Centre for Nanotechnology and Advanced Biomaterials, School of Chemical and Biotechnology, SASTRA University, Thanjavur, Tamil Nadu, 613401, India.
Nanotechnology. 2012 Nov 23;23(46):465603. doi: 10.1088/0957-4484/23/46/465603. Epub 2012 Oct 24.
Self-assembly of pristine multi-walled carbon nanotubes (CNTs) in aqueous dispersion using a protein, bovine serum albumin (BSA), has been demonstrated. Step-wise conformational changes in BSA as a function of temperature have been deployed to direct the assembly of nanotubes. More specifically, CNTs distributed randomly in native BSA at 35 °C as well as completely denatured BSA solution at 80 °C self-assemble in the intermediate temperature range of 45-65 °C, as evident from scanning and transmission electron microscopy. Fourier transform infrared (FTIR) and fluorescence studies indicate significant changes in the α-helical content of the protein with respect to the amide I and II bands and tryptophan emission intensity, respectively. The stability of CNT dispersion in BSA solution has been attributed to the hydrophobic interaction between nanotubes and the protein molecule by adding sodium cholate to the dispersion. Moreover, a mechanism based on electrostatic repulsion between BSA-bound CNTs has been proposed for the thermally reversible assembly of CNTs in BSA solution based on evidence from zeta potential measurements and FTIR spectroscopy. Thus the present report demonstrates bio-mimetic self-assembly of as-synthesized CNTs using changes in surface charge and conformation of an unfolding protein for biomedical applications and nanobiotechnology.
使用蛋白质牛血清白蛋白（BSA）在水溶液中自组装原始的多壁碳纳米管（CNT）已经得到证明。BSA 的构象变化可以作为温度的函数来指导纳米管的组装。更具体地说，在 35°C 下随机分布在天然 BSA 中的 CNT 以及在 80°C 下完全变性的 BSA 溶液在 45-65°C 的中间温度范围内自组装，这可以从扫描和透射电子显微镜中明显看出。傅里叶变换红外（FTIR）和荧光研究表明，与酰胺 I 和 II 带和色氨酸发射强度有关的蛋白质的α-螺旋含量发生了显著变化。通过向分散体中添加胆酸钠，将 CNT 分散在 BSA 溶液中的稳定性归因于 CNT 与蛋白质分子之间的疏水相互作用。此外，基于zeta 电位测量和 FTIR 光谱的证据，提出了基于 BSA 结合的 CNT 之间的静电排斥的机制，用于解释 CNT 在 BSA 溶液中的热可逆组装。因此，本报告展示了使用未折叠蛋白质的表面电荷和构象变化来仿生自组装合成 CNT，用于生物医学应用和纳米生物技术。
