Institute of Semiconductor Physics of NAS of Ukraine, 45, pr. Nauky, Kiev, 03028, Ukraine.
Health Phys. 2010 Feb;98(2):322-6. doi: 10.1097/01.HP.0000346796.30582.64.
Biological apatites (tooth enamel, bone) and their synthetic analogues were exposed to gamma rays, UV light, or thermal treatment and studied by electron paramagnetic resonance (EPR). The thermal generation of CO2- radicals in synthetic apatite was observed for the first time. It was shown that the experimental EPR spectra of all of the above-mentioned materials are caused by the contribution of two types of CO2- radicals: axial and orthorhombic. The ratio of their concentrations depends on the characteristic energy of the external influence (i.e., the energy of quantum for radiation or kT for thermal treatment) and also on the quality of the initial material (defectiveness). Based on the analysis of EPR spectra recorded immediately after gamma-irradiation, the authors conclude that the main short-lived radical in bioapatites is CO3(3)- . The unified mechanism of CO2- radical formation in hydroxyapatites at different external influences is proposed; the main stages of transformation are CO3(2)- + e --> CO3(3)- --> CO2-, where the electron (e) originates from the ionization of impurities by radiation/temperature.
生物磷灰石（牙釉质、骨骼）及其合成类似物经γ射线、紫外线或热疗处理后，采用电子顺磁共振（EPR）进行研究。首次观察到在合成磷灰石中热生成 CO2-自由基。实验结果表明，上述所有材料的 EPR 谱均由两种类型的 CO2-自由基的贡献引起：轴向和正交。它们的浓度比取决于外部影响的特征能量（即辐射的量子能量或热疗的 kT），也取决于初始材料的质量（缺陷）。基于对γ辐照后立即记录的 EPR 谱的分析，作者得出结论，生物磷灰石中的主要短寿命自由基是 CO3(3)-。提出了在不同外部影响下羟基磷灰石中 CO2-自由基形成的统一机制；主要的转化阶段为 CO3(2)- + e --> CO3(3)- --> CO2-，其中电子（e）源自辐射/温度对杂质的电离。
