基于近红外光激发的光动力疗法中相关科学问题的研究

发布时间：2018-04-21 16:35

本文选题：稀土纳米晶 + 荧光性质　；参考：《哈尔滨工业大学》2016年博士论文

【摘要】：近些年,稀土纳米晶在生物荧光成像和光动力治疗等医学领域有很广泛的研究,主要是因为稀土纳米晶具有近红外光激发、无光漂白、无光闪烁、自体荧光少、光损伤小、光谱丰富、谱带窄等特点。基于稀土上转换纳米晶结合的光敏剂(UCNC-PS)来开展光动力疗法是稀土纳米晶医学应用的主要部分,这主要是由于稀土上转换纳米晶的引入将激发光转移到了近红外区,有望实现深组织实体瘤的治疗。然而,UCNC-PS在应用中还存在活性氧产生效率低、激发光功率密度高、治疗效果可控性差等问题。本文针对如何提高上转换发光效率改善UCNC-PS的活性氧产率、增强生物荧光成像的对比度实现影像指导的光动力治疗、以及开发新型近红外光激发的光敏剂实施高效率的深组织实体瘤的光动力治疗等方面开展了研究。研究了环境对稀土离子发光中心荧光性质的影响。设计并制备了NaYF4/NaYF4:Yb3+,Er3+/Na YF4多层核壳纳米结构,这种特殊的核壳结构包括三部分,其中心是Na YF4的支撑核,在其外面包覆Na YF4:Yb3+,Er3+发光薄层,在最外层包覆一层屏蔽壳层,这种结构保证每个发光中心受到环境的作用影响相同,通过调节屏蔽壳层厚度能准确的探究环境对稀土发光中心的影响。利用上转换荧光光谱和时间分辨光谱探究了环境对稀土发光中心的荧光性质的影响规律,发现稀土发光中心的绿色上转换的荧光强度随着屏蔽壳层厚度的增加呈e指数增强的关系,当屏蔽壳层厚度减小到0时,其上转换荧光强度减小到饱和荧光强度的1/356;包覆NaYF4屏蔽壳层厚度在4 nm左右时,外界环境对发光中心的作用减小90%。进一步通过对发光中心能级辐射性质的研究阐述了环境对发光中心荧光性质影响的原因。基于NaYF_4:Yb3+,Tm3+纳米晶开发近红外单色的生物荧光探针。通过变化Tm3+的掺杂浓度对Na YF4:Yb3+,Tm3+纳米晶的光谱进行调节,实现单色的800nm上转换荧光。利用800 nm和470 nm的上转换荧光的强度比来衡量800 nm上转换荧光的单色性。通过对光谱的分析,发现800 nm单色性随着Tm3+掺杂浓度的增加呈e指数增长,当Tm3+掺杂浓度增加到4%时,其荧光强度比可高达757。进一步开展荧光成像研究,探究了Tm3+掺杂浓度与荧光量子产率之间的关系,当Tm3+浓度达到4%时,470 nm荧光的量子产率已经下降到10-7量级,而800 nm荧光的量子产率仍可达到10-3量级,利用此浓度的纳米晶的800nm上转换荧光实现了高对比度的荧光成像。提出了一种近红外光激发的新型光敏剂NaYF_4纳米晶。NaYF_4纳米晶具有近红外光激发,与氧之间能量传递效率高的特点,因此,NaYF_4纳米晶有望实现高效的深组织光动力治疗。NaYF_4纳米晶中光敏成分是Yb3+,具体的机制为Yb3+吸收近红外激发光,然后将能量传递给氧,进而产生活性氧。本文利用化学探针法验证了NaYb F4纳米晶可以产生活性氧,并根据Yb3+寿命随氧浓度的响应,得到了Yb3+与O2之间的能量传递速率,发现二者之间具有较高的能量传递速率。同时也将Na YbF4纳米晶作为光敏剂与UCNC-PS进行了对比,结果表明NaYb F4纳米晶具有更高的活性氧产生速率。基于NaYbF_4纳米晶开展了光动力疗法的研究。首先探究了活体光动力治疗条件,包括药物的孵育时间、孵育浓度、光照时间和光功率密度、药物毒性等。在此基础上进行了体外的光动力治疗,发现NaYF_4纳米晶对PC-9细胞有很好的杀伤效果,当药物浓度在10μg/m L,光照时间在0.5 h时,细胞存活率仍可降低到40%左右。同时,治疗条件和细胞存活率之间存在e指数关系,为实施可控的光动力治疗提供了实验依据。进一步通过流式细胞术对细胞的死亡机制进行了实验研究,结果表明光动力治疗过程中细胞凋亡和坏死均存在。体内光动力治疗结果表明基于NaYb F4纳米晶的光动力疗法可使肿瘤体积发生明显的缩小。
[Abstract]:In recent years, rare earth nanocrystals have been widely studied in biomedical fields such as bioluminescence imaging and photodynamic therapy, mainly because the rare earth nanocrystals have near infrared light excitation, no light bleaching, light scintillation, less autofluorescence, less light damage, rich spectrum and narrow band, and so on. The photosensitizer based on the nanocrystalline binding of rare earth (UCNC-PS) To carry out photodynamic therapy is the main part of the application of rare earth nanocrystalline medicine. This is mainly due to the introduction of rare earth's upconversion nanocrystals to transfer the excited luminescence to the near infrared region. It is expected to realize the treatment of deep tissue solid tumor. However, UCNC-PS still has low active oxygen production efficiency, high excitation light power density and therapeutic effect in the application. In this paper, the research on how to improve the efficiency of up conversion luminescence efficiency to improve the active oxygen yield of UCNC-PS, enhance the contrast of bioluminescence imaging to realize photodynamic therapy guided by image, and develop a new type of near infrared light stimulated photosensitizer to implement high efficiency photodynamic therapy for deep tissue solid tumor. The effects of the environment on the fluorescence properties of the rare earth ion luminescence center were investigated. The NaYF4/NaYF4:Yb3+, Er3+/Na YF4 multilayer nuclear shell nanostructures were designed and prepared. The special nuclear shell structure consists of three parts. The center is the support core of Na YF4, which covers the outer layer of Na YF4:Yb3+, Er3+ and the outer layer of a layer of shielding shell. The influence of environment on the luminescence center of rare earth can be accurately explored by adjusting the thickness of shielding shell. Using up conversion fluorescence spectrum and time resolved spectrum, the law of environment to the luminescence of rare earth luminescence center is explored, and the green on the luminescent center of rare earth is found. The fluorescence intensity of the converted shell is e exponentially enhanced with the increase of the shielding shell thickness. When the shielding shell thickness is reduced to 0, the upconversion fluorescence intensity decreases to 1/356 of the saturated fluorescence intensity. When the thickness of the coated NaYF4 shielding shell is about 4 nm, the effect of the external environment on the luminescent center is reduced by 90%. further through the luminescence center. The effect of energy level radiation on the fluorescence properties of the luminescent center is explained. Based on the NaYF_4:Yb3+, Tm3+ nanocrystals, the near-infrared monochromatic bioluminescence probe is developed. By changing the doping concentration of Tm3+, the spectra of Na YF4:Yb3+ and Tm3+ nanocrystals are regulated to realize the single color upconversion fluorescence of 800nm. 800 nm and 470 nm are used. The intensity ratio of upconversion fluorescence is measured to measure the monochromatic property of the upconversion fluorescence of 800 nm. Through the analysis of the spectrum, it is found that the monochromatic of 800 nm increases exponentially with the increase of Tm3+ doping concentration. When the Tm3+ doping concentration increases to 4%, the fluorescence intensity is up to 757. to further develop the fluorescence imaging study, exploring the Tm3+ doping concentration and fluorescence. When the Tm3+ concentration reaches 4%, the quantum yield of the 470 nm fluorescence has been reduced to 10-7, while the quantum yield of the 800 nm fluorescence can still reach 10-3. A high contrast fluorescence image is realized by using the 800nm up conversion fluorescence of the nanocrystalline in this concentration. A new type of photosensitivity excited by near infrared light is proposed. NaYF_4 nanocrystalline.NaYF_4 nanocrystals have the characteristics of near infrared light excitation and high energy transfer efficiency between oxygen and oxygen. Therefore, NaYF_4 nanocrystalline is expected to achieve efficient deep tissue photodynamic treatment of.NaYF_4 nanocrystalline photosensitive component is Yb3+, the specific mechanism for Yb3+ absorption near infrared excitation, and then transfer energy to oxygen, and then produce life. NaYb F4 nanocrystals can produce living oxygen by chemical probe, and the energy transfer rate between Yb3+ and O2 is obtained according to the response of Yb3+ life with oxygen concentration. It is found that there is a high energy transfer rate between the two and the Na YbF4 nanocrystals are also compared with UCNC-PS as photosensitizers. NaYb F4 nanocrystals have higher ROS production rate. Based on NaYbF_4 nanocrystals, the study of photodynamic therapy was carried out. First, the conditions of active photodynamic therapy were explored, including incubation time, incubation concentration, light time, light power density and drug toxicity. On this basis, photodynamic therapy in vitro was carried out and N was found. AYF_4 nanocrystals have a good killing effect on PC-9 cells. When the drug concentration is 10 mu g/m L and the light time is 0.5 h, the cell survival rate can still be reduced to about 40%. At the same time, the relationship between the treatment conditions and the cell survival rate is e index, which provides the experimental basis for the implementation of the controlled photodynamic therapy. The mechanism of cell death was experimentally investigated. The results showed that both apoptosis and necrosis existed during photodynamic therapy. Photodynamic therapy in vivo showed that photodynamic therapy based on NaYb F4 nanocrystals could significantly reduce tumor volume.

【学位授予单位】：哈尔滨工业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TB383.1;R73-36

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