Enzymatic assays

MeBioS Biosensors: Enzymatic assays Research

In the context of biosensors enzymes are the most interesting bio-selective components for LMW molecules such as sugars, organic acids, amino acids (or others). Enzymes are mainly used in two research contexts: (i) to study the effect of possible interfering components on the enzymes and (ii) to quantify a substrate of the involved enzyme.

In our research enzyme assays are used for the quantification of the most relevant taste components in fruit and vegetables, which includes following components: glucose, fructose, sucrose, sorbitol (sugars), citric and malic acid (organic acids) and glutamic acid (umami). Because of the high importance of vitamin C in fruit and vegetables for the human diet ascorbic acid has also been a subject of different studies.

The components, mentioned above, react specifically with a target enzyme which starts a cascade of different reactions. Thereby a signal is generated which can be correlated stoechiometrically with the component of interest. Different transducer systems are used to measure the output of the generated signal. Experience in the different transducer systems is available with studies on optical, electrochemical and microcalorimetric detection methods (in combination with the different enzymatic assays). Next to the practical implementation of the different methods, modeling is often involved in the different studies to optimize the assay conditions or to understand some fundamental phenomena at the interface of the transducer.

Since enzymes are quite expensive to work with, miniaturization of the assays is necessary to make that the enzymatic methods become cost-effective alternatives to replace standard techniques (such as HPLC or GC-MS) for the quantification of the LMW-analytes. Therefore miniaturization of the different assays was achieved by using microplates whereby total analysis volume ranges between 20 µL (microcalorimetric methods) and 200 µL (optical methods). In a next step the enzymatic assays will be implemented on a Lab-on-a-Chip device.