HBS (2×) for FIV

Na₂HPO₄ stock solution (52.5 g of Na₂HPO₄, 5000 mL of H₂O)

NaCl

HEPES (sodium salt)

To prepare, combine 80 g of NaCl, 65 g of HEPES (sodium salt), and 100 mL of Na₂HPO₄ stock solution and bring to a final volume of 5000 mL. Careful pH optimization is important. Prepare several batches and adjust pH with 1 n NaOH to several set points within a narrow range, e.g., pH 6.95, 7, and 7.05. Optimal pH is generally 6.95, but final preferred stocks will depend on empirical determination of transfection efficiency. Store frozen (−20°C). pH shifts with time, as may percent transfection obtained. Prepare fresh every 3–6 mo.

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