Electrochemical biosensors
First Claim
1. An electrochemical biosensor for determining in vivo in a mammal the level of a target chemical in a biological fluid, said biosensor comprising:
- an electrochemical system including a substrate which reacts with the target chemical to yield a system signal related to the concentration in the biological fluid of said target chemical;
a first membrane immobilizing said substrate and having a porosity permitting passage therethrough of the target chemical to react with said substrate, said first membrane having a surface characterized by electron donor sites susceptible to facilitating attachment thereon of proteins and fibrin, thus impairing said system signal; and
a second membrane bonded to said electron donor sites of and surrounding said first membrane, said second membrane being formed of poly-para-xylylene having connecting hydrogen atom donors, said hydrogen atom donors bonding to said electron donor sites of said first membrane at least sufficiently to form an outer surface on said first membrane without significantly changing the porosity provided by said first membrane, wherein said outer surface is exposed to the biological fluid and consists of phenyl rings;
and wherein said biosensor is implanted in a mammalian subject without biological fouling.
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Abstract
An electrochemical biosensor for determining the level of a target chemical in a biological fluid includes an electrochemical system including a enzyme substrate which reacts with the target chemical to yield a system signal related to the concentration in the biological fluid of said target chemical. The biosensor includes a first membrane for immobilizing the enzyme substrate. The first membrane has a porosity permitting passage therethrough of the target chemical to react with the enzyme substrate and a surface exposed to the biological fluid characterized by electron donor site susceptible to facilitating attachment thereon of proteins and fibrin which impair the system signal. A second membrane is bonded to the electron donor sites of the first membrane. The second membrane is formed of a phenyl based polymer having connecting hydrogen atom donors which bond to the hydrogen atom donors bonding to the electron donor sites at least sufficiently to form an outer surface on the first membrane exposed to the biological fluid consisting of phenyl rings without significantly changing the porosity provided by the first membrane.
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Citations
11 Claims
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1. An electrochemical biosensor for determining in vivo in a mammal the level of a target chemical in a biological fluid, said biosensor comprising:
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an electrochemical system including a substrate which reacts with the target chemical to yield a system signal related to the concentration in the biological fluid of said target chemical; a first membrane immobilizing said substrate and having a porosity permitting passage therethrough of the target chemical to react with said substrate, said first membrane having a surface characterized by electron donor sites susceptible to facilitating attachment thereon of proteins and fibrin, thus impairing said system signal; and a second membrane bonded to said electron donor sites of and surrounding said first membrane, said second membrane being formed of poly-para-xylylene having connecting hydrogen atom donors, said hydrogen atom donors bonding to said electron donor sites of said first membrane at least sufficiently to form an outer surface on said first membrane without significantly changing the porosity provided by said first membrane, wherein said outer surface is exposed to the biological fluid and consists of phenyl rings; and wherein said biosensor is implanted in a mammalian subject without biological fouling. - View Dependent Claims (2, 3, 4, 5)
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6. A biologically inert membrane composite substrate implanted in a mammal, comprising:
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a first membrane characterized by a porosity permitting passage therethrough of a target chemical and formed of a material having biologically active surface sites that support protein and tissue attachment when exposed to biological fluids; and a second membrane consisting of poly-para-xylylene having connecting hydrogen donors bonded to said biologically active surface sites sufficiently to render said sites biologically inert without significantly affecting said porosity of said first membrane wherein only the phenyl rings of the second membrane are exposed, and wherein said membrane composite substrate is implanted within a mammalian subject without biological fouling. - View Dependent Claims (7, 8)
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- 9. A method for biologically passivating a membrane having a porosity permitting passage therethrough of a chemical in a biological fluid and a surface with attractive sites for proteins and fibrin, comprising applying to said membrane a coating of poly-para-xylylene having connecting hydrogen bond donors bonded to said attractive sites in an amount sufficient to render said surface biologically inert but insufficient to impair passage through said membrane of said chemical.
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11. A cellular or chemical moiety which has been coated with a membrane, said membrane comprising poly-para-xylylene, wherein said moiety is implanted within a mammalian subject without biological fouling.
Specification