DI IDROSSIAPATITE NANOMETRICA SU IMPIANTI PROTESICI E PROCESSO ELETTROLITICO PER LA SUA REALIZZAZIONE
No full textLa presente invenzione riguarda un processo per
rivestire una superficie di un elemento metallico con un
coating a base di idrossiapatite biomimetica e
nanometrica, che comprende i seguenti passaggi:
a) predisporre un bagno elettrolitico comprendente
almeno ioni calcio e ioni fosfato ad una temperatura
compresa tra 5°C e 40°C; b) immergere in detto bagno elettrolitico almeno un catodo ed almeno un anodo, detto almeno un catodo
comprendendo l'elemento metallico da rivestire; c) far passare corrente elettrica continua attraverso detto bagno elettrolitico così da ottenere su detta superficie una deposizione elettrolitica di un composto calcio-fosfato comprendente cristalli nanometrici di
idrossiapatite; d) sottoporre l’elemento metallico rivestito del
composto calcio-fosfato ad un trattamento termico ad una
temperatura compresa tra 70°C e 800°C.
Tale processo consente di ottenere un dispositivo protesico ricoperto con un rivestimento a base di idrossiapatite che aderisce perfettamente alla superficie della protesi e ne permette una completa osteointegrazione.
Metalated nucleotide chemisorption on hydroxyapatite
No full textThe experiments here reported evidence on the importance of the residual charge of a nucleotide derivative, for the adsorption on nHAP (hydroxyapatite nanocrystals), in water solution.We found that the simple presence of phosphates on the nucleotide derivative does not guarantee adsorption on nHAP. On the other hand, we demonstrated that a cationic or neutral charge on a nucleotide derivative produces a strongly reduced chemical adsorption (chemisorption) whereas, in the presence of a net negative charge, relevant adsorption on nHAP is observed. The number of phosphates can only modulate the adsorption efficiency of a molecule provided that this latter bears an overall negative charge. The neutral zwitterionic nucleotide Pt(II) complexes, bearing negatively charged phosphates, are unable to give stable chemisorption. Previous considerations are important to model the binding ability of phosphate bearing nucleotide derivatives or molecules on hydroxyapatite. The findings reported in the present paper could be relevant in bone tissue targeting or nHAP mediated drug delivery
Hydroxyapatite nanocrystals as a smart, pH sensitive, delivery system for kiteplatin
Full text linkHydroxyapatite (HA) nanocrystals are important inorganic constituents of biological hard tissues in vertebrates and have been proposed as a bone substitute or a coating material for prostheses in biomedicine. Hydroxyapatite is also amenable for its capacity to bind to a great variety of biomolecules and therapeutic agents. As drug carriers, apatite nanoparticles also have the advantage of pH dependent solubility and low toxicity. Thus HA nanoparticles are negligibly soluble at physiological pH but their dissolution is accelerated at lower pH such as that typically found in the vicinity of tumors. In the present study we have investigated the adsorption on and the release from biomimetic HA nanoparticles of two platinum derivatives of cis-1,4-diaminocyclohexane ([PtX2(cis-1,4-DACH)], X2 = Cl2 (1) and 1,1-cyclobutanedicarboxylate (CBDCA, 2)). The first of the two compounds proved to be active against colon cancer cells also resistant to oxaliplatin. The release has been investigated as a function of pH to mimic the different physiological environments of healthy tissues and tumors, and the in vitro cytotoxicity of the releasates from the HA matrices has been assessed against various human cancer cell lines. The results fully confirmed the potential of 1-loaded HA nanoparticles as bone-specific drug delivery devices
MULTISTRATO A BASE DI CELLULOSA E SUOI DERIVATI
No full textMateriale multistrato che comprende un supporto cartaceo su cui è applicato almeno uno strato di cellulosa rigenerata, in cui l'accoppiamento tra supporto cartaceo e strato di cellulosa rigenerata è realizzato tramite un adesivo a base acquosa e lo strato di cellulosa
rigenerata comprende come rivestimento superficiale almeno uno strato di un materiale avente funzione di barriera alla penetrazione di acqua. Il multistrato risultante è essenzialmente costituito da solo materiale a base di cellulosa o suoi derivati, per cui è adatto alla realizzazione di manufatti "usa e getta" completamente biodegradabili e riciclabili all’interno della raccolta differenziata della carta
Mitochondrial changes induced by natural and synthetic asbestos fibers: studies on isolated mitochondria
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