Single-Walled Carbon Nanotubes: Mimics of Biological Ion Channels
نویسندگان
چکیده
Here we report on the ion conductance through individual, small diameter single-walled carbon nanotubes. We find that they are mimics of ion channels found in natural systems. We explore the factors governing the ion selectivity and permeation through single-walled carbon nanotubes by considering an electrostatic mechanism built around a simplified version of the Gouy-Chapman theory. We find that the single-walled carbon nanotubes preferentially transported cations and that the cation permeability is size-dependent. The ionic conductance increases as the absolute hydration enthalpy decreases for monovalent cations with similar solid-state radii, hydrated radii, and bulk mobility. Charge screening experiments using either the addition of cationic or anionic polymers, divalent metal cations, or changes in pH reveal the enormous impact of the negatively charged carboxylates at the entrance of the single-walled carbon nanotubes. These observations were modeled in the low-to-medium concentration range (0.1-2.0 M) by an electrostatic mechanism that mimics the behavior observed in many biological ion channel-forming proteins. Moreover, multi-ion conduction in the high concentration range (>2.0 M) further reinforces the similarity between single-walled carbon nanotubes and protein ion channels.
منابع مشابه
Single-walled carbon nanotubes are a new class of ion channel blockers.
Here we identify a novel class of biological membrane ion channel blockers called single-walled carbon nanotubes (SWNTs). SWNTs with diameter distributions peaked at approximately 0.9 and 1.3 nm, C60 fullerenes, multi wall nanotubes (MWNTs), and hyperfullerenes (nano-"onions") were synthesized by several techniques and applied to diverse channel types heterologously expressed in mammalian cells...
متن کاملDetection of single ion channel activity with carbon nanotubes
Many processes in life are based on ion currents and membrane voltages controlled by a sophisticated and diverse family of membrane proteins (ion channels), which are comparable in size to the most advanced nanoelectronic components currently under development. Here we demonstrate an electrical assay of individual ion channel activity by measuring the dynamic opening and closing of the ion chan...
متن کاملSynthetic cation-selective nanotube: permeant cations chaperoned by anions.
The ability to design ion-selective, synthetic nanotubes which mimic biological ion channels may have significant implications for the future treatment of bacteria, diseases, and as ultrasensitive biosensors. We present the design of a synthetic nanotube made from carbon atoms that selectively allows monovalent cations to move across and rejects all anions. The cation-selective nanotube mimics ...
متن کاملIrreversible blocking of ion channels using functionalized single-walled carbon nanotubes
We demonstrate irreversible blocking of ion channels using single-wall carbon nanotubes (SWNTs) functionalized with 2-aminoethylmethane thiosulfonate (MTSET). In contrast, as-produced and purified SWNTs exhibit reversible blocking, indicating that the MTSET molecule attached to SWNTs chemically interacts with the cysteine groups in the ion channels. Functionalization of SWNTs with MTSET is infe...
متن کامل