Smart polymers: Physical forms and bioengineering applications

Smart polymers (SP) have become one important class of polymers and their applications have been increasing significantly. Last two to three decades have witnessed explosive growth in the subject. SP which are also known as stimuli-responsive soluble-insoluble polymers or environmentally sensitive polymers have been used in the area of biotechnology, medicine and engineering. The present review is aimed to highlight the applications of SP when these polymers are presented in three common physical forms (i) linear free chains in solution where polymer undergoes a reversible collapse after an external stimulus is applied, (ii) covalently cross-linked reversible gels where swelling or shrinking of the gels can be triggered by environmental change and (iii) chain adsorbed or surface-grafted form, where the polymer reversibly swells or collapses on surface, once an external parameter is changed. Though there are number of reviews coming up in this area in recent times, the present review mainly addresses the developments of SP in the last decade with specific application areas of bioseparations, protein folding, microfluidics and actuators, sensors, smart surfaces and membranes.