{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,1]],"date-time":"2026-06-01T18:41:46Z","timestamp":1780339306583,"version":"3.54.1"},"reference-count":68,"publisher":"MDPI AG","issue":"21","license":[{"start":{"date-parts":[[2025,10,22]],"date-time":"2025-10-22T00:00:00Z","timestamp":1761091200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100023181","name":"Medical Research Agency","doi-asserted-by":"crossref","award":["2024\/ABM\/03\/KPO\/KPOD.07.07-IW.07-0211\/24-00"],"award-info":[{"award-number":["2024\/ABM\/03\/KPO\/KPOD.07.07-IW.07-0211\/24-00"]}],"id":[{"id":"10.13039\/501100023181","id-type":"DOI","asserted-by":"crossref"}]},{"name":"European Union through the National Recovery and Resilience Plan (KPO)\u2014NextGenerationEU"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>In this study, non-toxic, biodegradable, and pH-sensitive polyurethane hydrogels (PUs) were prepared by using hexamethylene diisocyanate (HDI), copolymers of \u0454-caprolactone (CL), rac-lactide (LA), and poly(ethylene glycol) (PEG), poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (PEO-bPPO-b-PEO), 1,4-butanediol (BD), and L-glutamine (Gln). The CL, LA, and PEG copolymers were obtained in the presence of a new synthesized catalytic system: diethylzinc\/ethyl-3,4-dihydroxybenzoate. Obtained PUs were screened for their cytotoxicity, evaluated for their swelling behavior and hydrolytic degradation, and employed as hydrogel pH-responsive anti-cancer drug delivery systems (DDSs). The novel and promising hydrogel DDSs, capable of releasing 5-fluorouracyl (5-FU) and fluorodeoxyuridine (5-fluoro-2\u2032-deoxyuridine, FUdR) in a sustained and controlled manner, were prepared and were nontoxic. Most prepared hydrogel DDSs were found to release anti-cancer drugs with first-order or zero-order kinetics. The drug release mechanism was generally denoted as Fickian or non-Fickian transport. The possibility of controlling the kinetics of drug release by changing the pH of the environment was also observed. The findings indicate that these PU hydrogels are suitable for use as intelligent DDSs for the targeted delivery of 5-FU or FUdR. We expect that the hydrogel DDSs developed will be utilized in the treatment of pancreatic cancer.<\/jats:p>","DOI":"10.3390\/ijms262110258","type":"journal-article","created":{"date-parts":[[2025,10,23]],"date-time":"2025-10-23T01:14:02Z","timestamp":1761182042000},"page":"10258","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["Preparation and Characterization of New pH-Sensitive Polyurethane Hydrogels as Anti-Cancer Drug Delivery Systems for 5-Fluorouracyl and Fluorodeoxyuridine"],"prefix":"10.3390","volume":"26","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-7362-8881","authenticated-orcid":false,"given":"Marcin","family":"Sobczak","sequence":"first","affiliation":[{"name":"Department of Pharmaceutical Chemistry and Biomaterials, Faculty of Pharmacy, Medical University of Warsaw, Banacha 1 Str., 02-097 Warsaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0187-9638","authenticated-orcid":false,"given":"Adam","family":"Kasi\u0144ski","sequence":"additional","affiliation":[{"name":"Department of Pharmaceutical Chemistry and Biomaterials, Faculty of Pharmacy, Medical University of Warsaw, Banacha 1 Str., 02-097 Warsaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3696-1618","authenticated-orcid":false,"given":"Karolina","family":"K\u0119dra","sequence":"additional","affiliation":[{"name":"Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44\/52 Str., 01-224 Warsaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-8983-7212","authenticated-orcid":false,"given":"Joachim","family":"Frankowski","sequence":"additional","affiliation":[{"name":"Department of Pharmaceutical Chemistry and Biomaterials, Faculty of Pharmacy, Medical University of Warsaw, Banacha 1 Str., 02-097 Warsaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Matylda","family":"Kurz\u0105tkowska","sequence":"additional","affiliation":[{"name":"Department of Pharmaceutical Chemistry and Biomaterials, Faculty of Pharmacy, Medical University of Warsaw, Banacha 1 Str., 02-097 Warsaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0009-0006-8745-628X","authenticated-orcid":false,"given":"Karolina","family":"Watrakiewicz","sequence":"additional","affiliation":[{"name":"Department of Pharmaceutical Chemistry and Biomaterials, Faculty of Pharmacy, Medical University of Warsaw, Banacha 1 Str., 02-097 Warsaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Karolina","family":"Mulas","sequence":"additional","affiliation":[{"name":"Department of Pharmaceutical Chemistry and Biomaterials, Faculty of Pharmacy, Medical University of Warsaw, Banacha 1 Str., 02-097 Warsaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6260-8423","authenticated-orcid":false,"given":"Katarzyna","family":"Strzelecka","sequence":"additional","affiliation":[{"name":"Department of Pharmaceutical Chemistry and Biomaterials, Faculty of Pharmacy, Medical University of Warsaw, Banacha 1 Str., 02-097 Warsaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Marcin","family":"Chodkowski","sequence":"additional","affiliation":[{"name":"Division of Medical and Environmental Microbiology, Military Institute of Hygiene and Epidemiology, 01-063 Warsaw, Poland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8409-3974","authenticated-orcid":false,"given":"Ma\u0142gorzata","family":"Krzy\u017cowska","sequence":"additional","affiliation":[{"name":"Division of Medical and Environmental Microbiology, Military Institute of Hygiene and 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