Dextran 75

Polyethylene glycol with an average molecular weight of 8000 (PEG-8000, lot SLBW6815) was purchased from Sigma-Aldrich (St. Louis, MO, USA). Ucon 50-HB-5100, a random copolymer of 50% ethylene oxide and 50% propylene oxide, with molecular weight of 3930 (Ucon-3930, lot SJ1955S3D2), was purchased from Dow-Chemical (Midland, MI, USA). Dextran with an average molecular weight of 75,000 (Dextran-75, lot 119945) was purchased from USB Corporation (Cleveland, OH, USA). Ficoll^TM with an average molecular weight of 70,000 (Ficoll-70, lot 10297022) was purchased from Cytiva (Marlborough, MA, USA). Sodium sulfate (Na₂SO₄, lot 195740), sodium chloride (NaCl, lot 212436), sodium phosphate dibasic heptahydrate (Na₂HPO₄·7H₂O, lot 190833), and sodium phosphate monobasic monohydrate (NaH₂PO₄·H₂O, lot 194198) of analytical reagent grade were purchased from Fisher Scientific (Waltham, MA, USA). Ultrapure water (18.5 mΩ) purified using a Milli-Q^® lab water system (EMD Millipore Sigma, Burlington, MA, USA) was used for the preparation of all solutions.