Development and Characterization of PEGylated Chromatographic Monoliths as a Novel Platform for the Separation of PEGylated RNase a Isomers

PEGylated or polyethylene glycol-modified proteins have been used as therapeutic agents in different diseases. However, the major drawback in their procurement is the purification process to separate unreacted proteins and the PEGylated species. Several efforts have been done to separate PEGylation reactions by chromatography using different stationary phases and modified supports. In this context, this study presents the use of chromatographic monoliths modified with polyethylene glycol (PEG) to separate PEGylated Ribonuclease A (RNase A). To do this, Convective Interaction Media (CIM) Ethylenediamine (EDA) monolithic disks were PEGylated using three PEG molecular weights (1, 10, and 20 kDa). The PEGylated monoliths were used to separate PEGylated RNase A modified, as well, with three PEG molecular weights (5, 20, and 40 kDa) by hydrophobic interaction chromatography. Performance results showed that Bovine Serum Albumin (BSA) can bind to PEGylated monoliths and the amount of bound BSA increases when ammonium sulfate concentration and flow rate increase. Furthermore, when PEGylated RNase A was loaded into the PEGylated monoliths, PEG-PEG interactions predominated in the separation of the different PEGylated species (i.e., mono and di-PEGylated). It was also observed that the molecular weight of grafted PEG chains to the monolith impacts strongly in the operation resolution. Interestingly, it was possible to separate, for the first time, isomers of 40 kDa PEGylated RNase A by hydrophobic interaction chromatography. This technology, based on PEGylated monoliths, represents a new methodology to efficiently separate proteins and PEGylated proteins. Besides, it could be used to separate other PEGylated molecules of biopharmaceutical or biotechnological interest.