Generation and screening of histamine-specific aptamers for application in a novel impedimetric aptamer-based sensor

Histamine is an important biomarker in both biomedical and food quality assurance sectors. Current methods of monitoring this compound via fluorescent, electrochemical, and enzymatic means have several drawbacks, preventing routine detection. This work reports on the isolation of single-stranded DNA-based, histamine-targeting aptamers generated by the Systematic Evolution of Ligands by Exponential Enrichment (SELEX) and the characterisation of these candidates via bioinformatics analysis. Aptamer binding affinity was determined by magnetic bead-based enzyme linked oligonucleotide assays, followed by the detection of unmodified histamine at a physiological pH via electrochemical impedance spectroscopy (EIS). Aptamer H47 demonstrated the lowest apparent binding affinity (72.8 ± 13.9 nmol L^-1) towards bead immobilised histamine. When immobilised to a gold surface, H47 demonstrated the largest biosensor response (ΔR_ct = 6.83 ± 2.00) compared to other single-stranded DNA sequences in the presence of dissolved histamine. The H47 EIS aptasensor also displayed a highly selective, concentration-dependent response towards histamine (linear range = 1 μmol L^-1 - 5 mmol L^-1), compared to other similar small molecules. Possessing an apparent binding affinity, limit of detection and limit of quantification of 7.80 ± 1.70 mmol L^-1, 4.83 mmol L^-1 and 16.08 mmol L^-1, respectively, the H47 EIS aptasensor demonstrates promise towards the development of aptasensors in applications which require the rapid detection of histamine in solution.