Study On The Photosensitivity Of Ethylenediamine Phthalocyanine

Cancer is one of the major threats to human health.How to cure cancer and save sufferers' life have become a serious problem worldwide.Compared to the traditional therapies such as surgical treatment,chemotherapy and radiotherapy,photodynamic therapy(PDT)has attracted more widespread interest due to its specific advantages including higher selectivity,less side effects and so on.As a result,PDT has been put into clinical applications to the treatment of cancer and other diseases for such a long time.During the photodynamic therapy process there have three essential elements,namely,light source,oxygen and photosensitizers.Among these three elements the photosensitizers is the most important one,of which the blood delivery,tumor targeting,photosensitive antitumor activity and other properties play a decisive role in photodynamic therapy.As a representative of the second generation of photosensitizers,phthalocyanines have stable chemical properties,high reactive oxygen species generation efficiency,high selectivity,low dark toxicity and high phototoxicity,which lead to a wide range of potential applications.2(3),9(10),16(17),23(24)-tetra-(((2-(diethylamino)ethylamino)methyl)phenoxy)phthalocyaninato-zinc(?)(ZnPc1)and 2(3),9(10),16(17),23(24)-tetra-(((2-(tritylamino)ethylamino)methyl)phenoxy)phthalocyaninato-zinc(?)(ZnPc2)have good prospects for clinical application because of excellent cellular uptake and photosensitive anti-cancer activity,which were synthesized earlier by our group.And their poor solubility in water was improved as well.The results show that the water-soluble cationic phthalocyanine obtained by protonation of its amino groups has better photosensitive anti-cancer activity as well as easier preparation.Based on the achievement of our earlier research,the effect of protonation degree of ZnPc1 on its photosensitive properties and the interaction between ZnPc2 and bovine serum albumin(BSA)have been studied concerning their transportation problems in blood.The main results are as follows:(1)The results also showed that the properties of hydrochloride derivatives exhibited some certain regularities along with different protonation degrees.That is to say,protonation degree can affect the properties of hydrochloride derivatives greatly.It is indicated that when the mole ratio of the precursor phthalocyanine ZnPc1 and hydrochloric acid(HC1)was 1:8,the UV-vis absorbance intensity,singlet oxygen generation efficiency and photosensititive anticancer activity towards HeLa cells reached maximum.(2)The interaction between ZnPc2 and bovine serum albumin(BSA)has been investigated and confirmed by UV-vis absorption and synchronous fluorescence.ZnPc2 can quench the intrinsic fluorescence of BSA by static quenching procedure according to the analysis of time-resolved fluorescence and steady-state fluorescence spectra.Further investigation shows that van der Waals force and hydrogen bond play major roles in the binding reaction and the number of binding sites of the interaction is 1,which prove that the binding stoichiometry is 1:1.In addition,the conformational changes of BSA in the presence of ZnPc are also analyzed by circular dichroism(CD)spectra which indicates that the interaction has effect on the secondary structure of BSA.