Cryogel bodies were modified to obtain epoxy groups by graft-copolymerization using both chemical and gamma irradiation initiation techniques. The free epoxy adsorbents were reacted further to introduce diethylaminoethanol (DEAE) functionalities. The resulting weak anion-exchange cryogel adsorbents showed dynamic binding capacities of ca. 27±3mg/mL, which was significantly higher than previously reported for this type of adsorbent material. Gamma irradiated grafting initiation showed a 4-fold higher capacity for proteins than chemical grafting initiation procedures. The phosphate capacity for these DEAE cryogels was 119mmol/L and also showed similar column efficiency as compared to commercial adsorbents. The large pores in the cryogel structure ensure convective transport of the molecules to active binding sites located on the polymer-grafted surface of cryogels. However, as cryogels have relatively large pores (10-100μm), the BET area available for surface activation is low, and consequently, the capacity of the cryogels is relatively low for biomolecules, especially when compared to commercial beaded adsorbents. Nevertheless, we have shown that gamma ray mediated surface grafting of cryogel matrices greatly enhance their functional and adsorptive properties.

A single‐stage clarification was developed using a single‐use chromatographic clarification device (CCD) to recover a recombinant protein from Chinese Hamster Ovary (CHO) harvest cell culture fluid (HCCF). Clarification of a CHO HCCF is a complex and costly process, involving multiple stages of centrifugation and/or depth filtration to remove cells and debris and to reduce process‐related impurities such as host cell protein (HCP), nucleic acids, and lipids. When using depth filtration, the filter train consists of multiple filters of varying ratios, layers, pore sizes, and adsorptive properties. The depth filters, in combination with a 0.2‐micron membrane filter, clarify the HCCF based on size‐exclusion, adsorptive, and charge‐based mechanisms, and provide robust bioburden control. Each stage of the clarification process requires time, labor, and utilities, with product loss at each step. Here, use of the 3M™ Harvest RC Chromatographic Clarifier, a single‐stage CCD, is identified as an alternative strategy to a three‐stage filtration train. The CCD results in less overall filter area, less volume for flushing, and higher yield. Using bioprocess cost modeling, the single‐stage clarification process was compared to a three‐stage filtration process. By compressing the CHO HCCF clarification to a single chromatographic stage, the overall cost of the clarification process was reduced by 17%–30%, depending on bioreactor scale. The main drivers for the cost reduction were reduced total filtration area, labor, time, and utilities. The benefits of the single‐stage harvest process extended throughout the downstream process, resulting in a 25% relative increase in cumulative yield with comparable impurity clearance.

BACKGROUND: ‘Expanded’ composite materials are of interest as an alternative, or as a supplement, to packed‐bed chromatography during bioproduct recovery and purification. Functionalized non‐woven fabrics and mega‐porous bodies are examples of systems that showed promise. However, there is scarce information on their suitability to capture and release plasmid DNA (pDNA), an important type of product employed in gene therapy.RESULTS: Composite adsorbents were prepared using either chemical (CG‐DEAE‐NW) or gamma‐irradiated graft‐polymerization (GIR‐DEAE‐MP), and subsequently modified to have diethylamino ethanol (DEAE) functionality. Capture experiments showed that pDNA can actually reversibly bind to the two mentioned adsorbents, with capacity values of 2.4 and 1.3 mg per mL, respectively. These values are in the range of what can be expected from commercial beaded adsorbents but lower that the values expected from monoliths.CONCLUSIONS: Expanded materials, due to their high voidage, may present limited capacity for pDNA. However, such materials are able to bind proteins and other contaminants from bacterial lysate, opening the way for their utilization in the ‘negative’ mode. © 2018 Society of Chemical Industry