A simple and effective “capping” approach to readily tune the fluorescence of near-infrared cyanines

A simple and effective capping approach was introduced to readily tune the fluorescence of NIR cyanines.


Table of contents
Materials and instruments: Unless otherwise stated, all reagents were purchased from commercial suppliers and used without further purification. Solvents used were purified by standard methods prior to use. Twice-distilled water was used throughout all experiments; Low resolution mass spectra were performed using an LCQ Advantage ion trap mass spectrometer from Thermo Finnigan or Agilent 1100 HPLC/MSD spectrometer; High-resolution electronspray (ESI-HRMS) mass spectra were obtained from Bruker APEX IV-FTMS 7.0T mass spectrometer; NMR spectra were recorded on an INOVA-400 spectrometer, using TMS as an internal standard; Electronic absorption spectra were obtained on a LabTech UV Power spectrometer; Photoluminescent spectra were recorded with a HITACHI F4600 fluorescence spectrophotometer with a 1 cm standard quartz cell; The fluorescence imaging of cells was performed with OLYMPUS FV1000 (TY1318) confocal microscopy; The fluorescence imaging of mice and solution was performed with IVIS Lumina XR (IS1241N6071) in vivo imaging system; The pH measurements were carried out on a Mettler-Toledo Delta 320 pH meter; TLC analysis was performed on silica gel plates and column chromatography was conducted over silica gel (mesh 200-300), both of which were obtained from the Qingdao Ocean Chemicals.

Imaging of pH Changes in Living Cells Using CyBN. EC109 cells were incubated
with CyBN (5 μM) for 30 min in an atmosphere of 5% CO 2 and 95% air, followed by washing with pH 7.0 PBS medium three times and were incubated in 0.5 mL pH 7.0 PBS medium for another 10 min. The cells were then imaged using OLYMPUS FV1000 (TY1318) confocal microscopy with an excitation filter of 635 nm and an emission range of 770-810 nm. Followed by addition of 10 μL 0.5 M NH 4 Cl (final concentration of 10 mM) into the medium, the cells were then continuously imaged within next 10 min.

Imaging of pH Changes in Living Mice Using CyBN.
The Kunming mice were divided into three groups. The mice of the first group were anesthetized and then injected with LPS (1 mg in 400 µl saline) in the peritoneal cavity. The mice of the second group injected with CyBN (50 nmol in 100 μL CH 3 OH) in the peritoneal cavity under anesthetic. For the third group, the anesthetic mice were first intraperitoneally injected with LPS (1 mg in 400 µl saline) in the peritoneal cavity, after 4 hours, followed by an intraperitoneal injection of CyBN (50 nmol in 100 μL CH 3 OH) at the same site. The mice were imaged using IVIS Lumina XR (IS1241N6071) in vivo imaging system with an excitation filter of 745 nm and an S5 emission range of 760-810 nm.

Imaging of Hg 2+ in Living Cells Using CyBS. EC109 cells were incubated with
CyBS (5 μM) for 30 min in an atmosphere of 5% CO 2 and 95% air, and washed tree times with PBS medium, followed by addition of Hg 2+ (5 μM) and incubated for another 5 min. The cells were imaged using OLYMPUS FV1000 (TY1318) confocal microscopy with an excitation filter of 635 nm and an emission range of 770-810 nm.
Imaging of Hg 2+ in Living Mice Using CyBS. The Kunming mice were divided into three groups. The mice of the first group were anesthetized and then injected with saline (0.2 mL) in the peritoneal cavity. The mice of the second group injected with CyBS (50 nmol in 100 μL CH 3 OH) in the peritoneal cavity under anesthetic. For the third group, the anesthetic mice were first intraperitoneally injected with CyBS (50 nmol in 100 μL CH 3 OH) in the peritoneal cavity, after 10 min, followed by an intraperitoneal injection of Hg 2+ (100 nmol in 100 μL deionized water) at the same site. The mice were imaged using IVIS Lumina XR (IS1241N6071) in vivo imaging system with an excitation filter of 745 nm and an emission range of 760-810 nm.      In the ball-and-stick representation, hydrogen, carbon, nitrogen, oxygen, and sulphur atoms are colored in grey, gray, blue, red, and yellow, respectively.  Figure S7. DFT optimized structures of CyBX. In the ball-and-stick representation, hydrogen, carbon, nitrogen, oxygen, and sulphur atoms are colored in grey, gray, blue, red, and yellow, respectively. S10 Table S3. Representative partial carbon charges of CyBX (The assignment of carbon atoms is listed in Figure  S6).