Free-standing molecularly imprinted photonic hydrogels based on β-cyclodextrin for the visual detection of l-tryptophan

Abstract

Inverse opals of molecularly imprinted photonic hydrogels (CD-MIPHs) based on β-cyclodextrin were first elaborated by using a colloidal crystal template method. The film can be exfoliated from the substrate in H₂O to get a free-standing photonic crystal film. L-Tryptophan imprinted polyacrylamide photonic hydrogels (PAM-MIPHs) and CD-MIPHs were fabricated in this paper. The PAM-MIPHs exhibited a good sensing property to L-Trp and the redshift of the Bragg diffraction peak was 83 nm. Furthermore, improved recognition of L-Trp can be achieved by using CD-MIPHs. The Bragg diffraction peak of CD-MIPHs redshifted by 126 nm when the CD-MIPHs were immersed in a series of concentrations of L-Trp solution, and a visually perceptible color change was clear. Moreover, enantioselective recognition of Trp enantiomers was accomplished by CD-MIPHs instead of PAM-MIPHs. In short, the resultant CD-MIPHs showed a rapid response, high selectivity, high sensitivity and specificity towards imprinted molecules in an aqueous environment.