56 research outputs found
A Model for the Ultrastructure of Bone Based on Electron Microscopy of Ion-Milled Sections
The relationship between the mineral component of bone and associated collagen has been a matter of continued dispute. We use transmission electron microscopy (TEM) of cryogenically ion milled sections of fully-mineralized cortical bone to study the spatial and topological relationship between mineral and collagen. We observe that hydroxyapatite (HA) occurs largely as elongated plate-like structures which are external to and oriented parallel to the collagen fibrils. Dark field images suggest that the structures (“mineral structures”) are polycrystalline. They are approximately 5 nm thick, 70 nm wide and several hundred nm long. Using energy-dispersive X-ray analysis we show that approximately 70% of the HA occurs as mineral structures external to the fibrils. The remainder is found constrained to the gap zones. Comparative studies of other species suggest that this structural motif is ubiquitous in all vertebrates
Natural-based nanocomposites for bone tissue engineering and regenerative medicine: a review
Tissue engineering and regenerative medicine has been providing exciting
technologies for the development of functional substitutes aimed to repair and
regenerate damaged tissues and organs. Inspired by the hierarchical nature of
bone, nanostructured biomaterials are gaining a singular attention for tissue
engineering, owing their ability to promote cell adhesion and proliferation, and
hence new bone growth, compared with conventional microsized materials.
Of particular interest are nanocomposites involving biopolymeric matrices and
bioactive nanosized fi llers. Biodegradability, high mechanical strength, and
osteointegration and formation of ligamentous tissue are properties required
for such materials. Biopolymers are advantageous due to their similarities with
extracellular matrices, specifi c degradation rates, and good biological performance.
By its turn, calcium phosphates possess favorable osteoconductivity,
resorbability, and biocompatibility. Herein, an overview on the available natural
polymer/calcium phosphate nanocomposite materials, their design, and properties
is presented. Scaffolds, hydrogels, and fi bers as biomimetic strategies for
tissue engineering, and processing methodologies are described. The specifi c
biological properties of the nanocomposites, as well as their interaction with
cells, including the use of bioactive molecules, are highlighted. Nanocomposites
in vivo studies using animal models are also reviewed and discussed.
 The research leading to this work has received funding from the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement no REGPOT-CT2012-316331-POLARIS, and from QREN (ON.2 - NORTE-01-0124-FEDER-000016) cofinanced by North Portugal Regional Operational Program (ON.2 - O Novo Norte), under the National Strategic Reference Framework (NSRF), through the European Regional Development Fund (ERDF)
An inexpensive device for freeze drying and plastic embedding tissues at low temperatures
Peri-implant bone organization surrounding zirconia-microgrooved surfaces circularly polarized light and confocal laser scanning microscopy study
Microprobe analysis of calcifying matrices and formative cells in developing mouse molars
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