**1. Introduction**

Monitoring of water pollution is very important for the preservation of the environment and prevention of negative impacts that it can have on human health. Therefore, great attention is paid to simplifying procedures for detection and monitoring of pollutants. Heavy metals are particularly dangerous due to their ability to accumulate over time in both plants and animals, as well as in water. For these reasons, there are already developed different methods that determine their concentrations generally in the environment.

Biosensors represent a simple, reliable, and fast solution for monitoring water pollution caused by various heavy metals. The small size of biosensor devices has enabled their in situ application, thus avoiding long-term and sometimes expensive measurements in laboratories.

According to IUPAC, biosensor represents a "self-contained integrated device, which is capable of providing specific quantitative or semi-quantitative analytical information using a biological recognition element (biochemical receptor) which is retained in a direct spatial contact with an electrochemical transduction element" [1, 2]. Biosensors allow not only determining the presence and overall biologically

available concentrations of heavy metals in water but also assessing their biological effects, such as toxicity or cytotoxicity, which are sometimes more important than chemical composition information.
