Amidation hydroxyapatite

Muzzarelli et al. (2000) described a method for coating prosthetic articles with chitosan-oxychitin. Plates of titanium (Ti) and its alloys were plasma sprayed with hydroxyapatite and glass layers, and subsequently a chitosan coat was deposited on the plasma-sprayed layers using chitosan acetate. These layers were treated with 6-oxychitin to form a polyelectrolytic complex. This complex was optionally contacted with l-ethyl-3-(3-dimethylami-nopropyl) carbodiimide at 4°C for 2 hours to form amide links between the two polysaccharides, or acetylation with acetic anhydride in methanol to obtain a chitin film. In all cases, the modified coats were insoluble, uniformly flat, and smooth. Prosthetic materials coated with chitosan-oxychitin were capable of provoking colonization by cells, osteogenesis, and osteointegration. 

Fibrous fillers for biomedical PLA-based FRPs include carbon and inorganic fibres [406], PLLA (i.e. self-reinforcement) [407,408], poly(p-dioxane) fibre [409], chitin [410], biodegradable fibre (e.g. bioactive glass, chitosan fibre, polyester amides) [411], hydroxyapatite fibre [412], hydroxyapatite whiskers [413], halloysite (Al2Si205(0H)4) nanotubes [414] and the fibre from different tissue types of Picea sitchensis [415],... 

Examples of Raman spectra from three different types of human coronary artery are shown in Fig. 17. The top spectrum was obtained from a sample of nonatherosclerotic (normal) coronary artery, the middle from a noncalcified atheromatous plaque, and the bottom from a calcified plaque. The spectra from these different artery types are distinct and provide clear features for the determination of the chemical composition and for a histological classification of the arterial wall. For example, the normal coronary artery spectrum is dominated by protein features such as the amide I and III modes at 1650 and 1250 cm respectively, and the CH2 bending modes at —1450 cm In noncalcified atheromatous plaques, spectral features of cholesterol and cholesterol esters constitute the major part of the spectrum. The symmetric stretch at 960 cm of the calcium hydroxyapatite phosphate group dominates the spectrum of calcified plaques. 

---