Showing papers by "Iain R. Gibson published in 2022"
TL;DR: In this article , a rapidly growing area of interest aimed at reducing the magnitude of anthropogenic greenhouse gas emissions is discussed, which is called CO2 utilisation, where CO2 is used to reduce CO2 emissions.
Abstract: CO2 utilisation is a rapidly growing area of interest aimed at reducing the magnitude of anthropogenic greenhouse gas emissions.
3 citations
TL;DR: In this paper , co-substituted lithium ion (Li+) and carbonate ion hydroxyapatite compositions were synthesized by an aqueous precipitation method, which can account for charge balance, which has been ignored in the synthesis of Li doped calcium phosphates to date.
Abstract: Hydroxyapatite is a commonly researched biomaterial for bone regeneration applications. To augment performance, hydroxyapatite can be substituted with functional ions to promote repair. Here, co-substituted lithium ion (Li+) and carbonate ion hydroxyapatite compositions were synthesised by an aqueous precipitation method. The co-substitution of Li+ and CO32- is a novel approach that accounts for charge balance, which has been ignored in the synthesis of Li doped calcium phosphates to date. Three compositions were synthesised: Li+-free (Li 0), low Li+ (Li 0.25), and high Li+ (Li 1). Synthesised samples were sintered as microporous discs (70-75 % theoretical sintered density) prior to being ground and fractionated to produce granules and powders, which were then characterised and evaluated in vitro. Physical and chemical characterisation demonstrated that lithium incorporation in Li 0.25 and Li 1 samples approached design levels (0.25 and 1 mol%), containing 0.253 and 0.881 mol% Li+ ions, respectively. The maximum CO32- ion content was observed in the Li 1 sample, with ~8 wt% CO3, with the carbonate ions located on both phosphate and hydroxyl sites in the crystal structure. Measurement of dissolution products following incubation experiments indicated a Li+ burst release profile in DMEM, with incubation of 30 mg/ml sample resulting in a Li+ ion concentration of approximately 140 mM after 24 h. For all compositions evaluated, sintered discs allowed for favourable attachment and proliferation of C2C12 cells, human osteoblast (hOB) cells, and human mesenchymal stem cells (hMSCs). An increase in alkaline phosphatase (ALP) activity with Li+ doping was demonstrated in C2C12 cells and hMSCs seeded onto sintered discs, whilst the inverse was observed in hOB cells. Furthermore, an increase in ALP activity was observed in C2C12 cells and hMSCs in response to dissolution products from Li 1 samples which related to Li+ release. Complementary experiments to further investigate the findings from hOB cells confirmed an osteogenic role of the surface topography of the discs. This research has shown successful synthesis of Li+ doped carbonated hydroxyapatite which demonstrated cytocompatibility and enhanced osteogenesis in vitro, compared to Li+-free controls.
3 citations