Singlet oxygen ( 1 O 2 ) plays a vital role in metabolism. However, because of its extremely high reactivity and short-lived state, the in vivo detection of 1 O 2 is challenging. To address this issue, for the first time, we herein constructed a nearinfrared (NIR) chemiluminescent probe (CL-SO) by caging the precursor of phenoxy-dioxetane scaffolds and a dicyanomethylchromone acceptor for selective 1 O 2 detection. This probe can detect 1 O 2 in vitro with a tremendous turn-on chemiluminescence signal in the NIR region (700 nm) and image intracellular 1 O 2 produced by the photosensitizer during the simulated action of photodynamic therapy (PDT). Notably, 1 O 2 level changes in the abdominal cavity and tumor of the various mice model under different stimulations and PDT action were effectively monitored by CL-SO, providing a novel chemiluminescence imaging platform to explore 1 O 2 generation in PDT-associated applications.

A 1,8-naphthalimide-based two-photon fluorescent probe was designed to visualize MGO levels in living cells and a diabetic mice model.

Self-labeling protein tags can introduce advanced molecular motifs to specific cellular proteins.Here we introduce the third-generation covalent TMPtag (TMP-tag3) and showcase its comparison with HaloTag and SNAP-tag. TMP-tag3 is based on a proximity-induced covalent Michael addition between an engineered Cys of E. coli dihydrofolate reductase (eDHFR) and optimized trimethoprim (TMP)acrylamide conjugates with minimal linkers. Compared to previous versions, the TMP-tag3 features an enhanced permeability when conjugated to fluorogenic spirocyclic rhodamines. As a small protein, the 18-kD eDHFR is advantageous in tagging selected mitochondrial proteins which are less compatible with bulkier HaloTag fusions. The proximal NÀ C termini of eDHFR also enable facile insertion into various protein loops. TMP-tag3, HaloTag, and SNAP-tag are orthogonal to each other, collectively forming a toolbox for multiplexed live-cell imaging of cellular proteins under fluorescence nanoscopy.