Intelligent thermoresponsive polymeric stationary phases for aqueous chromatography of biological compounds

Sensitive polymers with external physical, chemical, and electrical stimuli are termed as 'intelligent materials' and currently have been used in variety fields of engineering, and medicine. Numerous research papers utilizing stimuli-responsive intelligent materials are found in the literature to date. In this manuscript, the authors described several applications of surfaces and interfaces modified with stimuli-responsive polymers for stimuli-responsive surface property alteration and their application for the separation sciences. The special attention is paid to the temperature responsive polymers, poly(N-isopropylacrylamide) (PIPAAm) and its derivatives as surface modifiers for novel 'green' chromatography in which only aqueous mobile phase was utilized for separation of bioactive compounds. Several factors were investigated and discussed the effects on separation of bioactive compounds; these include the effects of the temperature-responsive hydrophilic/hydrophobic changes, copolymer composition, graft polymer molecular architecture and the incorporation of charged groups. Furthermore, application of PIPAAm-grafted surfaces for affinity separation of proteins will be discussed. The technique has superior characteristics in reducing organic wastes and costs to run chromatographic separation, and thus must be an environmentally friendly separation tool.