Analysis of Proteins, Biologics, and Nanoparticles in Biological Fluids Using Asymmetrical Flow Field-Flow Fractionation

Abstract

With the increasing interest in biopharmaceuticals such as proteins, antibodies, and nucleic acids, there is a corresponding increase in the need for characterizing such components. Much effort is spent on characterization in the early drug development phases as well as during formulation development and quality control. One parameter that is commonly investigated is the size distribution of the macromolecular components to deduce if there is aggregation or degradation occurring, if conformational changes occur, or if there are interactions with excipients. While the properties of the protein drug in the buffer system or in the pharmaceutical formulation are important, possibly even more interesting are the properties of the drug once it enters the body. Size characterization of macromolecules in biological fluids has traditionally been an area hampered by the complexity of the matrix. The large amount of indigenous components can interfere with commonly applied analytical techniques for size characterization. However, the separation technique asymmetrical flow field-flow fractionation (AF4) has recently shown increasing applicability for the characterization of components in blood plasma and serum. This article reviews some aspects of applying AF4 to plasma, serum, milk, and cerebrospinal fluid in the field of analysis and characterization of proteins, biologics, and nanoparticles in biological fluids.