国家重大科学研究计划项目“生物医学纳米材料对细胞作用的研究”工作进展与讨论

纳米材料与细胞作用的方法学研究

南京大学 朱俊杰 教授


1. 研究思路及技术路线


2. 开展具有生物识别和示踪功能的纳米探针的构建新方法

A versatile immunosensor using CdTe quantum dots (QDs) as electrochemical and fluorescent labels has been developed for sensitive protein detection. This sandwich-type sensor is fabricated on an indium tin oxide (ITO) chip covered with well-ordered gold nanoparticle (GNP) monolayer. Gel imaging systems were successfully introduced to develop a novel high-efficient optical immunoassay, which could perform simultaneous detection for the samples with a series of different concentrations of a target analyte. Herein, we used a simple and facile synthetic strategy to prepare uniform-size and highly luminescent water-soluble CdTe QDs and fabricated a versatile immunosensor to effectively detect protein based on the CdTe QDs label simultaneously as fluorescent and electrochemical signals. In the case of the preparation of the versatile immunosensor, the goat anti-human IgG antibody (Ab1) was immobilized on the ITO chip coated with well-ordered GNP. The analytical procedure consists of the immunoreaction of the antigen (Ag) with Ab1, followed by binding CdTe QDs-labeled mouse anti-human IgG antibody (CdTe QDs-Ab2). Formation of an Ab layer and the Ag-Ab complexes on the chip was characterized by atomic force microscopy (AFM), electrochemical impedance spectroscopy (EIS), fluorescence microscopy image, stripping voltammetry, and gel imaging systems. The detailed optimization and attractive performance characteristics of the developed versatile immunoassay are reported in the following sections. The linear range of this assay was between 0.1 ng/mL and 500 ng/mL and the assay sensitivity could be further increased to 0.005 ng/mL with the linear range from 0.005 to 100 ng/mL by stripping voltammetric analysis. The immunosensor showed good precision, high sensitivity, acceptable stability and reproducibility and could be used for the detection of real sample with the consistent results in comparison with those obtained by ELISA method. A 3 mm thick poly-dimethyl siloxane (PDMS) with a circular opening in diameter of 4 mm was formed from a predefined mold, and was bound to the ITO surface to form the Ab-Ag reaction area.

2.1 ITO 电极的CdTe量子点双通道信号识别的免疫传感


锡氧化物半导体透明导电膜(ITO)电极的CdTe量子点双通道信号识别的免疫传感
[Anal. Chem. 2007, 79 (22): 8494-8501]

Here we can see the fluorescence image of gel imaging systems on the ITO chip with the increase of HIgG concentration. The relative amount of each result was scored using Quantity One (Bio-Rad).We could observe that the fluorescence intensity of the Ab-spotted area increased with the increase of HIgG concentration from 0.1 to 500 ng/mL


(a) The fluorescence images of gel imaging systems on the ITO chips for different HIgG levels from (A) to (F) (0, 0.1, 1.0, 10, 100, and 500 ng mL-1 HIgG, respectively). (A’) full immunoassay using Ab2 instead of QDs-Ab2 omitting addition HIgG..


(b) Detection curve for HIgG plotted on a semi-log scale.

随着HIgG浓度的从 0.1 增加到 500 ng/mL,量子点荧光也增加: The detection limit: 0.03 ng/mL (n=3, 0.187 pM).

Stripping Voltammetric Analysis. The CdTe QDs remaining at the chip surface were dissolved by the addition of 100 μL, 0.10 M HNO3 solution. The solution was transferred into 900 μL of 0.20 M acetate buffer at pH 4.6, the amount and identity of the dissolved metal ions were determined by electrochemical stripping techniques. The square wave stripping voltammetric analysis (SWSV) was conducted using a CHI660 electrochemical workstation equipped with a stirring machine (CH Instruments Inc, USA). The three-electrode system used for running the SWSV consisted of a glassy carbon working electrode (GCE), SCE, and a platinum counter electrode. The electrochemical procedure involved a 1 min pretreatment at +0.6 V, and 10 min electrodeposition at -1.00 V, and stripping from -1.00 V to -0.45 V using a square wave voltammetric waveform, with 4 mV potential steps, 25 Hz frequency and 25 mV amplitude.


(a) Typical square wave voltammograms of electrochemical immunoassay with increasing HIgG concentration from (A) to (H) ( 0, 0.005, 0.01, 0.1, 1.0, 10, 50 and 100 ng mL-1 HIgG, respectively ).
(b) The resulting calibration curve of HIgG plotted on a semi-log scale.

The relative deviations between optical assay and ELISA method were in the range of -10.9%~10.3%, and the relative deviations between electrochemical assay and ELISA method were from -7.5% to 8.2%. It obviously indicates that there is no significant difference among the results given by three methods, that is, the developed versatile immunoassay may provide an interesting alternative tool for detection of protein in clinical laboratory.


Comparison of serum HIgG levels determined using optical assay, electrochemical assay, and ELISA method.

2.2 三维有序大孔金膜的电化学阻抗免疫传感


Preparation of 3DOM Gold Films
detection of C-reactive protein (CRP) using electrochemical impedance spectroscopy (EIS) technique


免疫传感器的构建


C反应蛋白的检测
a. Blank solution (b.-g.) 0.1ng mL-1, 0.5ng mL-1, 1.0ng mL-1, 5.0ng mL-1, 10.0ng mL-1 20.0ng mL-1 CRP-antigen

我们用垂直模板沉积法来将二氧化硅纳米球整齐地沉积在金膜的表面,再通过氯金酸溶液中进一步电沉积金膜,最后去除作为模板的二氧化硅纳米球,形成反卵石形的三维有序大孔电极(3DOM)

我们采用电沉积的方法可以在自组装纳米微球的空隙中填充生物亲和性材料,如纳米金,纳米银,导电聚合物等,然后去除作为模板的SiO2或PS纳米微球,这就成功地构建了三维有序大孔电极(3DOM)三维有序纳米大孔电极。该电极的突出优点在于大大增加了电极的实际面积,从而增加了生物分子的固定量,实现了高灵敏的生物检测。我们基于3DOM电极和电化学阻抗谱法(EIS)构建了新型的免疫传感器,在金片电极上制备了3DOM金膜电极,该电极的实际面积达到传统的平面电极的14.4倍。在这层多孔金膜上依次固定了巯基丙酸和C反应蛋白抗体(CRP-Ab),用来检测待测液中的相应抗原浓度。同时,我们还将该传感器应用于临床样品的检测中,得到了良好的一致性,说明了良好的实际应用前景。由于3DOM电极的规则性以及电极材料的生物亲和性,完全可能进一步构建成生物阵列电极实现多通道检测,并可以应用于细胞行为检测。目前国内外尚无相关类似的报道。
Anal. Chem. 2008, Accepted

3. 研究纳米探针的结构与功能关系及其生物学效应

3.1 复合纳米材料的肿瘤细胞电化学传感器


Gelatin: a reducing and a stabilizing agent. Gelatin is chemisorbed onto the AuNPs surface following synthesis through its amino group and carboxylic group binding with the Au surface.

纳米金-明胶与纳米金-明胶-单壁碳纳米管复合材料

在HL-60细胞固定在电极表面后,修饰电极在+0.80V处出现一个峰形良好的阳极峰,这来自于活细胞细胞质中鸟嘌呤的氧化,在电化学过程中鸟嘌呤分子能够穿过细胞膜。经过连续两次的循环伏安扫描,发现阳极响应逐渐消失;而在逆向扫描中,一直未见相应的还原峰出现,据此推断鸟嘌呤的氧化过程是不可逆的。

电化学活性物质的电子传递速率或电子传递阻抗与电极表面的性质密切相关。吸附于电极表面的细胞的数量、生长状况、形态上的变化都会影响电极的界面性质,通过氧化还原探针能有效地检测到这些性质的变化。

CV:检测不同细胞浓度。细胞浓度增加,氧化还原峰电流降低,ΔEp 增大,峰形变差,表明细胞吸附到电极表面后,电极的界面阻抗增加,从而阻碍了电活性物质的电子传递。


肿瘤细胞电化学传感器参数曲线

从上图可以看出:
a. 鸟嘌呤的氧化过程是不可逆的。
b. 电化学活性物质的电子传递速率或电子传递阻抗与电极表面的性质密切相关。
c. CV:检测不同细胞浓度。细胞浓度增加,氧化还原峰电流降低,ΔEp 增大,峰形变差,表明细胞吸附到电极表面后,电极的界面阻抗增加,从而阻碍了电活性物质的电子传递。

我们进一步利用交流阻抗法研究了HL-60在该纳米复合膜上的增殖和凋亡,并对吸附于电极表面的HL-60细胞的数量进行了检测。在优化的实验条件下,电化学响应与细胞浓度的对数在2.5×104- 1×107的范围成线性关系,检测限为1×104。


4. 探索细胞动态过程分析新技术,发展建立了细胞与纳米粒子相互作用研究的微流控芯片平台

4.1 与细胞作用的微流控芯片平台构建


PDMS/金纳米粒子复合膜在微流控芯片中的应用

工作总结

  • 在前两年的工作中我们已经完成了一系列的基于纳米材料的生物和细胞相容性界面的构建并形成传感器件,发表了相关的成果。
  • 掌握了特定功能尤其是具有细胞固定、细胞培养、选择性贴壁等细胞功能的微流控芯片系统的加工和制作技术,并已经将量子点等功能性的纳米材料与芯片技术相结合,产生了非常具有前景的交叉性学科生长点。
  • 针对某些特定的重大疾病和特定的肿瘤细胞开展了一系列的富有特色的研究,如针对与冠心病相关的低密度脂蛋白的电化学传感器的研究;针对悬浮性人白血病细胞不易固定特点的芯片-量子点药物筛选研究等等

已发表和录用的论文

  • Qing Zhang, Jing-Juan Xu*, Yan Liu and Hong-Yuan Chen* In-situ synthesis of poly(dimethylsiloxane)-gold nanoparticles composite films and its application in microfluidic systems, Lab on Chip, In press
  • Rong-Jing Cui, Hong-Cheng Pan, Jun-Jie Zhu*, Hong-Yuan Chen, Versatile Immunosensor Using CdTe Quantum Dots as Electrochemical and Fluorescent Labels, Anal. Chem. 2007, 79 (22): 8494-8501.
  • Jun Geng, Bo Liu, Lang Xu, Fang-Neng Hu, Jun-Jie Zhu*, Facile route to Zn-based II-VI semiconductor spheres, hollow spheres, and core/shell nanocrystals and their optical properties, Langmuir, 2007, 23, 10286-10293.
  • Jing-Jing Zhang, Yu-Ge Liu, Li-Ping Jiang* and Jun-Jie Zhu*, Synthesis, Characterizations of Silica-Coated Gold Nanorods and Its Applications in Electroanalysis of Hemoglobin , Electrochem. Commun. In Press
  • Wei Yan, Xiaomiao Feng, Xiaojun Chen, Wenhua Hou, Jun-Jie Zhu*, A Super Highly Sensitive Glucose Biosensor Based on Au Nanoparticles-AgCl@Polyaniline Hybrid Material, Biosensors and Bioelectronics,��In Press,
  • Wei Yan, Xiao-Jun Chen, Xing-Hua Li, Xiao-Miao Feng, Jun-Jie Zhu*, Fabrication of a label free low-density lipoprotein electrochemical immunosensor J. Phys. Chem. B, In Press,

研究专利

  • 一种多功能免疫芯片及其制法和在免疫检测中的应用, 朱俊杰,崔荣静, 申请号:200710025585.2
  • CdS、CdSe或CdTe空心纳米环及其制法, 朱俊杰,缪建军,姜立萍, 申请号: 200710022417.8
  • 一种CdTe纳米空心球或CdTe纳米管的制备方法, 朱俊杰,缪建军,姜立萍, 申请号: 200710022418.2
  • 芯片毛细管电泳中低速电渗流的测量方法,王伟,周方,朱俊杰,张剑荣,申请号:200710021018.X
  • 适合便携式微芯片毛细管电泳设备的简易进样方法,王伟,朱俊杰,张剑荣,申请号:200710021383.0

方案调整与计划

  • 继续深入地研究纳米探针的构建,采取有所偏向和侧重地合成某些纳米探针材料
  • 将构建新型的光学和电化学细胞生物传感的纳米探针作为下一轮研究的重点
  • 肿瘤细胞的纳米界面电化学研究
  • 建立细胞与纳米粒子相互作用研究的功能化微流控芯片平台和发展细胞检测的新方法