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fluorescence

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Giselle Tian

on 10 May 2013

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Transcript of fluorescence

Principles of Fluorescence Generation Previous Study Melanoma cancer and diagnosis Previous Study 1-Melanin Spectrum in vitro Study 1 Optical property of melanin Implementation Stage 1 Stage 2 Laser Spectrometer Melanin Stepwise multiphoton
fluorescence spectroscopy
for cutaneous melanin detection Yunxian (Giselle) Tian
Supervisor Dr. Haishan Zeng, Dr. Harvey Lui Introduction Melanin and optical property Limitation: Fluorescence Spectroscopy System Fluorescence properties of melanin change are due to different bioenvironment in melanoma and benign lesions Principle of fluorescence generation Previous Study 2-Three Photon Fluorescence Study 2 Limitation: Stage 3 Advantage Existing methods Absorption
Reflectance
Fluorescence Filter & Objective lens Dichroic mirror Filter & Objective lens Construct a non-invasive system to find fluorescence criteria for the differentiation in vivo between:
healthy skin tissue
malignant melanoma
Benign pigmented lesions demonstrated the possibility of generating stepwise three photon fluorescence. Spectra would be obtained even by CW laser (continued wave laser), which costs far less than pulsed laser Be able to distinguish benign nevi, malignant melanoma and intermediate stage by examining peaks and shapes of melanin spectra Design and construct stepwise multiphoton fluorescence system Use nanosecond laser, femtosecond laser and CW laser to study melanin in solvent, melanin powder form, skin tissue ex vivo and skin tissue in vivo Evaluate if it is practical to delineate malignant melanoma from benign nevus Stage 2- Optimize system Stage 3 - Measurement Fluorescence spectroscopy system Hypothesis Aim Reflectance imaging
One photon fluorescence imaging Interfered from other chromophore/ fluorophores, and until now there is no way to separate melanin signal from others Stage 1- construct system Stepwise two photon system comprises the following components:
Nitrogen pumped nanosecond dye laser
Fiber optics bundle delivery
system Spectrograph and CCD camera
Computer control and data acquisition Non continuous spectra
Setup not suitable for in vivo study
ex vivo study Be able to distinguish benign nevi, malignant melanoma and intermediate stage by examining peaks and shapes of melanin spectra System not suitable for in vivo study
Non continuous spectra
Not optimize excitation wavelength
No systematically study from melanin powder to solvent
No in vivo study Adjust the system by optimizing adapter to achieve max power output and best quality of spectra, find the best excitation wavelength Stage 4 demonstrated the possibility of generating stepwise three photon fluorescence. Spectra would be obtained even by CW laser (continued wave laser), which costs far less than pulsed laser Limitations: Non tissue sample Conclusion Obtained melanin solvent signal by using femtosecond laser Constructed and optimized stepwise two photon system Melanin specific spectra

Cost effective instrument First-order power dependence: one photon fluorescence

Second-order power dependence: two photon fluorescence

Third-order power dependence: three photon fluorescence System specification:
Spot size: 50 m
Average Power: 0.6 mw
Wavelength: 360-900 nm
Repetition rate: single shot- 20Hz Adjust the system by optimizing adapter to achieve max power output and best quality of spectra


Obtain spectra from phantom by viewing card


Using femtosecond laser, obtained emission wavelength by changing excitation wavelength from 760nm to 920nm, plot contour graph (EEM) and find the best excitation wavelength Use femtosecond laser to study melanin in solvent

Get second order power dependence relationship using femtosecond laser at 785nm Malignant tumor of malanocyte
Highest death rate Emission Excitation Build up a fiber based system for in vivo study Continuous spectra
Optimize excitation wavelength Systematically study from melanin powder to solvent
in vivo study
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