Determination And Application Of Dopamine By Fluorescence Aptasensor

PART 1 A novel label-free fluorescence aptasensor for dopamine detection based on an Exonuclease III aided amplification strategyObjective:A novel label-free fluorescence aptasensor was established for the detection of dopamine based on dopamine-triggered Exonuclease III-and SYBR Green I-assisted template DNA recycling and a decrease in fluorescence.Method:SYBR Green I was selected as the fluorescent indicator;SYBR Green I fluoresces upon binding to double stranded DNA(ds DNA).The template DNA(t DNA)was designed to contain two regions:one complementary to the complementary strand(cDNA)and the other complementary to the aptamer.Various concentrations of dopamine automatically triggered the Exonuclease III restriction digestion to release SYBR Green I.Consequently,the fluorescence signal significantly decreased.Therefore,a method for detecting the dopamine concentration was established.Polyacrylamide gel electrophoresis was also used to confirm the feasibility of the developed sensor for detecting dopamine.Results:Under optimal conditions,the variation in fluorescence wasConclusion:The developed aptasensor showed good selectivity and was successfully applied to detect dopamine in mouse brain tissues.Due to its remarkable sensitivity and selectivity,the constructed fluorescence aptasensor was applicable not only for the routine detection of dopamine but also for diagnosing disease.PART 2 A novel resonance Rayleigh scattering aptasensor for dopamine detection based on signal amplification by G-quadruplex nanowires formationObjective:A new method was constructed for detecting dopamine based on aptamer specific recognition and resonance Rayleigh scattering(RRS)of G—quadruplex nanowires(G—wires).Method:The dopamine aptamer was used to recognize the target dopamine,and the Exonuclease III(Exo III)was activated to cleave the hairpin DNA,and the G-wire formation was induced in the presence of K~+ electrophoresis.Thus,a quantitative relationship between the RRS intensity of the G-wires and the dopamine concentration was established.Results:We optimized the experimental conditions such as the concentration of Exo III in the reaction system,and investigated the interference substances such as uric acid,ascorbic acid and serotonin.Under the optimal conditions,the RRS intensity reached maximum peak at 363 nm,and it was linear with the logarithm of dopamine concentration in the rangeConclusion:The novel method for detecting dopamine had excellent selectivity and high sensitivity,and can be used for detecting dopamine levels in mice brain tissue.