Study And Application Of Spectral Characteristics Of Bilirubin With Metal Ions

Bilirubin?BR?,a linear tetrapyrrole,is mainly distributed in blood and bile in mammal body.It has special physical and chemical properties.Previous studies show that some kind of metal ions have significant impact on BR.For example,Cu²⁺ has an obvious quenching effect on the fluorescence of BR,while Zn²⁺ has a fluorescence enhancement phenomenon to BR.Due to such a special fluorescence property,BR can act as a biological probe for some metal ions.Based on this idea,the author investigates the BR's fluorescence mechanism and the excited-state dynamics of the interactions between BR and metal ions,furthermore,the application prospective of BR is also discussed.The specific research results are as follows:1.The fundamental Absorption and Fluorescence spectroscopy properties of BR are studied.We find that in the DMSO?GC?solution of BR,the characteristic absorption peak is located at 455 nm,and the fluorescence emission peak is found at 525 nm,this indicates that the Stock shift of BR is equal to 70 nm.Moreover,an obvious internal filter effect can be observed in the over-high concentrations of BR solution.Such the internal filter effect can result in the decrease in emission fluorescence.Besides,an extra measure uncertainty can be induced by using some of the plastic container.2.The excited state dynamics characteristics of the mixed solution of BR and metal ions Cu²⁺?Zn²⁺ are studied seperatily.When BR and Cu²⁺ are mixed,the charge transfer effect between BR and Cu²⁺ makes the solution occur the obvious fluorescence quenching phenomena.While in the mixed solution of BR and Zn²⁺,Zn²⁺ form a chemical charge coordination with BR,which increases the rigidity of the molecule structure and decreases the non-radiative transition channels of BR.As a result,an obvious fluorescence enhancement effect can be observed in the solution of BR and Zn²⁺.3.When Zn²⁺ is injected into the DMSO?GC?solution of BR,the maximal emission wavelength shift from 525 nm to 663 nm,corresponding to a 138 nm redshift.A good linear relationship between the concentration of Zn²⁺ and the fluorescence intensity ratio of wavelength 663 nm to wavelength 600 nm(I_663nm/I_{600 nm})is found in the mixed solution.Such a linear relation can be described by the equation y = 0.82923 x + 0.57379 with the correlation coefficient R² = 0.99987.Consequently,the ratio _663nm/I_{600 nm} can be regarded as the fluorescence probe for the concentration of Zn²⁺.The measured probing region is 0 10 ?M,and the response concentration is 0.1 ?M.4.The reaction time and the fluorescence intensity are also the dependent variables in the fluorescence experiments.The quantitative measurement results show that when the reaction time is less than 120 minuts,the fluorescence intensity increases significantly with the increase of the reaction time;when the reaction time is greater than 120 minuits,the fluorescence intensity on longer changes with the reaction time.A significant fluorescence enhancement effect is observed on the wavelength around 525 nm.In this paper,we investigate the spectral properties of BR-metal ion complex solution.The conclusion is that BR has a good fluorescence response capability to Cu²⁺ and Zn²⁺.Thus,the spectral characteristics of BR have positive application prospects in production.In the medicine,for example,BR can be used as the indicator of metabolism in human body.And in industry,BR can be made as the probe of Zn²⁺.