Zinc phosphate as versatile material for potential biomedical applications Part II

Abstract

Surface chemical reactivity of two modifications of synthetic zinc phosphate tetrahydrate (alpha - and beta -form of Hopeite, alpha -,beta -ZPT) has been studied by selective chemical and e-beam etching in presence of diluted phosphoric acid and ammonia by Scanning Electron Microscopy (SEM) and microelectrophoresis (zeta potential measurements) in correlation with the corresponding bulk properties and crystal size distributions. The subtitle crystallographic differences between alpha -and beta -ZPT originating from a unique hydrogen bonding pattern, induce drastic variations of both surface potential and surface charge. Biogenic Hydroxyapatite (HAP) and one of its metastable precursors, a calcium dihydrogen phosphate dihydrate (DCPD) or Brushite were used to underline this resulting variation of chemical reactivity in zinc phosphates. In-situ monitoring of the transformation of Brushite in Hydroxyapatite is also reported.

Dynamic Control of Nanoprecipitation in a Nanopipette

“…While the exact chemical composition of the precipitate is unknown at this time, clusters of zinc phosphate have been shown to have a net negative charge at neutral pH, as measured by zeta potential. (29) Precipitation and blocking of the pore will lead to an increased electric field at the pore, and thus a negative potential may move the precipitate out of the pore and into the bath by electrophoretic forces. While the applied voltages are low in these experiments (−300 to −500 mV), the voltage drop will be greatest across the region of highest impedance, such as the blocked pore.…”

Morphology, crystallization and enzymatic hydrolysis of poly(L‐lactide) nucleated using layered metal phosphonates

“…Metal phosphonates are a type of synthetic inorganic/organic hybrid material with a layered structure 29, 30. Layered metal phosphonates, prepared via simple precipitation or redox reactions, have been widely used in polymer composites, biomaterials and materials for developing oligonucleotide microarrays, protein binding and drug‐delivery systems 31–36. It was reported by Mitomo et al that metal phosphonate materials can accelerate the crystallization rate of PLLA 37.…”

Large-scale synthesis of hierarchically mesoporous phosphate nanocomposites using yeast cells as the template reactor

“…More recently, our previous study confirmed that the yeast cell surface has surplus negative charges as a result of cultivation [34]. When cations were added into the bioemulsion, positively charged cations were combined with the negatively charged -COO -and -OPO 3 2-groups, and were selfassembled to the yeast cells' surface by electrostatic interaction and gene regulation in the yeast cells. This self-assembly induced the formation of a phosphate layer on the surface of the yeast cell wall.…”

“…During the cultivation processes of yeast cells (fermentation), a bioemulsifier with acidic matrix macromolecules metabolites, including extracellular proteins and polysaccharides [29][30][31], was produced on the surface of cells. These biosurface-active macromolecules contain some hydrophilic anion groups, including carboxyl and -OPO 3 2- [32]. It should be mentioned that the hydrophilic anion groups mainly serve the following two purposes: (1) they provide oriented nucleation sites for target cations [33] and (2) they accumulate more negative charges on the biotemplate surface.…”