Abstract
Carbon nanotubes offer exciting opportunities for devising highly-sensitive detectors of specific molecules in biology and the environment. Detection limits as low as 10−11 M have already been achieved using nanotube-based sensors. We propose the design of a biosensor comprised of functionalized carbon nanotube pores embedded in a silicon-nitride or other membrane, fluorofullerene-Fragment antigen-binding (Fab fragment) conjugates, and polymer beads with complementary Fab fragments. We show by using molecular and stochastic dynamics that conduction through the (9, 9) exohydrogenated carbon nanotubes is 20 times larger than through the Ion Channel Switch ICS™ biosensor, and fluorofullerenes block the nanotube entrance with a dissociation constant as low as 37 pM. Under normal operating conditions and in the absence of analyte, fluorofullerenes block the nanotube pores and the polymer beads float around in the reservoir. When analyte is injected into the reservoir the Fab fragments attached to the fluorofullerene and polymer bead crosslink to the analyte. The drag of the much larger polymer bead then acts to pull the fluorofullerene from the nanotube entrance, thereby allowing the flow of monovalent cations across the membrane. Assuming a tight seal is formed between the two reservoirs, such a biosensor would be able to detect one channel opening and thus one molecule of analyte making it a highly sensitive detection design.
Highlights
Nanotubes have already attracted attention for use as highly sensitive biosensors due to their unique electrical and mechanical properties
molecular dynamics (MD) simulations are used to calculate the profile of potential of mean force (PMF) of (i) a potassium or chloride ion traversing through the carbon nanotube (CNT) and (ii) two fluorofullerenes (C60F36 and C60F60) binding to the
There are three main components of our biosensor design: the carbon nanotube pores embedded in a membrane, a fluorofullerene with a Fab fragment attached to its surface, and a soluble polymer bead with complementary Fab fragments
Summary
Nanotubes have already attracted attention for use as highly sensitive biosensors due to their unique electrical and mechanical properties. Developed a biosensor which mimics the canine nose comprised of olfactory nanovesicle fused carbon nanotube transistors which can detect hexanal, an indicator of oxidation of food, at 1 fM concentration by monitoring conductance change of the nanotube As well as their unique electrical properties, nanotubes are widely investigated due to their remarkable mechanical properties. It was one of the first antibiotics used clinically as it forms a channel across bacteria cell membranes and selectively conducts monovalent cations [23,24] This biosensor has been used for the detection of low molecular weight drugs, proteins and microorganisms [25]. It is constructed from a gold electrode to which is tethered a lipid membrane containing gramicidin ion channels linked to antibodies. We outline the construction and function of our proof-of-concept biosensor design
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