Highly selective electrochemical nanofilm sensor for detection of carcinogenic PAHs in environmental samples

A highly sensitive sensor based on molecularly imprinted polymer film was devised for determination of polycyclic aromatic hydrocarbon (PAHs) in aquatic solutions. In this paper we report, electro-polymerisation of 4-vinyl pyridine (4VP) and target, pyrene, using cyclic voltammeter in electrolyte medium, forming the pyrene imprinted polymer. After polymerisation, the pyrene was removed from imprinted polymer using methanol to produce sensory nanofilm characterised by infrared spectrometer, optical and atomic force microscopy. The mechanism of nanofilm sensing was established using atomic models and electrochemical response by differential pulse voltammeter with the redox system of ([Fe(CN)₆]^3-/[Fe(CN)₆]^4-). The π-π interaction between pyrene and 4VP was primary cause for pyrene recognition in aqueous solutions and the model binding score for this interaction was -5.10 kcal mol^-1. The electrochemical sensor determined pyrene in the concentration range of 1 × 10^-4 - 1 ng L^-1, resulting best linear regression (r² > 0.9) and detection limit of 0.001 ng L^-1. The recovery percentage of pyrene from the nanofilm was 83-110% in water samples and the imprinting factor value was 2.67. Therefore, the novel imprinted polymer nanofilm sensor showed highest sensitivity for target pyrene in aqueous samples compared to reported sensors.