非损伤微测Zn2+选择性微电极的研发及应用

非损伤微测技术(Non-invasive Micro-test Technology, NMT)是一种通过微电极实时测定进出活体材料离子和小分子流速的技术,已广泛应用于植物的生长发育和逆境胁迫等研究领域中。目前该技术专用的重金属微电极种类非常少,因此其在重金属胁迫研究中的应用也受到了限制。本文在前期工作的基础上开发了一种基于非损伤微测技术的Zn~(2+)选择性微电极,首次实现了活体条件下植物根际Zn~(2+)离子流的实时、动态检测。研发的微电极在去离子水中对Zn~(2+)的线性响应范围为10–6～10~(–1) mol/L,能斯特斜率为30.2mV/decade(浓度每增加或减少10倍电位值的变化),响应时间t_(95%)≤1s,正常工作pH范围为3.5～7.0;在简易模拟土壤溶液(0.1mmol/L Ca(NO_3)_2、0.1 mmol/L KNO_3、0.1 mmol/L Mg(NO_3)_2和1 mmol/L NaNO_3)中,其线性响应范围变为5×10~(-5)～10~(-1) mol/L,能斯特斜率为28.1mV/decade,对土壤溶液中的共存阳离子具有较好的抗干扰性。利用构建的非损伤微测Zn~(2+)选择性微电极对Zn/Cd超积累植物伴矿景天(Sedum plumbizincicola)根际不同微区的Zn~(2+)离子流进行了实时检测。该技术的成功研发为活体条件下深入认识Zn~(2+)在植物根际的微界面过程与机制提供了一种强有力的研究手段。

Development and Application of Zn2+ Selective Microelectrode for Non-invasive Micro-test Technology

Non-invasive Micro-test Technology (NMT) has been widely applied in the study of plant root growth and development as well as the response of plant cell and tissue to abiotic stresses. Due to the limitations of its microelectrodes types for different heavy metals, its application in the study of toxicological effects of heavy metals in plant is also limited. Based on our previous work, a NMT Zn²⁺ selective microelectrode was constructed and for the first time was used for real-time monitoring Zn²⁺ flux at plant rhizosphere under living condition. The developed microelectrode has a Nernstian response (30.1 mV/decade of Zn²⁺ activity) to Zn²⁺ within the concentration range of 10^-6 to 10^-1 mol/L in DI water. The response time of the microelectrode is less than or equal to 1 s and the microelectrode can work well within a wide pH range of 3.5 to 7.0. While in simple simulated soil solution (containing 0.1 mmol/L Ca(NO₃)₂, 0.1 mmol/L KNO₃, 0.1 mmol/L Mg(NO₃)₂ and 0.1 mmol/L NaNO₃), it displayed a Nernstian response within Zn²⁺ concentration range of 5.0×10^-5 to 10^-1 mol/L with slope of 28.1 mV/decade, which indicates that the microelectrode has good anti-interference performance to the coexisting cations in soil solution. The developed Zn²⁺ selective microelectrode was then used to monitor Zn²⁺ flux at the rhizosphere of Zn/Cd hyperaccumulator Sedum plumbizincicola. This developed technique provides a powerful method for understanding the process and mechanism of Zn²⁺ at the micro-interface of plant rhizosphere under living conditions.