QSAR Models for Leaching and Chemical Durability

The chemical durability of a glass refers to its ability to resist to liquid or atmospheric attacks. The modulation of this physical property of glasses is of fundamental importance in a number of technological area. 

The physico-chemical requirements for biocompatibility and bioactivity in terms of compositional limits and the role of additional ions in tailoring new important mechanical and biological properties for specific clinical applications [39] are poorly known at present. In the following we show, by summarizing the results of two case studies, how the relationships can be established and exploited among the structural role of some key elements that appear to control bioactivity. 

Zinc added to bioglasses improve their chemical durability, mechanical properties and endows antimicrobial activity moreover, the release of small concentration of zinc incorporated into an implant material promotes bone formation around the implant and accelerates recovery of the patients, improve adhesion of denture adhesives, etc... Still, it is important to control the Zn releasing rate in order to prevent adverse reactions and to optimize the glass composition to reduce glass degradation without affecting the hydroxyapatite deposition. 

The first example of a complete cycle in rational glass design has been reported for these glasses, and is summarized in Fig. 5.4. The authors [33, 50] derived the ratio of Zn/P concentration which produces an optimal dissolution in the body fluid in order to maintain the bioactivity. The QSPR model used accounts for the role of network polymerization on water chemical durability S%Xj = —1.92 Nx-o-x/ Otot + 1.33, n = 6, = 0.865, = 0.12, where %Xj, is the total leaching of the 

The results of the QSPR study (in silico study) indicated the HZ5 and HP5Z5 as candidates for further smdies. Chemical durability tests in water and in-vitro observations in a cellular medium [51, 52] confirmed that the HZ5, HP5Z5, but also 

---