Hydroxyapatite nanostructured

Chen F et al (2010) Hydroxyapatite nanorods/poly(vinyl pyrolidone) composite nanofibers, arrays and three-dimensional fabrics electrospun preparation and transformation to hydroxyapatite nanostructures. Acta Biomater 6(8) 3013-3020... 

In this work, simple (single-use) biosensors with a layer double stranded (ds) calf thymus DNA attached to the surface of screen-printed carbon electrode assembly have been prepared. The sensor efficiency was significantly improved using nanostructured films like carbon nanotubes, hydroxyapatite and montmorillonite in the polyvinylalcohol matrix. 

Results are different when solutions are used instead of suspensions. Chitosan-hydroxyapatite composites with a homogeneous nanostructure have been prepared by a coprecipitation method by Yamaguchi et al. [170]. 

The nanostructured surfaces resemble, at least to a certain degree, the architecture of physiological adhesion substrates, such as extracellular matrix, which is composed from nanoscale proteins, and in the case of bone, also hydroxyapatite and other inorganic nanocrystals [16,17,24-27]. From this point of view, carbon nanoparticles, such as fullerenes, nanotubes and nanodiamonds, may serve as important novel building blocks for creating artificial bioinspired nanostructured surfaces for bone tissue engineering. 

Ahn, E., Gleason, N. J., Nakahira, A., and Ying, X Y., Properties of nanostructured hydroxyapatite-based bioceramics. Proa Sixth World Biomaterials Congress 643 (2000). 

Huang, J., and Li, H. (2014) Hydroxyapatite/graphene-nanosheet composite coatings deposited by vacuum cold spray for biomedical applications inherited nanostructure and enhanced properties. Carbon, 67, 250-259. 

L. (2014) Fabrication, characterization and in.vitro evaluation of nanostructured zirconia/hydroxyapatite composite films on zirconium. Surf. Coat. Technol., 238, 58-67. 

Chitosan can form 3D scaffold that are too weak to be useful in tissue engineering. Hence, inclusion in the chitosan matrix and/or grafting onto chitosan of other substances such as collagen, other biopolymers, or hydroxyapatite has been achieved to improve the mechanical properties of the scaffold and to mimic the nanostructure of the tissue for a better cell adhesion/infiltration and/or to provide thermosensitivity for in situ gelation. 

Han, Y. et al. Evaluation of nanostructured carbonated hydroxyapatite coatings formed by a hybrid process of plasma spraying and hydrothermal synthesis. /. Biomed. Mater. Res., 2002,60 511-16. 

Chow, L.C., Sun, L., Hockey, B., 2004, Properties of nanostructured hydroxyapatite prepared by a spray drying technique, J. Res. Natl. Inst. Stan. Technol. 109, 11-12. 

The second hierarchical level of the nanostructure (1—4nm) can be a rather complicated stmcture. It stabilizes the nanosized carrier by modifying the surface with biocompatible coverage (polyacrylamide, silica, hydroxyapatite, titanium, or aluminum oxide, etc.). The presence of a modifying layer retains a high specific surface of the nanoparticles and allows the necessary chemical functionalization, for example, with hydroxyl, carboxyl, thiol, and amino groups. 

A variety of nanoeomposite materials designed to mimic the nanostructure and composition of natural bone have been proposed. The most common inorganic component is hydroxyapatite it is the mineral component of bone and indeed it provides good osteoconductivily and adhesion to existing bone tissues. 

Recently, reinforcement of chitosan film with carbon nanotubes was tested. This composite demonstrates a large increase in the tensile modulus with the incorporation of only 0.8% of multiwalled carbon nanotubes [133]. Many papers concern bio-inorganic composites, including hydroxyapatite, which increases the mechanical properties and mimics the nanostructure of bone [88, 134, 135]. 

Kim IS, Kumta PN. Sol-gel synthesis and characterization of nanostructured hydroxyapatite powder. Mater Sci Eng B-Solid 2004 111 232-6. 

Rojaee R, Fathi M, Raeissi K. Electrophoretic deposition of nanostructured hydroxyapatite coating on AZ91 magnesium alloy implants with different surface treatments. Appl Surf Sci 2013 285 664-73. 

PMMA/hydroxyapatite bone cement. Both nanostructures were found to capture the radicals produced during the cement polymerization process, thereby hampering their normal course and affecting the mechanical properties of the nanocomposites, especially the one-dimensional nanoform [145]. Recently, we have compared both 1D and 2D carbon nanostructures and the effect of functionalization on the thermomechanical properties. As seen in Figure 10.13, the nanofillers containing carboxylic groups provided the best mechanical response at 1 wt% loading. Additionally, the 2D carbon structures provided better reinforcement in the electrospun fibers when compared to the ID carbon nanomaterials [116,158]. 

Dental implants and prosthetics alone account for a substantial proportion of the dental industry. It is therefore of no surprise that researchers focus heavily on this avenue. In contrast to other industries, dental industry nanocoatings do not perpetually involve the deposition of thin nanolayers onto a substrate. Often they can refer to the incorporation of nanostructured materials or particles into coatings on contact surfaces. For instance, a recent piece of work examined the usage of nanostructured hydroxyapatite (HA) as a filler material for root canal. HA (a commonly used material in coating implants to aid cell proliferation) particles sized at approximately 26 mn were incorporated into root canal sealer at variable ratios. At high concentrations, there was little difference in film thickness (implying they would meet ISO standards for root canal sealers). The observed improvements suggested that nanostructured HA could be used to formulate more stable tooth material interfaces [40]. 

Collares FM, Leitune VC, Rostirolla FV, Trommer RM, Bergmann CP, Samuel SM. Nanostructured hydroxyapatite as filler for methacrylate-based root canal sealers. Int Endod J 2012 45(l) 63-7. Available from PM 21899568. 

Nanostructured hydroxyapatite Caio(P04)g(OH)2 (HAP) was synthesized using aqueous solutions of the corresponding salts of phosphorus ((NH4)2HP04) and nitric (Ca(N03) 2H20) acids (Vysotskaja et al. 2002) ... 

HGA composites with nanostructured hydroxyapatite and proteins (gelatin, BSA)... 

Sutmeneva MA, et al. Effect of silicate doping on the structure and mechanical properties of thin nanostructured RF magnetron sputter-deposited hydroxyapatite films. Surf Coat Technol 2015 275 176-84. 

Stupp and collaborators have used the reversible pH-induced self-assembly of peptide-amphiphiles to make nanostructured fibrous scaffold reminiscent of extracellular matrix. These fibers can be cross-linked by formation of intermolecular disulfide oxidation that reinforce the supramolecular assembly by covalent capture which is also made reversible by possible reduction to the thiol function. After cross-linking, the fibers are able to direct mineralization of hydroxyapatite to form a composite material in which the crystallographic c axes are aligned with the long axes of the fibers, which is similar to collagen fibrils and hydroxyapatite crystals in bone (Figure 12)." ... 

Supramoleciflar directed self-assembly of inorganic and inorganic-organic hybrid nanostructures has emerged as an active area of recent research. The recent advance shows a remarkable feasibihty to mimic natoal mineralization systems by a designed artificial organic template, where a supramolecular functional polymer can be directly employed as minerahzation template for the synthesis of novel inorganic nanoarchitectures [165] such as CdS helices [166] and hydroxyapatite (HAP) nanofibers [167]. 

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