Carbon-Binding Designer Proteins that Discriminate between sp2- and sp3-Hybridized Carbon Surfaces

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• 作者：Brandon L. Coyle ; Marco Rolandi ; Fran莽ois Baneyx
• 刊名：Langmuir
• 出版年：2013
• 出版时间：April 16, 2013
• 年：2013
• 卷：29
• 期：15
• 页码：4839-4846
• 全文大小：391K
• 年卷期：v.29,no.15(April 16, 2013)
• ISSN：1520-5827

文摘

Robust and simple strategies to directly functionalize graphene- and diamond-based nanostructures with proteins are of considerable interest for biologically-driven manufacturing, biosensing, and bioimaging. Here, we identify a new set of carbon-binding peptides that vary in overall hydrophobicity and charge and engineer two of these sequences (Car9 and Car15) within the framework of E. coli thioredoxin 1 (TrxA). We develop purification schemes to recover the resulting TrxA derivatives in a soluble form and conduct a detailed analysis of the mechanisms that underpin the interaction of the fusion proteins with carbonaceous surfaces. Although equilibrium quartz crystal microbalance measurements show that TrxA::Car9 and TrxA::Car15 have similar affinities for sp²-hybridized graphitic carbon (K_d = 50 and 90 nM, respectively), only the latter protein is capable of dispersing carbon nanotubes. Further investigation by surface plasmon resonance and atomic force microscopy reveals that TrxA::Car15 interacts with sp²-bonded carbon through a combination of hydrophobic and 蟺鈥撓€ interactions but that TrxA::Car9 exhibits a cooperative mode of binding that relies on a combination of electrostatics and weaker 蟺 stacking. Consequently, we find that TrxA::Car9 binds equally well to sp²- and sp³-bonded (diamondlike) carbon particles whereas TrxA::Car15 is capable of discriminating between the two carbon allotropes. Our results emphasize the importance of understanding both bulk and molecular recognition events when exploiting the adhesive properties of solid-binding peptides and proteins in technological applications.