Department of Chemistry, Beijing Key Laboratory for Analytical Methods and Instrumentation, Tsinghua University, Beijing 100084, PR China.
Chemistry. 2012 Mar 19;18(12):3687-94. doi: 10.1002/chem.201103259. Epub 2012 Feb 14.
A temperature-sensitive polymer/carbon nanotube interface with switchable bioelectrocatalytic capability was fabricated by self-assembly of poly(N-isopropylacrylamide)-grafted multiwalled carbon nanotubes (MWNT-g-PNIPAm) onto the PNIPAm-modified substrate. Electron microscopy and electrochemical measurements revealed that these fairly thick (>6 μm) and highly porous nanocomposite films exhibited high conductivity and electrocatalytic activity. The morphological transitions in both the tethered PNIPAm chains on a substrate and those polymers wrapping around the MWNT surface resulted in the opening, closing, or tuning of its permeability, and simultaneously an electron-transfer process took place through the channels formed in the nanostructure in response to temperature change. By combining the good electron-transfer and electrochemical catalysis capabilities, the large surface area, and good biocompatibility of MWNTs with the responsive features of PNIPAm, reversible temperature-controlled bioelectrocatalysis of 1,4-dihydro-β-nicotinamide adenine dinucleotide with improved sensitivity has been demonstrated by cyclic voltammetry and electrochemical impedance spectroscopy measurements. The mechanism behind this approach was studied by Raman spectroscopy, in situ attenuated total reflection FTIR spectroscopy, and contact angle measurements. The results also suggested that the synergetic or cooperative interactions of PNIPAm with MWNTs gave rise not only to an increase in surface wettability, but also to the enhancement of the interfacial thermoresponsive behavior. This bioelectrocatalytic "smart" system has potential applications in the design of biosensors and biofuel cells with externally controlled activity. Furthermore, this concept might be proposed for biomimetics, interfacial engineering, bioelectronic devices, and so forth.
通过将接枝了聚（N-异丙基丙烯酰胺）的多壁碳纳米管（MWNT-g-PNIPAm）自组装到 PNIPAm 修饰的基底上，制备了具有可切换生物电催化能力的温敏聚合物/碳纳米管界面。电子显微镜和电化学测量表明，这些相当厚（>6μm）且高度多孔的纳米复合薄膜具有高导电性和电催化活性。基底上固定的 PNIPAm 链和包裹在 MWNT 表面的聚合物的形态转变导致其渗透性的打开、关闭或调谐，同时通过纳米结构中形成的通道发生电子转移过程，响应温度变化。通过结合 MWNTs 的良好电子转移和电化学催化能力、大表面积和良好的生物相容性以及 PNIPAm 的响应特性，通过循环伏安法和电化学阻抗谱测量，展示了具有改进灵敏度的 1,4-二氢-β-烟酰胺腺嘌呤二核苷酸的可逆温度控制生物电化学催化。通过拉曼光谱、原位衰减全反射傅里叶变换红外光谱和接触角测量研究了这种方法的机理。结果还表明，PNIPAm 与 MWNTs 的协同或合作相互作用不仅导致表面润湿性增加，而且还增强了界面热响应行为。这种生物电化学“智能”系统具有在具有外部控制活性的生物传感器和生物燃料电池的设计中的潜在应用。此外，这个概念可能被提议用于仿生学、界面工程、生物电子设备等。
