Surface modification of graphene nanopores for protein translocation

Abstract

Studies of DNA translocation through graphene nanopores have revealed their potential for DNA sequencing. Here we report a study of protein translocation through chemically modified graphene nanopores. A transmission electron microscope (TEM) was used to cut nanopores with diameters between 5-20 nm in multilayer graphene prepared by chemical vapor deposition (CVD). After oxygen plasma treatment, the dependence of the measured ionic current on salt concentration and pH was consistent with a small surface charge induced by the formation of carboxyl groups. While translocation of gold nanoparticles (10 nm) was readily detected through such treated pores of a larger diameter, translocation of protein ferritin was not observed either for oxygen plasma treated pores, or for pores modified with mercaptohexadecanoic acid. Ferritin translocation events were reliably observed after the pores were modified with the phospholipid-PEG (DPPE-PEG750) amphiphile. The ion current signature of translocation events was complex, suggesting that a series of interactions between the protein and pore occur during the process.

Water desalination using nanoporous single-layer graphene

“…Finally, our plasma-etching treatment combines a defect production capability similar to that provided by high-energy ion bombardment with a time-tuned oxidative atmosphere and a minimum number of steps, which reduces the potential for mechanical disruption and tear formation 18 . We have observed some of the advantages of oxygen plasma treatment of suspended (multilayer) graphene in a previous study of surface treatment effects in designing nanopores for protein translocation 17 .…”

“…Selective gas transport for H 2 /CO 2 , H 2 /N 2 and CO 2 /N 2 has also been reported using graphene oxide membranes 14,15 . In addition, Garaj and co-workers created nanoporous graphene that functioned as a trans-electrode membrane and demonstrated DNA translocation through single nanopores 16 , while Shan and colleagues similarly used it for the translocation of proteins 17 . Interestingly, O'Hern and colleagues recently reported both selective ion and molecular transport through single-layer graphene membranes with sub-nanometre pores 18,19 .…”

Single-layer MoS2 nanopores as nanopower generators

“…21). However we also notice that, as with other nanofluidic systems 5,20 , the surface charge density varies from pore to pore, which means that different pores can have disparate values of the equilibrium constant, owing to the various combinations of Mo and S atoms 14 at the edge of the pores (as illuminated by molecular-dynamics simulations 7 ). Next, we introduced a chemical potential gradient by using the KCl concentration gradient system 5 .…”

Graphene Nanopores for Protein Sequencing

“…The interaction of proteins with graphene has been the subject of several computational [55, 63] and experimental [28] studies. Both simulation and experiment have found folded proteins to adsorb to graphene, leading to their partial denaturing or unfolding.…”

“…Both simulation and experiment have found folded proteins to adsorb to graphene, leading to their partial denaturing or unfolding. The adhesive interactions of protein and graphene are often regarded as detrimental to achieving the goal of protein sequencing and several approaches have been proposed to minimize such adhesive interactions [28, 47, 55]. …”