Gerhard Sontag - Academia.edu (original) (raw)
Papers by Gerhard Sontag
SPIE Proceedings, 1999
Metal clusters excited by light exhibit high local field enhancement and nanoscale resonant behav... more Metal clusters excited by light exhibit high local field enhancement and nanoscale resonant behavior. Absorptive properties of these metal clusters bound to a surface are the basis of various new and highly promising setups to transduce biorecognitive interactions into an optical signal. Multilayered highly resonant systems had been proposed and recently demonstrated employing a metal mirror, a nanometric polymer distance
Current Bioactive Compounds
In this article an overview of the analytical methods in lignan analysis is given. Sampling, samp... more In this article an overview of the analytical methods in lignan analysis is given. Sampling, sample preparation (including extraction and hydrolytic sample work up), chromatographic separation methods and several detection modes are discussed and validation parameters like limits of detection and quantitation, recoveries, repeatability and linear range are compared. The challenges of analytical analysis are discussed, advantages and limitations of the individual approaches are described and the state of the art methods are presented with main emphasis on sample preparation. Sources of error in sample work-up will be pointed out and recommendations for analysis of lignans in plant foods will be given.
Zeitschrift f�r Lebensmittel-Untersuchung und -Forschung, 1980
Determination of Methyl Caffeate und Ethyl Caffeate in Vegetables by High Pressure Liquid Chromat... more Determination of Methyl Caffeate und Ethyl Caffeate in Vegetables by High Pressure Liquid Chromatography with Electrochemical Detection Summary. A method for quantitative determination of methyl caffeate and ethyl caffeate was developed: After extraction and preliminary purification on polyamide columns the extracts were analysed by high pressure liquid chromatography, employing isocratic elution from Nucleosil 10 C 8. For identification and quantitative determination an electrochemical detector was used. The detection limit of methyl caffeate is 0.02 ppm and for ethyl caffeate it is 0.025 ppm. Selected ion monitoring mass spectrometry was applied for confirmatory identification of these compounds.
European Food Research and Technology, 2000
A HPLC method coupled with coulometric electrode array detection for determination of daidzein an... more A HPLC method coupled with coulometric electrode array detection for determination of daidzein and genistein in soy milk, soy-based infant food and nutritional supplements is described. The samples were spiked with bisphenol A (internal standard), extracted and hydrolyzed in an acid ethanolic solution. After purification of the extract on a C-18 cartridge the compounds were separated on a C-18 reversed phase column (50 mM sodium acetate adapted to pH 4.8 with glacial acetic acid/methanol at 450/550, v/v). The compounds were detected at eight electrodes set on potentials between +390 mV and +810 mV (in increments of 60 mV) against modified palladium electrodes. The contents of daidzein and genistein were determined in several commercial samples.
Current Bioactive Compounds, 2011
Microchimica Acta, 1976
... Von Gerhard Sontag, Manfred Kerschbaumer und Gerald Kainz ... Emmott3); Graphit (Barikov4); w... more ... Von Gerhard Sontag, Manfred Kerschbaumer und Gerald Kainz ... Emmott3); Graphit (Barikov4); wachsimprfignierter Graphit (Peronea); glasartiger Kohlenstoff (Miwa% PnevT); schliet~- lich rotierende Scheibenelektroden aus glasartigem Kohlenstoff (Stulikova 1, Allen s, Luongg ...
Zeitschrift für Lebensmitteluntersuchung und- …, 1988
... Gallhuber - 0,9 1,0 0,5 0,5 Osterreich Cognac Courvoisier, VSOP - 0,4 1,2 0,85 1,75 Courvoisi... more ... Gallhuber - 0,9 1,0 0,5 0,5 Osterreich Cognac Courvoisier, VSOP - 0,4 1,2 0,85 1,75 Courvoisier SA, Frankreich Remy Martin, VSOP 0,75 0,15 0,8 1,9 1,3 3,75 ... Ein RtickschluB auf die Lagerdauer ist jedoch nur dann zul/issig, wenn die Lagerung in Eichenf/issern er-folgte. ...
![Research paper thumbnail of Consumption of Brussels sprouts protects peripheral human lymphocytes against 2-amino-1-methyl-6-phenylimidazo[4, 5-b]pyridine (PhIP) and oxidative DNA-damage: results of a controlled human intervention trial](https://attachments.academia-assets.com/74446316/thumbnails/1.jpg)
](To find out if the cancer protective effects of Brussels sprouts seen in epidemiological studies ... more To find out if the cancer protective effects of Brussels sprouts seen in epidemiological studies are due to protection against DNA-damage, an intervention trial was conducted in which the impact of vegetable consumption on DNA-stability was monitored in lymphocytes with the comet assay. After consumption of the sprouts (300 g/p/d, n = 8), a reduction of DNA-migration (97%) induced by the heterocyclic aromatic amine 2-amino-1-methyl-6-phenyl-imidazo-[4,5-b]pyridine (PhIP) was observed whereas no effect was seen with 3-amino-1-methyl-5H-pyrido[4,3-b]-indole (Trp-P-2). This effect protection may be due to inhibition of sulfotransferase 1A1, which plays a key role in the activation of PhIP. In addition, a decrease of the endogenous formation of oxidized bases was observed and DNA-damage caused by hydrogen peroxide was significantly (39%) lower after the intervention. These effects could not be explained by induction of antioxidant enzymes glutathione peroxidase and superoxide dismutase, but in vitro experiments indicate that sprouts contain compounds, which act as direct scavengers of reactive oxygen species. Serum vitamin C levels were increased by 37% after sprout consumption but no correlations were seen between prevention of DNA-damage and individual alterations of the vitamin levels. Our study shows for the first time that sprout consumption leads to inhibition of sulfotransferases in humans and to protection against PhIP and oxidative DNA-damage.
Fresenius' Zeitschrift f�r Analytische Chemie, 1983
ABSTRACT
Fresenius' Journal of Analytical Chemistry, 1993
ABSTRACT
Monatshefte für Chemie - Chemical Monthly, 2009
In this study a design of an immunosensor for 1-nitropyrene is illustrated. First the response of... more In this study a design of an immunosensor for 1-nitropyrene is illustrated. First the response of 1-nitropyrene reduced at a glassy carbon electrode between 0 and -0.8 V was investigated with respect to pH and solvent. Then polyclonal anti-1-nitropyrene antibodies isolated from a rabbit antiserum were covalently bound to the surface of the glassy carbon electrode. This modified electrode was immersed in standard solutions or sample extracts for 5-15 min. 1-Nitropyrene was bound by the antibodies, accumulated and then analyzed at pH 6.5 in another supporting electrolyte by differential pulse voltammetry. Afterwards the immunosensor could be regenerated for the next measurement by rinsing with acetonitrile-water (40:60, v/v). A linear response was found between 20 and 100 ng/cm 3 . The limit of detection was 10 ng/cm 3 and the intraday reproducibility of three immunosensors assembled during two months was between 4.5 and 10%. This sensor was applied to the analysis of 1-nitropyrene in air particulate matter and smoked tea.
![Research paper thumbnail of Consumption of Brussels sprouts protects peripheral human lymphocytes against 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and oxidative DNA-damage: results of a controlled human intervention trial](https://attachments.academia-assets.com/47745816/thumbnails/1.jpg)
](Molecular Nutrition & Food Research, 2008
To find out if the cancer protective effects of Brussels sprouts seen in epidemiological studies ... more To find out if the cancer protective effects of Brussels sprouts seen in epidemiological studies are due to protection against DNA-damage, an intervention trial was conducted in which the impact of vegetable consumption on DNA-stability was monitored in lymphocytes with the comet assay. After consumption of the sprouts (300 g/p/d, n = 8), a reduction of DNA-migration (97%) induced by the heterocyclic aromatic amine 2-amino-1-methyl-6-phenyl-imidazo-[4,5-b]pyridine (PhIP) was observed whereas no effect was seen with 3-amino-1-methyl-5H-pyrido[4,3-b]-indole (Trp-P-2). This effect protection may be due to inhibition of sulfotransferase 1A1, which plays a key role in the activation of PhIP. In addition, a decrease of the endogenous formation of oxidized bases was observed and DNA-damage caused by hydrogen peroxide was significantly (39%) lower after the intervention. These effects could not be explained by induction of antioxidant enzymes glutathione peroxidase and superoxide dismutase, but in vitro experiments indicate that sprouts contain compounds, which act as direct scavengers of reactive oxygen species. Serum vitamin C levels were increased by 37% after sprout consumption but no correlations were seen between prevention of DNA-damage and individual alterations of the vitamin levels. Our study shows for the first time that sprout consumption leads to inhibition of sulfotransferases in humans and to protection against PhIP and oxidative DNA-damage.
Analytica Chimica Acta, 1993
ABSTRACT An enzyme-based flow-injection system with electrochemical detection suitable for the de... more ABSTRACT An enzyme-based flow-injection system with electrochemical detection suitable for the determination of salicylic acid in pharmaceuticals is described. The method makes use of the enzyme salicylate hydroxylase (EC 1.14.13.1), which is covalently bound to glass beads and put into the reactor of a flow system. The enzyme catalyses the stoichiometric conversion of salicylic acid to catechol, which can then be detected amperometrically at +0.45 V (vs. Ag/AgCl/KClsat.). The electrode response is linearly proportional to the concentration of salicylic acid between 5 and 150 μg ml−1. The detection limit is 0.4 μg ml−1. This method is simple, rapid and specific. The assayed samples yielded relative standard deviations between 0.5 and 2.0% and recoveries between 93 and 98%.
Monatshefte für Chemie - Chemical Monthly, 2010
A copolymer of N-vinylimidazole and N-vinyl-2-pyrrolidone, photo-crosslinked with sulfonated diaz... more A copolymer of N-vinylimidazole and N-vinyl-2-pyrrolidone, photo-crosslinked with sulfonated diazidostilbenes, showed swelling/shrinking behaviour due to interaction with divalent metal ions such as Mn 2? , Zn 2? , Ni 2? , and Co 2? . This effect was used to set up a resonance enhanced absorption chip; a solution of the copolymer in methanol, stabilized with the radical scavenger 2,6-di-tbutyl-4-methylphenol, was spin-coated onto a silanized aluminum chip and then sputtered with gold nanoparticles. The change in layer thickness caused by the interaction of ions with the copolymer interlayer resulted in a shift of the maxima of the reflection spectrum to lower wavelengths and thus also a visible colour change. This spectral shift was logarithmically related to the concentration of metal ions. Mn 2? turned out to react more rapidly and was detected with 100-fold greater sensitivity than the other investigated ions.
Analytica Chimica Acta, 1995
... 30 (1978), p. 81. View Record in Scopus | Cited By in Scopus (12). [4]. AM Molokhia, HI Al-Sh... more ... 30 (1978), p. 81. View Record in Scopus | Cited By in Scopus (12). [4]. AM Molokhia, HI Al-Shora and S. Al-Rhaman. J. Liquid Chromatogr. ... Abstract | PDF (270 K) | View Record in Scopus | Cited By in Scopus (14). [7]. SM Hassan and MA Hamada. Analyst 113 (1988), p. 1709. ...
Monatshefte für Chemie - Chemical Monthly, 2009
In this study a design of an immunosensor for 1-nitropyrene is illustrated. First the response of... more In this study a design of an immunosensor for 1-nitropyrene is illustrated. First the response of 1-nitropyrene reduced at a glassy carbon electrode between 0 and -0.8 V was investigated with respect to pH and solvent. Then polyclonal anti-1-nitropyrene antibodies isolated from a rabbit antiserum were covalently bound to the surface of the glassy carbon electrode. This modified electrode was immersed in standard solutions or sample extracts for 5-15 min. 1-Nitropyrene was bound by the antibodies, accumulated and then analyzed at pH 6.5 in another supporting electrolyte by differential pulse voltammetry. Afterwards the immunosensor could be regenerated for the next measurement by rinsing with acetonitrile-water (40:60, v/v). A linear response was found between 20 and 100 ng/cm 3 . The limit of detection was 10 ng/cm 3 and the intraday reproducibility of three immunosensors assembled during two months was between 4.5 and 10%. This sensor was applied to the analysis of 1-nitropyrene in air particulate matter and smoked tea.
Monatshefte für Chemie
A copolymer of N-vinylimidazole and N-vinyl-2-pyrrolidone, photo-crosslinked with sulphonated dia... more A copolymer of N-vinylimidazole and N-vinyl-2-pyrrolidone, photo-crosslinked with sulphonated diazidostilbenes, showed swelling/shrinking behaviour due to interaction with divalent metal ions such as Mn2+, Zn2+, Ni2+ and Co2+. This effect was used to set up a resonance enhanced absorption chip: a solution of the copolymer in methanol, stabilized with the radical scavanger 2,6-di-t-butyl-4-methylphenol, was spin-coated onto a silanized aluminium chip and then sputtered with gold nanoparticles. The change in layer thickness caused by the interaction of the ions with the copolymer interlayer resulted in a shift of the maxima of the reflection spectrum to lower wavelengths and thus also a visible colour change. This spectral shift was logarithmically related to the concentration of the metal ions. Mn2+ turned out to react more rapidly and was detected with 100-fold greater sensitivity than the other investigated ions.
Micro- and Nanofabricated Structures and Devices for Biomedical Environmental Applications II, 1999
SPIE Proceedings, 1999
Metal clusters excited by light exhibit high local field enhancement and nanoscale resonant behav... more Metal clusters excited by light exhibit high local field enhancement and nanoscale resonant behavior. Absorptive properties of these metal clusters bound to a surface are the basis of various new and highly promising setups to transduce biorecognitive interactions into an optical signal. Multilayered highly resonant systems had been proposed and recently demonstrated employing a metal mirror, a nanometric polymer distance
Current Bioactive Compounds
In this article an overview of the analytical methods in lignan analysis is given. Sampling, samp... more In this article an overview of the analytical methods in lignan analysis is given. Sampling, sample preparation (including extraction and hydrolytic sample work up), chromatographic separation methods and several detection modes are discussed and validation parameters like limits of detection and quantitation, recoveries, repeatability and linear range are compared. The challenges of analytical analysis are discussed, advantages and limitations of the individual approaches are described and the state of the art methods are presented with main emphasis on sample preparation. Sources of error in sample work-up will be pointed out and recommendations for analysis of lignans in plant foods will be given.
Zeitschrift f�r Lebensmittel-Untersuchung und -Forschung, 1980
Determination of Methyl Caffeate und Ethyl Caffeate in Vegetables by High Pressure Liquid Chromat... more Determination of Methyl Caffeate und Ethyl Caffeate in Vegetables by High Pressure Liquid Chromatography with Electrochemical Detection Summary. A method for quantitative determination of methyl caffeate and ethyl caffeate was developed: After extraction and preliminary purification on polyamide columns the extracts were analysed by high pressure liquid chromatography, employing isocratic elution from Nucleosil 10 C 8. For identification and quantitative determination an electrochemical detector was used. The detection limit of methyl caffeate is 0.02 ppm and for ethyl caffeate it is 0.025 ppm. Selected ion monitoring mass spectrometry was applied for confirmatory identification of these compounds.
European Food Research and Technology, 2000
A HPLC method coupled with coulometric electrode array detection for determination of daidzein an... more A HPLC method coupled with coulometric electrode array detection for determination of daidzein and genistein in soy milk, soy-based infant food and nutritional supplements is described. The samples were spiked with bisphenol A (internal standard), extracted and hydrolyzed in an acid ethanolic solution. After purification of the extract on a C-18 cartridge the compounds were separated on a C-18 reversed phase column (50 mM sodium acetate adapted to pH 4.8 with glacial acetic acid/methanol at 450/550, v/v). The compounds were detected at eight electrodes set on potentials between +390 mV and +810 mV (in increments of 60 mV) against modified palladium electrodes. The contents of daidzein and genistein were determined in several commercial samples.
Current Bioactive Compounds, 2011
Microchimica Acta, 1976
... Von Gerhard Sontag, Manfred Kerschbaumer und Gerald Kainz ... Emmott3); Graphit (Barikov4); w... more ... Von Gerhard Sontag, Manfred Kerschbaumer und Gerald Kainz ... Emmott3); Graphit (Barikov4); wachsimprfignierter Graphit (Peronea); glasartiger Kohlenstoff (Miwa% PnevT); schliet~- lich rotierende Scheibenelektroden aus glasartigem Kohlenstoff (Stulikova 1, Allen s, Luongg ...
Zeitschrift für Lebensmitteluntersuchung und- …, 1988
... Gallhuber - 0,9 1,0 0,5 0,5 Osterreich Cognac Courvoisier, VSOP - 0,4 1,2 0,85 1,75 Courvoisi... more ... Gallhuber - 0,9 1,0 0,5 0,5 Osterreich Cognac Courvoisier, VSOP - 0,4 1,2 0,85 1,75 Courvoisier SA, Frankreich Remy Martin, VSOP 0,75 0,15 0,8 1,9 1,3 3,75 ... Ein RtickschluB auf die Lagerdauer ist jedoch nur dann zul/issig, wenn die Lagerung in Eichenf/issern er-folgte. ...
To find out if the cancer protective effects of Brussels sprouts seen in epidemiological studies ... more To find out if the cancer protective effects of Brussels sprouts seen in epidemiological studies are due to protection against DNA-damage, an intervention trial was conducted in which the impact of vegetable consumption on DNA-stability was monitored in lymphocytes with the comet assay. After consumption of the sprouts (300 g/p/d, n = 8), a reduction of DNA-migration (97%) induced by the heterocyclic aromatic amine 2-amino-1-methyl-6-phenyl-imidazo-[4,5-b]pyridine (PhIP) was observed whereas no effect was seen with 3-amino-1-methyl-5H-pyrido[4,3-b]-indole (Trp-P-2). This effect protection may be due to inhibition of sulfotransferase 1A1, which plays a key role in the activation of PhIP. In addition, a decrease of the endogenous formation of oxidized bases was observed and DNA-damage caused by hydrogen peroxide was significantly (39%) lower after the intervention. These effects could not be explained by induction of antioxidant enzymes glutathione peroxidase and superoxide dismutase, but in vitro experiments indicate that sprouts contain compounds, which act as direct scavengers of reactive oxygen species. Serum vitamin C levels were increased by 37% after sprout consumption but no correlations were seen between prevention of DNA-damage and individual alterations of the vitamin levels. Our study shows for the first time that sprout consumption leads to inhibition of sulfotransferases in humans and to protection against PhIP and oxidative DNA-damage.
Fresenius' Zeitschrift f�r Analytische Chemie, 1983
ABSTRACT
Fresenius' Journal of Analytical Chemistry, 1993
ABSTRACT
Monatshefte für Chemie - Chemical Monthly, 2009
In this study a design of an immunosensor for 1-nitropyrene is illustrated. First the response of... more In this study a design of an immunosensor for 1-nitropyrene is illustrated. First the response of 1-nitropyrene reduced at a glassy carbon electrode between 0 and -0.8 V was investigated with respect to pH and solvent. Then polyclonal anti-1-nitropyrene antibodies isolated from a rabbit antiserum were covalently bound to the surface of the glassy carbon electrode. This modified electrode was immersed in standard solutions or sample extracts for 5-15 min. 1-Nitropyrene was bound by the antibodies, accumulated and then analyzed at pH 6.5 in another supporting electrolyte by differential pulse voltammetry. Afterwards the immunosensor could be regenerated for the next measurement by rinsing with acetonitrile-water (40:60, v/v). A linear response was found between 20 and 100 ng/cm 3 . The limit of detection was 10 ng/cm 3 and the intraday reproducibility of three immunosensors assembled during two months was between 4.5 and 10%. This sensor was applied to the analysis of 1-nitropyrene in air particulate matter and smoked tea.
Molecular Nutrition & Food Research, 2008
To find out if the cancer protective effects of Brussels sprouts seen in epidemiological studies ... more To find out if the cancer protective effects of Brussels sprouts seen in epidemiological studies are due to protection against DNA-damage, an intervention trial was conducted in which the impact of vegetable consumption on DNA-stability was monitored in lymphocytes with the comet assay. After consumption of the sprouts (300 g/p/d, n = 8), a reduction of DNA-migration (97%) induced by the heterocyclic aromatic amine 2-amino-1-methyl-6-phenyl-imidazo-[4,5-b]pyridine (PhIP) was observed whereas no effect was seen with 3-amino-1-methyl-5H-pyrido[4,3-b]-indole (Trp-P-2). This effect protection may be due to inhibition of sulfotransferase 1A1, which plays a key role in the activation of PhIP. In addition, a decrease of the endogenous formation of oxidized bases was observed and DNA-damage caused by hydrogen peroxide was significantly (39%) lower after the intervention. These effects could not be explained by induction of antioxidant enzymes glutathione peroxidase and superoxide dismutase, but in vitro experiments indicate that sprouts contain compounds, which act as direct scavengers of reactive oxygen species. Serum vitamin C levels were increased by 37% after sprout consumption but no correlations were seen between prevention of DNA-damage and individual alterations of the vitamin levels. Our study shows for the first time that sprout consumption leads to inhibition of sulfotransferases in humans and to protection against PhIP and oxidative DNA-damage.
Analytica Chimica Acta, 1993
ABSTRACT An enzyme-based flow-injection system with electrochemical detection suitable for the de... more ABSTRACT An enzyme-based flow-injection system with electrochemical detection suitable for the determination of salicylic acid in pharmaceuticals is described. The method makes use of the enzyme salicylate hydroxylase (EC 1.14.13.1), which is covalently bound to glass beads and put into the reactor of a flow system. The enzyme catalyses the stoichiometric conversion of salicylic acid to catechol, which can then be detected amperometrically at +0.45 V (vs. Ag/AgCl/KClsat.). The electrode response is linearly proportional to the concentration of salicylic acid between 5 and 150 μg ml−1. The detection limit is 0.4 μg ml−1. This method is simple, rapid and specific. The assayed samples yielded relative standard deviations between 0.5 and 2.0% and recoveries between 93 and 98%.
Monatshefte für Chemie - Chemical Monthly, 2010
A copolymer of N-vinylimidazole and N-vinyl-2-pyrrolidone, photo-crosslinked with sulfonated diaz... more A copolymer of N-vinylimidazole and N-vinyl-2-pyrrolidone, photo-crosslinked with sulfonated diazidostilbenes, showed swelling/shrinking behaviour due to interaction with divalent metal ions such as Mn 2? , Zn 2? , Ni 2? , and Co 2? . This effect was used to set up a resonance enhanced absorption chip; a solution of the copolymer in methanol, stabilized with the radical scavenger 2,6-di-tbutyl-4-methylphenol, was spin-coated onto a silanized aluminum chip and then sputtered with gold nanoparticles. The change in layer thickness caused by the interaction of ions with the copolymer interlayer resulted in a shift of the maxima of the reflection spectrum to lower wavelengths and thus also a visible colour change. This spectral shift was logarithmically related to the concentration of metal ions. Mn 2? turned out to react more rapidly and was detected with 100-fold greater sensitivity than the other investigated ions.
Analytica Chimica Acta, 1995
... 30 (1978), p. 81. View Record in Scopus | Cited By in Scopus (12). [4]. AM Molokhia, HI Al-Sh... more ... 30 (1978), p. 81. View Record in Scopus | Cited By in Scopus (12). [4]. AM Molokhia, HI Al-Shora and S. Al-Rhaman. J. Liquid Chromatogr. ... Abstract | PDF (270 K) | View Record in Scopus | Cited By in Scopus (14). [7]. SM Hassan and MA Hamada. Analyst 113 (1988), p. 1709. ...
Monatshefte für Chemie - Chemical Monthly, 2009
In this study a design of an immunosensor for 1-nitropyrene is illustrated. First the response of... more In this study a design of an immunosensor for 1-nitropyrene is illustrated. First the response of 1-nitropyrene reduced at a glassy carbon electrode between 0 and -0.8 V was investigated with respect to pH and solvent. Then polyclonal anti-1-nitropyrene antibodies isolated from a rabbit antiserum were covalently bound to the surface of the glassy carbon electrode. This modified electrode was immersed in standard solutions or sample extracts for 5-15 min. 1-Nitropyrene was bound by the antibodies, accumulated and then analyzed at pH 6.5 in another supporting electrolyte by differential pulse voltammetry. Afterwards the immunosensor could be regenerated for the next measurement by rinsing with acetonitrile-water (40:60, v/v). A linear response was found between 20 and 100 ng/cm 3 . The limit of detection was 10 ng/cm 3 and the intraday reproducibility of three immunosensors assembled during two months was between 4.5 and 10%. This sensor was applied to the analysis of 1-nitropyrene in air particulate matter and smoked tea.
Monatshefte für Chemie
A copolymer of N-vinylimidazole and N-vinyl-2-pyrrolidone, photo-crosslinked with sulphonated dia... more A copolymer of N-vinylimidazole and N-vinyl-2-pyrrolidone, photo-crosslinked with sulphonated diazidostilbenes, showed swelling/shrinking behaviour due to interaction with divalent metal ions such as Mn2+, Zn2+, Ni2+ and Co2+. This effect was used to set up a resonance enhanced absorption chip: a solution of the copolymer in methanol, stabilized with the radical scavanger 2,6-di-t-butyl-4-methylphenol, was spin-coated onto a silanized aluminium chip and then sputtered with gold nanoparticles. The change in layer thickness caused by the interaction of the ions with the copolymer interlayer resulted in a shift of the maxima of the reflection spectrum to lower wavelengths and thus also a visible colour change. This spectral shift was logarithmically related to the concentration of the metal ions. Mn2+ turned out to react more rapidly and was detected with 100-fold greater sensitivity than the other investigated ions.
Micro- and Nanofabricated Structures and Devices for Biomedical Environmental Applications II, 1999