Glass - Back to the Future!

Presenting Author:
#Claudia-Tatiana Santos Maldonado

article posted 31 March 2016

Claudia-Tatiana Santos Maldonado graduated with a B.S. in Geology at the University of Barcelona in 2015. Her bachelor’s thesis “Obtention of bioglasses of the system P2O5 – CaO – Na2O – ZrO2 for biomedical applications” included the production of phospate glasses to be used in orthopedic implants.

P2O5-Na2O-CaO-ZrO2 bioglasses for biomedical applications

1Claudia-Tatiana Santos Maldonado*, 2Jose Angel Delgado Garcia-Menocal; 1Mariona Tarrago; 2Lizette Morejon Alonso; 1Maite Garcia-Valles; 1Salvador Martinez
1. Dep. Cristalografia, Mineralogia i Dipòsits Minerals. Universitat de Barcelona C/ Martí i Franques s/n 08028 Barcelona.
2. Center of Biomaterials BIOMAT, University of Havana, La Havana, Cuba

One of the main trends regarding biomedical applications is the search for new materials to be used in order to gain control over properties such as degradation or mechanical resistance. Bioglasses corresponding to different chemical systems are currently under investigation to satisfy these needs. In this study, the i ssue has been addressed by producing five bioglasses within the P2O5-CaO-Na2O-ZrO2 system. The chemical composition of the base glass is 44.5 mol% P2O5 – 44.5 mol% CaO – 11 mol% Na2O, where Na2O is progressively replaced with ZrO2 up to 5 mol% ZrO2 in order to make the glass radiopaque.
The analytical methods used include electron microprobe analysis to characterize chemical composition and evaluate the homogeneity of the obtained glasses, dilatometric analysis to calculate glass transition temperature (Tg) and hot-stage microscopy to build the viscosity-temperature curves. The addition of ZrO2 causes a linear increase in Tg and also increases viscosity.
The morphologic and structural evolution of the produced bioglasses was studied during in vitro degradation in deionized water and Simulated Body Fluid (SBF) at 37ºC up to 13 weeks to determine their bioactivity and biodegradability. The dissolution rate was larger in deionized water than in SBF. This process was divided in two stages: the first is the destabilization of the system due to the soaking and reaction between the glass and each solvent, lasting around 15 days and especially intense at the surface; the second is dissolution at an increasing rate due to lower stability of the glass caused by the first stage. The observation with scanning electron microscopy (SEM) with EDX showed that the studied glasses have both a high biodegradability and bioactivity, as can be inferred from the presence of regions with Ca/P ratios similar to those of hidroxiapatite and brushite. This degradation occurred both by bulk and surface processes.