Biomedical subjects

Giovanni Vozzi

Publications and source records attributed to Giovanni Vozzi.

7 recordsLinked to original sources

PubMed2006

Characterization of tissue-engineered scaffolds microfabricated with PAM.

PAM (pressure-activated microsyringe) is a new microfabrication technique that allows the fabrication of two- and three-dimensional scaffolds with a well-defined geometry using polymers soluble in volatile solvents. In this study, polymeric scaffolds were realized with four different polymers--PCL, PLLA, PLGA, and a blend of PCL and PLLA--and with three different geometries-square grids, hexagonal grids, and octagonal grids. The scaffolds were characterized in terms of porosity, hydrophilicity, cell adhesion, and their mechanical properties. An analysis of the measured data shows that the physical and mechanical properties of the scaffold depend on its geometry and line width, both of which are easily modulated using PAM.

Biocompatible Materials↗

PubMed2005

Organic field effect transistors for textile applications.

In this paper, several issues concerning the development of textiles endowed with electronic functions will be discussed. In particular, issues concerning materials, structures, electronic models, and the mechanical constraints due to textile technologies will be detailed. The idea starts from an already developed organic field-effect transistor that is realized on a flexible film that can be applied, after the assembly, on whatever kind of substrate, in particular, on textiles. This could pave the way to a variety of applications aimed to conjugate the favorable mechanical properties of textiles with the electronic functions of transistors. Furthermore, a possible perspective for the developments of organic sensors based on this structure are described.

Clothing↗

PubMed2004

Innovative tissue engineering structures through advanced manufacturing technologies.

Awide range of rapid prototyping (RP) techniques for the construction of three-dimensional (3-D) scaffolds for tissue engineering has been recently developed. In this study, we report and compare two methods for the fabrication of poly-(epsilon-caprolactone) and poly-(epsilon-caprolactone)-poly-(oxyethylene)-poly-(epsilon-caprolactone) copolymer scaffolds. The first technique is based on the use of a microsyringe and a computer-controlled three-axis micropositioner, which regulates motor speed and position. Polymer solutions are extruded through the needle of the microsyringe by the application of a constant pressure of 10-300 mm Hg, resulting in controlled polymer deposition of 5-600 microm lateral dimensions. The second method utilises the heating energy of a laser beam to sinter polymer microparticles according to computer-guided geometries. Materials may be fed either as dry powder or slurry of microparticles. Both powder granulometry and laser working parameters influence resolution (generally 300 microm x 700 microm), accuracy of sintering and surface and bulk properties of the final structures. The two RP methods allow the fabrication of 3-D scaffolds with a controlled architecture, providing a powerful means to study cell response to an environment similar to that found

Animals↗

PubMed2003

Fabrication of PLGA scaffolds using soft lithography and microsyringe deposition.

Construction of biodegradable, three-dimensional scaffolds for tissue engineering has been previously described using a variety of molding and rapid prototyping techniques. In this study, we report and compare two methods for fabricating poly(DL-lactide-co-glycolide) (PLGA) scaffolds with feature sizes of approximately 10-30 microm. The first technique, the pressure assisted microsyringe, is based on the use of a microsyringe that utilizes a computer-controlled, three-axis micropositioner, which allows the control of motor speeds and position. A PLGA solution is deposited from the needle of a syringe by the application of a constant pressure of 20-300 mm Hg, resulting in a controlled polymer deposition. The second technique is based on 'soft lithographic' approaches that utilize a poly(dimethylsiloxane) mold. Three variations of the second technique are presented: polymer casting, microfluidic perfusion, and spin coating. Polymer concentration, solvent composition, and mold dimensions influenced the resulting scaffolds as evaluated by light and electron microscopy. As a proof-of-concept for scaffold utility in tissue engineering applications, multilayer structures were formed by thermal lamination, and scaffolds were rendered porous by particulate leaching. These simple methods for forming PLGA scaffolds with microscale features may serve as useful tools to explore structure/function relationships in tissue engineering.

Biocompatible Materials↗

PubMed2003

A new method for quantitative cellular imaging on 3-D scaffolds using fluorescence microscopy.

This paper presents a new image processing technique for estimating cell numbers and contours in three-dimensional (3-D) microfabricated scaffolds. The method is based on a statistical approach, and utilizes the extreme value theory, which assumes that cells in the image field are rare, high-intensity events. Confocal microscopy images of fibroblasts on 3-D structures were processed using the method, and the resulting data on cell numbers was compared with countings obtained using a Burker chamber. The results were identical to within a few percent.

3T3 Cells↗

PubMed2003

A comparative study of chemical derivatisation methods for spatially differentiated cell adhesion on 2-dimensional microfabricated polymeric matrices.

This paper describes a study of surface derivatisation methods applied to two-dimensional polymer matrices microfabricated using the Pressure-Assisted Microsyringe (PAM) technique. A blend of polylactide and polycaprolactone was used as the matrix material, and surface chemistry techniques based on silanes and polyethyleneglycol (PEG) derivatives were employed to render the surface underlying the scaffold anti-adhesive whilst polylysine was covalently coupled to the surface of the polymer matrix to enhance cell adhesion. Prior to cell-adhesion tests, the surfaces and matrices were analysed using physico-chemical techniques, such as surface tension, surface potential and fluorescence. Adhesion of primary endothelial cells was evaluated using cell counting techniques. The results demonstrate that both PEGs and silanes are about 66% efficient at demarcating endothelial cell adhesion in short term experiments and that covalently-bound polylysine to the polymer matrix increases cell adhesion twofold with respect to the adsorbed polypeptide.

Biocompatible Materials↗

PubMedDate not supplied

Blends of poly-(epsilon-caprolactone) and polysaccharides in tissue engineering applications.

Bioartificial blends of poly-(epsilon-caprolactone) (PCL) with a polysaccharide (starch, S; dextran, D; or gellan, G) (PCL/S, PCL/D, PCL/G 90.9/9.1 wt ratio) were prepared by a solution-precipitation technique and widely characterized by differential scanning calorimetry analysis (DSC), Fourier transform infrared-attenuated total reflectance spectroscopy (FTIR-ATR), optical microscopy (OM), wide-angle X-ray diffraction analysis (WAXD), and thermogravimetry (TGA). DSC showed that the polysaccharide reduced the crystallinity of PCL and had a nucleation effect, which was also confirmed by OM analysis. Hoffman-Weeks analysis was performed on PCL and blend samples allowing calculation of their equilibrium melting temperatures (). WAXD showed that the crystalline unit cell type was the same for PCL and blends. FTIR-ATR did not evidence interactions between blend components. Thermal stability was affected by the type of polysaccharide. Microparticles (<125 microm) were produced from blends by cryogenical milling and characterized by scanning electron microscopy analysis (SEM). Selective laser sintering (SLS), a new rapid prototyping technology for scaffold fabrication, was applied to sinter blend microparticles according to a PC-designed two-dimensional geometry (strips and 2 x 2 mm(2) square-meshed grids). The optimal experimental conditions for sintering were established and laser beam parameters (beam speed, BS, and power, P) were found for each blend composition. Morphology of sintered objects was analyzed by SEM and found to be dependent on the morphology of the sintered powders. Sintered samples were analyzed by chemical imaging (CI), FTIR-ATR, DSC, and contact angle analysis. No evidence of the occurrence of degradation phenomena was found by FTIR-ATR for sintered samples, whereas DSC parameters of PCL and blends showed changes which could be attributed to some molecular weight decrease of PCL during sintering. CI of sintered samples showed that the polysaccharide phase was homogeneously dispersed within the PCL matrix, with the only exception being the PCL/D blend. The contact angle analysis showed that all samples were hydrophilic. Fibroblasts were then seeded on scaffolds to evaluate the rate and the extent of cell adhesion and the effect of the polysaccharides (S, D, G) on the bioactivity of the PCL-based blends.

Animals↗