Study Of Optical And Electrochemical Sensors Based On Organic Molecular Probes

Carrier-based chemical sensors are conventional analysis methods in analytical chemistry field with well-defined theory and expected experiment results. However, there are still some drawbacks exposed during applications, such as potential instability, long response time, components leaching, shorter lifetime and so on.Calix[4]arene-based fluorescent sensors have unique advantages compared to other analytical methods, such as high sensitivity and selectivity, short response time and in situ analysis. Fluorescent sensors are mainly composed of ionophore and chemo-sensors.Calix[4]arene as a ionophore plays a critical part in ion selectivity and BODIPY as a chemosensor can transmit signal.The optical physical property of the chemo-sensor would change after the reaction of the analyte with an ionophore, including fluorescent intensity, quantum yield and fluorescence life time. In order to explore the chemical sensors with more ideally properties, lots of work has been done as follows:(1) Designed and prepared novel ion-selective optodes based on near infrared (NIR) calix[4]arene-BODIPY fluorescent dyes as pH chromionophores. First, calix[4]arene was synthesized from de-tert-butyl reaction of tert-butyl-calix[4]arene.5-BODIPY-calix[4]arene was synthesized by formylation of calix[4]arene and then reaction with 2,4-dimethyl pyrrole. 5,17-bis(BODIPY)-25,27-dipropoxycalix[4]arene was synthesized by formylation of 25,27-dipropoxycalix[4]arene and then reaction with 2,4-dimethyl pyrrole. Second, the spectrum property of the two dyes in homogeneous solution were then characterized via UV, Fluorescence Spectrophotometer and etc. By comparison of various effects of different plasticizers and ion-exchangers in the PVC membrane matrices, anion-exchanger TDMACl is a superior choice in the response of pH over cation-exchanger NaTFPB in the system of Dye 1. The response mechanism of the optode is achieved by the balance of protonation-deprotonation equilibria of chromionophore calix[4]arene in the membrane. The novel ion-selective optodes based on NIR dyes with extended conjugated systems can avoid the influence of tissue autofluoresence and light absorption of tissue between 650 and 900 nm, resulting in more sensitive and precise analysis of ions in biosystem.(2) A N-benzyl-N-isopropyl-acrylamide and butyl acrylate(BPA-BA-AU-1) copolymer, with calcium ionophore AU-1, has been used to fabricate plasticizer-free ion-selective membranes. Calcium ionophore AU-1 was covalently attached to the copolymer by organic synthesis. The ion-selectivity of AU-1 dispersed uniformly in PVC membrane or attached to the copolymer material was evaluated, respectively. The copolymer membranes were found to be similar to corresponding membrane made from poly(vinyl chloride) plasticized with bis(2-ethylhexyl sebacate)(PVC-DOS) and other plasticizer membranes. The copolymer membranes show good mechanical properties, excellent selectivity similar to the corresponding PVC-DOS/PVC-NPOE membranes. This made BPA-BA a potentially superior choice over alternative membrane matrices reported in the literature and a promising platform for the establishment of covalently immobilized membrande components.