Electrochemical and photoelectrochemical aptasensors for the detection of environmental pharmaceutical pollutants

Pharmaceutical substances are emerging contaminants with the potential to significantly lower the quality of the environment due to their persistence. Evaluating environmental pollution is a critical area of research that can benefit from on-site, affordable, and accessible analytical methods.

This review highlights recent advancements in electrochemical biosensors that use aptamers as recognition elements for pharmaceutical contaminants. The reasoning behind the selection of antibiotics, non-steroidal anti-inflammatories, and estrogen hormones is explained, considering factors such as environmental concentrations, toxicity, and selected aptamers. A thorough revision of the aptamers used in the studied literature, their characteristics, and functionalization was done. The coupling of aptamers with an electrochemical and photoelectrochemical transducer was explained, and the mechanisms for signal registration were detailed.

An important focus was the construction of the aptasensors, where the materials and the integration of aptamers strongly influence the cost, complexity, and performance of the biosensor. The main materials used were classified into carbon-based, metallic, and semiconductors, with a justification for the use of covalent and non-covalent aptamer immobilization in each case. The analytical performance was systematically evaluated through parameters like the limit of detection, linearity range, and selectivity. After the global analysis, a conclusion as to whether electrochemical aptasensors can be applied to environmental analysis is reached, with limitations and possible improvements debated.