Pollution caused by Copper and hydrogen sulfide pollution has severe adverse effects on the environment and organisms. Real-time, fast and accurate monitoring of Cu2+ and S2- faces serious challenges. In this study, we designed a novel biosensor and synthesized it by mimicking the structure of the main Cu(II)-binding site on bovine serum albumin. As a peptide-based sensor, FGGH (FITC-Gly-Gly-His-NH2) can perform the sequential detection of Cu2+ and S2- by fluorescence and colorimetry. The high water solubility and selectivity make it suitable for monitoring Cu2+ and S2- in environmental water samples with high sensitivity; its limit of detection (LOD) is as low as 1.42 nM for Cu2+ and 22.2 nM for S2-. The paper-based sensing platform of this probe was found to be a promising tool for the on-site visualization of real-time quantitative analysis of Cu2+ and S2- due to its rapid response and recyclable detection characteristics. Additionally, FGGH was successfully used to image Cu2+ and S2- in living cells and zebrafish models with adequate fluorescence stability and low cytotoxicity, providing the first visual evidence of the effect of the interactions between Cu2+ and S2- on the redox homeostasis of organisms.

The application of peptide-based biomaterials in nanocarriers can effectively reduce toxicity and improve the biocompatibility. In our study, a dual stimuli-responsive peptide-based drug delivery system was designed and synthesized, which was nontoxic and achieved the chem-photothermal therapy synergistic effect. Lanreotide (Lan), a kind of somatostatin analogue, was used as internal template to prepared lychee-shaped palladium (Pd) nanoparticles (Lan-PdNPs). Glutathione (GSH) and doxorubicin (DOX) were combined on the surface of Lan-PdNPs to obtain the nanosystem of Lan-PdNPs@GSH/DOX. Based on the lychee-shaped structures, the system demonstrated higher photothermal conversion performance and photothermal stability. Under NIR laser irradiation, Lan-PdNPs@GSH/DOX could convert light energy to heat in effect and accelerate drug release. Moreover, in acidic conditions, the system also exhibited the pH-responsive drug release. Owing to the synergism, the antitumor effects of Lan-PdNPs@GSH/DOX in vitro and in vivo were superior, and the inhibition ratio was much higher than that of chemotherapy or photothermal therapy alone. The good biocompatibility and nontoxicity of the system also provide the possibility for serving as an antitumor drug candidate.