Synthesis, characterization, and fluorescence study of tryptone-self-assembled and Zn(II)-coordinated nanoparticles

Peptides/amino acids are biodegradable and biocompatible and have been used as suitable biomaterials for many bioengineering and medical applications in the last few decades. However, sometimes they show very limited intrinsic optical properties when used as optical imaging probes for biological diagnostics and target-based drug monitoring applications. Here we synthesized novel tryptone-self-assembled and Zn(II)-coordinated nanoparticles (TZFNPs), which shifted the intrinsic fluorescence emission peak from ultraviolet (270 nm) of tryptone to the visible wavelength (470 nm). Furthermore, when coordinated with 4-chloro-7-nitrobenzofurazan (NBD-Cl), a fluorogenic reagent, the fluorescence signals of our TZFNPs were further enhanced directly and in the cellular environment as well. We also studied the fluorescent signals of these TZFNPs after transferring them into the intracellular space of U2OS and HeLa cell lines. These fluorescent nanoparticles are intrinsically fluorescent and suitable for bioimaging. We hope they will pave the new way for further applications in medical sciences from diagnostics to clinical trials.