Question: What is the highest BSA concentration that can be used in the single-cell suspension buffer?
Answer: We recommend cell washing and resuspension in PBS+0.04% BSA (BSA is added primarily to minimize cell losses and aggregation). But higher BSA concentrations (0.1-2% BSA) in the media will not have any adverse effects on workflow or data.
The presence of BSA in the washing and resuspension buffer results in a translucent/opaque rather than clear aqueous phase after breaking the GEMs with Recovery Agent (Figure 1). This is normal and will not impact downstream operations.
We recommend minimizing the volume of the cell resuspension mix added to the RT master mix to minimize the carryover effect (if any).
Figure 1. Tube A: Cell sample suspended in 1x PBS + 0.04% BSA - the aqueous phase appears clear. Tube B-H: Cell samples containing different input volumes of cells suspended in 1x PBS + 1.0% BSA - the aqueous phases may appear translucent/opaque.
We recommend PBS + 1% BSA for labeling and washing for use with our Cell Surface Protein labeling protocol with a final resuspension in PBS + 0.04% BSA. We have not tested adding up to 2% BSA for use with Cell Surface Proteins, but we would consider it low-risk.
Products: Single Cell Gene Expression, Single Cell Immune Profiling