Junqi Nie

A Ratiometric Fluorescent Probe for Monitoring Leucine Aminopeptidase in Living Cells and Zebrafish Model

Leucine aminopeptidase (LAP) is an important cancer-related biomarker, which shows significant overexpression in malignant tumor cells like liver cancer. Developing an effective method to monitor LAP in tumor cells holds great potential for cancer diagnosis, treatment, and management. In this work, we report a novel BODIPY-based fluorescent probe (BODIPY-C-Leu) capable of monitoring LAP in vitro and in vivo in both ratiometric and turn-on model. BODIPY-C-Leu contains an asymmetrical BODIPY dye for fluorescent signaling and a dipeptide (Cys-Leu) as the triggered moiety. Activation occurs by cleavage of the amide bond in dipeptides and subsequently an intramolecular S → N conversion to convert sulfur-substituted BODIPY to amino-substituted BODIPY, resulting in a dramatic fluorescence variation to realize the detection of LAP. Furthermore, we have successfully employed BODIPY-C-Leu to monitor LAP activity in different cancer cells, indicating that HeLa cells have a higher level of LAP activity than A549 cells. Importantly, we demonstrated the capability of the probe for real-time monitoring the drug-induced LAP level changes in zebrafish.

Synthesis of non-cross-linked polystyrene supported 5,5-dimethyl oxazolidinone chiral auxiliary

A new chiral auxiliary, non-cross-linked polystyrene supported 5,5-dimethyl oxazolidinone was synthesised in 25.1% yield using L-tyrosine as the starting material using a six-step method.

Synthesis of a new chiral auxiliary: non-cross-linked polystyrene bound (4S)-oxazolidine-2-thione

A new chiral auxiliary, non-cross-linked polystyrene bound (4S)-oxazolidine-2-thione, was synthesised from L-tyrosine in 24.2% by a seven step method.

A 1,2,3-triazolyl based conjugated microporous polymer for sensitive detection of p-nitroaniline and Au nanoparticle immobilization

A 1,2,3-triazolyl based fluorescent conjugated microporous polymer PTPTB was synthesized through FeCl3 promoted oxidative coupling of 1,3,5-tris(1-(3,5-di(thiophen-2-yl)phenyl)-1H-1,2,3-triazol-4-yl)benzene. The resulting product has a BET surface area of 808.6 m2 g−1 and exhibits a strong emissive peak centered at 525 nm upon excitation at 417 nm in DMF. As a chemical sensor, PTPTB showed good fluorescence sensing ability for p-nitroaniline (p-NA) with a Ksv of 7.08 × 104 M−1 and a detection limit of 4.2 × 10−6 M. The electron-rich polymer was further employed to load Au nanoparticles (NPs). The formed Au/PTPTB composite showed superior catalytic activity in the catalytic reduction of p-nitrophenol (p-NP) to p-aminophenol (p-AP) and the rate constant was obtained to be 0.812 min−1. Moreover, the catalyst can be readily recovered and reused for six runs without obvious loss of its activity.

Highly Sensitive Ratiometric Self-Assembled Micellar Nanoprobe for Nitroxyl and Its Application In Vivo

Nitroxyl (HNO) is a derivative of nitric oxide (NO) that plays an essential role in various biological and pharmacological events. Until now, the in situ trapping and specific detection of HNO in living samples is still challenging. In this project, we fabricated a novel BODIPY-based micellar nanoprobe for monitoring nitroxyl in vitro and in vivo in ratiometric mode in aqueous solution. The probe (P-BODIPY-N) contains an asymmetrical BODIPY dye for fluorescent signaling and a diphenylphosphinobenzoyl as the trigger moiety; then we encapsulated P-BODIPY-N into the hydrophobic interior of an amphiphilic copolymer (mPEG-DSPE) and prepared a novel BODIPY-based micellar nanoprobe: NP-BODIPY-N. As far as we know, this probe is the first reported ratiometric fluorescent nanoprobe for HNO, which exhibits ultrasensitivity, high selectivity, and good biocompatibility. Above all, this nanoprobe shows favorable cellular uptaken and was successfully used to detect intracellular HNO released by Angelis salt in living cells and zebrafish larvae. These results indicate that our newly designed nanoprobe will provide a promising tool for the studies of HNO in living system.

A High Loading and Recyclable Pentaerythritol Supported Imidazolidin-4-one Catalyst for Enantioselective Diels–Alder Reactions

The synthesis of high loading and recyclable pentaerythritol supported imidazolidin-4-one catalyst I and its application in enantioselective Diels–Alder reactions of cyclopentadiene and α,β-unsaturated aldehydes with high performance were described. Especially noteworthy, the pentaerythritol supported imidazolidin-4-one with high loading capacity can be recovered by simple precipitation and filtration, and recycled for up to four runs without observing significant decrease in catalytic activity.Graphical Abstract