Simulated body fluids

Kokubo et al. [16,17] showed that the hydroxyapatite formation on the surfaces of bioactive materials in the living body can be reproduced even in an acellular protein-free simulated body fluid (SB F) with ion concentrations nearly equal to those of human blood plasma. This indicates that the hydroxyapatite layer is formed through chemical reaction of the bioactive glass with the surrounding body fluids. The formed layer consists of carbonated hydroxyapatite with small crystallites and low crystallinity, which is similar to bone hydroxyapatite. Hence the bioactivity of a material can be evaluated even in vitro by examining the hydroxyapatite formation on its surface in SBF. 

SBF is a solution that has inorganic ion concentrations similar to those of human blood plasma but does not contain any cells or protein. A brief summary of SBF, introduced by Cho et al. [17], follows. The ion concentrations of SBF are given in Table 11.1 [17]. The pH of SBF is typically adjusted to 7.25 or 7.40 at 36.5 °C. This fluid is a metastable solution containing calcium and phosphate ions supersaturated with respect to hydroxyapatite. SBF is prepared by successively dissolving the reagent-grade chemicals in ultra-pure water in the order given in Table 11.2 [17]. Each new chemical is added after the previous one has completely dissolved. The temperature 

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Results were obtained on the calcium phosphate growth on phosphory-lated chitin fibres using the urea/H3P04 method and subsequently soaked in saturated Ca(OH)2 solution and in simulated body fluid solution. 

Ohtsuki, C., Kokubo, T. and Yamamuro, T. (1992) Mechanism of apatite formation on Ca0-Si02-P20s glasses in a simulated body fluid. Journal of Non-Crystalline Solids, 143, 84-92. 

Uchida, M., Kim, H.-M.Miyaji, F. Kokubo, T. and Nakamura, T. (2001) Bonelike apatite formation induced on zirconia gel in a simulated body fluid and its modified solutions. Journal of the American Ceramic Society, 84, 2041-2044. 

Tanahashi, M. and Matsuda, T. (1997) Surface functional group dependence on apatite formation on self-assembled monolayers in a simulated body fluid. Journal of Biomedical Materials Research, 34, 305-315. 

Kim, H.-M., Kishimoto, K., Miyaji, F., Kokubo, T., Yao, T., Suetsugu, Y., Tanaka, J. and Nakamura, T. (2000) Composition and structure of apatite formed on organic polymer in simulated body fluid with a high content of carbonate ion. Journal of Materials Science-Materials in Medicine, 11, 421—426. 

Fig. 12.6 Scanningelectron micrographs obtained forthe surface of a BG-PVAL hybrid material, before (A) and after (B) soaking in simulated body fluid.

The delivery curve of ibuprofen to simulated body fluid (SBF) from MCM-41 spheres in the low submicron range shows anomalies, which are ascribed to a temporary blocking of the pores, healed by the molecule itself. 

S.M. Barinov, I.V. Fadeeva, L.V. Fateeva, S.V. Tumanov, Delayed fatigue of hydroxy-and fluorhydroxyapatite ceramics in simulated body fluid, Key Eng. Mater. 290 (2005) 366-369. 

Kino, R., Ikoma, T., Monkawa, A., Yunoki, S., Munekata, M., Tanaka, J., and Asakura, T. "Deposition of bone-like apatite on modified silk fibroin films from simulated body fluid". J. Appl. Polym. Sci. 99(5), 2822-2830 (2006). 

Weng, J., Liu, Q., Wolke, X G. C., Zhang, X., and de Groot, K., Formation and characteristics of the apatite layer on plama-sprayed hydroxyapatite coatings in simulated body fluid. Biomaterials 18 (15), 1027-1035 (1997). 

Systemic injection (acute toxicity) is designed to determine the biological response to a single intravenous or intraperitoneal injection of an extract (50mg/kg) of a material over a 72-hour time period (35). Extracts are prepared using saline or other solutions that simulate body fluids. Animals are monitored for signs of toxicity immediately after injection and at various time intervals (1). 

Mechanical testing of the polyurethanes was performed by a modified identation/shear method described by Parsons and Black.(11) Relaxed and unrelaxed shear moduli of these polymers were measured in a simulated body fluid environment and compared to moduli of rabbit and human articular cartilage. This is shown in Table V. These tests, in addition to viscoelastic measurements of those polymers, indicate that this new polyurethane formulation is an excellent candidate for synthetic cartilage fabrication. 

Filmon et al. (25) observed that modification of PHEMA through carboxymethylation with bromoacetic acid in alkaline medium induced considerable calcium deposition. For immersion in simulated body fluid (SBF), Miyazaki et al. (26) found that calcification was favorable in some circumstances when the polymer contained 20 and 50 mole% carboxyl groups. 

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