Study On Near-infrared Fluorescent Probes Based On Cyanine Dyes

Near-infrared fluorescent probes have unique advantages for tracing molecular in vitro and in vivo,such as minimum photodamage to biological samples,deep tissue penetration and minimum interference from background autofluorescence in living systems.As the most important kind of near-infrared fluorophore,cyanine dyes have advantages of wide absorption wavelength range and large extinction coefficient.But,it is easy to reduce the photostability and increase the photobleaching of cyanine dyes using traditional method of expanding mathine chain to red shift the fluorescence emission wavelength.So,based on the structure modification of classic cyanine dyes,we substitute benziondoles for indole in order to extending the ? conjugate system,and develope two different near-infrared fluorescent probes through binding different analyte receptor.The main contents of this thesis are as follows:1.We design and synthesize a water-soluble boronate-functioned hemicyanine-naphthol hybrid BNBI as a novel ratiometric fluorescent probe for detecting hydrogen peroxide.The probe display a remarkable colour change from pale orange(?em = 590 nm)to pink(?em = 690 nm)in the presence of hydrogen peroxide within 5 minutes.A good linear relationship is obtained with the hydrogen peroxide concentration ranging from 0.3 to 25 ?M,with a limit of detection of 0.09 ?M.BNBI is highly selective over 5 equivalents of other classic reactive oxygen species and has been applied to the detection of trace amounts of hydrogen peroxide in real samples.2.We develope a new “turn-on” near-infrared fluorescent probe NTR-BI for detection of nitroreductase.Nitrobenzyl moieties,the receptor of nitroreductase,can be converted into aminobenzyl groups so that our probe is selective over 100 equivalents of other normal reductants.NTR-BI shows “off-on” fluorescent response to nitroreductase at the wavelength of 720 nm in the presence of reduced nicotinamide adenine dinucleotide,and the fluorescence emission intensity take ~80 fold increase.Meanwhile,we investigate the kinetic parameter of the enzyme-catalyzed reaction and calculate the Michaelis constant and maximum rate by Lineweaver-Burk plot.Finally,NTR-BI is applied for imaging nitroruductase in HeLa cells in order to investigate tumor hypoxia diagnosis.