Selective and sensitive fluorescent enhancement detection of keratin in aqueous media with aggregation-induced emission characteristics

Abstract

We present a new 1,8-naphthalimide-based fluorescent probe NapTpa-bs for keratin detection with AIE enhancement characterization in near infrared (NIR) emission. The fluorescent efficiency is obtained from the self-assembled agglomerates of NapTpa-bs with molecular stacking and interaction in aqueous solution. The corresponding AIE fluorescent quantum efficiency (ФF) of NapTap-bs at fPBS = 90% exhibits ca. 10.6-fold enhancement factor from pure DMSO (0.46) to the fPBS = 90% DMSO-PBS solution (4.88). After BSA was added into the NapTpa-bs solution, NapTpa-bs + BSA assembles were formed. An emission enhancement was ca. 6-fold at 629 nm for NapTpa-bs with 11 μM of BSA concentrations. NapTpa-bs + BSA assembles added by keratin induces the light-up AIE characteristics. The fluorescent intensity of NapTpa-bs + BSA + Keratin assembles displays significant advantage ca. 4-fold increasing in contrast with that of NapTpa-bs + BSA assembles at 629 nm. FCS and SEM testify that the active torsional/rotational motions of NapTpa-bs molecular is inhibited by BSA to induce the light-up AIE characteristic, and then the NapTpa-bs + BSA assembles parceled and agglomerated by keratin induces more stronger emission than the NapTpa-bs + BSA assembles. The NapTpa-bs + BSA assembles has excellent selectivity to keratin in contrast with other proteins and amino acids.