Hydrogel biosensor
First Claim
1. A biosensor for measuring the concentration of molecules of an analyte in a body fluid, comprising:
- a polymeric hydrogel having pendant moieties that are charged under physiological conditions;
an analyte binding molecule immobilized in the hydrogel and capable of binding the free analyte;
analyte molecules immobilized in the hydrogel; and
pressure detection means for measuring the osmotic pressure of the hydrogel.
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Accused Products
Abstract
A biosensor (10) has a hydrogel (30) in a rigid and preferably biocompatible enclosure (20). The hydrogel (30) includes an immobilized analyte binding molecule (ABM) and an immobilized analyte. The immobilized analyte competitively binds with free analyte to the ABM, thus changing the number of crosslinks in the hydrogel (30), which changes hydrogel swelling tendency (and thus the osmotic pressure) in its confined space in proportion to the concentration of free analyte concentration. By measuring the change in hydrogel pressure with a pressure transducer (40), the biosensor (10) is able to accurately measure the concentration of the free analyte molecule without the problem of oxygen limitations and interference encountered by prior art biosensors. A battery (64) powered telemeter (60) operably engaged to the pressure transducer (40) sends a radio data signal to a receiver (66) containing an alarm system operably attached to a computer (62). Furthermore, an alarm system utilizes such a sensor to automatically notify a person that the analyte level is outside desired predetermined parameters, and/or to automatically inject an agent to counteract the adverse analyte levels.
252 Citations
27 Claims
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1. A biosensor for measuring the concentration of molecules of an analyte in a body fluid, comprising:
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a polymeric hydrogel having pendant moieties that are charged under physiological conditions;
an analyte binding molecule immobilized in the hydrogel and capable of binding the free analyte;
analyte molecules immobilized in the hydrogel; and
pressure detection means for measuring the osmotic pressure of the hydrogel. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 23, 24, 25, 26, 27)
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17. A method of determining the concentration of free analyte in a solution, comprising the steps of:
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providing a hydrogel having pendant charged moieties, analyte molecules, and analyte-specific binding molecules covalently immobilized therein;
enclosing the hydrogel in a rigid structure which has at least one permeable portion available for contacting a test fluid with the hydrogel, the permeable portion constructed to permit free analyte to diffuse into the hydrogel;
contacting the hydrogel sequentially with a series of calibration solutions having known concentrations of free analyte;
measuring osmotic pressure in the hydrogel for each of the calibration solutions to produce a calibration curve of osmotic pressure versus analyte concentration;
contacting the hydrogel with the test fluid, and measuring a resulting osmotic pressure; and
comparing the resulting osmotic pressure with the calibration curve to determine analyte concentration of the test fluid. - View Dependent Claims (18, 19)
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20. A sensor for measuring the concentration of free molecules of an analyte in a fluid, comprising:
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a rigid enclosure having an open end and a closed end, the open end being covered by a semipermeable membrane;
a diaphragm positioned within the enclosure between the semipermeable membrane and the closed end;
a polymeric hydrogel having pendant moieties which are charged at physiological pH, the hydrogel being enclosed between the semipermeable membrane and the diaphragm such that changes in osmotic pressure within the hydrogel are accompanied by changes in pressure exerted on the diaphragm;
analyte binding molecules immobilized within the hydrogel;
analyte molecules immobilized within the hydrogel; and
a pressure transducer operatively engaged to the diaphragm. - View Dependent Claims (21)
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22. A method for using a biosensor to measure the concentration of free molecules of an analyte in a fluid, including:
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a first step of providing a biosensor comprising;
a rigid, biocompatible enclosure having an open end and a closed end, the open end being covered by a semipermeable membrane;
a diaphragm positioned between the semipermeable membrane and the closed end such that changes in osmotic pressure within the hydrogel are accompanied by changes in pressure exerted on the diaphragm;
a polymeric hydrogel having pendant moieties which are charged at physiological pH, the hydrogel being enclosed between the semipermeable membrane and the diaphragm such that changes in osmotic pressure within the hydrogel are accompanied by changes in pressure exerted on the diaphragm;
analyte binding molecules immobilized within the hydrogel;
analyte immobilized within the hydrogel, and osmotic pressure sensing means operatively engaged to the diaphragm for sensing the osmotic pressure exerted thereon and providing a data signal reflective thereof;
a second step of providing computing means connected to receive the data signal, compare it to a predetermined calibration curve of osmotic pressure vs, concentration of free analyte molecules, and output a concentration value;
a third step of inserting the biosensor into the fluid and allowing sufficient time for free analyte molecules to diffuse to equilibrium within the hydrogel; and
a fourth step of reading the concentration value output by the computing means.
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Specification