The synthesis and characterization of nanophase hydroxyapatite using a novel dispersant‐aided precipitation method

Abstract

The synthesis of nanophase hydroxyapatite (nHA) is of importance in the field of biomaterials and bone tissue engineering. The bioactive and osteoconductive properties of nHA are of much benefit to a wide range of biomedical applications such as producing bone tissue engineered constructs, coating medical implants, or as a carrier for plasmid DNA in gene delivery. This study aimed to develop a novel low‐temperature dispersant‐aided precipitation reaction to produce nHA particles (<100 nm), which are regarded as being preferable to micron‐sized agglomerates of nHA. The variables investigated and optimized include the reaction pH, the rate of reactant mixing, use of sonication, order of addition, and concentration of the primary reactants, in addition, the effect of using poly(vinyl alcohol) (PVA) surfactant and Darvan 821A® dispersing agent during the reaction was also examined. It was found that by fine‐tuning the synthesis parameters and incorporating the dispersing agent, monodisperse, phase‐pure nano‐sized particles under 100 nm were attained, suitable for clinical applications in bone regeneration. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2010.

The development of non-viral gene-activated matrices for bone regeneration using polyethyleneimine (PEI) and collagen-based scaffolds

“…The collagen nanohydroxyapatite (nHa) scaffold was fabricated by the addition 3.6g nHa to the standard collagen scaffold. nHa was synthesised using a novel dispersant-aided precipitation technique [48] which was incorporated into collagen slurries using a suspension method [40]. Scaffolds were cut to 9.5mm diameter using circular biopsy punches postlyophilisation.…”

Scaffold‐Based microRNA Therapies in Regenerative Medicine and Cancer

“…[93] However, research carried out by our lab has optimized CaPs for this purpose, using a formulation of the hydroxyapatite mineral phase as nonaggregating nanoparticles (nHA) previously developed in-house. [94] These NPs were originally investigated to develop a collagen-nHA composite scaffold with improved mechanical properties; [94] this material was then adapted to surpass the pDNA transfection efficiency of a commercial CaP transfection kit in hMSCs, [95] and was further tailored to deliver both reporter miR-mimics and antagomiRs to the same cell type, with a single low dose maintaining a silencing efficiency of greater than 90% over 1 week. [96] Although little is known regarding the uptake mechanisms of CaP-nucleic acid complexes, their ability to form precipitates on the cell surface and undergo clathrin and dynamin-dependent endocytosis has been documented, [37] and their pH-dependent solubility allows complex dissociation to commence within intracellular compartments.…”

“…[96,124] Studies on scaffold-based gene delivery in the lab originally began with the delivery of pDNA including BMP2 [95] and combinations of BMP2 and VEGF [155] utilizing the nHA particles [94] and coll-nHA scaffolds [94,156] developed in-house specifically for bone repair. Having demonstrated the dramatically enhanced therapeutic potential of such systems not only for bone but also cartilage and nerve repair, we also progressed to investigating the utility of alternative gene delivery vectors including PEI, [85,155,157] chitosan, [40,158] Lipofectamine 2000, [75] and cyclodextrin, [75,159] different genetic cargo such as pDNA, [85,95,155,157] miRNA, [96,124] and siRNA, [75,159] and various scaffold types including collagen alone, [85,95] collagennHA, [75,95,96,124,155,159] collagen-HA [85] and collagen hyaluronic acid (coll-HyA) [85] to tailor our systems depending on the final application required.…”

Non-viral gene-activated matrices

“…15 Since then, a number of further enhanced, bone-targeted, novel collagen-composite scaffolds have been produced by our group including the collagen-nHa scaffold which will be discussed primarily in this commentary. 14,16,17 Previous work within our laboratory has demonstrated the ability 1990s. 36,37 The scaffold essentially acts as a depot for the gene while simultaneously offering structural support and a matrix for new tissue deposition (Fig.…”