Biomedical subjects

S Iannace

Publications and source records attributed to S Iannace.

4 recordsLinked to original sources

PubMed1998

Viscoelastic behavior of composite ligament prostheses.

Despite the compelling need for artificial connective tissue replacements for orthopedic applications, to date, there is no material which can adequately reproduce the mechanical behavior of natural tissue with necessary long-term endurance. In this work, we introduce a novel soft composite material as a more suitable candidate for connective tissue replacement. The material proposed is based on a hydrogel-polymer matrix reinforced with poly(ethylene terephthalate) fibers wound helically to mimic the architecture of the collagen fibers in natural tissue. Macroscopic behaviors such as static stress-strain, stress relaxation, and dynamic frequency responses can be modulated with choice of the components and design of the composite structure. In doing so, the mechanical characteristics of natural ligaments can be qualitatively reproduced and sustained over time.

Composite Resins↗

PubMed1996

Synthesis and characterization of a new interpenetrated poly(2-hydroxyethylmethacrylate)-gelatin composite polymer.

Poly(2-hydroxyethylmethacrylate) [poly(HEMA)] is a widely used biomaterial which does not allow cell adhesion and growth on its surface, limiting its use in biomedical applications in which cell cohesion is detrimental. We have prepared a poly(HEMA)-gelatin composite hydrogel using a sequential interpenetrating polymer network technique. The properties of this material were compared with poly(HEMA) freeze-dried sponges in terms of morphology, mechanical properties and biocompatibility. Moreover, in vivo biocompatibility experiments highlighted the occurrence of cellular interactions on the surface of the poly(HEMA)-gelatin interpenetrating polymer network, which are usually absent when unmodified poly(HEMA) hydrogels are implanted in the same host organism. These tests also showed a progressive gelatin degradation from the surface to the bulk of the poly(HEMA)-gelatin specimens during short-term (7 d) implantation. Finally, in vitro tests confirmed an improved ability of this composite to scaffold for the cells.

3T3 Cells↗

PubMed1995

Mechanical behaviour of composite artificial tendons and ligaments.

The mechanical behaviour of a soft composite material based on a hydrogel polymer matrix reinforced with bundles of poly(ethylene terephthalate) (PET) fibres is analysed. The composite reproduces the typical J-shaped stress-strain curves displayed by natural tendons and ligaments. The lamination composite theory was used to investigate the role of the fibres and the matrix properties, as well as the role of the winding angle and the volumetric fraction of fibres, on the mechanical response of this system. The results suggested that large variations in the mechanical behaviour can be obtained by changing the winding angle of the fibres in the composite which determines the extent of the 'toe' region and the sensitivity of the system to the rigidity of the fibres.

Animals↗

PubMed1991

Comparative physical tests on segmented polyurethanes for cardiovascular applications.

In order to select a candidate segmented polyurethane (SPU) elastomer for cardiovascular prostheses, a series of physical tests was carried out on five commercially available biomedical polyurethanes. The tests were performed on uniformly thick sheets (0.2-0.3 mm), obtained by solvent casting from THF (Cardiothane 51, Pellethane 2363 80A, Estane 5714 F1, and Estane 58810) or DMAC (Biomer). Tensile mechanical tests at 23 and 37 degrees C showed for all the copolymers typical stress/strain behaviour of elastomeric materials, with small individual differences. Hydrolytic stability was investigated at 85, 60, and 37 degrees C, at increasing times of exposure (96-168 h), in water or alkaline buffer (pH = 10). As indicated by gel permeation chromatography, in almost all cases a degradation of the molecular weight (particularly the M w) was noticed after the hydrolytic tests, but tensile, thermal (by DSC) and dynamic mechanical properties were substantially not affected. SEM was also performed on the materials, before and after the hydrolytic tests. Changes in the morphology of the materials (related to degradation effects) was observed only in the case of Biomer, as shown also by the thermomechanical analyses. After this first series of physical tests, a clear choice of a particular SPU among the five investigated was not found.

Blood Vessel Prosthesis↗