Analysis of adsorption of a baculovirus bioreaction bulk on an ion-exchange surface by surface plasmon resonance

The binding and elution of the key components of a bioreaction bulk for the production of recombinant baculoviruses—a promising viral vector for gene therapy and vaccination—on a model ion-exchange surface have been successfully measured and interpreted by surface plasmon resonance (SPR) spectroscopy. The micro-scaled, ion-exchange surface was produced by immobilizing a typical ion-exchange ligand, diethylaminoethyl, onto commercially available planar gold sensor chip surfaces, which were pre-derivatized with a self-assembled monolayer of 11-mercaptoundecanoic acid. Each isolated analyte was injected into the SPR cell at defined operating conditions of salt and solute concentrations to determine the adsorption equilibrium plateau, and then eluted at the same salt concentration, upon which a well-defined, residual desorption equilibrium plateau was observed. From the analysis of the binding and elution curves and equilibrium plateaus for seven key biomolecules, it is possible to determine the adsorption isotherms over a broad range of equilibrium conditions for the three main cuts of the baculovirus bioreaction bulk: the product (the infective baculovirus), the main product-related impurities, and the main process-related impurities. A model that quantitatively explains the SPR-derived adsorption/desorption data was successfully developed for this complex biological system.