A Ratiometric Biosensor for Metallothionein Based on Dual Heterogeneous Electrochemiluminescent Responses from TiO2 Mesocrystals formed interface

Heterogeneous Electrochemiluminescent Responses from TiO2 Mesocrystals formed interface Hong Dai,a* Guifang Xu,a1 Shupei Zhang,a Zhensheng Hong,a Yanyu Lin a,b a College of Chemistry and Chemical Engineering, Fujian Normal University, Fuzhou 350108, P. R. China b Ministry of Education Key Laboratory of Analysis and Detection for Food Safety, and Department of Chemistry, Fuzhou University, Fuzhou 350002, P. R. China Chemicals and Materials. Metallothionein was purchased from Abcam (Cambridge, UK). Nafion 117 solution (5% w/v mixture of low molecular weight alcohols) was purchased from Sigma-Aldrich. Phosphate buffer solution (PBS) was prepared by mixing stock solution of 0.1 M NaH2PO4 and 0.1 M Na2HPO4 and adjusting the pH. Other reagents were of analytical regent grade. All solutions were prepared with deionized water by a Milli-Q water purification system (Millipore, Milford, MA, USA). Apparatus. ECL intensity versus potential was detected by using a system made in our laboratory, consisting of a BPCL Ultra-Weak Chemiluminescence Analyzer controlled by a personal computer with BPCL program (Institute of Biophysics, Chinese Academy of Sciences) in conjunction with a CHI 760 electrochemical analyzer (Shanghai Chenghua Instrument Co., China). The electrochemical analyzer was used for controlling waveforms and potentials. A conventional three-electrode system was used for the electrolytic system, including a bare GCE or modified GC electrode as the working electrode, a platinum wire as the counter electrode and Ag/AgCl electrode (sat. KCl) as the reference electrode. A commercial 5 ml cylindroid glass cell was used as ECL cell, and