Zourna, Kalliopi
(2009).
Smart magnetic affinity adsorbents.
University of Birmingham.
Ph.D.
Abstract
As the focus of research on ‘adaptive/responsive’ surfaces has in recent years contributed strongly towards the design of surface materials with ‘intelligent’ or ‘smart’ behaviour, current superparamagnetic adsorbents being employed both in small and large scale operations can be surface modified and improved by gaining dual functionalities. In this work, modification of M-PVA supports with polymer brushes of dual properties has been explored for their intended use in bioseparation technology, i.e. for both selectively protein binding and enhanced temperature elution of especially difficult to elute species such as haemoglobin. Tethering of polymer brushes was achieved by employing two different ‘grafting from’ routes, i.e. cerium (IV) initiated polymerisation and Atom Transfer Polymerisation Reaction (ATRP). By identifying the optimum cerium (IV) reaction conditions, the said chemistry was further utilised to attach different polymers (thermoresponsive and affinity ligands) and their combination (thermo-affinity) at fixed positions onto M-PVA supports, either as di-block or mixed functionality polymer brushes. The configuration of introduced polymer chains as well as the haemoglobin binding characteristics of the above materials was evaluated, and their efficiency for haemoglobin and GFP desorption via sequential temperature transitions was demonstrated. Mixed polymer brushes manufactured using sequential ATRP after partial bromination of AGE activated magnetic supports were characterised and tested likewise. Protein binding and release efficiency was dependent on brush configuration (length and spacing between the graft sites of polymers), pNIPAAm content, type of affinity ligand and type of protein employed. From the above materials those with polymer chains of sufficient pNIPAAm length and at such spacing allowing their ‘free’ expansion/collapse upon temperature change (especially those grafted via cerium (IV) route) were found efficient, as brush behaviour favour enhanced desorption of difficult to elute species.
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