Correction: Laser cleavable probes for in situ multiplexed glycan detection by single cell mass spectrometry†

Correction for ‘Laser cleavable probes for in situ multiplexed glycan detection by single cell mass spectrometry’ by Jing Han et al., Chem. Sci., 2019, 10, 10958–10962.


Syntheses of probes
Probes 1-4 were prepared according to the reported literature. [
3a-3d: (2a-2d, 1.0 equiv) was dissolved in anhydrous CH 2 Cl 2 , and 3chloroperbenzoic acid (69%, 1.1 equiv) was added to the solution at 0 ℃. The mixture was stirred for 1h, and then, 20% sodium thiosulfate aqueous solution was added to the solution to quench the reaction. The organic layer was collected and dried over anhydrous Na 2 SO 4 . The solvent was removed by evaporation, and the residue was purified using silica gel chromatography with EtOAc: hexane (v/v, 1:1) as eluent, was obtained 3a-3d as a yellow solid, which was used without purification. 4a : R = CH 3 4b : R = CH 2 CH 3 4c : R = CH 2 CH 2 CH 3 4d : R = CH 2 CH 2 CH 2 CH 3 4a-4d: (3a-3d, 1.0 equiv) and TFAA (3.0 equiv) were dissolved in CH 3 CN at 0 ℃ under N 2 . The mixture was stirred for 5 min, and then the deep yellow solution was concentrated by evaporation, and the crude product was precipitated in Et 2 O at 0 ℃.

S6
The resulting yellow solid was filtered, washed with cold anhydrous Et 2 O, and dried under reduced pressure to give the thionium salt 4a-4d as a deep yellow solid, which was used without further purification.  After removing excess FITC-labeled ConA-probe1 by washing with PBS, cells were imaged with a laser scanning confocal microscope.

Flow cytometry analysis: cells were trypsinized and incubated with FITC-labeled
ConA-probe1 at 37 °C for 30min. The cell suspension was centrifuged at 1000 rpm for 5 min, washed twice, resuspended in PBS buffer and filtered by 400-mesh sieve.
The fluorescence intensity of cells was determined by a Becton Dickinson FACS calibur flow cytometer. For each flow cytometric test sample, 10,000 events were acquired, and the mean fluorescence intensity was used for analysis.

S9
Viability assay: Cells were seeded in 96-well plate and cultured for 24 h. After washing with PBS, cells were incubated with different concentration of tunicamycin (0, 1, 10, 50, 75, 100 μg/mL) for 24 h. 10 μL CCK-8 (Cell Counting Kit-8) reagent was added into each well with 100 μL cell culture medium inside. Absorbance at 450 nm was measured by a microplate reader after 1 h incubation.

MCF-7 cells and MCF-7R cells were seeded at desired concentrations and
trypsinized. Lectin-probe was added and incubated with cells at 37 °C for 30min.
After washing three times with PBS buffer, cells were directly analyzed by LDI-MS.