CONTINUOUS BIOLOGICAL SENSOR WITH ENZYME IMMOBILIZATION
A working wire of a continuous biological sensor is disclosed. The working wire includes a substrate for the sensor having a conductive surface. An enzyme layer is on the conductive surface and includes an enzyme, an immobilization matrix, and an enzyme immobilization network. The enzyme immobilization network is formed using a polymeric crosslinking agent and a non-polymeric crosslinking agent crosslinking the enzyme and the immobilization matrix. The polymeric crosslinking agent and the non-polymeric crosslinking agent are a combination of polyethylene glycol (PEG) dialdehyde and glutaraldehyde. A protective layer is over the enzyme layer.
1 . A working wire of a continuous biological sensor, comprising:
a substrate for the sensor, the substrate having a conductive surface;
an enzyme layer on the conductive surface comprising:
an enzyme;
an immobilization matrix; and
an enzyme immobilization network formed using a polymeric crosslinking agent and a non-polymeric crosslinking agent crosslinking the enzyme and the immobilization matrix, wherein the polymeric crosslinking agent and the non-polymeric crosslinking agent are a combination of polyethylene glycol (PEG) dialdehyde and glutaraldehyde; and
a protective layer over the enzyme layer.
2 . The working wire of claim 1 , wherein the immobilization matrix is a polymer selected from polyurethane (PU), polyacrylic acid, polyacrylamide, polyvinylpyrrolidone (PVP), polyethylene glycol (PEG), or polyvinyl alcohol (PA) and its copolymers, or copolymers of N-(2-hydroxypropyl)-methacrylamide, polydimethylsiloxane (PDMS), polyamides, polyacrylates, polyethylene, polycarbonates, or combinations thereof.
3 . The working wire of claim 1 , wherein the immobilization matrix is a protein selected from a bovine serum albumin (BSA), human serum albumin (HSA), carboxymethyl cellulose (CMC), collagen, or combinations thereof.
4 . The working wire of claim 1 , wherein the enzyme immobilization network stabilizes a glucose sensitivity of the sensor over time.
5 . The working wire of claim 1 , wherein the polyethylene glycol (PEG) dialdehyde is configured to allow the enzyme to rotate around crosslinked bonds.
6 . The working wire of claim 1 , wherein the glutaraldehyde is configured to immobilize the enzyme, thereby stabilizing a glucose sensitivity of the sensor over time.
7 . The working wire of claim 1 , wherein the enzyme is glucose oxidase (GOx).
8 . The working wire of claim 1 , wherein the protective layer is a glucose limiting layer configured to restrict passage of glucose molecules into the enzyme layer.
9 . The working wire of claim 1 , wherein the sensor has a first measured electrical enzyme sensitivity prior to gas sterilization, a second measured electrical enzyme sensitivity after the gas sterilization, and the second measured electrical enzyme sensitivity is greater than the first measured electrical enzyme sensitivity.
10 . The working wire of claim 1 , wherein the enzyme immobilization network is configured to resist degradation caused by ethylene oxide (EtO) gas during sterilization.
11 . A method of manufacturing a working wire of a continuous biological sensor, comprising:
providing a substrate for the sensor, the substrate having a conductive surface;
forming an enzyme layer on the conductive surface, the forming comprising:
combining an enzyme with a solvent creating an enzyme mixture;
mixing an immobilization matrix with the enzyme mixture;
combining a polymeric crosslinking agent and a non-polymeric crosslinking agent with the enzyme mixture and the immobilization matrix creating a crosslinked mixture, wherein the polymeric crosslinking agent and the non-polymeric crosslinking agent are a combination of polyethylene glycol (PEG) dialdehyde and glutaraldehyde, to form an enzyme immobilization network that crosslinks the enzyme and the immobilization matrix; and
applying the crosslinked mixture to the substrate;
curing the crosslinked mixture on the substrate, after the applying; and
forming a protective layer over the enzyme layer.
12 . The method of claim 11 , further comprising allowing the crosslinked mixture to stabilize before applying the crosslinked mixture to the substrate.
13 . The method of claim 11 , wherein the immobilization matrix is a polymer selected from polyurethane (PU), polyacrylic acid, polyacrylamide, polyvinylpyrrolidone (PVP), polyethylene glycol (PEG), or polyvinyl alcohol (PA) and its copolymers, or copolymers of N-(2-hydroxypropyl)-methacrylamide, polydimethylsiloxane (PDMS), polyamides, polyacrylates, polyethylene, polycarbonates, or combinations thereof.
14 . The method of claim 11 , wherein the immobilization matrix is a protein selected from a bovine serum albumin (BSA), human serum albumin (HSA), carboxymethyl cellulose (CMC), collagen, or combinations thereof.
15 . The method of claim 11 , wherein the enzyme immobilization network stabilizes a glucose sensitivity of the sensor over time.
16 . The method of claim 11 , wherein the polyethylene glycol (PEG) dialdehyde is configured to allow the enzyme to rotate around crosslinked bonds.
17 . The method of claim 11 , wherein the glutaraldehyde is configured to immobilize the enzyme, thereby stabilizing a glucose sensitivity of the sensor over time.
18 . The method of claim 11 , wherein the mixing comprises high shear mixing.
19 . The method of claim 11 , wherein the enzyme is glucose oxidase (GOx).