High‐resolution synchrotron X‐ray analysis of bioglass‐enriched hydrogels

Abstract

Enrichment of hydrogels with inorganic particles improves their suitability for bone regeneration by enhancing their mechanical properties, mineralizability, and bioactivity as well as adhesion, proliferation, and differentiation of bone-forming cells, while maintaining injectability. Low aggregation and homogeneous distribution maximize particle surface area, promoting mineralization, cell-particle interactions, and homogenous tissue regeneration. Hence, determination of the size and distribution of particles/particle agglomerates in the hydrogel is desirable. Commonly used techniques have drawbacks. High-resolution techniques (e.g., SEM) require drying. Distribution in the dry state is not representative of the wet state. Techniques in the wet state (histology, µCT) are of lower resolution. Here, self-gelling, injectable composites of Gellan Gum (GG) hydrogel and two different types of sol-gel-derived bioactive glass (bioglass) particles were analyzed in the wet state using Synchrotron X-ray radiation, enabling high-resolution determination of particle size and spatial distribution. The lower detection limit volume was 9 × 10(-5) mm(3) . Bioglass particle suspensions were also studied using zeta potential measurements and Coulter analysis. Aggregation of bioglass particles in the GG hydrogels occurred and aggregate distribution was inhomogeneous. Bioglass promoted attachment of rat mesenchymal stem cells (rMSC) and mineralization.

Novel injectable gellan gum hydrogel composites incorporating Zn- and Sr-enriched bioactive glass microparticles: High-resolution X-ray microcomputed tomography, antibacterial and in vitro testing

“…This volume corresponds to an equivalent microparticle diameter of 8.5 μm (assuming a spherical microparticle shape). This is approximately one order of magnitude higher than the resolution obtained in our previous work on synchrotron X‐ray μCT analysis of microparticles (Gorodzha et al, ). Considering the microparticle diameters calculated by laser diffraction (Figure S1a), it appears that a high proportion of individual bioactive glass microparticles can be detected by the X‐ray μCT technique applied in this study.…”

“…A further advantage of using bioactive glasses is their high amorphousness and ability to release Ca 2+ to crosslink GG and induce GG hydrogel formation (T. E. Douglas, Piwowarczyk, et al, ; Gorodzha et al, ). Such composites can be implanted in a minimally invasive fashion by injection.…”

Ca:Mg:Zn:CO 3 and Ca:Mg:CO 3 —tri- and bi-elemental carbonate microparticles for novel injectable self-gelling hydrogel–microparticle composites for tissue regeneration

“…They have been enriched with pre-formed inorganic particles to improve their suitability for bone regeneration (Gkioni et al, 2010). One such hydrogel material is gellan gum (GG) (Douglas et al, 2014b, Gorodzha et al, 2016, which is an anionic polysaccharide, and can be crosslinked with divalent ions such as Ca 2+ , Mg 2+ and Zn 2+ to form hydrogels.…”

“…In this work, self-gelling hydrogel-particle composites were generated by addition of carbonate microparticles containing magnesium, calcium and zinc to the GG solution. This approach was used in previous work to cause formation of self-gelling composites of GG and bioactive glass particles (Douglas et al, 2014b, Gorodzha et al, 2016. Previous work on carbonate microparticles containing magnesium and calcium revealed that increasing Mg content of microparticles increased amorphicity, which presumably led to higher ion release (Douglas et al, 2016b).…”

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“…Because enhanced their mechanical properties also enhance mineralizability, and bioactivity as well as adhesion, proliferation, and differentiation of bone-forming cells, while maintaining injectability. 5 Polysaccharidebased (amphiphilic) injectable hydrogels are extremely advantageous and have a variety of biomedical applications, such as drug delivery and tissue engineering. These offers easy patient compliance, show tunable mechanical properties, cell deliverability, and facile administration at physiological condition with long-term functionality and hyaline cartilage construction.…”