基于钙钛矿的光电化学生物传感器的制备及分析方法研究

【作者】 杨浩；

【导师】 戴志晖；

【作者基本信息】 南京师范大学 ， 分析化学， 2021， 硕士

【摘要】 人体的健康与体内的许多物质的活性及浓度息息相关。例如,碱性磷酸酶活性的异常通常预示骨骼肝脏等器官发生了病变,而多巴胺的异常通常与神经性疾病有着千丝万缕的联系,因此实现这些物质的定量检测对于疾病的诊断具有重要的意义。光电化学生物传感器作为一种光源与信号分离的分析方法,具备成本低、设备简单并且抗背景信号干扰能力强等优点,近年来被广泛应用于各种目标物的检测。然而,光电活性材料的选择对于光电化学生物传感器的性能起着决定性的作用,对光电活性材料的制备及其调控,成为了光电化学生物传感器发展的关键。钙钛矿作为一种发展最快、最有前景的光电化学活性材料,吸引了人们的广泛关注。在过去几年的研究中,它们的光电转换效率已经提升至25.5%。除了扩散长度长、合成成本低和组成多样化外,钙钛矿因其载流子寿命长、光吸收系数大和高光催化活性等优点在许多领域都应用甚广,比如光电探测器、二极管、太阳能电池等。然而它们却很少被应用于生物传感中,主要的原因是,绝大部分钙钛矿均为铅基材料,对于生物体具有较高的毒性,并且钙钛矿的结构并不稳定,暴露在外部环境中时具有较差的稳定性,这极大的限制了它们的性能。更重要的是,它们的水溶性与生物相容性都非常差,对于生物传感器的构建非常不利。因此开发高稳定性、高生物相容性的钙钛矿材料对于提升光电化学生物传感器的性能至关重要。在本论文中,主要开发了具备高稳定性与生物相容性以及低毒性的钙钛矿及其复合材料,并充分利用其特点,用于构建高性能的光电化学生物传感器,主要包括以下两部分内容:1.通常在现有的光电系统中,光电活性材料的极化方向是不能调控的。这些传感系统不变的电子传输路径极大地限制了它们在各个领域的性能。我们通过原位半导体生成和酶催化反应来调控钙钛矿基异质结构的极化,成功建立了光电流极化方向可转换的光电传感系统。由于其能带排列,Cs₃Bi₂Br₉量子点（QDs）和Bi OBr可构成Z-scheme异质结结构,从而产生了明显的阳极光电流信号。在2-磷酸抗坏血酸（AAP）加入之后,Bi PO₄在Cs₃Bi₂Br₉QDs/Bi OBr异质结构的表面上原位生成,从而重新调整了Bi OBr的能带位置,进而导致光活性材料的极化发生转换,并且重新构造了具有反向电子传递路径的新的Z-scheme异质结结构,从而导致明显的阴极光电流响应。此外,通过用碱性磷酸酶（ALP）催化AAP水解,可以生成大量的电子供体（抗坏血酸）。在抗坏血酸的存在下,Bi OBr中的光生空穴优先被电子供体消除,从而阻止了Cs₃Bi₂Br₉QDs/Bi OBr/Bi PO₄异质结中光生电子的转移。因此,酶催化作用触发了电流的第二次极化转化,从而导致阳极光电流的恢复。基于这种对于钙钛矿基光电活性材料极化的调控作用,设计得到了一种具有两翼（two wings）信号开关功能的光电化学生物传感器。基于此方法,成功实现了人血清中的微量ALP的精准定量传感,有利于制备优越性能的光电化学传感器。2.尽管在钙钛矿上原位生成异质结可以显著的增强其生物传感性能,但是这仅仅局限于某些含有特殊离子如Bi³⁺的钙钛矿中,为了寻找更通用的提升钙钛矿生物传感性能的方法,在本章工作中,采用全无机钙钛矿Cs₃Bi₂I₉,使其在Ui O-66 MOF中原位生长,从而形成Ui O-66包封的Cs₃Bi₂I₉QDs@Ui O-66复合材料。Ui O-66 MOF中的孔道为钙钛矿量子点提供了良好的生长空间,由于MOF的包封作用,Cs₃Bi₂I₉QDs与外界环境相隔离,从而保证了钙钛矿良好的稳定性。同时Cs₃Bi₂I₉与Ui O-66的能带相匹配,从而可以在提高稳定性的同时,进一步提升了它的光电性能。此外Ui O-66中的羧基基团还使得Cs₃Bi₂I₉QDs@Ui O-66具有良好的亲水性与生物相容性,并由于Ui O-66的包封进一步降低Cs₃Bi₂I₉QDs的毒性,解决了钙钛矿普遍存在的稳定性与生物相容性的问题。在以上基础上,利用多巴胺的自聚合形成具有丰富苯醌电子受体基团的聚多巴胺,基于其加强电荷分离和传递效率的作用提升体系的生物分析性能,增大了多巴胺的检测范围,并且具有较低的检测限,本工作为钙钛矿材料应用于生物传感提供了一种通用的新思路。更多还原

【Abstract】 The health of the human body is closely related to the activity of many substances in the body.For example,the abnormality of alkaline phosphatase activity usually indicates that the bones and liver and other organs are diseased,and the abnormality of dopamine is usually inextricably linked with neurological diseases.Therefore,it is of great significance to realize the quantitative sensing of these substances.Photoelectrochemical biosensor,as an analysis method of light source and signal separation,has the advantages of low cost,simple equipment and strong ability to resist background signal interference.In recent years,it has been widely used in the construction of various sensors.However,the choice of photoelectric active materials plays a significant role in the performance of photoelectrochemical biosensors.As one of the fastest growing and most promising photoelectrochemical active materials so far,perovskite has attracted widespread attention.In the past few years of research,their photoelectric conversion efficiency has been increased to 25.5%.In addition to the long diffusion length,low synthesis cost and diversified composition,perovskites are widely used in many fields due to their long carrier life,large light absorption coefficient and high photocatalytic activity,such as photodetectors,diodes,solar cells,et al.However,they are rarely used in biosensing.The main reason is that most perovskites are lead-based materials,which are highly toxic to living organisms,and the structure of perovskites is not stable while exposed to the outer environment they have poor stability in the external environment,which greatly limits their performance.More importantly,their water solubility and biocompatibility are very poor,which is very unfavorable for the construction of biosensors.Therefore,the development of perovskite materials with high stability and high biocompatibility is essential to improve the performance of photoelectrochemical biosensors.In this paper,we mainly developed the perovskite and its composite materials with high stability,biocompatibility and low toxicity,and made full use of their characteristics to construct high-performance photoelectrochemical biosensors,mainly including the following two parts:1.Normally,polarization of photo-active materials in current photoelectric（PE）systems cannot be adjusted,and thus electron transfer route of these systems are unchangeable,which greatly limits their performance in various fields.Herein,we attempted to modulate the polarization of perovskite-based heterostructures by both in situ semiconductor generation and enzymatic catalysis.Owing to the band alignment,Cs₃Bi₂Br₉quantum dots（QDs）and Bi OBr are confirmed to construct a Z-scheme structure,leading to a large anodic photocurrent.In the presence of ascorbic acid2-phosphate（AAP）,Bi PO₄is in situ generated on the surface of Cs₃Bi₂Br₉QDs/Bi OBr heterostructure,reassigning energy bands of Bi OBr.As a result,polarization of photo-active materials is converted,and a new Z-scheme structure with reversed electron transfer route is constructed,which lead to an evident cathodic photocurrent.Furthermore,abundant electron donors（ascorbic acid）can be obtained by catalyzing AAP with alkaline phosphatase（ALP）.In this case,photogenerated holes in Bi OBr are preferentially annihilated by electron donors,thereby blocking transfer of photogenerated electrons in Cs₃Bi₂Br₉QDs/Bi OBr/Bi PO₄heterostructure.Consequently,a second polarization conversion is triggered by enzymatic catalysis,resulting in the recovery of an anodic photocurrent.Benefited from the polarization conversion,a PEC biosensor with a feature of two-wing signal switch is designed,and ALP in small volume of human serum can be quantified with this method.In this work,polarization of perovskite-based photo-active materials is tuned and employed in biosensing,proposing an alternative perspective on design of advanced PE systems.2.Although in-situ generation of heterostructures on perovskites can significantly enhance their biosensing performance,but this method only limits in certain perovskites containing special ions such as Bi³⁺,in order to find a more general method in improving the biosensing performance of perovskites,in the work of this chapter,an all-inorganic perovskite Cs₃Bi₂I₉was in situ generated in Ui O-66 to form a Cs₃Bi₂I₉QDs@Ui O-66 composite material.The holes in Ui O-66 happened to be the excellent growth position of Cs₃Bi₂I₉QDs.Due to the encapsulation of MOF,Cs₃Bi₂I₉QDs were isolated from the outside world,which ensured the good stability of these two materials.At the same time,the energy band matching of Cs₃Bi₂I₉and Ui O-66 further improved its photoelectrochemical properties.The carboxyl group in Ui O-66 makes Cs₃Bi₂I₉QDs@Ui O-66 have good water affinity and biocompatibility,and the encapsulation of Ui O-66 further reduces the toxicity of Cs₃Bi₂I₉QDs,which solves the general problem of toxicity and low stability and biocompatibility in perovskites.And we used the self-polymerization of dopamine to form polydopamine with abundant benzoquinone electron acceptor groups,and then took the advantage of the improve of charge transfer efficiency to use them in photoelectrochemical biosensors.Finally,the detection range of dopamine was increased and the whole detection system was with a lower detection limit.It was obtained a new general idea for the application of perovskite materials in biosensing.更多还原