20 research outputs found
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Development of potentially implantable glucose sensors.
No full textA novel glucose oxidase based needle-type glucose microsensor has been developed for subcutaneous glucose monitoring. The new configuration greatly facilitates the deposition of uniform enzyme and polymer films so that sensors with satisfactory in vitro characteristics (upper limit of linear range (>15 mM) and response time (60%). The sensor is equivalent in size to a 26 gauge needle (0.45 mm o.d.) and can be implanted with ease without any incision. The insertion of the sensor causes minimal trauma to the tissue and to the sensor itself. The multilayer structure of the sensor ensures satisfactory performance in subcutaneous tissue over extended periods of time (up to 20 days). The sensor response is largely independent of oxygen tension in the normal physiological range. It also exhibits the desired sensitivity and selectivity. A two-point in vivo calibration procedure is adapted for in vivo evaluation of the sensors. Both short-term and long-term implantation experiments are described. The methods of cell culture toxicity testing are modified and applied to locate the source of toxicity in a multi-component glucose sensor. It is shown that a non-toxic sensor can be readily obtained by removing the leachable toxic substances through extraction in phosphate buffer. A nonenzymatic glucose sensor that utilizes permselective membranes to achieve the selectivity required for screening glucose in biological fluids has been described. Interference from endogenous oxidizable substances such as amino acids, urea, ascorbic acid, and uric acid, as well as the effect of chloride and proteins on glucose response, is studied by using flow injection analysis. A set of membranes made of Nafion perfluorinated membrane and collagen, when arranged in front of the working electrode (gold), result in significant improvement in the system selectivity and sensitivity.This item was digitized from a paper original and/or a microfilm copy. If you need
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Implantable glucose sensor
No full textImplantable enzymatic sensors for biochemicals such as glucose are provided having an ideal size and geometry for optional long term implantation and linear responses over the concentration ranges of interest. The sensors include an elongated body supporting an indicative electrode section having an appropriate enzyme immobilized thereon to present an enzymatic indicating surface. A permeable synthetic polymer membrane is applied over the sensor body to protect the enzyme and regulate diffusion of analyte therethrough, to ensure linearity of sensor response. The sensors are of flexible design and can be implanted using a catheter. Alternatively, the sensor includes an internal indicating electrode body housed with an apertured, hollow needle. A holder affixed to the needle allows for easy manipulation and implantation of the sensor
Covalent enzyme coupling on cellulose acetate membranes for glucose sensor development
No full textInternational audienceMethods for immobilizing glucose oxidase (GOx) on cellulose acetate (CA) membranes are compared. The optimal method involves covalent coupling of bovine serum albumin (BSA) to CA membrane and a subsequent reaction of the membrane with GOx, which has previously been activated with an excess of p-benzoquinone. This coupling procedure is fairly reproducible and allows the preparation of thin membranes (5-20 µm) showing high surface activities (1-3 U/cm2) which are stable over a period of 1-3 months. Electrochemical and radiolabeling experiments show that enzyme inactivation as a result of immobilization is negligible. A good correlation between surface activity of membranes and their GOx load is observed
Effect of SBE4-β-CD, a sulfobutyl ether β-cyclodextrin, on the stability and solubility of O6-benzylguanine (NSC-637037) in aqueous solutions
No full text
Implantable glucose sensor
No full textImplantable enzymatic sensors for biochemicals such as glucose are provided having an ideal size and geometry for optional long term implantation and linear responses over the concentration ranges of interest. The sensors include an elongated body supporting an indicative electrode section having an appropriate enzyme immobilized thereon to present an enzymatic indicating surface. A permeable synthetic polymer membrane is applied over the sensor body to protect the enzyme and regulate diffusion of analyte therethrough, to ensure linearity of sensor response. The sensors are of flexible design and can be implanted using a catheter. Alternatively, the sensor includes an internal indicating electrode body housed with an apertured, hollow needle. A holder affixed to the needle allows for easy manipulation and implantation of the sensor
Design and in vitro studies of a needle-type glucose sensor for subcutaneous monitoring
No full textInternational audienceA new miniaturized glucose oxidase based needle-type glu¬ cose mlcrosensor has been developed for subcutaneous glu¬ cose monitoring. The sensor Is equivalent In shape and size to a 26-gauge needle (0.45-mm o.d.) and can be Implanted with ease without any Incision. The novel configuration greatly facilitates the deposition of enzyme and polymer films so that sensors with characteristics suitable for In vivo use (upper limit of linear range > 15 mM, response time 60%). The sensor response is largely Independent of ox¬ ygen tension In the normal physiological range. It also ex¬ hibits good selectivity against common interferences except for the exogenous drug acetaminophen
