Freitas Daniel N, Martinolich Andrew J, Amaris Zoe N, Wheeler Korin E
Department of Chemistry and Biochemistry, Santa Clara University, Santa Clara, CA, 95053, USA.
Department of Chemistry, Colorado State University, Fort Collins, CO, 80523-1872, USA.
J Nanobiotechnology. 2016 Jan 22;14:7. doi: 10.1186/s12951-016-0160-6.
In a biological system, an engineered nanomaterial (ENM) surface is altered by adsorbed proteins that modify ENM fate and toxicity. Thus far, protein corona characterizations have focused on protein adsorption, interaction strength, and downstream impacts on cell interactions. Given previous reports of Ag ENM disruption of Cu trafficking, this study focuses on Ag ENM interactions with a model Cu metalloprotein, Cu(II) azurin. The study provides evidence of otherwise overlooked ENM-protein chemical reactivity within the corona: redox activity.
Citrate-coated Ag ENMs of various sizes (10-40 nm) reacted with Cu(II) azurin resulted in an order of magnitude more dissolved ionic silver (Ag(I)(aq)) than samples of Ag ENMs only, ENMs mixed Cu(II) ions, or control proteins such as cytochrome c and horse radish peroxidase. This dramatic increase in ENM oxidative dissolution was observed even when Cu(II) azurin was combined with a diverse mixture of Escherchia coli proteins to mimic the complexity of the cellular conona. SDS PAGE results confirm that the multiprotein ENM corona includes azurin. A Cu(I)(aq) colorimetric indicator confirms Cu(II) azurin reduction upon interaction with Ag ENMs, but not with the addition of ionic silver, Ag(I)(aq).
Cu(II) azurin and 10-40 nm Ag ENMs react to catalyze Ag ENM oxidative dissolution and reduction of the model Cu metalloprotein. Results push the current evaluation of protein-ENM characterization beyond passive binding interactions and enable the proposal of a mechanism for reactivity between a model Cu metalloprotein and Ag ENMs.
在生物系统中，工程纳米材料（ENM）的表面会被吸附的蛋白质改变，这些蛋白质会改变ENM的命运和毒性。到目前为止，蛋白质冠层的表征主要集中在蛋白质吸附、相互作用强度以及对细胞相互作用的下游影响。鉴于之前有报道称银ENM会破坏铜的运输，本研究聚焦于银ENM与一种典型的铜金属蛋白——铜（II）蓝蛋白的相互作用。该研究提供了证据，证明在蛋白质冠层中存在此前被忽视的ENM-蛋白质化学反应性：氧化还原活性。
各种尺寸（10 - 40纳米）的柠檬酸盐包覆银ENM与铜（II）蓝蛋白反应后，溶解的离子银（Ag(I)(aq)）比仅含银ENM的样品、混合了铜（II）离子的ENM样品或诸如细胞色素c和辣根过氧化物酶等对照蛋白质的样品多出一个数量级。即使将铜（II）蓝蛋白与多种大肠杆菌蛋白质混合以模拟细胞冠层的复杂性，也观察到ENM氧化溶解的显著增加。SDS - PAGE结果证实多蛋白ENM冠层中包含蓝蛋白。一种铜（I）（aq）比色指示剂证实铜（II）蓝蛋白在与银ENM相互作用时会发生还原，但添加离子银（Ag(I)(aq)）时不会。
铜（II）蓝蛋白与10 - 40纳米的银ENM发生反应，催化银ENM的氧化溶解以及典型铜金属蛋白的还原。研究结果将目前对蛋白质 - ENM表征的评估从被动结合相互作用拓展到了其他方面，并提出了一种典型铜金属蛋白与银ENM之间反应性的机制。
