Identifying active ingredients and quantifying the effects of test substances is one of the laboratory’s most important fields of activity. Examples of investigations carried out on test substances are:

  • The production of reactive oxygen species (ROS) in living cells
  • Antioxidative potential (in-vitro test)
  • Growth inhibition
  • Inhibition of sterol biosynthesis
  • Inhibition of cell wall formation

Either new procedures are developed or the effects of test substances are investigated using existing procedures.

Test systems in microtiter plates (MTPs)

In the Biochemistry laboratory, test systems are used and developed in microtiter plates (MTPs) to identify active ingredients, to characterize the properties of test substances and to analyse a variety of samples to determine the individual analytes they contain.

The benefit of the 96- and 384-well microtiter plates that are used lies in the fact that a large number of samples can be tested for the desired properties simultaneously. When searching for new active substances, many substances can therefore be tested in a short time, making it possible to identify individual substances that may be of interest from a large number of compounds.

The tests in MTPs must be able to do without separation steps such as filtration and must ultimately provide an optical signal (usually absorption or fluorescence) that can be measured in MTP readers.

Typical methods are:

  • The determination of enzyme activities or metabolites with more or fewer purified enzymes.
  • Cell-based tests using genetically modified yeast strains that react to the effect of test substances by altering the production of reporter genes such as GFP.


The laboratory has several MTP readers that can measure absorption or fluorescence of all wells of a 96- or 384-well MTP within a short period of time.

For enzymatic determinations, the addition of all reagents is usually followed by a waiting period of 5 to 30 minutes, before an endpoint measurement is performed. To obtain kinetic data, a plate can also be left in the instrument over the course of the reaction and measured regularly.

For cell-based tests with significantly longer reaction times, an MTP can also be incubated in the instrument at a controlled temperature for 16 to 24 hours and measured regularly.

Automatic multichannel pipettes, dispensers integrated in the reader, an automatic 8-channel dispenser (Thermo “Multidrop”), and a pipetting robot are available for the rapid addition of the required solutions.

Performing automated tests

The laboratory’s automated workstation, consisting of MTP readers, an automatic pipettor, and a robotic arm for the transportation of MTPs, allows test procedures in MTPs to be carried out completely autonomously.

Substances can be filled from master plates or storage vessels into test MTPs and dilution series can be created. Test solutions can be added using an 8-channel pipettor or by using 1 and 8-channel dispensers.  Together with the MTP-Stacker, the robot arm makes it possible to process different MTPs sequentially and to measure them at different times.