Biomimetic reagent system and its use

Details Biomimetic reagent system and its use Biomimetic reagent system and its use

1999-09-10

2002-04-23

Snay, Jeffrey (Department: 1743)

Chemistry: analytical and immunological testing

Hydrocarbon

Aromatic

C436S167000, C422S086000, C422S088000

Reexamination Certificate

active

06376254

ABSTRACT:

FIELD OF THE INVENTION
The present invention pertains to a biomimetic reagent system, which is applied to a carrier and contains an oxygen donor and a catalyst based on porphyrin, to a device containing this reagent system, to its use for determining components of gas or vapor samples, especially aromatics, such as benzene, as well as to a process for hydroxylating aromatics, such as benzene, by using the biomimetic reagent system.
BACKGROUND OF THE INVENTION
Various embodiments of testing elements with reagent systems, by means of which especially gases or vapors can be tested for components contained in them in a simple manner, rapidly and at low cost, have been known.
A measuring apparatus operating with a reagent-containing indicator strip is described in DE 34 07 686 C1. The gas to be tested is drawn actively through this indicator strip. The reagents on the indicator strip react specifically with the components to be determined in the sample. This leads to a change in color, which is detected photometrically.
Another embodiment is a plaque. A flat disk, e.g., a paper disk, which is impregnated with a reagent, reacts with the components of the gas sample to be determined, e.g., air, based on diffusion, while the color of the disk changes. The intensity of the change in color within a certain period of time is an indicator of the concentration of the constituents of the air.
The testing elements are also often designed as so-called detector tubes. The reagents in these are applied, in general, as very thin layers to fine-grained carrier materials, which are in turn fixed in a glass tube. The gas sample (analyte) is then actively drawn through the glass tube by means of a pump. The components to be determined now react with the reagents, while the color changes. The length of the color layer formed relative to a defined sample volume is an indicator of the concentration of the component to be determined. A plurality of layers of different chemical reactivity, which are arranged one behind the other, may be used within the same tube. For example, the analyte can be converted in a preceding layer into a chemically different analyte, for the detection of which there will be a suitable color reaction in another layer.
The automatic optoelectronic evaluation of the corresponding change in color of miniaturized detector tubes is usually performed as described in DE 39 02 402 C1.
A great variety of chemical reagent systems, which must meet a great variety of requirements, are used precisely in detector tubes. Besides the redox reagent systems, which are used very frequently, the changes in the pH value or even condensation reactions also play an important role in the systems used. Since the reactions of the reagent systems usually must take place as completely as possible at room temperature and within a very short time, the reagent matrices are, in general, chemically highly corrosive; for example, redox reactions take place with the use of fuming sulfuric acid. The gases released during an active operation, e.g., sulfur trioxide in this case, may cause damage, especially in automated measuring systems. Such corrosive reagent systems consequently have limited suitability for use in automated measuring systems. Furthermore, an accurate and complicated coordination of the properties of the reagent system and the carrier material used must be usually performed.
Moreover, the use of biochemical reagent systems in detector tubes has been known. Even though these highly complex systems are characterized by a high selectivity, their limited shelf life is disadvantageous.
Testing elements in the form of so-called biomimetic sensors have been known from the state of the art as well. Biomimetic sensors simulate the function of organs of sense: Chemical signals are recoded into physical signals or also vice versa by influencing the interaction between the carrier and bioactive materials. The response of the biomimetic sensor to such signals simulates the response of an organ of sense. The physicochemical signals are then converted by means of so-called transducers into measurable electric signals and optionally suitably amplified by an electronic component.
A biomimetic sensor system for determining the concentration of CO and other pollutants in air has been known from U.S. Pat. No. 5,063,164. The sensor reacts to the presence of CO with a sensitivity similar to that of the human organs of sense, i.e., it simulates the response of the human body to the presence of CO, etc. The sensor disclosed in U.S. Pat. No. 5,063,164 has a good service life. However, it consists of a very complex reagent system, which comprises five groups of inorganic/organic reagents, and some of the inorganic reagents are enclosed in larger organic molecules and these are in turn introduced into the pores of suitable carriers. The biomimetic sensor known from U.S. Pat. No. 5,063,164 also has the drawback that organic materials are made accessible for detection only by preceding reaction steps, such as oxidation by corrosive oxidizing agents into CO or by reactions induced by increasing the temperature.
SUMMARY AND OBJECTS OF THE INVENTION
Thus, the object of the present invention is to provide a biomimetic reagent system, which is suitable for the determination of components of gas or vapor samples, especially for determining organic materials of high toxicity, such as benzene. The biomimetic reagent system should be characterized by mild reaction conditions, i.e., it shall be able to be used at room temperature and without additional chemically corrosive auxiliary reagents and have a service life sufficient for practical purposes. Another object of the present invention was to provide a gas sensor that contains the biomimetic reagent system.
According to the invention, a biomimetic reagent system is provided that includes an oxygen donor and a catalyst based on porphyrin which are applied to a carrier.
The present invention also pertains to the use of the reagent system according to the present invention for determining components, especially aromatics, such as benzene, in gas and vapor samples.
The present invention also pertains to a process for hydroxylating aromatics by using the reagent system according to the present invention.
The present invention also pertains to a device containing the reagent system according to the present invention.
As was described above, biomimetic reagent systems are chemical models for one or more biochemical reactions. In the present invention, they are metal complexes, which are able to imitate, as a biomimetic system, monooxygenase reactions that are catalyzed by cytochrome P-450. Monooxygenases are enzymes that are able to activate oxygen by taking up two electrons and two protons and to hydrolyze or epoxidize substrates as a result. These reactions, which take place in the human body, are indispensable for the human body for the detoxification of drugs and foreign substances and after metabolism in the liver, they usually lead to water-soluble compounds, which are excreted renally.
These reactions are oxygenation reactions, in which the oxygen must be reduced enzymatically by NADPH. However, these reductions are difficult to carry out in the model with oxygen as the oxidizing agent.
It was surprisingly found according to the present invention that by using a carrier-bound biomimetic system, which contains certain oxygen donors combined with catalysts based on porphyrin, it is possible to react aromatics, especially benzene, into 1,4-benzoquinone derivatives under mild conditions, and these derivatives can then be easily made visible in color by condensation with 2,4-dinitrophenylhydrazine into the hydrazone.
This is surprising especially because molecules of low reactivity, such as benzene, which is highly resistant especially to oxidation, do not normally react chemically under such mild conditions, especially at a solid-gas interface.
The oxygen donor in the reagent system according to the present invention is selected from the group comprising iodosobenzene, magnesium monop

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