A flexible tripod fluorescent probe for multiple cations detection and its application in living cells

A bisalicylhydrazone based fluorescent probe for detecting Al3+ with high sensitivity and selectivity and imaging in living cells

A bisalicylhydrazone based fluorescence probe, bisalicyladehyde benzoylhydrazone (BS-BH), has been designed to detect Al3+. It exhibited high sensitivity and selectivity towards Al3+ in methanol-water media in physiological condition. Large stokes shifts (∼122 nm) and over ∼1000-fold enhanced fluorescence intensity were observed, which was ascribed to the formation of the two relatively independent rigid extended π conjugated systems bridged by biphenyl group when binding with Al3+. A 1:2 binding ratio between BS-BH and Al3+ was shown by Job's plot. Based on the fluorescence titration data, the detection limit was down to 3.50 nM and the association constant was evaluated to be 1.12 × 109 M-2. The plausible fluorescence sensing mechanism of suppressed ESIPT, inhibited PET, activated CHEF and restricted C = N isomerization was confirmed by a variety of spectral experiments and DFT / TD-DFT calculations. The reversibility of recognition of Al3+ for probe BS-BH was validated by adding Na2-EDTA. In addition, the MTT assay showed the good biocompatibility of BS-BH and BS-BH could be used for imaging Al3+ in living cells.

A 1,8-Naphthalimide-based Tripodal Fluorescent Chemosensor to Selectively Detect Copper Ions

A 1,8-naphthalimide-based tripodal fluorescent ligand (L3) was synthesized through the copper (I) catalyzed Huisgen azide-alkyne cycloaddition reaction of 2-(2-azidoethyl)-6-morpholino-1 H-benzo[de]isoquinoline-1,3(2 H)-dione with triproparagylamine. Naphthalimide acts as the fluorophore while the triazole and amine nitrogens chelate the metal ion. L3 showed a selective fluorescence turn-off for Cu(II) over other metal ions in aqueous acetonitrile solution. A Job's plot, Benesi-Hildbrand plot and high-resolution mass spectrometry data confirm a 1:1 binding stoichiometry with a binding constant of 7.8 х105 M- 1 while addition of disodium EDTA demonstrates its reversibility. The structure and stability of the complex was supported by theoretical calculations. The limit of detection for Cu(II) was calculated to be 0.3 µM which is considerably lower than WHO recommended Cu(II) limit in drinking water.

Intraperitoneal Injection of Cyanine-Based Nanomicelles for Enhanced Near-Infrared Fluorescence Imaging and Surgical Navigation in Abdominal Tumors

Fluorescent surgical navigation can effectively aid tumor resection. As one of the most popular near-infrared (NIR) fluorophores, cyanine dye has the outstanding optical ability and the potential to act as a fluorescence probe for tumors. Herein, we report a polyethylene glycol-modified amphiphilic cyanine dye (Cy7-NPC) with an NIR luminescence performance, which can self-assemble to form uniform nanomicelles (Cy7-NPC-S) and which can be applied for the optical imaging of abdominal tumors and for fluorescence imaging-guided precision tumor resection. When applied to biological imaging, Cy7-NPC-S showed high biological safety, strong tissue penetration depth for optical imaging, and high optical imaging resolution. Intraperitoneal administration of Cy7-NPC-S produced remarkable imaging efficacy in abdominal tumors. Compared with intravenous injection, abdominal tumors took up intraperitoneal Cy7-NPC-S faster and in greater quantities, thus enabling Cy7-NPC-S to facilitate accurate recognition and extirpation of abdominal tumors in fluorescence-guided surgery. We believe that metabolizable Cy7-NPC-S with NIR luminescence has promising applications and value in the fields of in vivo imaging and fluorescent surgical navigation.