ABSTRACT
The performances and the stability of a novel subcutaneous glucose monitoring system have been evaluated. GlucoDay (A. Menarini I.F.R. S.r.l, Florence Italy) is a portable instrument provided with a micro-pump and a biosensor coupled to a microdialysis system capable of recording the subcutaneous glucose level every 3 min. Long and short term stability of the biosensor are discussed and the results of some critical in vitro and in vivo (on rabbits) experiments are reported. A linear response up to 30 mM has been found for in vivo glucose concentration. The sensitivity referred to blood glucose is better than 0.1 mM and the zero current is typically below the equivalent of 0.1 mM. In the accuracy study a mean bias of 2.7 mg/dl and a correlation coefficient equal to 0.9697 have been found. At room temperature, an excellent membrane stability assures good performances up to 6 months from the first use.
Subject(s)
Biosensing Techniques/methods , Blood Glucose Self-Monitoring/methods , Diabetes Mellitus/blood , Microdialysis/methods , Animals , Biosensing Techniques/instrumentation , Biosensing Techniques/statistics & numerical data , Blood Glucose/analysis , Blood Glucose Self-Monitoring/instrumentation , Blood Glucose Self-Monitoring/statistics & numerical data , Humans , In Vitro Techniques , Microdialysis/instrumentation , Microdialysis/statistics & numerical data , Rabbits , Sensitivity and SpecificityABSTRACT
The aim of this study was to evaluate the reproducibility, the accuracy and the reliability of a continuous subcutaneous glucose measuring system. The GlucoDay system (A. Menarini I.F.R. S.r.l.-Florence, Italy) is a portable instrument provided with a micro-pump and a biosensor, coupled to a microdialysis system (see part 1). This instrument has demonstrated high reliability coupled with a low degree of invasivity. The profiles of glucose monitoring allow to achieve an excellent knowledge of the real variation of glucose in diabetic patients. The reproducibility study showed a bias lower than 10% between instruments. The accuracy study showed a difference from the reference method lower than 15%.
Subject(s)
Biosensing Techniques/methods , Blood Glucose Self-Monitoring/methods , Diabetes Mellitus/blood , Microdialysis/methods , Biosensing Techniques/instrumentation , Biosensing Techniques/statistics & numerical data , Blood Glucose/analysis , Blood Glucose Self-Monitoring/instrumentation , Blood Glucose Self-Monitoring/statistics & numerical data , Humans , Male , Microdialysis/instrumentation , Microdialysis/statistics & numerical data , Reproducibility of Results , Sensitivity and SpecificityABSTRACT
This paper describes an electrochemical biosensor for free cholesterol monitoring. The sensor is a multienzymatic electrodic system in which horseradish peroxidase and cholesterol oxidase are simultaneously immobilized within a polymeric film, on the surface of a pyrolitic graphite electrode. From voltammetric and amperometric (flow-injection) data obtained, the efficiency, reproducibility and stability of the system are discussed. Results obtained, of interest for basic and applied biochemistry, represent a first step for construction of a mediator-free biosensor with potentialities for a successful application in the biosensor area.
Subject(s)
Biosensing Techniques , Cholesterol Oxidase , Cholesterol/analysis , Electrochemistry/instrumentation , Enzymes, Immobilized , Cholesterol/metabolism , Circular Dichroism , Flow Injection AnalysisABSTRACT
A single "one step" solid phase sandwich enzyme immunoassay was developed. The assay employs two monoclonal antibodies with affinity and specificity for different epitopes of the analyte: one is covalently coupled to peroxidase, while the other one is coupled to biotin. The addition of the reagent to an avidin-coated strip gave a specific and efficient mean for binding the sandwich complex to the solid phase, via the high affinity interaction between biotin and avidin. The methodology was applied to the determination of hypophysis hormones (LH, FSH, PRL), tumor markers (CEA, AFP, FRT, hCG beta free subunit, alpha subunit and others alpha-P Amylase). Analytical performances concerning the developed kits are described, demonstrating the good reproducibility, sensitivity, accuracy and the wide application field for this new technology.
