Electrochemical detection of manganese ions using aptamer-based layers

Heavy metals are one of the major pollutants found in drinking water and their abnormal level may pose a threat to human's health and life. Manganese also belongs to heavy metals group, and it is generally used in production of batteries, fertilizers, and ceramics. Even though, Mn is necessary for proper development of central nervous system, its elevated concentration might lead to certain diseases such as epilepsies, cell death in focal cerebral ischemia as well as neurodegenerative diseases such as Huntington and Alzheimer. Hence, it is crucial to elaborate novel methods for manganese ions detection that could be applied for in situ analysis of water samples. Herein, we present the studies on the electrochemical detection of manganese ions using aptamer-modified electrodes. This is the first attempt of application of aptamer strands as receptor layers for electrochemical analysis of manganese ions and for that purpose gold disk electrodes served as transducers, which were further modified with disulfide - based aptamers and 6-mercapto-1-hexanol blocking agent. The electrochemical measurements concerned the choice of the conditions for formation of aptamer receptor layer as well as the type of redox indicator that served as the source of current signal. The studies referred to the definition of aptasensor working parameters including the verification of the possibility of manganese ion detection in cell culture media. It was shown that it was possible to detect Mn²⁺ ions within 25 nM-1 μM concentration and the proposed aptasensor exhibited high selectivity towards target analyte for which at least 2 - times higher response was recorded than for interfering ions. Moreover, the possibility of Mn²⁺ detection in real samples was depicted followed by stability and regeneration studies.