Electrochemical epinephrine sensor using artificial receptor synthesized by sol-gel process

An artificial adrenergic receptor was fabricated with molecular imprinting silica. Epinephrine (EP) was imprinted in the organic-inorganic hybrid silica film through π-π interaction from phenyltrimethoxysilane (PTMOS). The epinephrine-imprinted film was spin coated on an indium tin oxide (ITO) glass. The affinity of epinephrine to the imprinted film was determined by the oxidation current of epinephrine. The epinephrine-imprinted film showed a good selectivity toward epinephrine. Epinephrine and isoproterenol (IPT) which have two more methyl group on amino-N had comparable current responses, 79.9% and 75.3%, respectively. Negatively charged analytes including 3,4-dihydroxy-l-phenylalanine, 3,4-dihydroxyhydrocinnamic acid, and ascorbic acid had current responses lower than 47%. The mechanism of facilitated transport by fixed-site carriers was suitable to explain the current enhancement by the imprinted film. Binding sites of epinephrine-imprinted film were believed to function as the fixed site carriers for the facilitated transport. The occupation of binding sites by 2-phenethylamine which structurally resembles epinephrine decreased the current at high epinephrine concentration.