Interference rejection membranes comprising crosslinked poly (vinyl alcohol) matrices for implantable glucose sensors
Embodiments of the invention provide amperometric analyte sensors having optimized elements such as interference rejection membranes as well as methods for making and using such sensors. The amperometric analyte sensor apparatus comprises: a base layer; a conductive layer disposed on the base layer and comprising a working electrode; an interference rejection membrane disposed on an electroactive surface of the working electrode, wherein the interference rejection membrane comprises poly(vinyl alcohol) (PVA) polymers crosslinked by an acid crosslinker, wherein the crosslinker is a dicarboxylic acid type monomer or a polymer comprising a carboxylic acid group; and an analyte sensing layer. While embodiments of the innovation can be used in a variety of contexts, typical embodiments of the invention include glucose sensors used in the management of diabetes.
1 . A method of making a sensor apparatus for implantation within a mammal comprising the steps of:
providing a base layer;
forming a conductive layer on the base layer, wherein the conductive layer includes a working electrode;
forming an interference rejection membrane over the working electrode, wherein the interference rejection membrane is selected to inhibit the diffusion of ascorbic acid, uric acid and/or acetaminophen therethrough and comprises poly(vinyl alcohol) polymers crosslinked with sulfosuccinic acid or poly(methyl vinyl ether-alt-maleic acid);
forming an analyte sensing layer over the interference rejection membrane, wherein the analyte sensing layer includes an oxidoreductase; and
forming an analyte modulating layer over the analyte sensing layer, wherein the analyte modulating layer includes a composition that modulates the diffusion of the analyte therethrough.
2 . The method of claim 1 , wherein:
the interference rejection membrane comprises 5 wt % poly(vinyl alcohol) crosslinked with 10-20 wt % crosslinker.
3 . The method of claim 1 , wherein materials forming the interference rejection membrane and materials forming the analyte modulating layer are selected so that the diffusivity of O 2 diffusion coefficient through said layers is at least 1.0×10 −5 cm2/s.
4 . The analyte sensor apparatus of claim 1 , wherein the poly(vinyl alcohol) polymer has a molecular weight (Mw) of at least 45K.
5 . The method of claim 1 , wherein the degree of hydrolysis of the poly(vinyl alcohol) polymer is from 87% to 98%.
6 . The method of claim 1 , wherein the interference rejection membrane is between 0.3-2 μm thick, and formed on the electrode by a spin coating process at 400-1200 rpm and cured at a temperature between 130° C.-150° C.
7 . The method of claim 1 , wherein the interference rejection membrane is between 0.4-0.8 μm thick, and formed on the electrode by a spin coating process at 400-500 rpm and cured at a temperature of 130° C. for at least 40 minutes.
8 . A method of making a sensor apparatus for implantation within a mammal comprising the steps of:
providing a base layer;
forming a conductive layer on the base layer, wherein the conductive layer includes a working electrode;
forming an interference rejection membrane over the working electrode, wherein the interference rejection membrane is selected to inhibit the diffusion of ascorbic acid, uric acid and/or acetaminophen therethrough and comprises poly(vinyl alcohol) polymers crosslinked with a crosslinking agent selected from the group consisting of sulfosuccinic acid (SSA), maleic acid, citric acid, oxalic acid, fumaric acid, poly(acrylic acid), poly(acrylic acid-co-maleic acid) (PAM), succinic acid, malonic acid, and poly(methyl vinyl ether-alt-maleic acid) and the interference rejection membrane is crosslinked with 5-35 wt % crosslinking agent;
forming an analyte sensing layer over the interference rejection membrane, wherein the analyte sensing layer includes an oxidoreductase; and
forming an analyte modulating layer over the analyte sensing layer, wherein the analyte modulating layer includes a composition that modulates the diffusion of the analyte therethrough.
9 . The method of claim 8 , wherein the interference rejection membrane comprises 5 wt % poly(vinyl alcohol) crosslinked with 10-20 wt % of the crosslinking agent.
10 . The method of claim 8 , wherein the poly(vinyl alcohol) polymer has a molecular weight (Mw) of at least 45K.
11 . The method of claim 8 , wherein the interference rejection membrane inhibits the diffusion therethrough of compounds having a molecular weight greater than 140 Daltons.
12 . The method of claim 11 , wherein the interference rejection membrane inhibits the diffusion of acetaminophen therethrough in a manner that decreases a signal in the analyte sensor apparatus that results from a concentration of acetaminophen by at least 50% as compared to a control analyte sensor apparatus lacking the interference rejection membrane.
13 . The method of claim 12 , wherein the crosslinking agent is sulfosuccinic acid.
14 . The method of claim 13 , wherein the interference rejection membrane comprises 5-35 wt % sulfosuccinic acid.
15 . The method of claim 11 , wherein the interference rejection membrane comprises 5 wt % poly(vinyl alcohol) crosslinked with 10 wt % sulfosuccinic acid.
16 . The method of claim 8 , wherein the degree of hydrolysis of the poly(vinyl alcohol) polymer is from 87% to 98%.
17 . The method of claim 8 , wherein the interference rejection membrane has a thickness of 0.3-2 μm.
18 . The method of claim 17 , wherein the interference rejection membrane has a thickness of 0.4-0.8 μm.