{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T04:43:37Z","timestamp":1787028217739,"version":"build-2736575974"},"reference-count":46,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2025,9,17]],"date-time":"2025-09-17T00:00:00Z","timestamp":1758067200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"UTRGV"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Gels"],"abstract":"<jats:p>Soft tissues exhibit remarkable stretchability, fracture toughness, and stress\u2013relaxation ability. They possess a large water content to support cellular processes. Mimicking such a combination of mechanical and physical properties in hydrogels is important for tissue engineering applications but remains challenging. This work aims to develop a hydrogel that can combine excellent mechanical properties with cellular viability. The research focused on polyvinyl alcohol (PVA)\/agar double-network (DN) hydrogels, fabricated by thermal gelation and freeze\u2013thawing methods. Their mechanical properties were characterized through tension, compression, fracture, and stress\u2013relaxation tests, and their cellular viability was measured through cytotoxicity tests. The results show that the PVA\/agar DN gels are highly stretchable (&gt;200%) and compressible (&gt;30%) while containing high water content. The incorporation of agar by 6 wt% improved the fracture toughness of hydrogels from 1 to 1.76 kJ\/m2. The degree of stress\u2013relaxation, a key indicator of gel viscoelastic properties, improved by roughly 170% with an increase in agar content from 0 to 6 wt%. Cytotoxicity analysis showed that the gels, being physically cross-linked, were able to promote cellular proliferation. This work shows that tough and viscoelastic PVA\/agar DN gels are suitable for soft tissue engineering applications, especially cartilage repair.<\/jats:p>","DOI":"10.3390\/gels11090747","type":"journal-article","created":{"date-parts":[[2025,9,17]],"date-time":"2025-09-17T11:00:00Z","timestamp":1758106800000},"page":"747","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Tissue-like Fracture Toughness and Stress\u2013Relaxation Ability in PVA-Agar-Based Hydrogels for Biomedical Applications"],"prefix":"10.3390","volume":"11","author":[{"suffix":"Jr.","given":"Ismael","family":"Lamas","sequence":"first","affiliation":[{"name":"Department of Mechanical Engineering, University of Texas Rio Grande Valley, Edinburg, TX 78539, USA"},{"name":"Biomedical Engineering Program, University of Texas Rio Grande Valley, Edinburg, TX 78539, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bhuvana L.","family":"Chandrashekar","sequence":"additional","affiliation":[{"name":"School of Podiatric Medicine, University of Texas Rio Grande Valley, Edinburg, TX 78539, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4503-3108","authenticated-orcid":false,"given":"Claudia C.","family":"Biguetti","sequence":"additional","affiliation":[{"name":"School of Podiatric Medicine, University of Texas Rio Grande Valley, Edinburg, TX 78539, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1210-6086","authenticated-orcid":false,"given":"Mohammad R.","family":"Islam","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering, University of Texas Rio Grande Valley, Edinburg, TX 78539, USA"},{"name":"Biomedical Engineering Program, University of Texas Rio Grande Valley, Edinburg, TX 78539, USA"},{"name":"Materials Science and Engineering Program, University of Texas Rio Grande Valley, Edinburg, TX 78539, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,9,17]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"44","DOI":"10.1179\/1743280413Y.0000000022","article-title":"Mechanical characterisation of hydrogel materials","volume":"59","author":"Oyen","year":"2014","journal-title":"Int. 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