Carbon Electrodes with Gold Nanoparticles for the Electrochemical Detection of miRNA 21-5p

Abstract

Extracellular vesicles are involved in many physiological and pathological activities. They transport miRNAs to recipient cells during their role in intercellular communication, making them emerging biomarkers of many diseases. Interest in exosomal miRNAs has grown after they have shown numerous advantages as biomarkers for diagnosis, prognosis, and evaluation of cancer treatment. This work describes the development of a biosensor for the detection of 21-5p miRNA in human serum using screen-printed carbon electrodes modified with gold nanoparticles fabricated in situ, an innovative approach to avoid the use of more expensive gold substrates that provide better analytical outputs. The several variables involved in the assembly of the biosensor were optimized by univariant mode. Under the best conditions, the biosensor showed a linear response from 0.010 fM to 10 pM, with a limit of detection (LOD) of 4.31 aM. The sensitivity was 0.3718 relative Ω per decade concentration in buffered saline solutions, and the standard deviation of the blank is 2.94 Ω. A linear response was also obtained when human serum samples were tested with miRNA 21-5p. Interference from similar miRNA and miss-match miRNA sequences was evaluated and good selectivity for miRNA 21-5p was observed. Overall, the device proposed is an alternative approach to gold substrates, which typically result in more sensitive systems and lower LODs, which compares favorably to current gold-based biosensors for the targeted miRNA. This design may be further extended to other nucleic acids.