Study On Synthesis And Aggregation Behavior Of Water-soluble Cationic Porphyrins

The research on water-soluble cationic porphyrins has received much interest in recent years. Because of their excellent bioactivity water-soluble cationic porphyrins can be used as potential anticancer or antibacterial agents and probe for structure and dynamics of DNA. Serum albumin is the natural carrier protein for photosensitizers such as porphyrin. Porphyrin molecules were carried to tumour region selectively and were transported into tumour cells by serum albumin. The binding interaction between porphyrin and protein with one or several binding sites can affect the transportation and metabolism of porphyrin. On the contrary, the binding of porphyrin on protein will change the molecular conformation and thus affect the physiological function of protein. Meanwhile the molecular structure and aggregate state of porphyrin are closely related to its function. So it has great significance to study on the aggregation behavior of water-soluble cationic porphyrins in various systems and the interactions between porphyrin and biomacromolecules such as serum albumin or DNA. In this paper, the aggregation behavior of water-soluble cationic porphyrins with bioactivity in various systems and the interactions between porphyrin and biomacromolecules were studied systematically. The main contents of this paper were provided as follows:In the first part, the research significance and the research status of water-soluble cationic porphyrins as well as the aggregation types were described briefly. The research contents and the characteristics of this paper were also included.And in the second part, the reaction mechanism of Adler-Longo method for the synthesis of porphyrin was introduced. An amphiphilic nonionic porphyrin, meso-tetra (4-hydroxyphenyl) porphyrin (THPP) and three water-soluble cationic porphyrins, meso-tetra (4-N, N, N-trimethylanilinium) porphyrin (TMAP), 5, 10, 15-triphenyl -20- (N-methylpyridyl) porphyrin (TPMPyP) and 5-phenyl-10, 15, 20- tri(N-methylpyridyl) porphyrin (TriMPyP), were synthesized. These porphyrins were characterized by spectroscopic methods and the molar absorptivity and fluorescence quantum yield were also calculated.The aggregation behavior of porphyrins in water solutions with anionic surfactant was studied in the third part. J-aggregate of THPP was formed in AOT solutions. A new emission band and strong RLS signal were observed. Obviously ionic strength influences the formation of aggregate which was independent of the THPP concentration. The THPP monomers can convert into J-aggregates while the concentration of AOT is higher than cmc. The interaction between TMAP and anionic surfactant leads to the formation of J- and H-aggregate while the concentration of surfactant is lower than cmc. It mainly leads to H-aggregate while the pH value of solution is 6.8 and J- aggregate while the pH value of solution is 2.0.The fourth part is about the interaction between TMAP and biomacromolecules. TMAP exists as monomers in water solution and can aggregate on the surface of DNA when the R ratio of TMAP concentration to that of DNA is larger than 1. The absorption spectrum had significant hypochromic effect and the fluorescence was enhanced greatly. TriMPyP exists as self-aggregates in water solution and the addition of DNA promotes the aggregation. The ionic strength can change the binding mode of porphyrin with DNA. In neutral solutions, the addition of serum albumin enhanced the fluorescence of TMAP and the intrinsic fluorescence of serum albumin was quenched. These two phenomenon belong to different energy transfer processes. The number of binding sites of TMAP on serum albumin is about 1. There is no obvious effect on the molecular conformation of serum albumin due to the binding of TMAP.