Purification of antibodies through convective chromatography

Downstream processing of immunoglobulin G is conventionally performed by bead-based column chromatography; affinity chromatography with Protein A is the most selective process in biotechnological industry for the purification of antibodies. However, this method suffers from several limitations, such as high pressure drops across the column, compaction of the granular porous bed and low diffusivity between the particles. In addition to fluid dynamic problems, the traditional process is affected by limitations related to the use of Protein A as affinity ligand. Materials activated with Protein A are very expensive, since the production cost of this recombinant protein is very high. Finally, ligand leakage causes contamination of the final product. The aim of the present work was to overcome the limitations that affect the traditional process through the development of new convective chromatographic supports, like membranes and monoliths, functionalized with synthetic affinity ligands to be used instead of columns packed with Protein A beads. The performance of regenerated cellulose membranes functionalized with two affinity ligands were studied; the commercial A2P ligand and the new recently synthesized HPTA were used to replace Protein A. Static and dynamic binding capacity and elution recoveries, were determined for the affinity membranes prepared, using pure solutions of IgG. Mixtures and complex solutions containing IgG were tested to determine ligands selectivity. A processing method for the preparation of porous cellular ceramic monoliths was developed. Cellular Al2TiO5 and Al2TiO5-Al2O3 composites ceramics were obtained by emulsification of liquid paraffin in aqueous suspensions of mixed Al2O3 and TiO2 powders, with subsequent burnout of the organic phase and two-step reactive firing. The ceramic monolith were fully characterized to assess their use as novel chromatographic stationary phases, measuring porosity, axial dispersion coefficient and permeability; the surface was chemically modified to obtain functional groups to be used for ligand or direct protein immobilization

Simultaneous Continuation of Infinitely Many Sinks Near a Quadratic Homoclinic Tangency

We prove that the $C^3$ diffeomorphisms on surfaces, exhibiting infinitely many sinksnear the generic unfolding of a quadratic homoclinic tangency of a dissipative saddle, can be perturbed along an infinite dimensional manifold of $C^3$ diffeomorphisms such that infinitely many sinks persist simultaneously. On the other hand, if they are perturbed along one-parameter families that unfold generically the quadratic tangencies, then at most a finite number of those sinks have continuation

Effect of the spacer arm on non-specific binding in membrane affinity chromatography

The preparation, screening, and characterization of affinity membranes require a deep knowledge of the behavior of all components of the affinity material. Several studies report the effect of different spacers in combination with the ligand molecule, but the effect of the spacer arm \u201cper se\u201d is generally disregarded. The effect of the spacer 1,2-diaminoethane on non-specific protein adsorption was recently investigated and the results were compared with the ones obtained with A2P affinity membranes. The results show that this spacer has indeed an important effect and that similar specific studies need to be performed for every spacer molecule

Use of the Dispersion Coefficient as the Sole Structural Parameter to Model Membrane Chromatography

The characterization and modelling of membrane chromatography processes require the axial dispersion coefficient as a relevant and effective intrinsic property of porous media, instead of arbitrary assumptions on pore size distribution. The dispersion coefficient can be easily measured by experiments completely independent of chromatographic tests. The paper presents the prediction of experimentally obtained breakthrough curves using B14-TRZ-Epoxy2 membranes as a test case; the mathematical model implemented is based on the use of the experimentally measured axial dispersion coefficient as an input parameter. Application of the model and its comparison with the data demonstrate that alternative ways of explaining the shape of breakthrough curves, based on unverified assumptions about the membrane pore size distribution, are not feasible and not effectively supported by experimental evidence. In contrast, the axial dispersion coefficient is the only measurable parameter that accounts for all the different contributions to the dispersion phenomenon that occurs in the membrane chromatography process, including the effects due to porous structure and pore size distribution. Therefore, mathematical models that rely on the mere assumption of pore size distribution, regardless of the role of the axial dispersion coefficient, are in fact arbitrary and ultimately misleading

Indoor Air Quality Real-Time Monitoring in Airport Terminal Areas: An Opportunity for Sustainable Management of Micro-Climatic Parameters

Indoor air quality (IAQ) management in public spaces is assuming a remarkable importance. Busy environments, like airport terminals, are currently regarded as possible hotspots and IAQ is a crucial element for passengers and staff protection, as well as a key aspect of airport passenger experience. A one-month monitoring period has been performed on IAQ in the airport of Bologna (Italy), as prototypal example of large regional airport. Four strategic areas within the airport have been equipped with electronic monitoring platforms, including different contaminants and two microclimatic sensors. Data suggest that daily variation in IAQ parameters typically follow the activity pattern of the different environments under study (i.e., passengers\u2019 flows) for gaseous contaminants, where particulate matter counts oscillate in a definite range, with a significant role played by ventilation system. Gaseous contaminants show a correlation between indoor and outdoor concentrations, mainly due to airside activities. Micro-climatic comfort parameters have been tested to match with standards for commercial environments. As results appears in line with typical households IAQ values, the current air ventilation system appears to be adequate. Nevertheless, an integrated air management system, based on real-time monitoring, would lead to optimization and improvement in environmental and economical sustainability