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Copper ions are known to be very important for homeostasis, which is critical for the metabolism and development of living organisms. In addition, sulfide ions, as an important endogenously produced gasotransmitter, have been proved to be implicated in a variety of physiological functions such as anti-apoptosis, vasodilation, antioxidation, and anti-inflammation. Herein, we report the development of a novel fluorescence chemosensor (L) based on a tetra-peptide conjugated with dansyl groups as a promising analytical tool for detecting Cu and S in 100% aqueous solutions, which exhibits excellent cell biotoxicity and intracellular biosensing ability. The chemosensor L displays an "on-off-on" response type fluorescence change upon the addition of Cu and S to aqueous media and living cells. Moreover, L displays high selectivity and sensitivity with the detection limits for Cu and S measured to be 88 nM and 75 nM, respectively. This study raises the new possibility of a highly selective and sensitive peptide-based fluorescence chemosensor for multifunctional detection, including cation and anions, using a successive fluorescence response strategy in environmental and biological systems.

With the rapid development of information science, it is urgent that memory devices possessing high security, density, and desirable storage ability should be developed. In this work, a smart duplicate response of stimuli has been developed and a time-gate nanohybrid based on variable valence Eu 2+ /Eu 3+ coencapsulated has been fabricated and acts as active material in the multilevel and multidimensional memory devices. The luminescence lifetime of Eu 3+ in this nanohybrid gave a stimuli response due to which the energy level of the coordinated ligand could be modulated. Furthermore, by a simple sintering procedure, Eu 3+ was partially in situ reduced to Eu 2+ with a short lifetime in the system. And the in situ reduction ensured both Eu 3+ and Eu 2+ ions' uniform distribution in the nanohybrid and simultaneous response upon light excitation of variable valence Eu ions. Interestingly, Eu 3+ revealed a prolonged lifetime because of the presence of an energy-transfer effect of Eu 2+ → Eu 3+ . Such a nanohybrid had abundant luminescent properties, including the short lifetime of Eu 2+ , the energy transfer from the Eu 2+ to Eu 3+ ions, and the stimuli response of the Eu 3+ lifetimes when exposed to acidic or basic vapor, thus giving birth to interesting recording and encryption performance in spatial−temporal dimensions. We believe that this research will point out a new direction for the future development of multilevel and multidimensional optical recording and encryption materials.