Controlling Association and Separation of Gold Nanoparticles with Computationally Designed Zinc-Coordinating Proteins
Controlling Association and Separation of Gold Nanoparticles with Computationally Designed Zinc-Coordinating Proteins
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DOI：
10.1021/jacs.7b04786
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发表时间：
2017-12-13
影响因子：
15
通讯作者：
Saven，Jeffery G.
中科院分区：
文献类型：
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作者：
Eibling，Matthew J.;MacDermaid，Christopher M.;Saven，Jeffery G.
纳米粒子与生物聚合物的功能化已经产生了广泛的结构化和响应性杂化材料。DNA提供了使用互补寡核苷酸序列编程长度和识别的能力。然而，自然界更经常利用蛋白质的多功能性，其中结构，组装和识别对于工程师来说更加微妙。在此，蛋白质被计算设计为呈现多个Zn 2+配位位点并协同自缔合以形成反平行螺旋同源二聚体。每个亚基是非结构化的情况下，锌+或当阳离子螯合剂螯合。当通过半胱氨酸结合到金纳米颗粒的表面时，蛋白质在颗粒之间提供了可逆的分子连接。纳米粒子协会和粒子间分离的变化进行了监测的红移在表面等离子体共振（SPR）带和透射电子显微镜（TEM）。用Zn2+滴定显示在亚微摩尔浓度下的S形转变。引发缔合所需的金属离子浓度随纳米颗粒上蛋白质的负载、溶液离子强度和所用阳离子而变化。螺旋（七肽）重复单位的数量增加，赋予了对蛋白质长度和纳米颗粒分离的控制。通过延伸螺旋结构设计了两种不同长度的蛋白质。透射电镜和消光测量显示纳米颗粒分离的分布与预期的蛋白质结构一致。纳米颗粒缔合、颗粒间分离和SPR性质可以使用计算设计的蛋白质来调节，其中蛋白质结构、折叠、长度和对分子种类（如Zn 2+）的响应可以被工程化。
Functionalization of nanoparticles with biopolymers has yielded a wide range of structured and responsive hybrid materials. DNA provides the ability to program length and recognition using complementary oligonucleotide sequences. Nature more often leverages the versatility of proteins, however, where structure, assembly, and recognition are more subtle to engineer. Herein, a protein was computationally designed to present multiple Zn2+coordination sites and cooperatively self-associate to form an antiparallel helical homodimer. Each subunit was unstructured in the absence of Zn2+or when the cation was sequestered with a chelating agent. When bound to the surface of gold nanoparticles via cysteine, the protein provided a reversible molecular linkage between particles. Nanoparticle association and changes in interparticle separation were monitored by redshifts in the surface plasmon resonance (SPR) band and by transmission electron microscopy (TEM). Titrations with Zn2+revealed sigmoidal transitions at submicromolar concentrations. The metal-ion concentration required to trigger association varied with the loading of the proteins on the nanoparticles, the solution ionic strength, and the cation employed. Specifying the number of helical (heptad) repeat units conferred control over protein length and nanoparticle separation. Two different length proteins were designed via extension of the helical structure. TEM and extinction measurements revealed distributions of nanoparticle separations consistent with the expected protein structures. Nanoparticle association, interparticle separation, and SPR properties can be tuned using computationally designed proteins, where protein structure, folding, length, and response to molecular species such as Zn2+can be engineered.