Assessing Skills Development Across The Undergraduate Degree Programme: An IEP Review – Biochemical Engineering

Ensuring technical competency has traditionally been at the centre of engineering pedagogy in university education, however with ever more increasing emphasis on the need for professional skills by accreditation bodies and employers, there have been pressures on the education system to address this. Communication and teamwork competencies have been shown to be the most highly coveted by employers and in 2014, the Integrated Engineering Programme (IEP) at UCL was designed to address the inclusion of professional skills development in the curriculum in the first year of undergraduate studies. However, what is not clear is whether these skills are transferred into 2nd and 3rd year. This study investigated this by interviewing members of staff in Biochemical Engineering responsible for modules where these skills form part of the learning outcomes. The results indicate that whilst there is a general consensus that presentation skills are well developed, issues still arise in 2nd and 3rd year with teamwork skills and possible contributing factors could be related to a lack of awareness of suitable team formation strategies. Further findings included changes in students’ perception of skills-based teaching as well as the need for sharing of best practice among IEP-related and non-IEP related staff alike

Mechanical characterisation of agarose-based chromatography resins for biopharmaceutical manufacture

Mechanical characterisation of agarose-based resins is an important factor in ensuring robust chromatographic performance in the manufacture of biopharmaceuticals. Pressure-flow profiles are most commonly used to characterise these properties. There are a number of drawbacks with this method, including the potential need for several re-packs to achieve the desired packing quality, the impact of wall effects on experimental set up and the quantities of chromatography media and buffers required. To address these issues, we have developed a dynamic mechanical analysis (DMA) technique that characterises the mechanical properties of resins based on the viscoelasticity of a 1ml sample of slurry. This technique was conducted on seven resins with varying degrees of mechanical robustness and the results were compared to pressure-flow test results on the same resins. Results show a strong correlation between the two techniques. The most mechanically robust resin (Capto Q) had a critical velocity 3.3 times higher than the weakest (Sepharose CL-4B), whilst the DMA technique showed Capto Q to have a slurry deformation rate 8.3 times lower than Sepharose CL-4B. To ascertain whether polymer structure is indicative of mechanical strength, scanning electron microscopy images were also used to study the structural properties of each resin. Results indicate that DMA can be used as a small volume, complementary technique for the mechanical characterisation of chromatography media

Chromatography resin characterisation to analyse lifetime and performance during biopharmaceutical manufacture

This thesis, completed in collaboration with Eli Lilly & Co., aims to understand and assess the structural and mechanical changes that occur as agarose-based chromatography resins are exposed to different bioprocessing conditions in an attempt to explore the mechanisms by which different resins age. By understanding this, there is significant potential for facilitating timely and improved decisions in large-scale chromatographic operations, maximising resin lifetime whist maintaining acceptable column performance. Scanning electron microscopy (SEM) was used to image the structural properties of nine widely used agarose-based chromatography resins before use while pressure-flow analysis was used to characterise the mechanical properties of the same fresh resins. The results showed that the Capto family had the highest critical velocities (Capto Adhere- 492, Capto Q- 477 cm/hr), whilst Sepharose CL-6B, Sepharose 4 Fast Flow and Sepharose CL-4B had the lowest critical velocity values (283, 204, 149 cm/hr respectively). There were practical limitations in using the pressure-flow technique alone to for mechanical characterisation, including the large quantity of chromatography resin and buffers and the stringent criteria required to pack a column. Dynamic mechanical analysis (DMA) was therefore developed as a novel technique in this field to address these limitations and allowed for further mechanical characterisation based on the viscoelastic properties using 1ml of resin. The technique was applied to the nine studied resins and correlated with the results obtained using the pressure-flow technique. The same trends were observed – The Capto family showed the highest resistance to deformation (Capto Adhere- 2.7, Capto Q- 1.92 1/%min-1) through to Sepharose CL-6B, Sepharose 4 Fast Flow and Sepharose CL-4B which exhibited the lowest slurry resistances (0.59, 0.4, 0.3 1/%min-1 respectively). These results indicate that DMA can be used as a small volume, high-throughput technique, relative to pressure-flow analysis, for the mechanical characterisation of chromatography media. The structural imaging and mechanical testing tools developed in this study were then applied to measure changes in resins that had undergone lifetime studies. These studies expose the resins to repeated cycles of use to understand how they age in a particular bioprocess, enabling decision making about their use. The first set of experiments exposed the resins to the cleaning cycle only, whilst in the second set of experiments, the resins had been used for lifetime studies in the production of monoclonal antibodies (termed ‘aged’ resins). The results indicated that MabSelect (highly cross-linked protein A resin) and Q-Sepharose High Performance (anion exchange cross-linked resin) appeared to show similar mechanisms of aging. Their matrices showed agarose fibre breakage with increased exposure to process conditions. In the case of Capto Adhere (highly cross-linked multimodal anion exchange resin) and MabSelect Xtra (highly cross-linked protein A resin), the mechanism of aging appeared to be associated foulants coating the surface fibres. The results indicate that the interaction of CIP reagents and foulants (as opposed to CIP reagents alone) cause the greatest impact on the structural integrity of the resins. Pressure-flow and DMA characterisation were used to examine the mechanical properties of the cycled resins to provide the first systematic study of these issues. The results showed that fresh resins were consistently more robust than either of the cycled resins but the greatest mechanical differences were observed between fresh resins and aged resins, which corroborated the structural analysis data. Statistical analysis was performed with one way ANOVA to determine whether DMA could be independently used to assess the impact of process conditions on the mechanical properties of chromatography media and the results show a >80% certainty that DMA can be employed for this purpose

Drying techniques for the visualisation of agarose-based chromatography media by scanning electron microscopy

The drying of chromatography resins prior to scanning electron microscopy is critical to image resolution and hence understanding of the bead structure at sub-micron level. Achieving suitable drying conditions is especially important with agarose-based chromatography resins, as over-drying may cause artefact formation, bead damage and alterations to ultrastructural properties; and under-drying does not provide sufficient resolution for visualisation under SEM. This paper compares and contrasts the effects of two drying techniques, critical point drying and freeze drying, on the morphology of two agarose based resins (MabSelect(TM) : dw ~ 85 µm and Capto(TM) Adhere: dw ~75 µm) and provides a complete method for both. The results show that critical point drying provides better drying and subsequently clearer ultrastructural visualisation of both resins under SEM. Under this protocol both the polymer fibres (thickness ~20 nm) and the pore sizes (diameter ~100 nm) are clearly visible. Freeze drying is shown to cause bead damage to both resins, but to different extents. MabSelect resin encounters extensive bead fragmentation, whilst Capto Adhere resin undergoes partial bead disintegration, corresponding with the greater extent of agarose crosslinking and strength of this resin. While freeze drying appears to be the less favourable option for ultrastructural visualisation of chromatography resin, it should be noted that the extent of fracturing caused by the freeze drying process may provide some insight into the mechanical properties of agarose-based chromatography media

Lifetime and Aging of Chromatography Resins during Biopharmaceutical Manufacture

Poor understanding of the events leading to chromatography column aging makes it difficult to monitor column lifetimes. The lack of established procedures in this area has made it difficult to establish industry standards. Therefore, it is important to understand resin aging mechanisms and techniques to monitor column aging during operation

Case report - Lassa Fever Mimicking Ectopic Pregnancy: A Report Of Three Cases

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