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Purely organic luminescent materials concurrently exhibiting thermally activated delayed fluorescence (TADF) and aggregation-induced emission (AIE) features are in great demand due to their high efficiency in aggregation-state toward efficient nondoped OLEDs. Herein, a class of TADF emitters adopting phenyl(pyridyl)methanone as electron-accepting segments and di(tert-butyl)carbazole and 9,9-dimethyl-9,10-dihydroacridine (or phenoxazine) as electron-donating groups are designed and synthesized. The existence of intramolecular hydrogen bonding is conducive to minish the energy difference between a singlet and a triplet (ΔEst), suppress nonradiative decay, and increase the luminescence efficiency. By using 3CPyM-DMAC as the emitter, the nondoped device via a solution process realize a high current efficiency (CE) and external quantum efficiency (EQE) of 35.4 cd A–1and 11.4%, respectively, which is superior to that of CBM-DMAC with a CE and EQE of 14.3 cd A–1and 6.7%. This work demonstrates a promising tactic to the establishment of TADF emitters with AIE features via introducing intramolecular hydrogen bonding.

In this work, a simple and ultrasensitive localized surface plasmon resonance (LSPR) method that use Au nanoflowers (AuNFs) as a probe was designed for in situ monitoring of alkaline phosphatase (ALP) activity. The AuNFs were fabricated by hydrogen tetrechloroaurate-induced oxidative disruption of polydopamine-coated Au nanoparticles (AuNPs), and subsequently, growth of Au nanopetals on AuNPs occurred. The as-prepared AuNFs showed a much higher LSPR capability and stronger scattering color change than AuNPs. The strategy for in situ cellular ALP activity detection relied on the deposition of Ag on the AuNFs surface, which changed the morphology of AuNFs and led to a tremendous LSPR response and scattering color change. The deposition of Ag shell on AuNFs was related to ALP activity, where ALP catalyzed the hydrolysis of l-ascorbic acid 2-phosphate sesquimagnesium salt hydrate to form l-ascorbic acid (AA), and then AA reduced Ag+to Ag and deposited onto AuNFs. With this concept, the ALP activity could be monitored with a detection limit of 0.03 μU L–1. Meanwhile, the ALP activity of single HepG2 cells and HEK 293 cells was tracked with a proposed approach, which indicated the trace expression level of ALP in HEK 293T cell and overexpressed level of ALP in HepG2 cells. After treatment with drugs, the cellular ALP activity of HepG2 cells was decreased with the treating time and dose increasing. Therefore, the proposed strategy could be used for tracking the cellular ALP activity, which paved a new avenue for cell studies and held great potential for discovering novel ALP-based drugs applications.

A simple salicylaldehyde-based fluorescent probe 1 for Zn2+was prepared. The probe 1 has been proven to be highly selective and very sensitive to Zn2+, and also shows remarkable fluorescence emission improvement upon combining with Zn2+in a Tris–HCl buffer system at pH 7.2. The great fluorescence changes of probe 1 after incorporation with Zn2+are mainly ascribed to the photo-induced electron transfer (PET) mechanism. The experimental results reveal that probe 1 could effectively complex Zn2+at a molar ratio of about 1 : 1 and the binding constant (K) between probe 1 and Zn2+was determined to be 3.78 × 106M−1. The detection limit (DL) of probe 1 was also calculated to be 5.9 × 10−9M. In addition, the probe has been successfully applied to fluorescence imaging in living MCF-7 cells.

A biocompatible, label-free and sensitive fluorescence “turn-on” approach was designed to detect BRCA1and TB4DNA sequences using poly(3-[(S)-5-amino-5-carboxyl-3-oxapentyl]-2,5-thiophenylene hydrochloride) (POWT). The fluorescence intensity of POWT in solution could be efficiently quenched by adding either BRCA1or TB4DNA sequences. The Stern–Volmer equation was used to fit the quenching effect and the LOD could thus be obtained. The fluorescence would recover its initial intensity after the addition of completely complementary ssDNA, but not with sequences with 1–3 mismatched bases. The influences of buffer pH and buffer composition were investigated systematically in order to improve the sensitivity of this fluorescent probe. For the BRCA1DNA sequence, the KSV(Stern–Volmer constant) and LOD were 8.254 × 109M−1and 2.231 × 10−12M, respectively. For the TB4DNA sequence, the KSVand LOD were 6.924 × 109M−1and 2.659 × 10−12M, respectively. In addition, the quantitative linearity range for detecting these two DNA sequences was from 1 × 10−11M to 5 × 10−11M, and the response time for the quenching effect was less than 10 minutes for both sequences. Hence, with fine biocompatibility, high sensitivity, fast response and high recovery rate, a serine functionalized POWT might be a promising candidate for detecting the BRCA1DNA sequence and TB4DNA sequence as well as their mutations, which might possibly be applied to clinical diagnosis of breast cancer or ovarian tumours.