Poly(N-isopropylacrylamide)-Based Polymers: Recent Overview for the Development of Temperature-Responsive Drug Delivery and Biomedical Applications

Temperature is a widely incorporated stimulus in pharmaceutical applications because of its efficiency as a therapeutic medium; thus, substantial evidence on temperature-responsive polymer applications is reported. Poly(N-isopropylacrylamide) (PNIPAAm) is a well-established, temperature-responsive polymer that exhibits a low critical solution temperature (LCST) at ≈ 32°C, which is close to physiological temperature. Hence, they are widely used in various pharmaceutical applications, such as drug delivery with nanocarriers and thermogels. Varying the LCST for different applications can be achieved by copolymerization with other hydrophobic or hydrophilic molecules, making it a favorable smart polymer. PNIPAAm is reported to enhance drug delivery by incorporation with nanocarriers and to facilitate prolonged drug delivery, thereby avoiding the burst release of drugs in temperature-responsive hydrogels. The application of PNIPAAm is not limited to drug delivery, and it is also applied in biomedical applications such as chromatography systems and cell culture applications, where its incorporation in cell culture media enhances cell production. The unique and versatile properties of PNIPAAm render it a promising smart polymer for various functional applications. Hence, this review focuses on the diverse applications of PNIPAAm.