组成图示
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传感器类型
电化学生物传感器
检测对象
葡萄糖（glucose）；样品基质：磷酸盐缓冲液（PBS, pH 6.0），面向血液/体内血糖监测
检测原理
该传感器以金电极为换能基底，PANI与CS-CNTs构成导电/介导网络，GOD作为识别与催化元件。葡萄糖进入电极表面后，被GOD特异性催化氧化，其催化电子经CS-CNTs与PANI介导传递至金电极；碳纳米管提供导电通道，壳聚糖提供生物相容微环境，PANI作为导电聚合物促进电子转移。三维CS-CNTs网络增加GOD负载量并改善电极-酶接触，使稳态安培电流随葡萄糖浓度升高而增大。在0.5 V恒定电位下，1–20 mM范围内电流与浓度呈线性关系，体现酶催化-电子介导-安培读出机制。
检测灵敏度
LOD: about 0.1 mM；线性范围: 1-20 mM；灵敏度: 21 µA/(mM·cm2) (or 16.5 µA/mM)
效应效果
该传感器在0.5 V下响应时间约8–10 s，线性范围1–20 mM，覆盖体内监测常用5–20 mM。与无PANI电极相比，灵敏度由约5.2 µA/(mM·cm2)提高到21 µA/(mM·cm2)，表观Michaelis-Menten常数由14.85 mM降至5.35 mM，酶活性更高。10个电极RSD约5.0%；4 °C PBS储存1个月和2个月分别保持约95%和83%初始电流。0.3 mM抗坏血酸和尿酸在1.0 mM葡萄糖下干扰可接受，对乙酰氨基酚干扰可忽略。共价固定可防止GOD流失，适用于高灵敏度葡萄糖传感。
传感器的构成
- 基底/换能器电极：金电极（Au electrode），提供导电基底与安培换能
- 自组装单分子层：4-氨基苯硫酚（4-aminothiophenol）SAM，提供氨基锚定位点
- 导电聚合物修饰层：聚苯胺（PANI），氧化接枝形成，介导电子转移并放大信号
- 双功能连接层：戊二醛（glutaraldehyde, GA），与PANI氨基反应并连接CS-CNTs
- 纳米复合材料修饰层：壳聚糖-偶联碳纳米管（CS-CNTs），由多壁碳纳米管（MWCNT）与壳聚糖共价偶联，形成三维导电网络
- 酶识别/催化元件：葡萄糖氧化酶（glucose oxidase, GOD），识别并催化葡萄糖
- 酶固定连接剂：1,4-碳酰二咪唑（1,4-carbonyldiimidazole, CDI），活化壳聚糖羟基并共价固定GOD
中文摘要
本文报道了一种基于共价固定壳聚糖-偶联碳纳米管（CS-CNTs）于聚苯胺（PANI）修饰金电极的安培型葡萄糖生物传感器（Au-g-PANI-c-(CS-CNTs)-GOD）。首先以4-氨基苯硫酚在金电极表面形成自组装单分子层，再通过氧化接枝聚合苯胺制备PANI层；随后以戊二醛为双功能连接剂，将CS-CNTs共价偶联到PANI修饰金基底上；最后以1,4-碳酰二咪唑为连接剂，将葡萄糖氧化酶（GOD）共价固定于壳聚糖侧链羟基上。XPS证实各功能化步骤，FESEM显示电极表面形成三维网络结构，可提供空间生物相容微环境，提高固定酶量与生物催化活性并促进电子转移。该传感器对葡萄糖在1–20 mM范围内呈线性响应，灵敏度为21 µA/(mM·cm2)，重现性良好，储存2个月后仍保持初始响应电流的80%以上。
英文摘要
An amperometric glucose biosensor was prepared using polyaniline (PANI) and chitosan-coupled carbon nanotubes (CS-CNTs) as the signal amplifiers and glucose oxidase (GOD) as the glucose detector on a gold electrode (the Au-g-PANI-c-(CS-CNTs)-GOD biosensor). The PANI layer was prepared via oxidative graft polymerization of aniline from the gold electrode surface premodified by self-assembled monolayer of 4-aminothiophenol. CS-CNTs were covalently coupled to the PANI-modified gold substrate using glutaradehyde as a bifunctional linker. GOD was then covalently bonded to the pendant hydroxyl groups of chitosan using 1,4-carbonyldiimidazole as the bifunctional linker. The surface functionalization processes were ascertained by X-ray photoelectron spectroscopy (XPS) analyses. The field emission scanning electron microscopy (FESEM) images of the Au-g-PANI-c-(CS-CNTs) electrode revealed the formation of a three-dimensional surface network structure. The electrode could thus provide a more spatially biocompatible microenvironment to enhance the amount and biocatalytic activity of the immobilized enzyme and to better mediate the electron transfer. The resulting Au-g-PANI-c-(CS-CNTs)-GOD biosensor exhibited a linear response to glucose in the concentration range of 1-20 mM, good sensitivity (21 μA/(mM·cm(2))), good reproducibility, and retention of >80% of the initial response current after 2 months of storage.