Understanding the role of oxidative stress in disease requires real time monitoring of redox status within a cell. We report a FRET-based, ratiometric redox probe which can be applied to monitor cellular oxidative capacity using three different modalities – confocal microscopy, fluorescence lifetime imaging and flow cytometry.

Recently, nanoluminophores with the potentialresolved multicolor electrochemiluminescence (PRMCECL) property have emerged and shown promising applications in sensitive, selective, and accurate bioassays, bioimaging, and multicolor emitting devices. However, only limited PRMCECL nanoluminophores and their applications in ratiometric biosensors eliminating proportional errors have been reported. Herein, a novel PRMCECL nanoluminophore was synthesized by encapsulating CdS quantum dots (CdSQDs) into MOF-5 (CdSQDs@MOF-5). Using K 2 S 2 O 8 as a coreactant, two electrochemiluminescence (ECL) peaks, ECL-1 centered at 685 nm and ECL-2 centered at 475 nm, were observed at −1.4 and −1.8 V, respectively. Related ECL mechanisms have been proposed. Based on the potentialresolved ECL signals, a label-free differential ECL immunosensor for the determination of cardiac troponin I (cTnI) was established by assembly of poly(diallyldimethylammonium chloride), CdSQDs@MOF-5, and cTnI antibody-functionalized silver nanoparticles on the surface of the fluorine-doped tin oxide electrode subsequently. In the presence of cTnI, cTnI was captured by the sensing interface, leading to an increase in ECL-1 and ECL-2 intensity. cTnI could be determined in the range of 0.01−1000 pg/mL with a detection limit of 5.01 fg/mL using the intensity difference between ECL-1 and ECL-2. This work provides a new family member of PRMCECL nanoluminophores. The proposed label-free differential ECL immunosensor provides a new strategy based on potentialresolved ECL signals, which could effectively eliminate the additive error and show better sensitivity, selectivity, and accuracy for the detection of cTnI than the single-signal strategy and ratiometric strategy.

We report a series of seven cationic heteroleptic copper(I) complexes of the form [Cu(P^P)(dmphen)]BF 4 , where dmphen is 2,9-dimethyl-1,10-phenanthroline and P^P is a diphosphine chelate, in which the effect of the bite angle of the diphosphine ligand on the photophysical properties of the complexes was studied. Several of the complexes exhibit moderately high photoluminescence quantum yields in the solid state, with Φ PL of up to 35%, and in solution, with Φ PL of up to 98%. We were able to correlate the powder photoluminescence quantum yields with the % V bur of the P^P ligand. The most emissive complexes were used to fabricate both organic lightemitting diodes and light-emitting electrochemical cells (LECs), both of which showed moderate performance. Compared to the benchmark copper(I)-based LECs, [Cu(dnbp)(DPEPhos)] + (maximum external quantum efficiency, EQE max = 16%), complex 3 (EQE max = 1.85%) showed a much longer device lifetime (t 1/2 = 1.25 h and >16.5 h for [Cu(dnbp)(DPEPhos)] + and complex 3, respectively). The electrochemiluminescence (ECL) properties of several complexes were also studied, which, to the best of our knowledge, constitutes the first ECL study for heteroleptic copper(I) complexes. Notably, complexes exhibiting more reversible electrochemistry were associated with higher annihilation ECL as well as better performance in a LEC.