| Surface enhanced Raman scattering (SERS) spectroscopy and Laser Induced Fluorescence (LIF) spectroscopy technology, are only two optical methods that can achieved single-molecule (SM) detection sensitivity, which is the most sensitive method. The top cause of induce human deaths was cancer, the therapy key is early detection, which need to study the rapid, sensitive and convenient detection technology, so SERS application in the biomedical field will lead to profound changes in cancer diagnosis and treatment. According to the optical properties of biological tissue, near infrared (NIR) is a good optical band in tissue penetration, the optical signal effective injection and piercing, then high sensitivity diagnosis could be achieved. In this paper, NIR surface-enhanced Raman scattering and related content for cancer diagnosis and treatment were studied, NIR photosensitive dye 3.3 ’2-ethyl-S of aldehyde 3 carbocyanine iodine (DTTC) was used as the Raman probe molecules, and gold nanorods (Au-NRs) were used as surface enhanced raman substrate for its well NIR resonance absorption characteristics, a number of innovative achievements were obtained in the thesis as following:(1) Raman spectra calculation and measurement of DTTC moleculeThe composition of biological tissue is very complex, every elements of the tissue may be show by analysis the spectral measurements, so the spectra analysis of synthesis need to be supported by solid underlying data. While DTTC was selected as near-infrared Raman probe molecule, the natural Raman spectroscopy must be studied, for the SERS spectrum analysis and subsequent applications. Raman and infrared spectra of DTTC was calculated firstly according to first principles, using density functional theory (DFT) method and Hartree-Fock (HF) method, based on B3LYP/6-31G basis set. The natural Raman spectra was also measured firstly using DTTC doping DSE-PEG membrane method. Through careful comparative analysis, theoretical spectra are in good agreement with experimental spectra.(2) Au-NS preparation, characterization, surface-enhanced electric field calculation and the Raman enhancement for DTTCGold nanoparticles (Au-NP) has a non-toxic and good biological compatibility. Au-NS has become a common medical reagents. In the experiments, Au-NS of two diameter(50nm and 60nm) were prepared and characterized with ABS, TEM, PSA. Subsequently, the Au-NRs surface molecule surfactant cetyltrimethylammonium bromide (CTAP) was replaced by Raman probe molecules DTTC, then sulfur polyethylene glycol (SH-PEG) was used as a surfactant to protect Au-NS dispersing and stability in body fluids, to facilitate it was applied to cells and biological tissue. SERS spectra of DTTC was measured, intensity and signal to noise ratio are much better than its natural Raman spectrum for DTTC Molecular Raman scattering coefficients was enhanced by Au-NS surface plasmon resonance.In the theoretical calculations, surface enhanced electric field and laws was calculated firstly, based on surface plasmon resonance model, using discrete dipole method, with incident laser wavelength (477,532,632.8,785,850,1064nm) excitation, and Au-NS (diameter of 20,40,60,80,100,120,140nm).(3) Au-NRs preparation, characterization, surface-enhanced electric field calculation and the Raman enhancement for DTTCDue to the vertical surface plasma oscillations, the absorption characteristics of Au-NRs could be modulated with the aspect ratio, and the resonance absorption peaks is in the infrared band while the diameter greater than 3. In the experiments, Au-NRs were synthesized using the seed growth method, with diameter 5-20nm, aspect ratio in the range of 1.5 to 15, its absorption spectrum range between 700 and 1100nm. It were used as absorbing medium or SERS Enhanced substrate to meet the demand in the cancer diagnosis and treatment, and were characterized by ABS, TEM and PSA, then DTTC SERS spectra were also studied. In the theoretical calculation, surface enhanced electric field and laws were calculated firstly, with incident laser wavelength (477,532,632.8,785,850,1064nm) excitation, Au-NRs (diameter 10nm, length of 20,40,60,80,100,120,140nm).(4) DTTC Raman spectra identifyIn the previous work, the natural Raman spectrum, theoretical calculations Raman spectra, and SERS spectra of DTTC were obtained and compared with relevant reference, so Raman peaks were determine firstly between 500 to 1800 cm-1 mainly composed as the following few lines:611 cm-1,670 cm-1,740 cm-1,775 cm-1,838 cm-1,925 cm-1,970 cm-1, 1008 cm-1,1072 cm-1,1113 cm-1,1171 cm-1,1218 cm-1,1275 cm-1,1320 cm-1,1375 cm-1, 1414 cm-1,1455 cm-1,1515 cm-1,1566 cm-1 and 1685cm-1. By studying similar structures and theoretical calculations, the corresponding vibrational modes of DTTC were given in Raman spectra, and because 970,1020cm-1 were greatly enhanced so that the DTTC molecules were physical adsorpted on the surface of gold nanoparticles with vertical spatial structure through N atom in pyrrole groups.(5) Application in cancer diagnosis and treatment of Au-NRs and DTTCAu-NRs and DTTC can be well applied to vivo body cancer detection and treatment corresponding to their infrared spectral characteristics. Based on previous study, the DTTC Raman probe and Au-NRs combinations were feed to macrophage cells, and vivo body SERS spectra were obtained. And it was injected into mice back, and under skin SERS spectra were obtained with portable infrared light Raman spectrometer, then 808nm infrared laser irradiate mouse back area, temperature rising more high 2.6℃in injection Au-NRs area than others was observed. The stduy is the base of apply Au-NRs to cancer diagnosis and treatment. |
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