Disclosed herein are methods of preparing a composition comprising crystalline biomolecules, for example, crystalline antibodies. In exemplary embodiments, the method comprises forming a fluidized bed of crystalline biomolecules using, for example, a counter-flow centrifuge to exchange buffer and/or to concentrate the crystalline biomolecules in a solution. Also provided are methods of detecting crystalline biomolecules and/or amorphous biomolecules in a sample.