Thermoresponsive-polymer-based materials for temperature-modulated bioanalysis and bioseparations

Many bioactive compounds, pharmaceutical proteins, and therapeutic cells are used in medical treatments. Methods for the effective purification of such compounds that retain their activities are greatly needed. This review article describes various types of materials based on thermoresponsive polymers for bioanalysis and bioseparations, e.g., thermoresponsive chromatography and thermally modulated cell separation. Poly(N-isopropylacrylamide) (PIPAAm) and its derivatives show temperature-dependent hydrophilic/hydrophobic alterations and conformational changes of their polymer chains in response to external temperature changes. These intrinsic thermoresponsive properties are used to induce thermally modulated interactions between a PIPAAm-modified stationary phase and analytes, or thermally modulated cell adhesion and detachment, enabling modulation of the separation driving force by changing the external temperature. These separation techniques are potentially useful for various applications in biotechnology and biomedicine, because separation can be achieved by simply changing the external temperature, without using reagents that damage and deactivate biological compounds, proteins, and cells.