Poly(n-Isopropylacrylamide) Hydrogel Incorporating Squaraine: Synthesis, Drug Delivery and Photodynamic Properties

Abstract

In the present work, we describe the fabrication of a thermosensitive hydrogel. To fabricate the hydrogel (Sq1@PNIPAAm), we opted to use biocompatible poly(N-isopropylacrylamide) (PNIPAM) and squaraine dye (Sq1) as the polymer and the crosslinker, respectively. It is noteworthy that Sq1@PNIPAAm can be loaded with fluorescein, and we evaluated the fluorescein release behavior of Sq1@PNIPAAm hydrogel. We noted that on demand sustainable release of fluorescein was feasible upon gradual heating of Sq1@PNIPAAm hydrogel. Furthermore, Sq1@PNIPAAm hydrogels can be used as photosensitizers pertinent to photodynamic therapy (PDT). Our results show that hydrogel possesses favorable biological safety for use in in vitro anticancer studies. In vitro experiments confirmed that Sq1@PNIPAAm hydrogels could kill over 40% of cancer cells. Overall, we have successfully shown that Sq1@PNIPAAm enabled photodynamic therapy. Moreover, fluorescein loading into Sq1@PNIPAAm was possible, and it could be used to successfully accomplish temperature-controlled on-demand release. Given the abundance of low-cost, commercially accessible monomers available for use in hydrogel synthesis, this method offers access to a wide range of functional hydrogels for use in biomedical applications.