Gold nanoparticle based signal enhancement liquid crystal biosensors for tyrosine assays

A novel liquid crystal (LC) biosensor based on seedless production of gold nanoparticles (AuNPs) has been developed for the detection of l-tyrosine (Tyr). In this study, tyrosinase (TR) stimulated the biocatalyzed hydroxylation of Tyr to l-DOPA, which mediated the generation and growth of AuNPs. The large-size of AuNPs greatly changed the surface topology of LC sensing interface, the corresponding images were regulated under MATLAB, which allows the quantitative detection of Tyr. Under the optimum conditions, the limit of Tyr detection could be as low as 2 × 10−7 mol/L. Results also showed that phenylalanine (Phe), tryptophan (Trp) and threonine (Thr) caused no interference. This method provides a simple, label-free and sensitive strategy for determination of Tyr.