The influence of pH and temperature on the morphology of hydroxyapatite synthesized by hydrothermal method

In this review article, the state-of-the-art of calcium orthophosphate-based biocomposites and hybrid biomaterials suitable for biomedical applications is presented. This subject belongs to a rapidly expanding area of science and research, because these types of biomaterials offer many significant and exciting possibilities for hard tissue regeneration. Through the successful combinations of the desired properties of matrix materials with those of fillers (in such systems, calcium orthophosphates might play either role), innovative bone graft biomaterials can be designed. The review starts with an introduction to locate the reader. Further, general information on composites and hybrid materials including a brief description of their major constituents are presented. Various types of calcium orthophosphate-based bone-analogue biocomposites and hybrid biomaterials those are either already in use or being investigated for various biomedical applications are then extensively discussed. Many different formulations in terms of the material constituents, fabrication technologies, structural and bioactive properties, as well as both in vitro and in vivo characteristics have been already proposed. Among the others, the nano-structurally controlled biocomposites, those with nanosized calcium orthophosphates, biomimetically fabricated formulations with collagen, chitin and/or gelatin, as well as various functionally graded structures seem to be the most promising candidates for clinical applications. The specific advantages of using calcium orthophosphate-based biocomposites and hybrid biomaterials in the selected applications are highlighted. As the way from a laboratory to a hospital is a long one and the prospective biomedical candidates have to meet many different necessities, the review also examines the critical issues and scientific challenges that require further research and development.

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Calcium Orthophosphate-Based Biocomposites and Hybrid Biomaterials

Various types of grafts have been traditionally used to restore damaged bones. In the late 1960s, a strong interest was raised in studying ceramics as potential bone grafts due to their biomechanical properties. A bit later, such synthetic biomaterials were called bioceramics. In principle, bioceramics can be prepared from diverse materials but this review is limited to calcium orthophosphate-based formulations only, which possess the specific advantages due to the chemical similarity to mammalian bones and teeth. During the past 40 years, there have been a number of important achievements in this field. Namely, after the initial development of bioceramics that was just tolerated in the physiological environment, an emphasis was shifted towards the formulations able to form direct chemical bonds with the adjacent bones. Afterwards, by the structural and compositional controls, it became possible to choose whether the calcium orthophosphate-based implants remain biologically stable once incorporated into the skeletal structure or whether they were resorbed over time. At the turn of the millennium, a new concept of regenerative bioceramics was developed and such formulations became an integrated part of the tissue engineering approach. Now calcium orthophosphate scaffolds are designed to induce bone formation and vascularization. These scaffolds are often porous and harbor different biomolecules and/or cells. Therefore, current biomedical applications of calcium orthophosphate bioceramics include bone augmentations, artificial bone grafts, maxillofacial reconstruction, spinal fusion, periodontal disease repairs and bone fillers after tumor surgery. Perspective future applications comprise drug delivery and tissue engineering purposes because calcium orthophosphates appear to be promising carriers of growth factors, bioactive peptides and various types of cells.

/pdf/calcium-orthophosphate-based-bioceramics-4c2yzraois.pdf

Calcium Orthophosphate-Based Bioceramics

Hydrothermal synthesis of hydroxyapatite nanopowders using cationic surfactant as a template

In the late 1960s, much interest was raised in regard to biomedical applications of various ceramic materials. A little bit later, such materials were named bioceramics. This review is limited to bioceramics prepared from calcium orthophosphates only, which belong to the categories of bioactive and bioresorbable compounds. There have been a number of important advances in this field during the past 30–40 years. Namely, by structural and compositional control, it became possible to choose whether calcium orthophosphate bioceramics were biologically stable once incorporated within the skeletal structure or whether they were resorbed over time. At the turn of the millennium, a new concept of calcium orthophosphate bioceramics—which is able to promote regeneration of bones—was developed. Presently, calcium orthophosphate bioceramics are available in the form of particulates, blocks, cements, coatings, customized designs for specific applications and as injectable composites in a polymer carrier. Current biomedical applications include artificial replacements for hips, knees, teeth, tendons and ligaments, as well as repair for periodontal disease, maxillofacial reconstruction, augmentation and stabilization of the jawbone, spinal fusion and bone fillers after tumor surgery. Exploratory studies demonstrate potential applications of calcium orthophosphate bioceramics as scaffolds, drug delivery systems, as well as carriers of growth factors, bioactive peptides and/or various types of cells for tissue engineering purposes.

https://www.mdpi.com/2079-4983/1/1/22/pdf

Calcium Orthophosphates as Bioceramics: State of the Art

Hydroxyapatite/0%-30% hydroxyapatite-whisker (HAp/0%-30%HAp(w)) composites have been fabricated by pressureless sintering, hot pressing, and hot isostatic pressing (HIP). Composites that were HIPed at 1000°-1100°C (2 h, 190 MPa) exhibited the best properties: relative densities of 97.0-99.5%, fracture toughness of 1.4-2.0 MPa·m1/2 (as compared with 1.0 MPam1/2 for the nonreinforced HAp matrix). Compressive pre-stressing and crack deflection contributed mostly to the increase of fracture toughness. Depending on processing conditions, grain growth in the HAp matrix and/or Rayleigh instability of the HAp whiskers were probably responsible for microstructural changes in the composites. The HAp/HAp(w) composites exhibited improved toughness, attaining the lower fracture-toughness limit of bone without a decrease of bioactivity and biocompatibility.

Hydroxyapatite/Hydroxyapatite (Whiskers) Composites without Sintering Aids ­ Mechanical Properties and Microstructural Evolution

PURPOSE:To produce high-performance compound oxide suitable for a superconductor, comprising a single phase. CONSTITUTION:One or more selected from a carbonate, hydroxide, sulfate, carboxylate, halide and alkoxide of a metal to form a complex oxide is reacted with a hydroxycarboxylic acid or polyamino chelating agent to give a metal complex, which is subjected to polymerization reaction in a solvent to form a complex polymer, and then the complex polymer is burnt.

Production of compound oxide by complex polymerization method

PROBLEM TO BE SOLVED: To provide a method capable of simply, safely and efficiently obtaining a high quality group 13 element nitride compound, especially a bulky single crystal of gallium nitride. SOLUTION: In the method for manufacturing the group 13 element nitride crystal, the bulky single crystal is obtained by performing crystal growth by heating and melting a mixture of a group 13 element nitride raw material and a metal halide. COPYRIGHT: (C)2005,JPO&NCIPI

Method for manufacturing group 13 element nitride crystal

PROBLEM TO BE SOLVED: To provide a method of producing metal oxide nano-crystal by which the crystallite diameter of the metal oxide nano-crystal can be precisely controlled in increments of several nanometers. SOLUTION: The metal oxide is obtained by treating an oxygen-containing organic solvent containing a metal oxide precursor and water coexisting in an amount of 15-50 times of the molar number of the metal oxide precursor by a solvothermal method. COPYRIGHT: (C)2008,JPO&INPIT

Method of producing metal oxide nano-crystal

PURPOSE: To easily and surely form a Pb(Zr, Ti)O 3 film on Ti metal at a low temp. without necessitating any post-treatment process. CONSTITUTION: The lead titanate zirconate (Pb(Zr, Ti)O 3 ) film is formed on the Ti substrate or on the Ti metal film formed on the surface of the Ti substrate by dipping the Ti substrate or the substrate on which the Ti metal film is formed into an alkaline aq. solution having ≥pH14 containing ≥0.1mol/l lead (Pb) chemical species and ≥0.05mol/l zirconium (Zr) chemical species and hydrothermally treating at ≥200°C. COPYRIGHT: (C)1994,JPO&Japio

昌弘吉村

Papers

Hydroxyapatite/Hydroxyapatite (Whiskers) Composites without Sintering Aids Mechanical Properties and Microstructural Evolution

Production of compound oxide by complex polymerization method

Method for manufacturing group 13 element nitride crystal

Method of producing metal oxide nano-crystal

Production of composite body containing film of titanium metal and lead titanate zirconate and composite body

昌弘 吉村

Papers

Hydroxyapatite/Hydroxyapatite (Whiskers) Composites without Sintering Aids ­ Mechanical Properties and Microstructural Evolution

Production of compound oxide by complex polymerization method

Method for manufacturing group 13 element nitride crystal

Method of producing metal oxide nano-crystal

Production of composite body containing film of titanium metal and lead titanate zirconate and composite body

昌弘吉村

Hydroxyapatite/Hydroxyapatite (Whiskers) Composites without Sintering Aids Mechanical Properties and Microstructural Evolution