量子点复合材料及应用于药物载体和金属离子检测的研究

发布时间：2018-05-14 21:56

  本文选题：羧甲基-β-环糊精 + Fe_3O_4磁性纳米颗粒　； 参考：《山东大学》2017年博士论文

【摘要】：近年来,半导体量子点独特的尺寸依赖光学性质,在荧光标记、生物传感、太阳能电池等领域具有广泛的应用前景。然而,将量子点与磁性纳米颗粒复合制备的多功能药物载体,普遍存在载药量不高,稳定性不好及荧光猝灭等问题,因而限制了其更广泛的应用。同时,基于量子点的荧光性能已发展了多种荧光探针用于金属离子检测,然而由于选择性和检测灵敏度不高,如何实现对目标分析物的高选择性分析测定仍是目前具有挑战性的课题。本论文深入研究量子点的表面修饰及功能化,进一步实现量子点与其它纳米材料的组装与复合,从而获得更有实用价值的量子点材料。制备复合纳米药物载体的关键技术在于选择一个良好的介质能够同时稳定磁性材料和量子点。壳聚糖及其衍生物具有良好的稳定性和缓释性能,作为表面修饰稳定材料和药物载体方面具有明显优势。因此,本论文首先利用聚合物(CM-β-CD或CMCS)对磁性颗粒进行表面修饰,其修饰层不仅可以提高药物的负载量,降低对量子点荧光性能的影响,其表面丰富的功能基团有利于与量子点的有效结合。其次,聚合物改性的磁性纳米颗粒与量子点,经化学键合法共同包埋于壳聚糖基体中,得到稳定的复合纳米药物载体。同时,基于量子的荧光特性及电催化性能,经特异性表面配体分子修饰,通过采用ZnSe量子点溶液,ZnSe-XG纳米复合物及CS/ZnSe生物膜,三种策略构建用于金属离子检测的电化学传感器及荧光传感器,实现对金属离子的高选择性分析测定。主要内容归纳如下:(1)基于壳聚糖基体制备磁性复合纳米药物载体(CS-CDpoly-MNPs),利用羧甲基-β-环糊精修饰磁性纳米颗粒,其疏水空腔结构,经疏水包合作用对微溶性抗癌药物(5-Fu)具有优越的承载能力。药物载体的形貌和性能受制备过程中交联剂用量、交联时间及CS/5-Fu/CM-β-CD质量比等因素的影响。磁性纳米颗粒表面CM-β-CD的最大接枝量为6.5 wt%,复合纳米药物载体具有良好的磁性能(43.8 emu/g)和药物负载能力(44.7 ±1.8%)。(2)基于壳聚糖基体制备磁性荧光复合纳米药物载体(DCMFNPs),利用壳聚糖(CS)、羧甲基壳聚糖(CMCS)修饰的Fe304和谷胱甘肽(GSH)稳定的CdSe@ZnSQDs表面丰富的氨基基团,以戊二醛为交联剂,通过醛基与氨基的共价交联反应制备出具有良好磁性能和荧光性能的DCMFNPs,其化学键合作用结合不同组分明显提高了药物载体的稳定性。磁性纳米颗粒表面羧甲基壳聚糖(CMCS)的修饰作用有效降低了对量子点荧光性能的影响。DOX的累积释放主要涉及壳聚糖的溶胀行为和不同组分之间的静电作用力。体外细胞实验研究表明:CMFNPs具有低的细胞毒性和良好的生物相容性,且具有良好的成像功能。随孵育时间的延长,肿瘤细胞对药物载体的摄入量明显增加。(3)制备以羧甲基壳聚糖(CMCS)为基体的复合纳米材料载药体系,利用CMCS表面丰富的氨基和羧基基团,将量子点、CMCS修饰的Fe3O4及叶酸酸通过共价酰胺结合有效包埋在羧甲基壳聚糖基体中。与物理相互作用(如静电作用力)相比,各成分之间的共价键合作用有利于药物载体在生理环境中的稳定性。磁性荧光复合纳米药物载体(DOX-CLM)具有良好磁响应性和荧光性能,其药物释放具有pH依赖性可控释放。体外细胞实验研究表明,复合纳米颗粒具有良好的生物相容性,肿瘤细胞对药物载体的摄入主要是特异性受体介导的内吞机制。细胞凋亡数据表明,随孵育时间延长,细胞的早期凋亡和晚期凋亡的比例明显增加。(4)基于谷胱甘肽(GSH)修饰的ZnSe量子点的荧光猝灭法,开发一种检测铜离子的方法,并成功用于环境样品中铜离子的测定。与其它文献报道的量子点荧光探针相比,显示出优异的检测限和选择性,这主要归因于Cu(Ⅱ)加入导致量子点表面配体分子的剥离及量子点的表面状态的改变;同时,谷胱甘肽与Cu2+离子之间的电荷转移,还原后的Cu+可与GSH形成多种模式的配合物,进一步诱导量子点荧光的有效猝灭。在最佳条件下,此荧光探针对Cu2+的检出限为2×10-10 mol/L。同时,外来离子在Cu2+离子检测中显示出低的干扰响应。此外,ZnSe量子点不变的吸收峰和衰减的荧光寿命分析证实,此猝灭过程为动态猝灭过程。(5)研发一种ZnSe-XG纳米复合物作为电极修饰材料,并基于该修饰电极构建了用于Cd(Ⅱ)选择性检测的电化学传感器。与单独的ZnSeQDs相比,由于ZnSe和XG之间的氢键和络合作用,ZnSe-XG电极膜的检测稳定性和对Cd(Ⅱ)离子的吸附能力具有显著优势。ZnSe-XG纳米复合物及多壁碳纳米管(MWCNT)的引入均为电子转移提供了有利途径,且对Cd(Ⅱ)的检测显示出更优良的电催化活性。修饰电极对Cd(Ⅱ)检测的线性范围为0.336-5.6 mg/L,并且显示出高的灵敏度22.257μA·mg-1·L-1 和低的检测限6.11 μg/L。修饰电极对Cd(Ⅱ)的催化氧化过程证明是表面吸附控制,其饱和吸附量为3.45×10-9mol/cm2。该修饰电极显示出良好的检测灵敏度、选择性、再现性和长期稳定性,可以作为金属离子电化学检测的理想电极材料。(6)基于量子点溶液和量子点生物膜的荧光猝灭开发两种灵敏的荧光传感器用于检测Cd(Ⅱ)和Cu(Ⅱ)离子。量子点生物膜(CS/ZnSe)的荧光传感器有望应用于便携式感测装置的开发。随着金属离子浓度的增加,量子点的光致发光强度成比例地减小,并且荧光猝灭程度与金属离子浓度的关系可通过Stern-Volmer方程进行线性拟合。同时,基于黄原胶(XG)和ZnSe量子点(ZnSe-XG)纳米复合物构建可对两种金属离子实现单独和同步检测的电化学传感器。在最佳实验条件下,其峰值电流与金属离子的浓度具有良好的线性关系,并且对于Cd(Ⅱ)和Cu(Ⅱ)的检测限分别为6.1和0.074 μg/L。三种测定方法均对Cu2+比Cd2+具有更高的检测灵敏性和更低的检测限。对基于量子点的荧光传感器与电化学传感器的性能进行系统比较,结果表明,电化学传感器在重复性、灵敏度、选择性和检测限(LOD)方面具有显著优势。
[Abstract]:In recent years, semiconductor quantum dots have a wide range of applications in the fields of fluorescence labeling, biosensing, solar cells and other fields. However, the multifunctional drug carriers, which are prepared by the combination of quantum dots and magnetic nanoparticles, have a wide range of problems such as low drug loading, poor stability and fluorescence quenching. At the same time, based on the fluorescence properties of quantum dots, a variety of fluorescent probes have been developed for metal ion detection. However, because of the low selectivity and detection sensitivity, it is still a challenging task to realize the high selective analysis of the target analytes. This paper is a thorough study of the surface of quantum dots. The key technology for the preparation of a compound nanoscale drug carrier is to select a good medium to stabilize the magnetic material and the quantum dots. The chitosan and its derivatives have good stability. As a surface modified stable material and drug carrier, it has obvious advantages. Therefore, the surface modification of magnetic particles is first used in this paper (CM- beta -CD or CMCS). The modified layer can not only improve the load of the drug, but also reduce the effect of the fluorescence of the quantum dots. Secondly, the polymer modified magnetic nanoparticles and quantum dots are embedded in the chitosan matrix by the chemical bond method to obtain a stable compound nanoscale drug carrier. At the same time, based on the quantum fluorescence and electrocatalytic properties, the ZnSe quantum dots are used by the specific surface ligand molecular modification. Solutions, ZnSe-XG nanocomposites and CS/ZnSe biofilms, three strategies to construct electrochemical sensors and fluorescence sensors for metal ion detection, to achieve high selectivity and determination of metal ions. The main contents are as follows: (1) the preparation of magnetic compound nanoscale drug carrier (CS-CDpoly-MNPs) based on chitosan matrix and using carboxymethyl - Beta cyclodextrin modified magnetic nanoparticles, the hydrophobic cavity structure, the hydrophobic inclusion effect of the micro soluble anticancer drug (5-Fu) has superior bearing capacity. The morphology and properties of the drug carrier are affected by factors such as the amount of crosslinking agent, the crosslinking time and the mass ratio of CS/5-Fu/CM- beta -CD in the preparation process. Most of the CM- beta -CD on the surface of magnetic nanoparticles The large grafting amount is 6.5 wt%, and the composite nanoscale drug carrier has good magnetic properties (43.8 emu/g) and drug loading capacity (44.7 + 1.8%). (2) magnetic fluorescent composite nanomaterials (DCMFNPs) based on chitosan matrix, Fe304 and glutathione (GSH) modified CdSe@ZnSQDs surface modified by chitosan (CS), carboxymethyl chitosan (CMCS) The rich amino group, with glutaraldehyde as the crosslinking agent, was prepared by the covalent crosslinking reaction of aldehyde group and amino group, and the DCMFNPs with good magnetic energy and fluorescence properties was prepared. The chemical bonding combined with different components obviously improved the stability of the drug carrier. The modification effect of carboxymethyl chitosan (CMCS) on the surface of magnetic nanoparticles was effectively reduced. The effect of.DOX on the fluorescence properties of quantum dots is mainly related to the swelling behavior of chitosan and the electrostatic force between different components. In vitro cell experiments show that CMFNPs has low cytotoxicity and good biocompatibility, and has good imaging function. With the prolongation of incubation time, the tumor cells are drug The intake of the carrier is significantly increased. (3) the preparation of a compound nanomaterial carrier system based on Carboxymethyl Chitosan (CMCS), using the rich amino and carboxyl groups on the surface of CMCS, can be effectively embedded in the carboxymethyl chitosan matrix by binding the quantum dots, CMCS modified Fe3O4 and folic acid through covalent amides. In contrast, the covalent bond between the components is beneficial to the stability of the drug carrier in the physiological environment. The magnetic fluorescent composite nano drug carrier (DOX-CLM) has good magnetic responsiveness and fluorescence properties, and the release of the drug has a pH dependent controlled release. Biocompatibility, the intake of tumor cells to drug carriers is mainly specific receptor mediated endocytosis. Apoptosis data show that the proportion of early apoptosis and late apoptosis increased significantly with incubation time. (4) a kind of copper ion detection was developed based on the fluorescence quenching method of glutathione (GSH) modified ZnSe quantum dots. The method has been successfully used for the determination of copper ions in environmental samples. Compared with other reported quantum dots, the detection limits and selectivity are excellent, which is attributed to the Cu (II) addition leading to the dissection of the ligand molecules on the surface of the quantum dots and the change of the surface state of the quantum dots; at the same time, between glutathione and Cu2+ ions The charge transfer, the reduced Cu+ can form a variety of mode complexes with GSH, and further induce the effective quenching of the quantum dots fluorescence. Under the optimum conditions, the detection limit of the fluorescence probe to Cu2+ is 2 x 10-10 mol/L., and the external ions show low interference response in the Cu2+ ion detection. In addition, the constant absorption peaks of ZnSe quantum dots and the same absorption peaks are found. The decay of the fluorescence lifetime analysis confirms that the quenching process is a dynamic quenching process. (5) a ZnSe-XG nanocomposite is developed as an electrode modifier, and an electrochemical sensor for selective detection of Cd (II) is constructed based on the modified electrode. Compared with the single ZnSeQDs, the hydrogen bond and complexation between ZnSe and XG, ZnSe-XG electricity The detection stability of the polar membrane and the adsorption capacity of Cd (II) ions have significant advantages. The introduction of.ZnSe-XG nanocomposites and multi walled carbon nanotubes (MWCNT) provides a favorable way for electron transfer, and shows better electrocatalytic activity for the detection of Cd (II). The linear range of the modified electrode for Cd (II) detection is 0.336-5.6 mg/L, and The high sensitivity of 22.257 A. Mg-1. L-1 and low detection limit 6.11 mu g/L. modified electrode for Cd (II) was proved to be a surface adsorption control. The saturated adsorption capacity was 3.45 * 10-9mol/cm2., and the modified electrode showed good detection sensitivity, selectivity, reproducibility and long-term stability, which could be used as metal ions. Ideal electrode materials for electrochemical detection. (6) based on the fluorescence quenching of quantum dots solution and quantum dot biomembrane, two sensitive fluorescent sensors are used to detect Cd (II) and Cu (II) ions. The fluorescence sensors of the quantum dot biomembrane (CS/ZnSe) are expected to be applied to the development of portable sensing devices. The photoluminescence intensity of the subpoints is reduced proportionately, and the relationship between the fluorescence quenching degree and the concentration of metal ions can be linearly fitted by the Stern-Volmer equation. At the same time, the electrochemical sensors based on the xanthan gum (XG) and ZnSe quantum dots (ZnSe-XG) nanocomposites can be constructed to detect two kinds of metal ions separately and synchronously. Under good experimental conditions, the peak current has a good linear relationship with the concentration of metal ions, and the detection limits for Cd (II) and Cu (II) are 6.1 and 0.074 micron g/L. respectively, which have higher detection sensitivity and lower detection limit for Cu2+ than Cd2+. The results show that electrochemical sensors have significant advantages in repeatability, sensitivity, selectivity and detection limit (LOD).

【学位授予单位】：山东大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TQ460.1;O657.3
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本文编号：1889624