Citrate-selective electrochemical μ-sensor for early stage detection of prostate cancer

The extremely specialised anatomical function of citrate inside the prostate, make it one of the preferred biomarkers for early stage detection of prostate cancer. However, current detection methods are seriously limited due to the very low citrate concentrations that need to be measured in order to follow disease progression. In the present work, we report a novel citrate-selective μ-sensor based on iron (III) phthalocyanine chloride-C-monoamido-Poly-n-Butyl Acrylate (Fe(III)MAPcCl-P-n-BA) modified gold μ-electrodes for the electrochemical determination and estimation of the pathophysiological range of citrate. The newly synthesised ionophore has been structurally characterised using Fourier transform infrared (FTIR) and UV-vis spectroscopy. Contact angle measurements and atomic force microscopy (AFM) have been used to investigate the adhesion and morphological properties of the membrane. The developed citrate-selective μ-electrodes had a Nernstian sensitivity of −19.34 ± 0.83 mV/decade with a detection limit of about 9 × 10−6 M and a linear range from 4 × 10−5 M to 10−1 M, which covered the pathologically important clinical range. Electrochemical impedance spectroscopy (EIS) showed very high sensitivity with a lower Limit of detection ≈1.7 × 10−9 M and linear detection range (10−8-10−1 M), which is very important not only for the early-stage diagnosis and screening procedures, but also in mapping the stage of the cancer too.