An infrared study of the interaction of polymethyl methacrylate with the protein and mineral components of bone.

We used Fourier transform infrared (FT-IR) microscopic mapping techniques to investigate the infiltration of polymethyl methacrylate (PMMA), a widely used medium for embedding biological tissues, into rat femur sections. Monitoring of the infrared absorbances of the PMMA carbonyl stretch, the protein amide I, and the apatite mineral phosphate stretch over a 225 x 975-microns region of the epiphyseal growth plate region of the rat femur enabled comparison of the relative amount of each component in distinct regions of the tissue. It was found that PMMA penetrates less into regions of greater mineral density and that the frequency of the PMMA carbonyl absorbance from the embedded tissue, 1729 cm-1, is identical to the free PMMA carbonyl frequency. This is consistent with a diffusion mechanism of infiltration of the PMMA, with no specific chemical interaction between the PMMA and the tissue components.