Novel chlorin e6-based conjugates of tyrosine kinase inhibitors: Synthesis and photobiological evaluation as potent photosensitizers for photodynamic therapy.

Since tyrosine kinase inhibitor (TKI) could reverse ABCG2-mediated drug-resistance, novel chlorin e6-based conjugates of Dasatinib and Imatinib as photosensitizer (PS) were designed and synthesized. The results demonstrated that conjugate 10b showed strongest phototoxicity against HepG2 and B16-F10 cells, which was more phototoxic than chlorin e6 and Talaporfin. It could reduce efflux of intracellular PS by inhibiting ABCG2 in HepG2 cells, and localize in mitochondria, lysosomes, golgi and ER, resulting in higher cell apoptosis rate and ROS production than Talaporfin. Moreover, it could induce cell autophagy and block cell cycle in S phase, and significantly inhibit tumor growth and prolong survival time on BALB/c nude mice bearing HepG2 xenograft tumor to a greater extent than chlorin e6. Consequently, compound 10b could be applied as a promising candidate PS due to its good water-solubility and stability, low drug-resistance, high quantum yield of 1O2 and excellent antitumor efficacy in vitro and in vivo.

[Fluorescence spectral characteristics of human blood and its endogenous fluorophores].

The three-dimensional fluorescence spectra and excitation-emission matrix of human blood were measured, and an attempt was made to exploit the endogenous fluorophores of major peaks in the UV and visible. The result indicates that the absorption peaks of human blood appear at 274, 345, 415, 541 and 576 nm. Based on the analysis of fluorescence excitation-emission matrix, the major emission peaks of human blood occur at excitation-emission wavelength pairs of 260-630, 280-340, 340-460 and 450-520 nm, which are attributed to endogenous porphyrins, tryptophan, reduced nicotinamide adenine dinucleotide (NADH) or reduced nicotinamide adenine dinucleotide phosphate (NADPH), and flavin adenine dinucleotide (FAD), respectively. These results can be used to analyze and explain the effect of blood on the distortion of fluorescence signal of human tissues for optical diagnosis.

Autofluorescence excitation-emission matrices for diagnosis of colonic cancer.

AIM: To investigate the autofluorescence spectroscopic differences in normal and adenomatous colonic tissues and to determine the optimal excitation wavelengths for subsequent study and clinical application. METHODS: Normal and adenomatous colonic tissues were obtained from patients during surgery. A FL/FS920 combined TCSPC spectrofluorimeter and a lifetime spectrometer system were used for fluorescence measurement. Fluorescence excitation wavelengths varying from 260 to 540 nm were used to induce the autofluorescence spectra, and the corresponding emission spectra were recorded from a range starting 20 nm above the excitation wavelength and extending to 800 nm. Emission spectra were assembled into a three-dimensional fluorescence spectroscopy and an excitation-emission matrix (EEM) to exploit endogenous fluorophores and diagnostic information. Then emission spectra of normal and adenomatous colonic tissues at certain excitation wavelengths were compared to determine the optimal excitation wavelengths for diagnosis of colonic cancer. RESULTS: When compared to normal tissues, low NAD(P)H and FAD, but high amino acids and endogenous phorphyrins of protoporphyrin IX characterized the high-grade malignant colonic tissues. The optimal excitation wavelengths for diagnosis of colonic cancer were about 340, 380, 460, and 540 nm. CONCLUSION: Significant differences in autofluorescence peaks and its intensities can be observed in normal and adenomatous colonic tissues. Autofluorescence EEMs are able to identify colonic tissues.

[Fluorescence spectroscopy and imaging for optical biopsy].

In the past few years extensive attention has turned toward optical biopsy, because of its ability to perform noninvasive, real time and accurate diagnosis of tissue pathologies, especially precancer. Fluorescence spectroscopy is one of a series of techniques widely developed for optical biopsy, and can be generally divided into two categories: fluorescence spectroscopy and imaging. This paper reviews the applications of autofluorescence and exogenous fluorescence to optical biopsy, and the principle and advantages as well as the clinic applications of various steady-state and time-resolved fluorescence spectroscopy and imaging techniques. Furthermore, the development perspectives of optical biopsy by using fluorescence spectroscopy and imaging are also briefly discussed.

[Time-resolved fluorescence studies of hematoporphyrin monomethyl ether for photodynamic diagnosis].

Time-resolved fluorescence spectroscopic measurements of second-generation new photosensitizer of hematoporphyrin monomethyl ether (HMME) were carried out in the physiological saline and different human serums by picosecond fluorescence lifetime spectrometer, respectively. The objective was to assess the fluorescence lifetime of HMME as a new enhanced contrast parameter between normal and malignant tissues for the photodynamic diagnosis of various cancers. The influence of emission wavelength and photosensitizer concentration, on the lifetime of HMME was also presented. No significant change in fluorescence decay was found between emission wavelength 625 and 690 nm. The lifetimes of HMME diluted in the physiological saline and human serum were about 14.6 and 16.6 ns, respectively. Experimental results also indicate a quite stable behavior with a decay time of 16.6 ns when HMME was diluted with different concentration. Time-resolved fluorescence spectrum of HMME can serve as a characteristic marker for optical biopsy of the malignant tissue because of the useful property of selective retention in malignant tumors after intravenous injection. Furthermore, the results in this study will contribute to the improvement of nanosecond fluorescence lifetime imaging method.

[Spectral properties of new photosensitizers for photodynamic diagnosis and therapy].

The spectral properties of new photosensitizer ZnPcS2P2, PsD-007 and HMME, as well as traditional photosensitizer HpD have been studied by comparing their spectra in physiological saline and in physiological saline with 10 percent serum. Experimental results show that the maximum absorption peaks for PsD-007, HMME and HpD in the physiological saline with 10 percent serum appear at 400 nm in the soret region, while at 670 nm for ZnPcS2P2. The fluorescence excitation spectra closely resemble the absorption spectra. When excited by the light at the wavelengths of 413 and 514.5 nm, the fluorescence emission peaks for PsD-007, HMME and HpD appear at 625 and 690 nm, respectively. The fluorescent excitation efficiency of the same photosensitizer with the same concentration excited by the light at the wavelength of 413 nm is about three fold higher than that at 514.5 nm. Furthermore, the fluorescent excitation efficiency is the highest for HMME, but is lower for HpD and lowest for PsD-007. These results are significant in the selection of photosensitizers for photodynamic diagnosis and therapy.