Carbon nanotube sensors employing synthetic multifunctional peptides for surface functionalization
Inventors
Kim, Steve S. • Kuang, Zhifeng • Naik, Rajesh R. • Farmer, Barry L.
Assignees
United States Department of the Air Force • United States Department of the Army
Publication Number
US-8716029-B1
Publication Date
2014-05-06
Expiration Date
2031-09-19
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Abstract
A biosensor that utilizes carbon nanotubes functionalized with a protein sequence. One domain of the multifunctional peptide sequence noncovalently binds to the surface of single-walled carbon nanotubes (SWNTs), while a second domain of the sequence recognizes and binds to a target molecule. The sequence of the peptide may be tailored to allow it to recognize and bind to specific target molecules, such as chemicals, biological materials, and explosives. The binding of the target molecule to the peptide may alter a material property of the SWNTs.
Core Innovation
The invention provides a biosensor that utilizes carbon nanotubes functionalized with a protein sequence composed of multifunctional peptides. One domain of this peptide sequence noncovalently binds to the surface of single-walled carbon nanotubes (SWNTs), while a second domain recognizes and selectively binds to a target molecule, such as chemicals, biological materials, or explosives like trinitrotoluene (TNT). The binding of the target molecule to the peptide alters a material property of the SWNTs, such as electrical or thermal conductivity, enabling its use as a sensor device.
The problem being solved arises from the limitations of earlier carbon nanotube-based sensors, which although highly sensitive due to the nanotubes' molecular adsorption properties, generally suffered from poor selectivity as almost any gas or liquid could alter their properties. Additionally, sensors functionalized with naturally occurring biomolecules often required auxiliary linking mechanisms and such biomolecules frequently lost biological activity or stability upon binding to carbon nanotubes or exposure to environmental conditions.
The present invention overcomes these challenges by using a stable peptide sequence that binds directly and noncovalently to the SWNTs without needing additional linking mechanisms. The peptide is designed to be long enough to maintain selectivity but short enough to avoid instability and degradation. The multifunctional peptide comprises a domain that binds the nanotube surface and another that selectively binds the target molecule, maintaining its recognition ability even when bound to the nanotube. The invention further enables reusable sensors due to the noncovalent binding allowing removal of the target molecule.
Claims Coverage
The patent includes multiple independent claims covering device configurations and a peptide sequence, each with particular inventive features relating to carbon nanotube functionalization and selective detection.
Device with multifunctional peptide domains for selective detection
A device comprising single-wall carbon nanotubes coated with a peptide sequence having two domains: one that binds noncovalently to the nanotube surface (SEQ ID No. 1) and another that selectively binds to a target molecule (SEQ ID No. 2), linked via a tetraglycine sequence (SEQ ID No. 4). The device detects changes in nanotube conductivity upon target binding.
Selectable target molecule including explosives
The device is adapted to detect target molecules which include chemicals and biological molecules, specifically explosives such as trinitrotoluene (TNT).
Noncovalent binding enabling device reusability
The target molecule binding to the peptide is noncovalent, allowing removal of the target molecule and reuse of the detection device.
Integration with substrates and sensing elements
The device may include substrates such as silicon, silicon dioxide, silicon nitride, aluminum oxide, or hafnium oxide, with nanotubes distributed by methods including chemical vapor deposition, dielectrophoretic deposition, spray-painting, or drop-casting, and further includes sensing elements capable of detecting conductivity changes.
Reusable device specialized for explosive detection
A reusable device specifically for explosive detection with peptide sequence SEQ ID No. 3 combining both nanotube-binding and target molecule-binding domains, where single-wall carbon nanotubes' electrical conductivity changes upon binding explosive molecules like trinitrotoluene.
Field-effect transistor integration with electrode configurations
The device includes substrate configurations featuring gate, drain electrode, and source electrode with bottom-gate or liquid-gate configurations, where binding of explosives alters source-drain current, and includes a reference electrode for monitoring applied electrochemical potential.
Peptide sequence for trinitrotoluene detection
A peptide sequence (SEQ ID No. 3) capable of binding both the outer surface of single-wall carbon nanotubes via SEQ ID No. 1 and selectively binding trinitrotoluene via SEQ ID No. 2.
The claims comprehensively cover sensor devices based on multifunctional peptides bound to single-wall carbon nanotubes for selective detection of target molecules, focusing on peptide sequences, device structures, selective binding, and reusability.
Stated Advantages
The peptide functionalization provides high sensitivity and selectivity for detecting specific target molecules such as TNT.
Noncovalent binding between peptide and nanotubes avoids alteration of conductive properties and allows the sensor to be reusable by removing the target molecule.
The peptide combines sufficient length to maintain selectivity and sufficient stability to avoid degradation and loss of function common with larger proteins.
The peptide eliminates the need for auxiliary mechanical or chemical linking mechanisms to bind functionalizing agents to the nanotube surface.
Documented Applications
Selective detection of explosives, particularly trinitrotoluene (TNT).
Detection of chemical and biological molecules.
Integration into field-effect transistor devices for monitoring electrical conductivity changes upon target molecule binding.
Use in gaseous and aqueous environments for sensing applications.
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