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687 results on '"Pitarresi, G"'

131. Strain Measurement on Composites: Effects due to Strain Gauge Misalignment.

Author

Ajovalasit, A. and Pitarresi, G.

Subjects
*COMPOSITE materials research, *STRAIN gages, *POISSON'S ratio, *STIFFNESS (Mechanics), *SPREADING electric resistance
Abstract

The present work analyses the errors affecting the strains measured by misaligned strain gauges installed on orthotropic-composite laminae. Various analytical relationships are derived showing that, besides the fibre and strain gauge orientations, the misalignment error in unidirectional off-axis orthotropic composite samples depends also on the lamina stiffness properties ( E, E, ν, G). If the fibres are aligned with the loading axis, it is found that the higher Poisson's ratio ν is the only elastic property influencing the misalignment error. Experimental results are shown confirming the theoretical predictions. [ABSTRACT FROM AUTHOR]

Published
2011
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132. Crosslinked hyaluronan with a protein‐like polymer: Novel bioresorbable films for biomedical applications.

Author

Pitarresi, G., Palumbo, F. S., Calabrese, R., Craparo, E. F., and Giammona, G.

Abstract

In this work, novel hydrogel films based on hyaluronan (HA) chemically crosslinked with the α,β‐poly(N‐2‐hydroxyethyl) (2‐aminoethylcarbamate)‐D,L‐aspartamide (PHEA–EDA) were produced by solution casting method. The goal was to exploit both the biological key role of HA in tissue repair and regeneration, and the versatility of a synthetic protein‐like polymer as the PHEA–EDA, in order to obtain biomaterials with physicochemical and biological properties suitable for a clinical use. By varying the molar ratio between the PHEA–EDA amino groups and HA carboxyl groups, three different films were obtained and characterized. Particularly FTIR, swelling, hydrolysis, and enzymatic degradation studies were performed. In addition, the cytocompatibility of HA/PHEA–EDA hydrogel films was evaluated using human derm fibroblasts, by means of MTT and trypan blue exclusion assays. The high swelling capability, the long‐term hydrolysis resistance, and the resistance to hyaluronidase greater than that of only HA, together with the cell compatibility, have suggested the potential application of these novel HA‐based hydrogel films in the biomedical field of tissue engineering. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008 [ABSTRACT FROM AUTHOR]

Published
2008
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133. Synthesis and characterization of water-swellable α, β-polyasparthydrazide derivatives.

Author

Giammona, G., Pitarresi, G., Tomarchio, V., Dispenza, C., and Spadaro, G.

Abstract

α, β-polyasparthydrazide (PAHy) was crosslinked by glutaraldehyde to form water-swellable materials possessing a three-dimensional molecular network. Different crosslinking degrees were prepared varying glutaraldehyde/PAHy ratio and samples containing 5-fluorouracil were obtained by incorporating the drug into the polymer networks during the crosslinking reaction. All samples were characterized by swelling tests, thermal, x-ray and SEM analysis. Their microstructure was observed through scanning electron microscopy. Furthermore, for samples containing the anticancer drug, in vitro release studies were performed in pH 7.4 buffer solution. [ABSTRACT FROM AUTHOR]

Published
1995
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134. Synthesis and characterization of water-swellable α, β-polyasparthydrazide derivatives.

Author

Giammona, G., Pitarresi, G., Tomarchio, V., and Spadaro, G.

Abstract

The synthesis of a new crosslinked polymer by reaction of α, β-polyasparthydrazide and glutaraldehyde is reported. Different crosslinking degrees were obtained by varying the ratio between the aldehyde and the starting polymer. The crosslinked polymer was characterized by water swelling tests and thermal analysis. In particular, the crosslinking density and its effects on the glass transition temperature of the material were studied. Finally, the microstructure of the obtained polymer was observed using scanning electron microscopy. [ABSTRACT FROM AUTHOR]

Published
1994
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135. pH-Sensitive Hydrogel Based On A Novel Photocross-Linkable Copolymer

Author

Mandracchia, D., Pitarresi, G., Palumbo, F. S., Carlisi, B., and Giammona, G.

Abstract

A pH sensitive hydrogel has been prepared by a UV irradiation technique. Starting polymer was the PHM (poly hydroxyethylaspartamide methacrylated) obtained from polyaspartamide (PHEA) partially derivatized with methacrylic anhydride (MA). This new copolymer has been further derivatized with succinic anhydride (SA) to obtain PHM-SA that has been cross-linked by UV irradiation to form a pH sensitive hydrogel. The network, recovered after washing as a powder, has been been characterized by FT-IR spectrophotometry and particle size distribution analysis. Moreover, to have information about water affinity of the prepared sample, swelling measurements have been carried out in aqueous media mimicking biological fluids. The possibility to employ the prepared hydrogel as a pH-sensitive drug delivery system (DDS) has been investigated. In particular, ibuprofen ((S)(+)4-isobutyl-α-methylphenyl-acetic acid), chosen as a model drug, has been entrapped into the PHM-SA hydrogel, and in vitro release studies have showed that its release rate depends on different swelling of the network as a function of the environmental pH.

Published
2004

136. Polymeric Prodrug for Release of an Antitumoral Agent by Specific Enzymes

Author

Cavallaro, G., Pitarresi, G., Licciardi, M., and Giammona, G.

Abstract

The clinical usefulness of antitumor chemotherapy has been strongly limited by the lack of specificity of most anticancer drugs, which act also against healthy cells. The aim of this work was to design, synthesize, and evaluate a macromolecular prodrug of Cytarabine, a known antitumor drug, which is a specific substrate for plasmin enzyme whose concentration is high in various kinds of tumor mass as a result of plasminogen activator secretion. α,β-Poly(N-hydroxyethyl)-dl-aspartamide (PHEA), a known synthetic and biocompatible polyamino acid, was used as a drug carrier, and Cytarabine was linked to PHEA by d-Val-Leu-Lys spacer synthesized beginning from Cbz-d-Val-LeuOH dipeptide and N6-CbzLys methyl ester. The content of Cytarabine in the purified PHEA-d-Val-Leu-Lys-Cytarabine conjugate was equal to 3% w/w. In vitro experiments in the presence of plasmin evidenced the ability of this enzyme to strongly increase drug release from the macromolecular prodrug, as well as plasma incubation shows high stability of drug−polymer linkage. The direct linkage of Cytarabine to PHEA was also performed and, like PHEA-d-Val-Leu-Lys-Cytarabine conjugate, the obtained PHEA−Cytarabine conjugate showed high stability in plasma, but no release of Cytarabine was revealed in the presence of plasmin.

Published
2001

140. Acryloylated α,/β-poly (N-hydroxyethyl)-DL-aspartamide and α,β-polyasparthydrazide. Synthesis, characterization and radiation formation of polymeric networks

Author

Giammona, G., Tomarchio, V., Pitarresi, G., and Cavallaro, G.

Abstract

In the present study the derivatization of two water-soluble and synthetic polymers, such as α,β-poly(N-hydroxyethyl)-DL-aspartamide (PHEA) and α,β-polyasparthydrazide (PAHy), with glycidylmethacrylate (GMA) is described. This reaction allowed the introduction of double bonds in the macromolecular chains of PHEA and PAHy in order to make easier the crosslinking by a radical mechanism. Different parameters affected the reaction of derivatization, such as reaction pH, GMA concentration and reaction time. As far as PHEA is concerned the amount of GMA linked to the polymer increased until reaching a plateau. On the contrary, the reaction of PAHy with GMA proceeded with a zero order kinetics and the GMA amount in the polymer increased regularly. Some aqueous solutions of PHEA-GMA and PAHy-GMA copolymers at various GMA content were submitted to gamma radiation processing, thus obtaining crosslinked structures. The derivatization of PHEA and PAHy with GMA was a convenient method to introduce insaturations in their chains and it allowed to obtain gels at lower doses with respect to the starting polymers.

Published
1997
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148. Biocompatibility and biodegradability of electrospun phea-pla scaffolds: Our preliminary experience in a murine animal model

Author

Lo Monte, A. I., Licciardi, M., Bellavia, M., Damiano, G., Palumbo, V. D., Palumbo, F. S., Abbruzzo, A., Fiorica, C., Pitarresi, G., Cacciabaudo, F., Tripodo, C., Belmonte, B., Spinelli, G., Roberta Altomare, Gioviale, M. C., Cassata, G., Sammartano, A., Genova, P., Salina, A., Buscemi, G., Giammona, G., LO MONTE, AI, LICCIARDI, M, BELLAVIA, M, DAMIANO, G, PALUMBO, VD, PALUMBO, FS, ABRUZZO, A, FIORICA, C, PITARRESI, G, CACCIABAUDO, F, TRIPODO, C, BELMONTE, B, SPINELLI, G, ALTOMARE, R, GIOVIALE, MC, CASSATA, G, SAMMARTANO, A, GENOVA, P, SALINA, A, BUSCEMI, G, and GIAMMONA, G

Subjects
Settore MED/18 - Chirurgia Generale, PHEA-PLA, Electrospinning, Three-dimensional scaffold, Three-dimensional scaffolds, Settore CHIM/08 - Chimica Farmaceutica
Abstract

We obtained a nano-fibrillar scaffold starting from a polymeric solution which, through electrospinning, gave a biodegradable material with optimal mechanical features and the capacity to allow cell adhesion. In this paper we report the in-vivo application on a murine animal model of two electrospun biodegradable materials, specifically designed to create tubular structures. In one case PHEA-PLA was co-spun with silk fibroin (Fibro-PHEAPLA) by a parallel electrospinning process to obtain a scaffold with two different polymeric fibers. In the other case, PHEA-PLA was mixed with polycaprolactone (PCLPHEA-PLA) to obtain a hybrid fibers scaffold. The in-vitro assay showed fibroblast colonization in both materials. The scaffolds were implanted in the dorsal fascial pouch of rats to evaluate their in-vivo Biocompatibility and tissue integration. Histopathological findings showed that after implantation a neutrophilic reaction associated to colliquative necrosis was predominant, particularly for PCL-PHEA-PLA. Fibro-PCL-PHEA caused a non organized stromal reaction. Cell adhesion was confirmed at SEM scan. Both materials were totally absorbed after 40 days with an inflammatory reaction. This preliminary study showed that biocompatibility of the scaffolds needs further investigation. The capability of the materials to be functionalized could allow us to modulate the inflammatory host response.

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