Nano-Hydroxyapatite Derived from Biogenic and Bioinspired Calcium Carbonates: Synthesis and In Vitro Bioactivity

Abstract

Biogenic calcium carbonates naturally contain ions that can be beneficial for bone regeneration and therefore are attractive resources for the production of bioactive calcium phosphates. In the present work, cuttlefish bones, mussel shells, chicken eggshells and bioinspired amorphous calcium carbonate were used to synthesize hydroxyapatite nano-powders which were consolidated into cylindrical pellets by uniaxial pressing and sintering 800–1100 °C. Mineralogical, structural and chemical composition were studied by SEM, XRD, inductively coupled plasma/optical emission spectroscopy (ICP/OES). The results show that the phase composition of the sintered materials depends on the Ca/P molar ratio and on the specific CaCO3 source, very likely associated with the presence of some doping elements like Mg2+ in eggshell and Sr2+ in cuttlebone. Different CaCO3 sources also resulted in variable densification and sintering temperature. Preliminary in vitro tests were carried out (by the LDH assay) and they did not reveal any cytotoxic effects, while good cell adhesion and proliferation was observed at day 1, 3 and 5 after seeding through confocal microscopy. Among the different tested materials, those derived from eggshells and sintered at 900 °C promoted the best cell adhesion pattern, while those from cuttlebone and amorphous calcium carbonate showed round-shaped cells and poorer cell-to-cell interconnection.

Nano-Hydroxyapatite vs. Xenografts: Synthesis, Characterization, and In Vitro Behavior

“…The XRD pattern in Figure 1 was matched by the calcite (CaCO 3 ) phase with a high degree of crystallinity evidenced by sharp diffraction peaks. The results are in good agreement with numerous references, which present egg-shells as a calcium carbonate source [ 24 , 25 ]. In addition, a calcium content of 96.38 wt.% was observed after XRF examination, made on egg-shells before calcination.…”

“…Therefore, natural sources for biological apatite synthesis have been extended, year by year, from mammalian bone sources next to fish bones and scales [ 20 , 21 , 22 ], egg-shells [ 23 , 24 ], and exoskeletons of marine organisms (snails, starfish, coral, and seashell) [ 25 , 26 , 27 , 28 ] or botanic sources (Calendula flower, Papaya leaf, and orange peel), where all of them need chemical and thermal preparation before use as a mammalian xenograft. However, the interest in this topic is still present, a fact proved by several recent publications [ 23 , 24 , 25 ]. Mammalian bone, after thermal treatments, provides so-called biological apatite [ 3 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ]; egg-shells (hen, crocodile etc.)…”

“…Mammalian bone, after thermal treatments, provides so-called biological apatite [ 3 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ]; egg-shells (hen, crocodile etc.) and marine organism skeletons, including corals and starfish, are special sources of biogenic calcium carbonate [ 23 , 24 , 25 , 26 , 27 , 28 ]; phytogenic calcium carbonates could be used after the extraction process in the original form, preserving the porous structure, calcium-rich source, and biomolecules (Ovalbumin, Carotene, Papain, and vitamins) [ 10 , 11 ].…”

In Vitro Degradation and Cytotoxicity of Eggshell-Based Hydroxyapatite: A Systematic Review and Meta-Analysis

“…Out of 71 relevant article titles collected from SCOPUS, PubMed, and Google Scholar, only 36 were included after screening the title, abstract, and content for in vitro degradation and cytotoxicity testing for the biocompatibility of eggshell-based hydroxyapatite. The articles came from several countries, such as India [ 11 , 14 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 ], Bangladesh [ 41 , 42 ], China [ 43 ], Korea [ 25 , 44 , 45 ], Turkey [ 46 , 47 , 48 ], Thailand [ 49 , 50 ], Brazil [ 26 ], Italy [ 51 ], USA [ 52 ], Romania [ 2 ], Vietnam [ 53 , 54 ], Colombia [ 55 ], and Egypt [ 56 ]. The study selection of the articles included in the systematic review is shown in Figure 1 .…”

Coupled effect of particle size of the source materials and calcination temperature on the direct synthesis of hydroxyapatite

“…In particular, it has been widely used for the removal of heavy metals [ 15 , 16 ] and arsenic from wastewater [ 17 ]. Regarding the importance of Hap, day by day researchers are exploring their focus on developing various synthetic routes using either chemical sources or biogenic resources/ bio-wastes [ 10 , 18 – 20 ].…”