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Ireland—Evaluation of amperometric glucose biosensors
Biosensors & Bioelectronics VoL 10 No. 8 (1995)
A b i e n z y m e e l e c t r o d e b a s e d on the amplification of a signal has been developed which allows the determination of picoto nanomolar concentrations of p-aminophenol. The active element of the sensor comprised of coimmobilised laccase and g l u c o s e dehydrogenase enzymes coupled with an oxygen electrode. Laccase catalyzes p-aminophenol oxidation by oxygen to give p-lminoquinone. The latter is reduced by excess of glucose in the presence of glucose dehydrogenase and results in recycling of the substrate. The detection is realized by measuring the decrease in oxygen c o n c e n t r a t i o n . T h e d e t e c t i o n l i m i t for p-aminophenol is 100 pM. The feasibility of the determination of a number of other substrates (polyphenols, polyamines, ferrocene derivatives) in the nanomolar range has been demonstrated. A significant background signal has been found for p-aminophenylphosphate. This background is probably caused by the ability of laccase to catalyze the oxidative dephosphorylation. In the presence of phosphate ions this background is practically completely eliminated. 50 pM of alkaline phosphatase could be determined after a 2 min incubation in p-aminophenylphosphate solution by determination of the p-aminophenol formed as the result of hydrolysis. The whole analysis time does not exceed 5 min. The new technique is suitable for application in alkaline phosphatase based enzyme immunoassays.
Contact: Department Analytical Biochemistry, University of Potsdam, Potsdam, Germany. Japan Glucose sensor based on carbon paste electrode -
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In ANAL. CHIM. ACTA ( 304/] (33-39) 1995) C. Saby, E Mizutani and S. Yabuki of the National Institute Bioscience report on "Glucose sensor based on carbon paste electrode incorporating poly(ethylene glycol)-modified glucose oxidase and various mediators ". Amperometric bioelectrodes constituted of carbon paste electrode incorporating poly(ethylene glycol)-modified glucose oxidase and mediators are studied. Influences of the nature
of the mediators (anthraquinone, methylene blue, 2,6-dichlorophenolindophenol, tetracyanoquinodimethane, 1, l'-dimethylferrocene) on the characteristics (potential window, apparent Michaelis constant, response time, stability) of the bioelectrodes are investigated. It is possible to show that the behaviour of the mediator is influenced by the pasting liquid contained in the carbon paste. Moreover, the water solubility of the mediator is the cause of a decrease of the apparent Michaelis constant in the case of methylene blue. A comparison between the stability of a low water soluble mediator (tetracyanoquinodimethane) and a more water soluble mediator (methylene blue) shows that the leakage of mediator from the carbon paste is not the cause of the lack of stability of such bioelectrodes. A m o n g the various mediators tested, tetracyanoquinodimethane seems the most appropriate for the construction of a bioelectrode.
Contact: Biomaterials Laboratory, National Institute Bioscience, Higashi 1-1, Tsukuba, Ibaraki 205, Japan. Ireland m Evaluation of amperometric glucose biosensors In ANAL. CHIM. ACTA (304/2 (127-138) 1995) M. Pravda, C.M. Jungar, E.I. Iwuoha , M.R. Smyth, K. Vytras and A Ivaska of Dublin City. University report on "Evaluation of amperometric glucose biosensors based on co-immobilisation of glucose oxidase with an osmium redox polymer in electrochemically generated polyphenol films". The authors prepared three types of glucose sensors by electrochemical deposition of glucose o x i d a s e ( G O D ) , [Os(bpy)2(PVP)loCI]CI (Os-polymer) (bpy = 2,2'-bipyridyl, PVP = poly(4-vinylpyridine)) within polyphenol (PPh) films on a platinum electrode. The enzyme and Os-polymer in these reagentless sensors were entrapped in stable and reproducible PPh films grown potentiodynamically by cycling the potential between 0 and +950mV at 50 mV/s. The first sensor was prepared by immobilising only GOD in a PPh film and was based on H202 detection. The Os-polymer-containing electrodes were prepared by two different procedures. In one
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Biosensors & Bioelectronics Vol. 10 No. 8 (1995)
t y p e , the O s - p o l y m e r and G O D w e r e electrochemically deposited on a Pt surface simultaneously with the PPh film. The other type was a bilayer electrode in which the Os-polymer was first adsorbed on a Pt electrode prior to covering with a GOD/PPh film. The latter electrode exhibited better sensitivity to glucose, less interference from electroactive compounds a n d v e r y low b a c k g r o u n d n o i s e . T h e e l e c t r o c h e m i c a l behaviour of paracetamol, ascorbic acid and uric acid, which normally interfere with glucose detection, was studied with electrodes similar to the glucose biosensors except that they did not contain GOD. The three compounds showed no interaction with the PPh film, which they permeate, and undergo faradaic reaction at the underlying platinum surface. P a r a c e t a m o l e x h i b i t e d the g r e a t e s t f i l m permeation of the insulating PPh film. The relative response (I(ss, modified electrode)/I(ss, Pt)) of paracetamol was ca. 85-fold and 9-fold in excess of those of ascorbic acid and uric acid, respectively.
Contact: School of Chemical Sciences, Dublin City University, Dublin 9, Ireland. UK m Continuous m e a s u r e m e n t of blood gases
In J. MED. ENG. TECHNOL. (18/5 (165-168) 1994) B. Venkatesh, T.H. Clutton-Brock and S.P. Hendry of Wycombe General Hospital report on "Continuous measurement of blood gases using a c o m b i n e d e l e c t r o c h e m i c a l and s p e c t r o photometric sensor ". The use of a combined electrochemical and fibreoptic continuous intra-arterial blood gas sensor is described. The purpose of the study was to evaluate the performance of the sensor in 10 patients in the intensive therapy unit following insertion through a femoral arterial cannula. To our knowledge this is the first published study on the valuation of an intravascular blood gas sensor through a femoral arterial cannula. A total of 71 sets of data comparing the sensor with the blood gas analyser were obtained. The bias and precision for pH, PCO2 and PO2 were 0.006 and 0.07 pH units, 0.2 and 1.65 kPa (4.6% and 29%)
XXVIll
and 0.8 and 2.7 kPa (5.1% and 14.3%), respectively. There was a degree of imprecision of the PCO2 sensor, the reasons for which are discussed. In summary, the intra-arterial sensor functioned well when inserted into the femoral artery in post-cardiopulmonary bypass patients. There were no complications attributable to sensor placement.
Contact: Department of Anaesthesia, Wycombe General Hospital, Queen Alexandra Road, High Wycombe, Bucks HPll 217, UK. U S A m Highly selective biosensing
In ANAL. CHIM. ACTA (304/1 (41--46) 1995)J. Wang, Q. Chen, M. Pedrero of New Mexico State University report "Highly selective biosensing of l a c t a t e at l a c t a t e o x i d a s e c o n t a i n i n g rhodium-dispersed carbon paste electrodes". A remarkably selective lactate biosensor, based on the immobilization of lactate oxidase within a rhodium-dispersed carbon paste is described. The effective catalytic action of the rhodium microparticles towards the generated hydrogen peroxide or consumed oxygen allows tuning of the operating potential to a region where unwanted reactions are prevented. Contributions from all major easily oxidizable substances are eliminated, without the need for membrane barriers or artificial electron mediators. The detection limit is 1.5 x 10 -5 M and the response time is 8 s. A fast and sensitive flow injection operation is illustrated.
Contact: Department of Chemistry/ Biochemistry, New Mexico State University, Las Cruces, NM 88003, USA. Japan - - Highly sensitive i m m u n o s e n s o r s for detection of herbicides
In ANAL. CHIM. ACTA (304/2 (139-145) 1995) K. Yokoyama, K. Ikebukuro, E. Tamiya, I. Karube, N. Ichiki and Y. Arikawa of Japan Inst. of S c i e n c e / T e c h n o l o g y report on "Highly sensitive quartz crystal immunosensors for multisample detection of herbicides". The authors have developed a piezoelectric quartz crystal immunosensor for the multisample
A b i e n z y m e e l e c t r o d e b a s e d on the amplification of a signal has been developed which allows the determination of picoto nanomolar concentrations of p-aminophenol. The active element of the sensor comprised of coimmobilised laccase and g l u c o s e dehydrogenase enzymes coupled with an oxygen electrode. Laccase catalyzes p-aminophenol oxidation by oxygen to give p-lminoquinone. The latter is reduced by excess of glucose in the presence of glucose dehydrogenase and results in recycling of the substrate. The detection is realized by measuring the decrease in oxygen c o n c e n t r a t i o n . T h e d e t e c t i o n l i m i t for p-aminophenol is 100 pM. The feasibility of the determination of a number of other substrates (polyphenols, polyamines, ferrocene derivatives) in the nanomolar range has been demonstrated. A significant background signal has been found for p-aminophenylphosphate. This background is probably caused by the ability of laccase to catalyze the oxidative dephosphorylation. In the presence of phosphate ions this background is practically completely eliminated. 50 pM of alkaline phosphatase could be determined after a 2 min incubation in p-aminophenylphosphate solution by determination of the p-aminophenol formed as the result of hydrolysis. The whole analysis time does not exceed 5 min. The new technique is suitable for application in alkaline phosphatase based enzyme immunoassays.
Contact: Department Analytical Biochemistry, University of Potsdam, Potsdam, Germany. Japan Glucose sensor based on carbon paste electrode -
-
In ANAL. CHIM. ACTA ( 304/] (33-39) 1995) C. Saby, E Mizutani and S. Yabuki of the National Institute Bioscience report on "Glucose sensor based on carbon paste electrode incorporating poly(ethylene glycol)-modified glucose oxidase and various mediators ". Amperometric bioelectrodes constituted of carbon paste electrode incorporating poly(ethylene glycol)-modified glucose oxidase and mediators are studied. Influences of the nature
of the mediators (anthraquinone, methylene blue, 2,6-dichlorophenolindophenol, tetracyanoquinodimethane, 1, l'-dimethylferrocene) on the characteristics (potential window, apparent Michaelis constant, response time, stability) of the bioelectrodes are investigated. It is possible to show that the behaviour of the mediator is influenced by the pasting liquid contained in the carbon paste. Moreover, the water solubility of the mediator is the cause of a decrease of the apparent Michaelis constant in the case of methylene blue. A comparison between the stability of a low water soluble mediator (tetracyanoquinodimethane) and a more water soluble mediator (methylene blue) shows that the leakage of mediator from the carbon paste is not the cause of the lack of stability of such bioelectrodes. A m o n g the various mediators tested, tetracyanoquinodimethane seems the most appropriate for the construction of a bioelectrode.
Contact: Biomaterials Laboratory, National Institute Bioscience, Higashi 1-1, Tsukuba, Ibaraki 205, Japan. Ireland m Evaluation of amperometric glucose biosensors In ANAL. CHIM. ACTA (304/2 (127-138) 1995) M. Pravda, C.M. Jungar, E.I. Iwuoha , M.R. Smyth, K. Vytras and A Ivaska of Dublin City. University report on "Evaluation of amperometric glucose biosensors based on co-immobilisation of glucose oxidase with an osmium redox polymer in electrochemically generated polyphenol films". The authors prepared three types of glucose sensors by electrochemical deposition of glucose o x i d a s e ( G O D ) , [Os(bpy)2(PVP)loCI]CI (Os-polymer) (bpy = 2,2'-bipyridyl, PVP = poly(4-vinylpyridine)) within polyphenol (PPh) films on a platinum electrode. The enzyme and Os-polymer in these reagentless sensors were entrapped in stable and reproducible PPh films grown potentiodynamically by cycling the potential between 0 and +950mV at 50 mV/s. The first sensor was prepared by immobilising only GOD in a PPh film and was based on H202 detection. The Os-polymer-containing electrodes were prepared by two different procedures. In one
xxvii
Biosensors & Bioelectronics Vol. 10 No. 8 (1995)
t y p e , the O s - p o l y m e r and G O D w e r e electrochemically deposited on a Pt surface simultaneously with the PPh film. The other type was a bilayer electrode in which the Os-polymer was first adsorbed on a Pt electrode prior to covering with a GOD/PPh film. The latter electrode exhibited better sensitivity to glucose, less interference from electroactive compounds a n d v e r y low b a c k g r o u n d n o i s e . T h e e l e c t r o c h e m i c a l behaviour of paracetamol, ascorbic acid and uric acid, which normally interfere with glucose detection, was studied with electrodes similar to the glucose biosensors except that they did not contain GOD. The three compounds showed no interaction with the PPh film, which they permeate, and undergo faradaic reaction at the underlying platinum surface. P a r a c e t a m o l e x h i b i t e d the g r e a t e s t f i l m permeation of the insulating PPh film. The relative response (I(ss, modified electrode)/I(ss, Pt)) of paracetamol was ca. 85-fold and 9-fold in excess of those of ascorbic acid and uric acid, respectively.
Contact: School of Chemical Sciences, Dublin City University, Dublin 9, Ireland. UK m Continuous m e a s u r e m e n t of blood gases
In J. MED. ENG. TECHNOL. (18/5 (165-168) 1994) B. Venkatesh, T.H. Clutton-Brock and S.P. Hendry of Wycombe General Hospital report on "Continuous measurement of blood gases using a c o m b i n e d e l e c t r o c h e m i c a l and s p e c t r o photometric sensor ". The use of a combined electrochemical and fibreoptic continuous intra-arterial blood gas sensor is described. The purpose of the study was to evaluate the performance of the sensor in 10 patients in the intensive therapy unit following insertion through a femoral arterial cannula. To our knowledge this is the first published study on the valuation of an intravascular blood gas sensor through a femoral arterial cannula. A total of 71 sets of data comparing the sensor with the blood gas analyser were obtained. The bias and precision for pH, PCO2 and PO2 were 0.006 and 0.07 pH units, 0.2 and 1.65 kPa (4.6% and 29%)
XXVIll
and 0.8 and 2.7 kPa (5.1% and 14.3%), respectively. There was a degree of imprecision of the PCO2 sensor, the reasons for which are discussed. In summary, the intra-arterial sensor functioned well when inserted into the femoral artery in post-cardiopulmonary bypass patients. There were no complications attributable to sensor placement.
Contact: Department of Anaesthesia, Wycombe General Hospital, Queen Alexandra Road, High Wycombe, Bucks HPll 217, UK. U S A m Highly selective biosensing
In ANAL. CHIM. ACTA (304/1 (41--46) 1995)J. Wang, Q. Chen, M. Pedrero of New Mexico State University report "Highly selective biosensing of l a c t a t e at l a c t a t e o x i d a s e c o n t a i n i n g rhodium-dispersed carbon paste electrodes". A remarkably selective lactate biosensor, based on the immobilization of lactate oxidase within a rhodium-dispersed carbon paste is described. The effective catalytic action of the rhodium microparticles towards the generated hydrogen peroxide or consumed oxygen allows tuning of the operating potential to a region where unwanted reactions are prevented. Contributions from all major easily oxidizable substances are eliminated, without the need for membrane barriers or artificial electron mediators. The detection limit is 1.5 x 10 -5 M and the response time is 8 s. A fast and sensitive flow injection operation is illustrated.
Contact: Department of Chemistry/ Biochemistry, New Mexico State University, Las Cruces, NM 88003, USA. Japan - - Highly sensitive i m m u n o s e n s o r s for detection of herbicides
In ANAL. CHIM. ACTA (304/2 (139-145) 1995) K. Yokoyama, K. Ikebukuro, E. Tamiya, I. Karube, N. Ichiki and Y. Arikawa of Japan Inst. of S c i e n c e / T e c h n o l o g y report on "Highly sensitive quartz crystal immunosensors for multisample detection of herbicides". The authors have developed a piezoelectric quartz crystal immunosensor for the multisample