Quantitative magnetic resonance imaging of urea and lysozyme in protein chromatography

In-column ATR-FTIR spectroscopy to monitor affinity chromatography purification of monoclonal antibodies

In recent years many monoclonal antibodies (mAb) have entered the biotherapeutics market, offering new treatments for chronic and life-threatening diseases. Protein A resin captures monoclonal antibody (mAb) effectively, but the binding capacity decays over repeated purification cycles. On an industrial scale, replacing fouled Protein A affinity chromatography resin accounts for a large proportion of the raw material cost. Cleaning-in-place (CIP) procedures were developed to extend Protein A resin lifespan, but chromatograms cannot reliably quantify any remaining contaminants over repeated cycles. To study resin fouling in situ, we coupled affinity chromatography and Fourier transform infrared (FTIR) spectroscopy for the first time, by embedding an attenuated total reflection (ATR) sensor inside a micro-scale column while measuring the UV 280 nm and conductivity. Our approach quantified the in-column protein concentration in the resin bed and determined protein conformation. Our results show that Protein A ligand leached during CIP. We also found that host cell proteins bound to the Protein A resin even more strongly than mAbs and that typical CIP conditions do not remove all fouling contaminants. The insights derived from in-column ATR-FTIR spectroscopic monitoring could contribute to mAb purification quality assurance as well as guide the development of more effective CIP conditions to optimise resin lifespan.

Spatially resolved quantification of metal ion concentration in a biofilm-mediated ion exchanger

A bioremediation process to remove Co(2+) from aqueous solution is investigated in this study using a magnetic resonance imaging (MRI) protocol to rapidly obtain multiple 2D spatially resolved Co(2+) ion concentration maps. The MRI technique is described in detail and its ability to determine the evolution in both axial and radial concentration profiles demonstrated, from which total column capacity can be determined. The final ion exchange column design allows operation in the 'plug flow' regime, hence making use of its full capacity before breakthrough. Conventional techniques for such process optimization are either restricted to the analysis of the exchanger outlet, which provides no information on the spatial heterogeneity of the system, or are invasive and need a variety of sample points to obtain 1D concentration information. To the best of our knowledge, our results represent the first concentration maps describing the bioremediation of metal ion contaminated water.