Bioinspired Fluorescent Peptidyl Nanoparticles with Rainbow Colors.

The growing enthusiasm to mimic the luminous properties of fluorescent proteins (FPs) has expanded to include the potential biomedical applications of FP analogues. We developed a series of non-fluorescent oligopeptides (Fc-(X); where X = F, Y, W, and H; = 1-3) that can aggregate into fluorescent nanoparticles with rainbow colors, termed the peptidyl rainbow kit (PRK). The PRK encompasses the full visible color spectrum, and its photoluminescent properties may have originated from aggregation-induced emission (AIE). Intermolecular forces restricted the intramolecular motions of the oligopeptide residues, providing a barrier to non-radiative conformational relaxation pathways and leading to AIE fluorescence. The PRK oligopeptides are pH sensitive, biocompatible, and photostable under physiological conditions, making the PRK a promising fluorescence candidate for biomedical applications.