利用纳米金对DNA构型的区分效应设计了一种快速灵敏可视化的pH计。 对i-motif DNA-纳米金体系的紫外可见吸收光谱变化进行了系统研究， 考察了盐浓度、 i-motif DNA浓度、 四重体形成时间以及DNA序列对pH响应的影响。 在既定条件下， 纳米金的紫外-可见吸收光谱在pH 5.3～7.0范围内呈现规律性变化， 在520 nm处的吸光度逐渐增大， 在700 nm处的吸光度逐渐减小， 纳米金的颜色逐渐由蓝紫色变化至红色。 该pH计具有纳米金无需修饰、 可视化、 成本低、 速度快等特点， 有望用于某些pH值发生变化的生命过程的监测。

A fast, sensitive, colorimetric method for the detection of pH based on the differentiate effect of gold nanoparticles to the configuration of DNA was developed in this study. The UV-Vis absorption spectroscopy of the i-motif DNA-Au NPs system has been investigated, and the effect of the concentration of salt and i-motif DNA, reaction time and DNA sequence on the pH response of the system have been also optimized. Under the optimum conditions, the UV-Vis absorption spectroscopy of the Au NPs is changed regularly with pH in the range of 5.3～7.0, the absorbance at 520 nm is increased gradually while at 700 nm decreased. Correspondingly, the color of the Au NPs is varied from violet to red. The pH sensor is no need to modification, low cost, fast and can be carried out by naked eyes. It is promising to use in monitoring some life process which associated with pH variation.