Department of Chemistry and Biochemistry, UCLA, Los Angeles, California 90095-1569, United States.
ACS Nano. 2011 Oct 25;5(10):7730-8. doi: 10.1021/nn202493w. Epub 2011 Oct 7.
Cowpea chlorotic mottle virus is a single-stranded RNA plant virus with a diameter of 28 nm. The proteins comprising the capsid of this virus can be purified and reassembled either by themselves to form hollow structures or with polyanions such as double-stranded DNA or single-stranded RNA. Depending on pH and ionic strength, a diverse range of structures and shapes can form. The work presented here focuses on using these proteins to encapsulate a fluorescent polyanionic semiconducting polymer, MPS-PPV (poly-2-methoxy-5-propyloxy sulfonate phenylene vinlyene), in order to obtain optically active virus-like particles. After encapsulation, fluorescence from MPS-PPV shows two distinct peaks, which suggests the polymer may be in two conformations. A combination of TEM, fluorescence anisotropy, and sucrose gradient separation indicate that the blue peak arises from polymer encapsulated into spherical particles, while the redder peak corresponds to polymers contained in rod-like cages. Ionic strength during assembly can be used to tune the propensity to form rods or spheres. The results illustrate the synergy of hybrid synthetic/biological systems: polymer conformation drives the structure of this composite material, which in turn modifies the polymer optical properties. This synergy could be useful for the future development of synthetic/biological hybrid materials with designated functionality.
豇豆花叶病毒是一种单链 RNA 植物病毒，直径为 28nm。该病毒衣壳蛋白可自行纯化和重组，形成空心结构，或与双链 DNA 或单链 RNA 等多阴离子结合。根据 pH 值和离子强度的不同，可以形成多种不同的结构和形状。本研究旨在利用这些蛋白来包封荧光多阴离子半导体聚合物 MPS-PPV（聚-2-甲氧基-5-丙氧基磺酸盐苯乙烯），从而获得具有光学活性的类似病毒的颗粒。包封后，MPS-PPV 的荧光显示出两个明显的峰，这表明聚合物可能存在两种构象。TEM、荧光各向异性和蔗糖梯度分离的组合表明，蓝色峰来自包封在球形颗粒中的聚合物，而较红的峰对应于棒状笼中的聚合物。组装过程中的离子强度可用于调节形成棒状或球状的倾向。结果表明了杂合合成/生物系统的协同作用：聚合物构象驱动了这种复合材料的结构，进而改变了聚合物的光学性质。这种协同作用可能对未来具有指定功能的合成/生物杂化材料的发展有用。
