We report the synthesis and self-assembly of fluorescent peptide amphiphiles (NBD-PA) composed of a fluorescent NBD probe and a peptide derivative VVAADD with a C12-alkyl-chain as the linker (NBD-C12-VVAADD). The self-assembly of NBD-PA formed beta-sheet structures at neutral pH in aqueous solution, contributed to an ∼10-fold increase in the fluorescence and quantum yield of NBD molecules, and conferred a supramolecular hydrogel with excellent viscoelastic properties, while gel-to-sol transition of NBD-PA occurred rapidly when the pH value was adjusted to strongly alkaline (e.g. pH 11). Through the pH-responsive self-assembly behavior, we further explored the relationship between fluorescence of NBD-PA and pH values. Interestingly, the fluorescence of the NBD-PA system exhibited an excellent sigmoidal function relationship (R2 = 0.9999) with the alkaline pH values, which enabled accurate pH measurement regardless of salt types and ionic strength of solvents. Furthermore, the fluorescence of NBD-PA was fully reversible upon cycles of pH shifts, with the chemical structure of NBD-PA well-maintained throughout the process. These features of NBD-PA would facilitate the design of in situ pH detection systems as well as pH-responsive actuators for various applications in future.
Advancing enzyme-based electrochemical biosensor research heightens the need for improved biosafety and reduced biotoxicity. Conventional electrode materials face biotoxicity challenges, limiting their biomedical applications. Fluorescent peptide nanomaterials, however, provide superior biosafety, strong biological activity, and excellent electrochemical properties, offering significant advantages. In this study, a novel electrochemical biosensor was developed by utilizing phenylalanine-tryptophan (WF) dipeptide fluorescent nanoparticles (WF-DNPs) as the modified materials of electrode for immobilizing horseradish peroxidase (HRP). This electrochemical biosensor was employed for the determination of hydrogen peroxide (H 2 O 2 ). The incorporation of WF-DNPs not only facilitated electron transfer on the electrode surface but also provided a biocompatible microenvironment for the immobilization of HRP, thereby preserving the enzyme's catalytic activity. Under optimal experimental conditions, the constructed electrochemical biosensor exhibited a signal amplification effect, enabling the sensitive detection of H 2 O 2 with a detection limit of 1.8 μM. Graphical abstract
危险品化学品经营许可证（带存储）