Molecularly imprinted photonic polymer based on β-cyclodextrin for amino acid sensing

A novel molecularly imprinted photonic polymer (MIPP) using maleic anhydride modified β-cyclodextrin (β-CD) and acrylic acid as functional monomers has been presented for amino acid sensing. Reactive β-CD monomer carrying vinyl carboxylic acid functional groups was first synthesized. MIPP was fabricated by filling precursor solution into the interstitial spaces of polystyrene photonic crystal templates, followed by a thermal polymerization at 55 °C. Characterization showed that the MIPP possessed an opal photonic crystal structure. This β-CD-based MIPP could undergo a swelling change from 590 nm to 704 nm and still retain the molecular imprinting recognition ability during the sensing of l-phenylalanine (l-Phe). A function relationship was found between the diffraction wavelength shift and the logarithm of l-Phe concentration in the range of 10−8 M to 10−4 M at pH 6. A wavelength shift of 114 nm for l-Phe was observed within 30 s, whereas there were no obvious shifts for d-Phe, l-tyrosine and l-tryptophan, indicating that the β-CD-based MIPP had high specificity and rapid response to l-Phe. The developed MIPP sensor has been applied to detect l-Phe in compound amino acid injection sample.