Amicon 0.5 ml cellulose ultra centrifugal filters

All chemicals and reagents were purchased from MilliporeSigma (Burlington, MA, USA) and used as received without further purification unless otherwise noted. Aqueous solutions were made in nanopure deionized water (H₂O) from Milli-Q water (MilliporeSigma). Ammonium acetate (AA) was purchased from Fisher Scientific (Fair Lawn, NJ). Bradford protein assay reagent was purchased from Bio-Rad (Hercules, CA, USA). A 10% gel (10 or 15 comb well, 10.0 cm × 10.0 cm, 1.0 mm thick) for SDS-polyacrylamide gel electrophoresis (SDS-PAGE) was homemade. Thermo Scientific Cimarec+ stirring hot plates were purchased from ThermoFisher Scientific. Amicon 0.5 mL cellulose ultra centrifugal filters with a molecular weight cutoff (MWCO) of 10 kDa were purchased from MilliporeSigma. The recombinant SARS-CoV-2 spike regional-binding domain protein expressed in the HEK 293 cell line was purchased from Sino Biological Inc. (cat. 40592-VNAH).

All reagents were purchased from MilliporeSigma (Burlington, MA, USA) unless otherwise noted. Buffers were prepared with HPLC-grade water from Fisher Scientific (Fair Lawn, NJ, USA). Isopropanol and acetonitrile were purchased from Fisher Scientific (Fair Lawn, NJ, USA). Amicon, 0.5 mL cellulose ultra-centrifugal filters with a molecular weight cutoff (MWCO) of 10 kDa were purchased from MilliporeSigma.