In vitro behavior of albumin‐loaded carbonate hydroxyapatite gel

Abstract

Hydroxyapatite (HA) powder, porous HA, plasma-sprayed HA, apatite cements, and sintered HA have all been investigated as delivery systems for compounds such as human growth hormone and vancomycin. However, many previous studies showed that the period of release was limited to 2-3 weeks. The concept of using a nanoporous matrix as a means of immobilizing proteins is well known but has largely been confined to silica-based systems. Carbonate hydroxyapatite (CHA) is more soluble in vivo than HA, and when formed as an aqueous precipitate, it is often formed as nanocrystals. This study investigated the release profiles of ovine albumin (OVA) from CHA gel stored in phosphate-buffered saline (PBS) and double distilled water (DDW) for times of up to 1 year. It was found that 7.9% OVA could be loaded onto apatitic gels by means of a purely aqueous process. This process provided a simple low-temperature method of protein adsorption on a high surface area apatitic matrix at physiological pH. The rate of short-term release of OVA was lower from CHA gels than from microcrystalline HA powder. However, the period of release from the CHA gel was short term and may have been associated with recrystallization of the gel. OVA loaded into CHA gel was found to remain undegraded in vitro at 37 degrees C for periods of up to 1 year.

Effect of silicon level on rate, quality and progression of bone healing within silicate-substituted porous hydroxyapatite scaffolds

“…Whether this is a surface charge alteration affecting protein adsorption, cell attachment and differentiation, or a direct interaction between cell metabolism and bioavailable free Si is unclear. Protein conformation is sensitive to surface chemistry [47]; when calcium phosphates and specific proteins are combined under the correct conditions, calcium phosphate dissolution [48,49], nucleation [50] or ageing [51] can be modulated as can adsorbed protein species [49], conformation [52] and stability [53] demonstrating a reciprocal relationship between protein adsorption and calcium phosphate chemistry. More specifically, the quality and quantity of proteins adsorbed in vitro is sensitive to silicate substitution levels, which has a downstream effect on osteoblast-like cell attachment and metabolism [29].…”

Preparation of Iron Doped Hydroxyapatite Microsphere by Mist Process

“…This local alignment of these ions are necessary for new bone formation. 25,26) This result suggests that the possibility to use the obtained microsphere as a scaffold of artificial implant due to an excellent biodegradability.…”

Characterization of Scale Formed on the Surfaces of Toilet Bowls

“…These results suggested that the proteins were not derived from the urine itself, but were produced mostly as a result of the metabolism of dirt and grime by bacteria and mold. As is well known, proteins adsorb on the surface of apatite [23,24] and often inhibit the growth of apatite [25,26]. The formation of amorphous apatite in the scale might be partly attributed to the adsorption of the protein.…”