Magnetic core–shell carbon dot@MFe ₂ O ₄ hybrid materials are successfully prepared and used for the catalytic reduction of p -nitrophenol.

A highly sensitive carbon dot–imidazole (CD–imidazole) nanoprobe is prepared through covalently conjugating imidazole group onto the surface of carbon dots for water fluorescence. In organic solvents, quenching of fluorescence occurs via photoinduced electron transfer (PET) process from the imidazole nitrogen to the CD acceptor. Addition of a trace amount of water into CD nanocomposites in various organic solvents leads to a fluorescence turn-on response, which can be attributed to the suppression of PET due to the formation of the “free” ion pair by proton transfer from the carboxyl groups that are on the CDs surface to the imidazole nitrogen through a water-bridge. This phenomenon can be used for the highly selective detection of trace amounts of water in organic solvents. Laser confocal microscope experiment shows the potential utilization of CD–imidazole for the probed proton-transfer reactions in living cells.

A europium functionalized silicon nanoparticle (SiNP) ratiometric fluorescence transducer based on Fluorescence Resonance Energy Transfer (FRET) was designed to detect tetracyline (TC) as an effective antibiotic with high sensitivity and selectivity. SiNPs were prepared by one-step microwave-assisted synthesis from low-cost ethylenediaminetetraacetic acid disodium salt and (3-aminopropyl)triethoxysilane (APTES) as the precursor. The obtained SiNPs served as co-ligands for coordinating with Eu³⁺ ions, energy donors in FRET, and also a fluorescence reference. The fluorescence intensity ratio of I₆₁₇/I₄₅₀ of the transducer displayed a good linear response to TC concentrations in the range of 10 nM to 120 μM with a detection limit of 5.4 nM, and was applied successfully to determine the levels of TC in normal mouse sera and milk samples with high selectivity.

The mechanochromic luminescence phenomenon was first reported in the low-cost mechanochemical (MC) synthesis process of a covalent organic framework (COF-TpMA (MC)) which shows excellent performance as a hydroxyl radical detector in living systems.