Synthesis Of Cationic Porphyrins And Their Applications In The Biological Sensing

pH measurement is widely used in many fields such as agriculture, wastewater treatment, industrial processes and environment monitoring. It is reported that the normal physiological pH range was between 7.36~7.44, but the acidification of cells will lead to the apoptosis of tumor cells. So it is very important to study the precise measurement of the pH value in the chemical biology. More and more pH-sensitive materials and techniques have been developed for pH-sensing. In these, optical methods have received particular attention. However, optical measurements are readily suffered from the interferences from various factors, such as light scattering, the fluctuation of light-source intensity, probe concentration and inhomogeneous distribution, the sensitivity of instruments. To alleviate these limitations, ratiometric measurements were developed by calculating the ratio of the signals at two wavelengths, one of which is used as a reference. Because of such a self-referencing capability, better detection precision can be provided by ratiometric measurements than those using only one wavelength. In this thesis, five cationic porphyrin probes have been designed as colorimetric and fluorescent bimodal ratiometric pH-senses. The further investigation is showed that these probes have excellent reversibility, good accuracy and low cytotoxicity, and can be successfully applied in pH-sensing inside living cells.The following aspects were included in this thesis:1) A new cationic porphyrin derivative TTAPo PP has been synthesized and structural characterized firstly.2) The UV and fluorescent spectra of five water-soluble cationic porphyrin derivatives has been studied in the pH range of 2.1-8.0. The results showed that these porphyrins can be developed as colorimetric and fluorescent bimodal ratiometric pH-senses. And the pH-sensing mechanism has been investigated initially.3) The reversibility and the accuracy of these cationic porphyrin probes has been studied. The influence of the probe concentration and different pH buffers for the probes has also been investigated.4) The cytotoxicity of the porphyrin derivatives TTAPoPP and TMMorEOPP was investigated using the standard MTT assay and the confocal fluorescence microscopy imaging of living cells of the probes has been measured. The results showed the porphyrin probes are of low cytotoxicity and can be successfully used in pH-dependent bioimaging of living cells.