Abstract

The class of ceramics used for repair and replacement of diseased and damaged parts of musculoskeletal systems are termed bioceramics. Bioceramics range in biocompatibility from the ceramic oxides, which are inert in the body, to the other extreme of resorbable materials. To the most used bioresorbable ceramics belong calcium orthophosphates, represented by hydroxyapatite (HA). In past decades, many different methods have been introduced and presented for preparing HA nanoparticles with precise control for microstructure, particle shape and size. Mineral phase can be also obtained from a wide range of natural sources, called as bioapatite (BAp), as an alternative to processes for preparing synthetic apatite. It is believed that nanosized BAp isolated or prepared from biogenic sources is the best material for tissue replacement and regeneration. It exhibits enhanced resorbability and much higher bioactivity than micron-sized or synthetic HA. The release of calcium ions from nanosized BAp is also similar to the behaviour of the apatitic phase in real tissue. In recent decades, a number of isolation and preparation routes for producing BAp have been developed and published. This chapter will summarize recent and very recent work on isolating and preparing bioapatites from various natural sources. First, the physicochemical properties of bioapatites will be briefly described. Then a general summary of natural, that is animal (mammalian, birds, reptiles, fish, corals, cephalopoda, mussels, sea urchins) and vegetal (fruit and vegetable peels, flowers, leaves, stalks) sources for bioapatite production from various environments, such as terrestrial (animal bones and eggshells, vegetation) and water (animal bones, scales and exoskeletons, water weeds) will be made. Special attention will be paid to describing individual methods for acquiring bioapatite from biogenic sources, that is direct isolation of bioapatite, and indirect biomimetic synthesis with the aid of naturally derived biomolecules or biomembranes.

In the field of tissue engineering a variety of different multicomponent materials are currently being used as scaffolds for soft or hard tissue defects reconstruction. These engineered composite materials has to provide the functionality associated with specific living biological tissues. In other words, they should provide the appropriate biological, structural, chemical, and mechanical cues to promote normal cellular behavior and function, and thus provide help for early reparation of the defected tissue. This chapter will focus on the composites based on various naturally derived components and the strategies for preparing them. It will summarize recent work on preparing a class of materials termed bio-nanocomposites which can be defined as multiphase materials where at least one of the phases has a biological origin and one of the phases has dimension of less than 100 nm. Beside the bio-nanoceramics based composites, the summary of natural polymers, for example collagen, gelatin, chitin, chitosan and their derivates, hyaluronan, cellulose, based composites will be made. Special attention will be paid to combination of bio-nanoceramics and biodegradable synthetic polymers including poly(α-hydroxy acids), for example poly(lactid acid), poly(glycolid acid) and their copolymers and poly(ɛ-caprolactone).

Keywords

Bioapatite

Calcium Phosphate

Hydroxyapatite

Nanoceramics

Nanocomposite

Naturally Derived Material

Polymer

1 Bio-nanoceramics   29

1.1 Bioapatites   30

1.2 Preparation of synthetic apatites simulating native BAp   33

1.3 Isolation and preparation of BAp from various biogenic sources   38

1.3.1 Isolation of BAps from biowastes   38

1.3.2 Preparation of apatites by reacting extracted Ca precursor with phosphate ions   41

1.3.3 In situ synthesis using naturally derived biomolecules or biomembranes   42

2 Bio-nanocomposites   43

2.1 Composites containing apatites with natural polymer matrices   44

2.2 Composites containing BAp with polymer matrices   48

3 Summary and Perspectives   51

Acknowledgment   52

References   52

Table 1

Composition and lattice parameters of mineral phase of bone compared with stoichiometric HAp, as reported by Dorozhkin and Epple...