Molecularly imprinted sensor based on Russian Matryoshka structured molecules for enhanced specific identification and double amplification in ultra-trace Tb3+ determination

Publication date: 30 June 2018
Source:Biosensors and Bioelectronics, Volume 109
Author(s): Jianping Li, Bin Yang, Hongcheng Pan, Guobao Xu
The selective and sensitive detection of rare earth elements is thought to be difficult because the concentration of those elements in the sample is commonly at a low level and they normally have severe mutual interference which is caused by homologous chemical properties. In this study, a novel molecularly imprinted polymer (MIP) sensor was fabricated for highly sensitive and selective determination of ultra-trace Tb³⁺. The Tb³⁺-ethylenediaminetetraacetic acid complex (Tb-EDTA) as the template molecule was incorporated into mono-6-mercapto-β-cyclodextrin (mono-6-SH-β-CD) to form a Russian Matryoshka (RM)-structured molecule (CD/Tb-EDTA). Titanium isopropoxide was utilized in vapor sol–gel polymerization to construct MIP membrane. Moreover, the selectivity of the RM MIP sensor was remarkably enhanced by the "triple-selectivity" recognition of EDTA-to-Tb³⁺, β-CD-to-(Tb-EDTA), and 3D cavity-to-(CD/Tb-EDTA), while the sensitivity of the MIP sensor was significantly improved by ECL signal enhancement based on double amplification, in other words, the electrochemiluminescence resonance energy transfer (ECL-RET) between the ECL donor of CD/Tb-EDTA and the ECL acceptor of Ru(bpy)3²⁺, and the ECL enhancement by the co-reactant of CD/Tb-EDTA on Ru(bpy)3Cl2. When the imprinted cavities were occupied by Tb-EDTA during rebinding, the host-guest inclusion structured complex was formed and the ECL intensities produced by the Ru(bpy)3Cl2 ECL system increased with increasing concentration of Tb-EDTA. The proposed sensor was used for quantitative analysis of Tb³⁺ with concentrations ranging from 8.00 × 10^–13 mol/L to 4.00 × 10^–9 mol/L and successfully applied to detect Tb³⁺ in seawater samples. The detection limit of the sensor was found to be 3.90 × 10^–13 mol/L (DL = 3δb/K), which is lower than previously reported values. Thus, the fabricated sensor is feasible for practical applications.



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