Daar Eman, King L, Nisbet A, Thorpe R B, Bradley D A
Department of Physics, University of Surrey, Guildford, Surrey, UK.
Appl Radiat Isot. 2010 Apr-May;68(4-5):746-50. doi: 10.1016/j.apradiso.2009.10.022. Epub 2009 Oct 22.
Hyaluronic acid (HA) is a significant component of the extracellular matrix (ECM), particular interest being shown herein in synovial fluid. The present study aims to investigate the degrading effects of X-ray radiation on HA at radiotherapy doses. Measurements of viscosity and shear stresses on HA solutions have been made at different shear rates using various types of viscometer for different concentrations in the range 0.01-1% w/v of HA. The HA has been subjected to doses of 6 MV photon radiation ranging from 0 to 20 Gy, the major emphasis being on doses below 5 Gy. It is found that there is a dose-dependent relationship between viscosity and shear rate, viscosity reducing with radiation dose, this being related to polymer scissions via the action of radiation-induced free radicals. The dependency appears to become weaker at higher concentrations, possibly due to the contribution to viscosity from polymer entanglement becoming dominant over that from mean molecular weight. Present results, for HA solutions in the concentration range 0.01% to 1% w/v, show reduced viscosity with dose over the range 0-4 Gy, the latter covering the dose regime of interest in fractionated radiotherapy. The work also shows agreement with previous Raman microspectrometry findings by others, the possible bond alterations being defined by comparison with available published data.
透明质酸（HA）是细胞外基质（ECM）的重要组成部分，本文特别关注其在滑液中的情况。本研究旨在探究X射线辐射在放疗剂量下对HA的降解作用。使用各种类型的粘度计，在不同剪切速率下对浓度范围为0.01 - 1% w/v的HA溶液进行了粘度和剪切应力测量。HA接受了0至20 Gy的6 MV光子辐射剂量，主要重点是低于5 Gy的剂量。研究发现，粘度与剪切速率之间存在剂量依赖关系，粘度随辐射剂量降低，这与辐射诱导自由基作用导致的聚合物链断裂有关。在较高浓度下，这种依赖性似乎变弱，可能是由于聚合物缠结对粘度的贡献超过了平均分子量的贡献。对于浓度范围为0.01%至1% w/v的HA溶液，目前的结果表明在0 - 4 Gy范围内粘度随剂量降低，后者涵盖了分次放疗中感兴趣的剂量范围。该研究还与其他人之前的拉曼光谱研究结果一致，通过与现有已发表数据比较确定了可能的键变化。
