Structural characterisation of hypoxia-mimicking bioactive glasses

Area of Science:

• Biomaterials Science
• Materials Chemistry
• Tissue Engineering

Background:

• Nickel and cobalt ions stimulate hypoxia-inducible factor-1 (HIF-1α).
• HIF-1α activation promotes blood vessel formation, essential for tissue engineering.
• Bioactive glasses can serve as controlled delivery systems for therapeutic ions.

Purpose of the Study:

• To investigate the structural role of nickel (Ni) and cobalt (Co) in doped bioactive glasses.
• To understand how Ni and Co incorporation affects the glass structure and its properties.
• To correlate structural findings with potential bioactivity and ion release.

Main Methods:

• Neutron diffraction with isotopic and isomorphic substitution was employed.
• Structural analysis focused on the coordination environments of Ni and Co ions.
• Comparison of structural parameters with archetypal 45S5 Bioglass®.

Main Results:

• Nickel and cobalt ions occupy mixed structural sites: two-thirds in a five-fold coordination (network-modifying) and one-third in a tetrahedral coordination (network-forming).
• No significant differences were observed in primary structural correlations (e.g., Si-O, Ca-O) compared to 45S5 Bioglass®.
• The incorporation of Ni or Co does not adversely affect the fundamental glass structure.

Conclusions:

• Nickel and cobalt integrate into bioactive glasses in specific coordination geometries.
• The structural integrity of the bioactive glass is maintained upon Ni and Co doping.
• These findings suggest that Ni- and Co-doped bioactive glasses retain their bioactivity and dissolution properties for controlled ion delivery in tissue engineering.