We’ve tested our Nuclear LCS dyes under these conditions:

HeLa cells were labeled with LCS dyes at various concentrations, from 5 uM - 0.5 uM, for 30 mins in Henderson-Hasselbalch (HH) buffer. Cells were then washed with HH buffer 2-3 times. After washing, cells were incubated for 24 hours in a regular DMEM medium. Fluorescence images were taken in cells before and after incubation in DMEM to test for long-term stability. Cell Meter™ Colorimetric WST-8 Cell Quantification Kit (Cat#22770) was applied for cytotoxicity testing. 

1. Cytotoxicity of LCS dyes:

• Nuclear Violet^™ LCS1 (Cat#17543) has the least cytotoxic effect.
• Cells labeled with 5 uM of Nuclear Red^™ LCS1 (Cat#17542) were still viable.   
• Cells labeled with Nuclear Green^™ LCS1 (Cat#17540) or Nuclear Red^™ LCS1 at concentrations lower than 1.5 uM remained viable after 24 hours. 
• Nuclear Red^™ LCS2 (Cat#17545) showed similar cytotoxic effects compared to Nuclear Green^™ LCS1, BUT the fluorescence signal was low.

2. All of our Nuclear LCS1/LCS2 dyes are quite stable.

3. In general, photostability can be ranked as such:

• Red (more stable) > Green > Violet and Blue (least stable)