Molecular design of dynamically thermoresponsive biomaterials.

Abstract

Dynamically thermoresponsive biomaterials, particularly those utilizing poly(N-isopropylacrylamide) (PNIPAAm), have attracted much attention in biomedical applications due to their reversible phase transition near body temperature. These biomaterials provide innovations across drug delivery system, chromatography, and tissue engineering. Molecular designs, such as the incorporation of hydrophilic comonomers or graft copolymers in PNIPAAm hydrogels, enhance rapid kinetics of the gels when jumping the temperature across the phase transition temperature, because of avoiding 'skin layer' formation on the surface of the gels. Nanocarriers possessing PNIPAAm coronas facilitate spatial drug delivery and temporally on-demand drug release to targeted cancers in combination with hyperthermic therapy. Downsizing of PNIPAAm hydrogels accelerates the kinetics of shrinkage/swelling, leading to applications as thermoresponsive chromatographic matrices and cell cultureware. PNIPAAm-modified surfaces support thermoresponsive cell culture systems for the non-invasive recovery of intact cell sheets, enabling advanced regenerative therapies and layered 3D tissue formation. Recent developments also integrate growth factor delivery for sustained cell stimulation on culturewares. Newly developed biomaterials, including dynamically thermoresponsive PNIPAAm, are expected to expand the opportunity for novel treatment technologies such as targeted therapies and regenerative medicine.