In biomedicine research field

the fluorescent phenomena of biological sample is feeble and its time relaxation mostly is between fs and ns.By means of ultrashort pulses laser

feeble fluorescence of the biological sample can be detected expediently and efficiently. The object of this study was to explore the ultrafast photodynamic process of hematoporphyrin derivative (HPD) which is a kind of photosensitisers for diagnosing and therapying cancer. By means of ultrafast pulses laser spectral technique and picosecond time-correlated single-photon counting system

fluorescence spectrum

the characteristic of fluorescence lifetime and fluorescence peak intensity fluctuation dependent on time of cancer cells sample and normal cells sample were measured.It was observed that cancer cells sample had special spectral peak at near 645 nm. Moreover

fluorescence lifetime's fast part of cancer cells and normal cells were about 150 and 300 ps respectively

and fluorescence intensity of cancer cells and normal cells decayed approximate 10% and 55% separately in twelve hours. According to the measured fluorescence spectrum curve and analyzed time-resolved fluorescence decay curve

it was calculated that the HPD concentration in cancer cells sample increased two orders of magnitude while the HPD concentration in normal cells sample had no apparent change. What's more

it was computed that the fluorescence lifetimes of cancer cells and normal cells were about 824 and 1 798 ps and that HPD's stay time in cancer cells sample and normal cells sample were about 17 days and 6 days respectively. The results indicated that the differences between cancer cells and normal cells in fluorescence spectrum

the characteristic of fluorescence lifetime and the fluorescence peak intensity dependent on time were large. This study demonstrated that it was feasible to diagnose and therapy cancer using fluorescence spectrum technique. The study also provides an important guidance for further studying and developing the technique of diagnosing and therapying early cancer using ultrashort pulses laser technique and is significant to clinic application.