Phenylalanine detection using matrix assisted pulsed laser evaporation of molecularly imprinted amphiphilic block copolymer films

Matrix assisted pulsed laser evaporation was used to deposit molecularly imprinted polymer films of an amphiphilic block copolymer imprinted with an amino acid. This method avoids the need for a common solvent for host and template, and permits fabrication of layers with controlled thicknesses in the nanometer range. Polystyrene-block-polyethylene oxide copolymer and phenylalanine template were co-deposited onto surface plasmon resonance (SPR) sensors from a water/toluene emulsion. FTIR confirmed removal and reintroduction of phenylalanine, and SPR measurements were used for quantitative analysis. A binding ratio of more than 10 was obtained for phenylalanine on imprinted sensors vs. the non-imprinted control surfaces of the same polymer, and a detection limit of 0.5 mM phenylalanine was established. Exposure of sensors to alanine, glutamine, tryptophan, and tyrosine demonstrated that the sensors were highly specific.