CouCyCF3

Operating Instructions
(The following is a recommended experimental protocol for guidance only; adjust according to specific requirements)

1. Stock Solution Preparation
1.1 Solvent: Most dyes are typically dissolved in organic solvents, such as anhydrous DMSO.
1.2 Recommended Concentration: Prepare a high-concentration stock solution at 1-10 mM.

2. Working Solution Preparation
2.1 Diluent: 1× PBS, Lysogeny Broth (LB), RPMI + 10% FBS.
2.2 Working Concentration: 1-2 μM.
2.3 Notes: Adjust the working solution concentration as needed; prepare fresh before use.

3. Staining Procedure
3.1 Sample Types^[1]:
3.1.1 Bacterial samples: Gram-negative bacteria (E. coli) and Gram-positive bacteria (S. epidermidis; S. aureus, including methicillin-resistant S. aureus MRSA and methicillin-sensitive S. aureus MSSA).
3.2 Incubation Conditions:
3.2.1 Incubate bacterial samples with 1 μM CouCyCF3 at 37°C for 20 min.
3.2.2 Acid shock assay: Incubate stained bacterial samples in LB at pH 3 for up to 30 min.
3.2.3 Host-pathogen interaction assay: Pre-stain bacterial samples with 1 μM CouCyCF3 first, then co-culture with immune cells/blood cells at a multiplicity of infection (MOI) of 3, followed by incubation for 10 min post-infection.
3.3 Washing Step: No washing step is specified.

4. Control Setup
4.1 For acid shock assays using the E. coli ΔcfaS knockout strain, use the parental E. coli strain as the control.
4.2 For intracellular bacterial phagocytosis assays, use the extracellular bacterial population as the control.

5. Detection and Analysis
5.1 Instruments:
5.1.1 Fluorescence microscope (confocal): Excitation at 445 nm/emission at 472/30 nm (blue channel), excitation at 640 nm/emission at 708/75 nm (red channel).
5.1.2 Flow cytometer: Excitation at 405 nm/emission at 515/20 nm (blue channel), excitation at 639 nm/emission at 670/30 nm (red channel); or excitation at 405 nm/emission at 435-505 nm (blue channel), excitation at 642 nm/emission at 642-745 nm (red channel).
5.2 Result Analysis:
5.2.1 Fluorescence intensity changes: Under acidic conditions, the fluorescence intensity of the red channel increases; when the pH rises, the fluorescence intensity of the blue channel increases.
5.2.2 Fluorescence localization: Fluorescence accumulates in the bacterial cytoplasm.
5.2.3 Ratio analysis: Calculate the I_red/I_blue ratio; this ratio decreases with increasing pH, showing a linear response in the pH range of 5.0 to 7.5. Intracellular bacteria in phagolysosomes have a higher I_red/I_blue ratio than extracellular bacteria. Under acid shock conditions, the E. coli ΔcfaS strain has a higher I_red/I_blue ratio than the parental E. coli strain.

MedChemExpress (MCE) has not independently confirmed the accuracy of these methods. They are for reference only.