Charged carbon nanotubes for use as sensors

A biosensor responsive to a chemical property in an environment, comprising:

• (a) one or more single charged carbon nanotubes forming an array and showing a dependence of the chemical property, wherein at least one or more of the single-wall carbon nanotubes has a linear charge density ξ in the range of about ξ=0.059 eÅ−1 to about ξ=5.9 eÅ−1;
• and
• (b) a processor coupled to one or more of the single wall charged carbon nanotubes for processing the response of the plurality of single-wall carbon nanotubes to the chemical property.

An optical pH sensor comprising at least one charged single-wall carbon nanotube in solution wherein said charged single-wall nanotube has a linear charge density ξ in the range of about ξ=0.059 eÅ−1 to about ξ=5.9 eÅ−1.

An optical sensor comprising:

• (a) a charged single-wall carbon nanotube of finite length having an electrical contact pad at each end thereof;
• and (b) a plurality of self-assembled molecules on a surface of said carbon nanotube, said molecules serving to modulate electrical conductivity of said carbon nanotube by either a reversible change in dipole moment of said molecules or by a reversible molecule-assisted electron/energy transfer from said molecules onto said carbon nanotube and wherein said charged single-wall nanotube has a linear charge density ξ in the range of about ξ=0.059 eÅ−1 to about ξ=5.9 eÅ−1.

A method for measuring an interaction at an interface between a charged single-wall carbon nanotube probe and a target, said method comprising measuring an effect of said interaction between said probe and said target at said interface using a surface-selective linear or nonlinear optical technique and wherein said charged single-wall nanotube has a linear charge density ξ in the range of about ξ=0.059 eÅ−1 to about ξ=5.9 eÅ−1.

A method for measuring an interaction at an interface between an attached probe consisting of a charged carbon nanotube and a biological component in a cell, said method comprising measuring changes in the ion properties leading to changes in the nonlinear properties of said nanotube, wherein said changes in said nonlinear properties of said nanotube are detected using a surface-selective linear or nonlinear optical technique and wherein said charged single-wall nanotube has a linear charge density ξ in the range of about ξ=0.059 eÅ−1 to about ξ=5.9 eÅ−1.

A single-wall charged carbon nanotube having a linear charge density ξ in the range of about ξ=0.059 eÅ−1 to about ξ=5.9 eÅ−1.

An optical sensor for sensing a physical quantity in a chemical or biological environment, said optical sensor comprising:

• a charged single-wall carbon nanotube material having an optical characteristic which depends on light wavelength;
• a housing having first and second optical elements for defining a cavity in which the charged single-wall carbon nanotube material is disposed, for transmitting light to the charged single-wall carbon nanotube material, and for transmitting light which has been made incident on the charged single-wall carbon nanotube material;
• and a controlling element for controlling the charged single-wall carbon nanotube material in accordance with the physical quantity to cause a change to an optical characteristic of the charged single-wall carbon nanotube material which depends on light wavelength and wherein said charged single-wall carbon nanotube has a linear charge density ξ in the range of about ξ=0.059 eÅ−1 to about ξ=5.9 eÅ−1.

A detector comprising a charged single-wall carbon nanotubes wherein at least one charged single-wall carbon nanotube emits near-infrared fluorescence and wherein said charged single-wall carbon nanotube has a linear charge density ξ in the range of about ξ=0.059 eÅ−1 to about ξ=5.9 eÅ−1.