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Synthesis and Characterization of Temperature-Sensitive and Chemically Cross-Linked Poly(N-isopropylacrylamide)/Photosensitizer Hydrogels for Applications in Photodynamic Therapy

Belali, Simin; Savoie, Huguette; O’Brien, Jessica M.; Cafolla, Atillio A.; O’Connell, Barry; Karimi, Ali Reza; Boyle, Ross W.; Senge, Mathias O.

Authors

Simin Belali

Huguette Savoie

Jessica M. O’Brien

Atillio A. Cafolla

Barry O’Connell

Ali Reza Karimi

Mathias O. Senge



Abstract

Copyright © 2018 American Chemical Society. A novel poly(N-isopropylacrylamide) (PNIPAM) hydrogel containing different photosensitizers (protoporphyrin IX (PpIX), pheophorbide a (Pba), and protoporphyrin IX dimethyl ester (PpIX-DME)) has been synthesized with a significant improvement in water solubility and potential for PDT applications compared to the individual photosensitizers (PSs). Conjugation of PpIX, Pba, and PpIX-DME to the poly(N-isopropylacrylamide) chain was achieved using the dispersion polymerization method. This study describes how the use of nanohydrogel structures to deliver a photosensitizer with low water solubility and high aggregation tendencies in polar solvents overcomes these limitations. FT-IR spectroscopy, UV-vis spectroscopy, 1 H NMR, fluorescence spectroscopy, SEM, and DLS analysis were used to characterize the PNIPAM-photosensitizer nanohydrogels. Spectroscopic studies indicate that the PpIX, Pba, and PpIX-DME photosensitizers are covalently conjugated to the polymer chains, which prevents aggregation and thus allows significant singlet oxygen production upon illumination. Likewise, the lower critical solution temperature was raised to ∼44 °C in the new PNIPAM-PS hydrogels. The PNIPAM hydrogels are biocompatible with > 90% cell viability even at high concentrations of the photosensitizer in vitro. Furthermore, a very sharp onset of light-dependent toxicity for the PpIX-based nanohydrogel in the nanomolar range and a more modest, but significant, photocytotoxic response for Pba-PNIPAM and PpIX-DME-PNIPAM nanohydrogels suggest that the new hydrogels have potential for applications in photodynamic therapy.

Journal Article Type Article
Publication Date May 14, 2018
Journal Biomacromolecules
Print ISSN 1525-7797
Electronic ISSN 1526-4602
Publisher American Chemical Society
Peer Reviewed Peer Reviewed
Volume 19
Issue 5
Pages 1592-1601
Institution Citation Belali, S., Savoie, H., O’Brien, J. M., Cafolla, A. A., O’Connell, B., Karimi, A. R., …Senge, M. O. (2018). Synthesis and Characterization of Temperature-Sensitive and Chemically Cross-Linked Poly(N-isopropylacrylamide)/Photosensitizer Hydrogels for Applications in Photodynamic Therapy. Biomacromolecules, 19(5), 1592-1601. https://doi.org/10.1021/acs.biomac.8b00293
DOI https://doi.org/10.1021/acs.biomac.8b00293
Keywords Materials Chemistry; Bioengineering; Polymers and Plastics; Biomaterials
Publisher URL https://pubs.acs.org/doi/10.1021/acs.biomac.8b00293
Copyright Statement © 2018 American Chemical Society

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