Osteointegration of PLDLA/PCL blends: in vitro and in vivo study

Author(s)

Marcelo Roberto Pinto

• Document type: Master's Dissertation
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Engenharia Mecânica
• Defense date: 2007-10-07

Examining board members

Eliana Aparecida de Rezende Duek; Cecília Amélia de Carvalho Zavaglia; Maria do Carmo Alberto Rincon

• Advisor: Eliana Aparecida de Rezende Duek

Abstract

Bioreabsorbable polymers present great potential in biomedical applications, because they are usually, easy to process and they present a similar biological mechanical characteristics, as it is the case of poly(L- lactic acid) very studied in the last decades. A way to modify the properties of a homopolymer for orthopedic applications is obtention of blends, aiming to improve their properties compared to the pure polymers. The aim of this study was: 1) to evaluate the in vitro degradation of PLDLA/PCL blends, in the 100/0, 90/10, 80/20 and 70/30 compositions and to characterize them by SEM, DSC, GPC analyses and mechanical properties before and after degradation process phosphate buffer. 2) to accomplish the in vivo study. The in vitro results by DSC, SEM and mechanical properties until 180 days, for all the blends, presented a discreet degradation signals, and after this period, all the materials presented degraded. GPC analyses, was the most sensitive compared with others, in other words, although loss of molar mass was verified, the thermal properties are stable. The same behavior was seen in DSC analyses. The mechanical properties of blends did not present significant modifications up to 180 days of degradation, showing that with the largest addition of PCL, the blends became more elastic and less fragile. SEM analyses showed a discreet degradation of 70/30 blends in 180 days and complete degradation process for all the blends after 220 days. Based in in vitro study the 100/0 and 70/30 blends were chosen to be implanted. The results revealed that the degree of tissue organization was function of implanted time. Until the 180 days of implantation there was not differentiates relevant in vivo between pure PLDLA and the 70/30 blends. In that experiment the histological cuts revealed absence of inflammatory cells and foreign body cells reaction in the bone interface in longer periods of implants. It was predominant the ósteo-progenitors cells populating the interface, surrounded by mineralized tissue around of polymers (AU)