Subcutaneous glucose electrode
First Claim
1. An electrode comprising:
- a non-corroding, conducting wire coated with an insulating polymer;
a recess at one end of said coated wire, forming a channel in the insulating polymer coat devoid of wire and bounded at one end by the wire and at an opposite end by the environment adjacent the coated wire;
a multilayered polymeric composition within said channel, the composition comprising;
a redox layer adjacent to and contacting said wire, the redox layer comprising a redox enzyme crosslinked to a redox polymer;
a biocompatable polymer layer adjacent to the environment outside the coated wire; and
an analyte diffusion limiting barrier layer positioned between said redox layer and said biocompatable layer.
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Abstract
A small diameter flexible electrode designed for subcutaneous in vivo amperometric monitoring of glucose is described. The electrode is designed to allow “one-point” in vivo calibration, i.e., to have zero output current at zero glucose concentration, even in the presence of other electroreactive species of serum or blood. The electrode is preferably three or four-layered, with the layers serially deposited within a recess upon the tip of a polyamide insulated gold wire. A first glucose concentration-to-current transducing layer is overcoated with an electrically insulating and glucose flux limiting layer (second layer) on which, optionally, an immobilized interference-eliminating horseradish peroxidase based film is deposited (third layer). An outer (fourth) layer is biocompatible.
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Citations
30 Claims
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1. An electrode comprising:
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a non-corroding, conducting wire coated with an insulating polymer;
a recess at one end of said coated wire, forming a channel in the insulating polymer coat devoid of wire and bounded at one end by the wire and at an opposite end by the environment adjacent the coated wire;
a multilayered polymeric composition within said channel, the composition comprising;
a redox layer adjacent to and contacting said wire, the redox layer comprising a redox enzyme crosslinked to a redox polymer;
a biocompatable polymer layer adjacent to the environment outside the coated wire; and
an analyte diffusion limiting barrier layer positioned between said redox layer and said biocompatable layer. - View Dependent Claims (3, 4, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 23, 24, 27, 28, 29, 30)
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2. A method for producing an in vivo glucose biosensor comprising the steps of:
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coating a non-corroding metal or carbon wire with a biocompatible insulating polymer containing less than 5% water when in equilibrium with physiological body fluids to form a coated wire;
etching said coated wire to form a recess at one end of said coated wire, said recess devoid of metal or carbon;
immobilizing within said recess, adjacent to said wire, a redox composition comprising glucose oxidase and a redox polymer;
overcoating contents of the recess with a biocompatable polymer;
wherein said etched wire with said polymer overcoated recess and contents form a glucose biosensor having substantially no current output at zero glucose concentration, even in the presence of interfering eletroreactive species.
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5. A biosensor comprising:
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a non-corroding metal or carbon electrode;
a sensing layer adjacent to and in electrical contact with the electrode, the sensing layer comprising a redox polymer and a redox enzyme;
a biocompatable layer coating an outer surface of the electrode and sensing layer and adjacent to an environment outside the sensor, said biocompatable layer comprised of a biocompatable polymer containing not less than 20% water by weight when in equilibrium with physiological body fluids. - View Dependent Claims (6, 21, 22)
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- 25. The method of claim 25, wherein said contacting is implanting the electrode subcutaneously.
Specification