Application of Electron Spin Resonance Spectroscopy in bone regeneration studies

Electron spin resonance (ESR) is a spectroscopic technique that detects unpaired electrons, such as the ones present in free radicals. When a calcifed tissue is irradiated, free radicals are generated, like the CO₂⁻. This paper presents a preliminary study on the application of this spectroscopic technique for monitoring bone mineralization processes during the bone repair in animal model, induced by polyurethane in two forms, as an occlusive membrane and as a bone grafting. In the first experiment, the ESR results and microscopic analysis demonstrate centripetal bone growth and advanced stage of bone regeneration in the treated group. In the second experiment, the ESR spectrum of collected bone pieces presents the superposition of the spectrum of the biomaterial and the radical CO₂⁻. The separation of the components was made using spectral simulation, and the percentage of mature bone tissue in the defect region was determined through the comparison with the spectrum of the native bone. In both experiments, ESR provided results consistent with microscopic analysis, demonstrating the feasibility of the technique for monitoring bone regeneration. (author)