Electrochemical uranyl cation biosensor with DNA oligonucleotides as receptor layer

• The analytical performance of DNA-based UO22 +-selective voltammetric sensors was optimized.
• The relationship between DNA sequence and sensor selectivity was observed.
• The application of monolayer diluter improves the linear range of the biosensor response.
• The electrochemical response of proposed sensor was found to be independent of the electrode surface area.
• The method for regeneration of the receptor layer was developed.

The present study aims at the further development of the uranyl oligonucleotide-based voltammetric biosensor, which takes advantage of strong interaction between UO22 + and phosphate DNA backbone. Herein we report the optimization of working parameters of previously elaborated electrochemical DNA biosensor. It is shown that the sensor sensitivity is highly dependent on the oligonucleotide probe length and the incubation time of sensor in a sample solution. Consequently, the highest sensitivity was obtained for 10-nucleotide sequence and 60 min incubation time. The lower detection limit towards uranyl cation for developed biosensor was 30 nM. The influence of mixed monolayers and the possibility of developing a non-calibration device were also investigated. The selectivity of the proposed biosensor was significantly improved via elimination of adenine nucleobases from the DNA probe. Moreover, the regeneration procedure was elaborated and tested to prolong the use of the same biosensor for 4 subsequent determinations of UO22 +.