Turning the Spotlight on Surface Water

Researchers quantify the ecotoxicological impact of pharmaceuticals in real time

Demographic change in industrial nations is fueling stronger demand for pharmaceuticals. We are already seeing major volumes of substances with pharmacological effects entering the waste water system and sewage treatment plants. These substances are rarely removed effectively, and as a result organisms in surface water are increasingly exposed to a harmful cocktail of drugs. The Steinbeis Innovation Center for Cell Culture Technology has been working with the Steinbeis Transfer Center for Ecotoxicology and Ecophysiology as part of an interdisciplinary consortium. New kinds of biosensors have been developed, now making it possible to detect pharmaceuticals in water more effectively and determine their impact. The sensors allow scientists to assess the effects of pharmaceuticals in the drug classes of beta-blockers and non-steroidal anti-inflammatory drugs (NSAIDs) in real time, providing highly specific and highly sensitive measurements.

Medicines do not just have nasty side effects on people, they can also harm fish. Even concentrations of several μg per liter of water are enough for a drug like the painkiller Diclofenac to damage health. Ecotoxicologists and environmental chemists are constantly trying to work out how to quantify the increasingly diverse occurrence of drugs in water and estimate their negative impact on the environment.

The principle of the new biosensor: The receptor binding of drugs immediately generates a fluorescent
signal in exposed cells; this can be quantified using fluorescent photometry. Images: Manfred Frey

As part of a network project call EffPharm, biologists, biochemists, and analytical chemists at a variety of institutions have been tackling this issue together. The project is being sponsored by the Federal Environmental Agency and coordinated by the Tubingen-based ecotoxicology expert Prof. Dr. Rita Triebskorn (Steinbeis Transfer Center for Ecotoxicology and Ecophysiology; the Institute of Evolution and Ecology (EvE) at Tubingen University). Dr. Manfred Frey, director of the Steinbeis Innovation Center for Cell Culture Technology at the University of Mannheim, is spearheading a working group that has for the first time succeeded in developing cell-based biosensors for two of the identified drug classes. These sensors make it possible to identify the primary binding of substances with target molecules (receptors) in supposedly clean waste water in real time. The project also received the support of Dr. Marco Scheurer from the Water Technology Center in Karlsruhe. Scheurer demonstrated that the new kind of biosensors detect a high percentage of the compounds. Previously, identifying these compounds using chemical analysis was expensive and time-consuming. The testing methods also cover the effects of unknown compounds and metabolites with biological effects that cannot be detected by chemical analysis. This is extremely important given the ecological significance of pollution. The University of Tubingen team working under Professor Rita Triebskorn and Professor Heinz Kohler, from the working group looking at the physiological ecology of animals, were able to prove how sensitive the biosensors are. The sensors can even detect the extremely low concentrations of drugs at which initial damage can be caused to water organisms.

The recently developed biosensors offer a variety of benefits compared to previous methods. Unlike conventional so-called reporter gene assays, the sensors detect the primary impact of chemicals on cells in real time, thus avoiding misleading information possible by interfering with the transcription/translation machinery which requires up to 48 hours until a signal output can be measured. Within seconds of coming into contact with drugs in a sample, the biosensor cell lines emit a florescent signal. The new testing systems are extremely sensitive in the nanomolar range down to one millionth of a part per thousand, making them comparable with chemical analysis. Because they focus on effect mechanisms, they can also show the impact of future beta-blockers and NSAIDs, even if their chemical composition is not yet known. As a result, the researchers expect the new technique to be applied to future monitoring programs aimed at assessing water quality and the cleansing effectiveness of sewage treatment plants. The methods should fill an important information gap regarding the occurrence of drugs in water and their impact on the health of organisms found in water.