【作者】 李明亮；

【导师】 崔洪亮；

【作者基本信息】 吉林大学 ， 测试计量技术及仪器， 2018， 博士

【摘要】 太赫兹波(Terahertz wave,THz)是指频率介于0.1-10THz之间的电磁辐射,处于电子学到光子学的过渡区域。作为光谱测量技术的一个重要手段,太赫兹时域光谱(THz-TDS)技术展现出独特的优势。太赫兹技术为生物学、物理学、化学等诸多学科的发展提供了新的研究手段。太赫兹波技术在林业科学相关研究、食品质量安全、医学检测及诊断、爆炸物检测、太赫兹通信、有机生物分子探测、天文遥感等方面都很好的应用前景。太赫兹时域光谱技术可同时测量电场的相位和幅度,经傅里叶变换,样本材料在该波段的吸收系数、折射率以及复介电常数等参数都可以获得。太赫兹电磁波谱与有机物及生物分子(如DNA、RNA、蛋白质等)的转动和振动能量对应,是研究生物分子和有机物方面非常有效的工具。太赫兹辐射光子能量非常低,在进行生物检测时不会造成生物电离;同时太赫兹波属于远红外和毫米波范畴,具有低散射的特点。以上优点使太赫兹做生物检测时具有天然的优势。本文在国家973计划“活细胞的太赫兹波无标记检测技术基础研究”(2015CB755401),国家自然科学基金项目“‘十二五’国家科技支撑计划项目”(2012BAK04B03),重庆市科学技术委员会项目“太赫兹复合材料无损检测成像设备”(cstc2013yykfC00007)的共同资助下,利用太赫兹时域光谱技术鉴别固相生物分子的种类;研究液相生物分子的相互作用;与超材料相结合,鉴别液相生物分子种类;研究液相生物分子间的相互作用。主要研究内容如下:1、对应用太赫兹光谱技术研究生物分子的研究现状进行了详细梳理与总结;重点介绍了与用THz-TDS技术检测固相样本、液相样本以及液相样本与超材料结合相关的研究成果;对后续章节中实验中用到的样品制作工艺和实验设备进行描述。在此基础上,提出本文的主要研究思路和内容。2、详细说明了不同生物分子样本的制作流程及注意事项;对太赫兹辐射源的工作原理、结构及太赫兹波的探测手段和方法进行介绍;介绍了THz-TDS系统的工作原理及结构;重点讨论了透射式THz-TDS技术的原理和系统结构以及提取材料参数的理论依据和方法。3、对外观相似,直观上难以区分,且没有明显的特征吸收峰的固相生物分子进行鉴别,首先利用主成分分析(Principal Component Analysis,PCA)提取了不同生物分子样本的透射光谱数据的主成分,然后结合基于网格搜索算法的支持向量机(Grid Search-SVM)和基于遗传算法的支持向量机(GA-SVM)进行模式识别。从分类结果上看,GA-SVM是一种高效,平行和综合的搜索算法,其自动控制搜索过程可以通过自适应确定最优解,即使在训练样本有限的情况下,该算法仍产生准确的识别结果并展现良好的收敛特性。THz-TDS技术与模式识别相结合的方法,在鉴别不同固相生物分子的种类方面具有可行性。4、针对传统生物医学方法在检测液相生物分子相互作用时会受到荧光剂干扰的问题,提出了采用THz-TDS技术进行无标记检测生物分子相互作用的方法;选取具有重要生物学意义的雌激素受体α抗体(AER-α)以及与它的特异性抗原雌激素受体α多肽片段(ERP-α)作为研究对象,测量了AER-α与ERP-α反应前后的太赫兹光谱,应用水化动力学角度分析两种生物分子相互作用的机制,并从介电性质变化方面进一步分析两种生物分子相互作用前后的介电损耗角变化。最后,与传统生物医学方法相比较,证明了THz-TDS技术在检测液相生物分子相互作用方面具有可行性和可靠性。5、针对于一些液相生物分子在常规条件下对太赫兹场响应不敏感的情况,提出使用开口谐振环(Split-ring resonator,SRR)结构来增强太赫兹场局域电磁响应,从而增强太赫兹光谱对液相生物分子的检测灵敏度的方案。实现对不同液相生物分子的检测。设计并制造了SRR结构,实际制造出来的SRR结构参数与理论仿真吻合较好;首先,利用SRR结构与THz-TDS相结合,得到了油酸,亚油酸,α-亚麻酸和γ-亚麻酸四种不同脂肪酸的太赫兹透射谱,从光谱信息实部和虚部成功区分出不同种类的脂肪酸;其次,基于SRR结构,获得了不同浓度的免疫球蛋白(Rabbit IgG)溶液太赫兹透射光谱,实验结果显示可以有效区分不同浓度的Rabbit IgG蛋白溶液,且最小检测浓度为0.001mg/ml。随后将不同浓度的Rabbit IgG蛋白与频率偏移进行了拟合,从水化动力学角度分析了不同浓度蛋白产生不同频率偏移量的原因。测量了Rabbit IgG+anti-Rabbit IgG(抗体)溶液组合以及Rabbit IgG+BSA(牛血清蛋白)溶液组合基于SRR结构的太赫兹透射光谱,通过比对谐振峰的频率偏移量的差异,成功无标记检测了两种蛋白是否发生相互作用。更多还原

【Abstract】 Terahertz(THz)radiation is in the frequency range of 0.1-10 THz of the electromagnetic spectrum,sandwiched between microwave and infrared,bridging the transition area of traditional electronics and photonics,As an important approach of spectral measurement technology,the terahertz time-domain spectroscopy(THz-TDS)technology exhibits a number of unique advantages,enabling direct extraction of absorption coefficient,refractive index,and complex dielectric permittivity in the terahertz band.THz photons have energies corresponding to excitations of vibrations,rotations,configurational and conformational changes of organic and biomolecules(such as DNA,RNA,protein,etc.),making THz spectroscopy a very effective tool for studying biomolecules and organic matter.THz-TDS provides a new perspective on further understanding of the structural properties of matter,especially biological matter(tissues,cells,and biomolecules).Based on the analysis and reference to previous research on THz-TDS,we attempted using THz-TDS technology to detect the three phases of matter,i.e.,solid-phase,liquid-phase,and liquid-phase combined with the metamaterials,and the measurement results are discussed,and argued in favor of the feasibility of terahertz technology in the accurate detection of such matter.This paper is supported by National 973 Program of China(Project No.2015CB755401),the Chinese Ministry of Science and Technology(Project No.2012BAK04B03),the Chongqing Science and Technology Commission(Project No.cstc2013yykfC00007).The main research contents are as:1)A detailed review and summary of the research status of the application of terahertz spectroscopy in study of biomolecules;Focuses on the research results associated with the use of THz-TDS technology for the detection of solid-phase samples,liquid-phase samples and the metamaterials combined with liquid-phase samples;In the following sections,the sample making process and experimental equipment used in the experiment are described.On this basis,the main research ideas and contents of this paper are put forward.2)The production process and cautions of different biomolecular samples are described in detail;The principle and system structure of terahertz time domain spectroscopy are introduced,and the theoretical basis and method of extracting material parameters are discussed;The principle and system structure of the transmissive THz-TDS technology and the theoretical basis and method of extracting material parameters are discussed in detail.3)Considering that some biomolecules have no distinctive absorption peaks,we used principal component analysis(PCA)to extract the main components of the spectral data of different biomolecule samples.Then,the support vector machine(GA-SVM)of the genetic algorithm and the grid search-SVM are compared and analyzed.The results show that GA-SVM is an efficient,parallel and integrated search algorithm that automatically controls the search process to determine the optimal solution adaptively.The algorithm produces accurate recognition results and converges well,even if the training samples are limited.The combination of THz-TDS technology and pattern recognition has the potential to identify different types of solid-phase biomolecules.4)Considering the problem that the traditional biomedical method will interfere with the fluorescent agent when detecting the interaction of liquid biomolecules,a method for label-free detection of biomolecular interaction using THz-TDS is proposed;THz spectroscopy was employed to detect the binding reaction of AER-α with the AER-α-specific antigen ERP-α.Compared with classical methods(ELISA and IHC),THz spectroscopy is fast,convenient and label-free,which can potentially avoid the interference of the fluorescent agent in the binding reaction,and better reflect the true physiological state of the antigen-antibody binding.The measurement results showed that the hydration shell was constantly present in the AER-α,and AER-α /ERP-α solutions,and played an important role in the THz absorption of these solutions.Specifically,the binding interaction of AER-α and ERP-α effectively caused the hydration shell to diminish gradually until it disappeared.This hitherto unreported phenomenon shows that THz spectroscopy can be used to detect the configurational change of protein caused by occupation and population of antibody/antigen binding sites.Finally,compared with traditional biomedical methods,it is proved that THz-TDS technology is feasible and reliable in detecting liquid biomolecular interactions.5)Some liquid-phase biomolecules that are not sensitive to the terahertz field response under normal conditions,a split-ring resonator(SRR)structure is proposed to enhance the local electromagnetic response of the terahertz field,thereby enhancing the terahertz spectrum.A solution for the detection sensitivity of liquid biomolecules.To achieve the detection of different liquid biomolecules.The SRR structure was designed and manufactured,and the actually manufactured SRR structure parameters agree well with the theoretical simulation.Four different fatty acids were distinguished from the real and imaginary parts of the transmission spectrum by using SRR combined with THz-TDS for four different fatty acids: oleic acid,linoleic acid,α-linolenic acid and γ-linolenic acid.We also used THz-TDS combined with SRR structure to measure the transmission mode of different concentrations of protein solution.From the experimental results,we could effectively differentiate the protein solution;and the frequency shift of the resnance peak was fitted with the protein concentration.The minimum detection concentration was 0.001 mg/ml.Then the Rabbit IgG proteins with different concentrations were fitted to the frequency offset,and the reasons for the different frequency shifts at different concentrations of protein were analyzed from the perspective of hydration kinetics.The terahertz transmission spectra of Rabbit IgG + anti-Rabbit IgG solution combination and Rabbit IgG + BSA solution combination based on the SRR structure were measured.By comparing the difference in the resonance frequency shift of resonance peaks,twe obtained that the SRR structure based on THz-TDS was able to determine the reaction of the two proteins.更多还原