Novel Macroporous Adsorbents with Variable Functionalities: From Preparation to Application

Macroporous chromatographic supports are ideal for preparative applications, where good throughput, i.e. speed of separation, is required. In this regard, large throughpores provide high bed permeability, which allows operation at high flow rates.  Meanwhile, if these large pores are able to accommodate a fraction of convective flow, so-called perfusive pores, then separation efficiency is independent of the flow rate.

To this end, by combining elements from colloidal and polymer reaction engineering, a novel macroporous packing material with advanced mass transfer properties was developed. Specifically, aggregation and breakage under flow of polymeric microclusters allows the control final cluster size and pore size distribution, while post-polymerization imparts high mechanical stability.

Owing to surface-bound ATRP initiators a versatility of functionalities can be realized, in order to employ different separation modes, relying on different types of substrate-solute interaction. So far, conventional cation and anion exchange chromatography have been addressed, as well as an alternative temperature-responsive modality, where instead of ionic strength or polarity of the mobile phase, temperature is utilized to control interactions. This is advantageous from the environmental and cost-reduction viewpoint, as well as for preserving bioactivity of the purified compounds.

As polymer brushes are grafted from the substrate surface, multiple active sites are available per unit area, offering increased binding capacities. Meanwhile, the flexibility of such chains allows for favorable steric distributions, so that large molecules like proteins, can be better accommodated.  As a matter of fact, application examples demonstrate that our functionalized adsorbents may compete with existing commercial chromatographic supports.

Figure 1.  SEM image of supporting microcluster. White circles indicate large throughpores.

Figure 2.  Pore functionalization scheme.

Figure 3. Illustrative separation of Lysozyme, α-Chymotrypsinogen and Cytochrome-c (elution order) by an anionic-PE functionalized column versus a commercial exchanger. Conditions: 30mM phosphate buffer pH7.0, linear gradient elution from 0.0M to 1.0M NaCl (dashed line) at 1ml/min. Peak resolution was calculated using the indicated formula.