U(Ⅵ)在人体组织液中的形态模拟

Simulation of U(Ⅵ) Speciation in Human Interstitial Fluid

铀的毒性与其体内形态密切相关,研究铀在人体组织液的形态有助于了解铀的人体毒理。本工作采用热力学平衡模拟方法研究U（Ⅵ）在人体组织液中的形态。建立了含多种金属离子和小分子配体组成的多相组织液热力学平衡模型,模拟研究了H2O-CO32--PO43-体系中UO22＋的形态分布、组织液中UO22＋的形态分布及总CO32-次氮三酯酸（NTA）浓度对组织液中UO22＋形态分布的影响。结果表明,在H2O-CO32--PO43-体系中,当UO22＋总浓度为1.5μmol/L、pH〉7.0时,UO22＋主要以[UO2（CO3）3]4-和[UO2（CO3）2]2-存在,pH〈6.0时,主要以UO2HPO4和UO2（H2PO4）2存在;当UO22＋浓度为0.15 mmol/L、pH〉7.0时,UO22＋仍以[UO2（CO3）3]4-和[UO2（CO3）2]2-为主,pH3~6时,主要以固相（UO2）3（PO4）2出现。在组织液模型中,当UO22＋总浓度为1.5μmol/L、pH〉7.0时,UO22＋主要以[UO2（CO3）3]4-、[UO2（CO3）2]2-和[UO2Cit2]4-存在,pH〈6.0时,主要以[UO2Cit2]4-存在;当UO22＋浓度为0.15 mmol/L、pH〉7.0时,UO22＋仍以[UO2（CO3）3]4-、[UO2（CO3）2]2-和[UO2Cit2]4-存在,pH 3~6时,以固相（UO2）3（PO4）2为主。当UO22＋浓度为1.5μmol/L或0.15 mmol/L时,提高CO32-浓度能改变UO22＋在组织液中的形态分布：[UO2（CO3）3]4-含量升高,[UO2（CO3）2]2-和[UO2Cit2]4-含量降低。NTA的加入改变了组织液中UO22＋的形态分布,但并没产生UO22＋的NTA螯合物形态。当UO22＋浓度为1.5μmol/L时,提高NTA浓度可使UO22＋主要以[UO2Cit2]4-存在;当UO22＋浓度为0.15 mmol/L时,UO22＋主要以[UO2（CO3）2]4-形式存在。

A multi-phase equilibrium model consisted of multi-metal ion and low molecular mass ligands in human interstitial fluid were constructed to discuss the speciation of UO22＋.Computer simulations indicated that the major UO22＋ species were [UO2（CO3）3]4-and [UO2（CO3）2]2-at pH 7.0,and the major species were UO2 HPO4 and UO2（H2PO4）2 at pH6.0 when [U] was 1.5 μmol/L in H2O-CO32——PO43-model,whereas,the major species was solid（UO2）3（PO4）2 at pH3~6 when [U] was 0.15 mmol/L.Speciation study showed that UO22＋ existed mainly in the forms of [UO2（CO3）3]4-,[UO2（CO3）2]2-and [UO2Cit2]4-at pH7.0 and in the form of [UO2Cit2]4-at pH6.0 when [U] was 1.5 μmol/L,and the major species was solid（UO2）3（PO4）2 at pH 3~6 when [U] was 0.15 mmol/L.The percentage of [UO2（CO3）3]4-increased with the while the percentage of [UO2（CO3）2]2-and [UO2Cit2]4-decreased with higher whenever the [U] was 1.5 μmol/L or 0.15 mmol/L.The UO22＋ was not chelated with NTA despite of its speciation was inflected when NTA was in the interstitial fluid model.The dominant species was [UO2Cit2]4-when high concentration NTA in the interstitial fluid model when [U] was 1.5 μmol/L,and the major species was [UO2（CO3）3]4-when [U] was 0.15 mmol/L.