Polymer membrane ion selective electrode is a potential sensor technology developed in the 1960s. It has the advantages of high selectivity, easy to use, low price, reliable performance, etc. It has been widely used in clinical detection and environmental analysis And other fields. In order to further improve the response characteristics of the membrane electrode and expand the application field of potential sensing, the research team of Qin Wei, the Key Laboratory of Coastal Zone Environmental Process and Bioremediation, Yantai Coastal Zone Research Institute, Chinese Academy of Sciences, conducted a systematic study:
1. Highly sensitive potential detection under strong electrolyte background conditions
Due to the susceptibility to interfering ions, ion-selective electrodes have not been used for the determination of background samples of strong electrolytes such as seawater for a long time. To this end, the research group developed an asymmetric polymer ion selective membrane, that is, the lipophilic ion exchanger is directly coated on the surface of the polymer membrane rather than uniformly dissolved in the polymer membrane, effectively eliminating the electrode membrane surface The diffusion of the main ions into the membrane improves the sensitivity of the ion selective electrode to detect trace ions; at the same time, the rotating electrode technology is used to significantly reduce the thickness of the aqueous phase diffusion layer and increase the diffusion rate of the main ions in the aqueous phase. In this study, copper ions were used as the detection object. Under the background condition of 0.5 mol / L NaCl, the asymmetric polymer sensitive membrane rotating electrode system was used to realize the highly sensitive potential detection of copper ions in the strong electrolyte matrix. The detection limit can reach 3.5 × 10-10 mol / L. This research work provides a new idea for the further development of trace heavy metal ion detection technology in seawater. Relevant research results were published in "Analytical Chemistry" in the United States (Anal. Chem., 2012, 84 (24), 10509–10513; IF = 5.856).
2. Potential biosensing technology based on unsteady state intermediate product ion response
The traditional ion-selective electrode biosensing technology generally uses the potential signal of the reactant or steady-state product ion in the chemical reaction for sensing; some chemical reactions of important analytical significance, because the reactant and product are non-ionic, long-term It has been considered unsuitable for potential detection. To this end, the research group proposed a detection idea based on the potential response of the ionic intermediate product, that is, by designing a sensitive membrane that can selectively capture the ionic intermediate product, to realize the potential detection of such chemical reactions. Taking peroxidase-catalyzed hydrogen peroxide oxidation of N, N ", N, N" -tetramethylbenzidine as an example, by capturing unsteady cation radicals and imine cations, dinonylnaphthalenesulfonic acid doped The polymer liquid membrane can achieve a highly sensitive indication of the reaction. The detection limit of hydrogen peroxide in this method is 10-9M, which is three orders of magnitude lower than the detection limit of hydrogen peroxide in the current potential analysis technology, which can meet the needs of hydrogen peroxide detection in environmental water bodies such as seawater and rain . Related research results were published in the British "Chemical News" (Chem. Commun. 2012, 48, 4073-4075; IF = 6.169).
3. New biosensing mode based on neutral molecular potential response
The potential response of neutral phenol molecules on polymer membrane electrodes is one of the important discoveries in the field of potential analysis in the past two decades. However, due to the problem of low sensitivity, the potential response of neutral phenol has never been used in environmental or biological analysis. The research team found for the first time that neutral oligomeric phenols have a significantly better anionic potential response than the monomeric phenol on quaternary ammonium salt doped polymer liquid membrane electrodes. Based on this, the first potential nuclease biosensor was developed by utilizing the properties of G-quadruplex nuclease to catalyze the formation of oligomeric phenol from monomeric phenol. Compared to photometric analysis and fluorescence analysis, potentiometric nuclease sensors have the advantages of high sensitivity, low cost, and resistance to color and turbidity interference. The sensing technology can realize nucleic acid hybridization analysis and DNA damage detection in a homogeneous solution, and has good application prospects in the identification of nucleic acid toxicity of environmental pollutants. Related results have been published online in the US "Analytical Chemistry" (Anal. Chem., 2013, DOI: 10.1021 / ac3035629; IF = 5.856).
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