{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,16]],"date-time":"2026-10-16T05:55:27Z","timestamp":1792130127708,"version":"4.4.0"},"reference-count":35,"publisher":"American Chemical Society (ACS)","issue":"29","license":[{"start":{"date-parts":[[2026,7,14]],"date-time":"2026-07-14T00:00:00Z","timestamp":1783987200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100004410","name":"T?rkiye Bilimsel ve Teknolojik Arastirma Kurumu","doi-asserted-by":"publisher","id":[{"id":"10.13039\/501100004410","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,7,28]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>Microneedles (MNs) provide a minimally invasive substitute for hypodermic injections, making them a revolutionary breakthrough in transdermal medication delivery. However, high prices and geometric limitations frequently restrict traditional fabrication techniques like micromolding. This work investigates the use of high-precision vat photopolymerization 3D printing to create hydrogel-forming microneedle arrays from poly(vinyl alcohol) (PVA). By modification of PVA with methacrylic anhydride to methacrylated PVA (MPVA) and using lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP) as a biocompatible photoinitiator, we created a photo-cross-linkable bioink. This study examined the effects of three different UV light exposure periods (30, 50, and 70 s) on the mechanical integrity, thermal stability, and morphological fidelity of the MPVA MNs in order to optimize the photopolymerization kinetics. The effective grafting of methacrylate groups onto the PVA backbone was verified by chemical analysis using FT-IR and NMR spectroscopies. A crucial trade-off was discovered by mechanical compression testing and scanning electron microscopy (SEM): while short exposure intervals (30 s) produced sharp but mechanically brittle structures, lengthy exposure times (70 s) produced strong but geometrically dull needles. The best processing window was found to be 50 s, which produced microneedles with enough mechanical stiffness. These results were further supported by differential scanning calorimetry (DSC), which demonstrated that longer exposure times improve the cross-linking density and heat stability of the polymer network. Parafilm-based insertion testing confirmed the functional penetration capability of MPVA-50 arrays, validating the optimized exposure condition as suitable for transdermal application These findings show that Vat photopolymerization printing of MPVA is a reliable, scalable, and adjustable technique for creating transdermal delivery systems.<\/jats:p>","DOI":"10.1021\/acsomega.6c04499","type":"journal-article","created":{"date-parts":[[2026,7,14]],"date-time":"2026-07-14T09:34:34Z","timestamp":1784021674000},"page":"44284-44293","source":"Crossref","is-referenced-by-count":1,"title":["Influence of Light Exposure Time on the Vat Photopolymerization\nof Methacrylated PVA Microneedles"],"prefix":"10.1021","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0009-0007-9910-3112","authenticated-orcid":true,"given":"Kaan","family":"Danis","sequence":"first","affiliation":[{"name":"Yildiz Technical University , , ,","place":["Istanbul, Turkey, 34210"]},{"name":"Yildiz Technical University , , ,","place":["Istanbul, Turkey, 34349"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sule","family":"Ilgar","sequence":"additional","affiliation":[{"name":"Yildiz Technical University , , ,","place":["Istanbul, Turkey, 34210"]},{"name":"Yildiz Technical University , , ,","place":["Istanbul, Turkey, 34349"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shhd","family":"Saraj","sequence":"additional","affiliation":[{"name":"Yildiz Technical University , , ,","place":["Istanbul, Turkey, 34210"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4435-7776","authenticated-orcid":true,"given":"Murat","family":"Topuzogullari","sequence":"additional","affiliation":[{"name":"Yildiz Technical University , , ,","place":["Istanbul, Turkey, 34210"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Oguzhan","family":"Gunduz","sequence":"additional","affiliation":[{"name":"Marmara University , , ,","place":["Istanbul, Turkey, 34854"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4439-0878","authenticated-orcid":true,"given":"Cem Bulent","family":"Ustundag","sequence":"additional","affiliation":[{"name":"Yildiz Technical University , , ,","place":["Istanbul, Turkey, 34210"]},{"name":"Yildiz Technical University , , ,","place":["Istanbul, Turkey, 34349"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"316","published-online":{"date-parts":[[2026,7,14]]},"reference":[{"key":"2026072810100767300_cit1","doi-asserted-by":"publisher","first-page":"1249","DOI":"10.1016\/j.biopha.2018.10.078","article-title":"Microneedles: A smart approach and increasing potential\nfor transdermal drug delivery system","volume":"109","author":"Waghule","year":"2019","journal-title":"Biomed.\nPharmacother."},{"key":"2026072810100767300_cit2","doi-asserted-by":"publisher","first-page":"2815","DOI":"10.3390\/polym13162815","article-title":"A Comprehensive\nReview of Microneedles:\nTypes, Materials, Processes, Characterizations and Applications","volume":"13","author":"Aldawood","year":"2021","journal-title":"Polymers"},{"key":"2026072810100767300_cit3","doi-asserted-by":"publisher","first-page":"320","DOI":"10.3390\/macromol4020019","article-title":"Microneedles\u2019\nDevice: Design, Fabrication, and Applications","volume":"4","author":"Oliveira","year":"2024","journal-title":"Macromol"},{"key":"2026072810100767300_cit4","doi-asserted-by":"publisher","first-page":"569","DOI":"10.3390\/pharmaceutics12060569","article-title":"Microneedle-Based Delivery:\nAn Overview\nof Current Applications and Trends","volume":"12","author":"Guillot","year":"2020","journal-title":"Pharmaceutics"},{"key":"2026072810100767300_cit5","doi-asserted-by":"publisher","first-page":"1607210","DOI":"10.3389\/fphar.2025.1607210","article-title":"Advances in clinical\napplications of microneedle","volume":"16","author":"Chen","year":"2025","journal-title":"Front. Pharmacol."},{"key":"2026072810100767300_cit6","doi-asserted-by":"publisher","first-page":"909","DOI":"10.1007\/s12551-025-01317-7","article-title":"Recent\nadvances and perspectives of MicroNeedles\nfor biomedical applications","volume":"17","author":"Maia","year":"2025","journal-title":"Biophys. Rev."},{"key":"2026072810100767300_cit7","doi-asserted-by":"publisher","first-page":"33312","DOI":"10.1039\/D5RA05275K","article-title":"Evolving transdermal\ntherapeutics: a review on self-dissolving polymeric microneedles via\n3D printing","volume":"15","author":"Madhusoodanan","year":"2025","journal-title":"RSC Adv"},{"key":"2026072810100767300_cit8","doi-asserted-by":"publisher","first-page":"1433","DOI":"10.3390\/mi15121433","article-title":"Advancements in Materials for 3D-Printed\nMicroneedle Arrays: Enhancing Performance and Biocompatibility","volume":"15","author":"Razzaghi","year":"2024","journal-title":"Micromachines"},{"key":"2026072810100767300_cit9","doi-asserted-by":"publisher","first-page":"1157541","DOI":"10.3389\/fbioe.2023.1157541","article-title":"Fabrication\nand optimization of 3D printed gelatin\nmethacryloyl microneedle arrays based on vat photopolymerization","volume":"11","author":"Baykara","year":"2023","journal-title":"Front. Bioeng. Biotechnol."},{"key":"2026072810100767300_cit10","doi-asserted-by":"publisher","first-page":"101700","DOI":"10.1016\/j.mtla.2023.101700","article-title":"Innovative transdermal drug delivery system\nbased on amoxicillin-loaded gelatin methacryloyl microneedles obtained\nby 3D printing","volume":"27","author":"Erkus","year":"2023","journal-title":"Materialia"},{"key":"2026072810100767300_cit11","doi-asserted-by":"publisher","first-page":"6025","DOI":"10.1021\/acsabm.5c00621","article-title":"Digital Light Processing of Methacrylated Silk Fibroin\nMicroneedles: Precision Engineering for Enhanced Transdermal Delivery\nand Skin Regeneration","volume":"8","author":"Tong","year":"2025","journal-title":"ACS Appl. Bio Mater."},{"key":"2026072810100767300_cit12","doi-asserted-by":"publisher","first-page":"125800","DOI":"10.1016\/j.ijpharm.2025.125800","article-title":"HAMA\/GelMA-based\nhydrogel\nmicroneedle patch via DLP 3D bioprinting for high-efficiency ISF extraction","volume":"680","author":"Zhang","year":"2025","journal-title":"Int. J. Pharm."},{"key":"2026072810100767300_cit13","doi-asserted-by":"publisher","first-page":"25179","DOI":"10.1021\/acsomega.2c01993","article-title":"Fabrication\nof a PVA-Based Hydrogel\nMicroneedle Patch","volume":"7","author":"Oh","year":"2022","journal-title":"ACS Omega"},{"key":"2026072810100767300_cit14","doi-asserted-by":"publisher","first-page":"436","DOI":"10.1007\/s13346-024-01679-7","article-title":"3D printed\nmicroneedles: revamping transdermal drug delivery systems","volume":"15","author":"Prabhu","year":"2025","journal-title":"Drug Delivery Transl. Res."},{"key":"2026072810100767300_cit15","doi-asserted-by":"publisher","first-page":"2074","DOI":"10.3390\/polym14102074","article-title":"A Review on Modeling\nCure Kinetics and Mechanisms of Photopolymerization","volume":"14","author":"Lang","year":"2022","journal-title":"Polymers"},{"key":"2026072810100767300_cit16","doi-asserted-by":"publisher","first-page":"397","DOI":"10.1016\/j.jmbbm.2014.09.015","article-title":"Monitoring\nthe penetration process of single microneedles with varying tip diameters","volume":"40","author":"Ro\u0308mgens","year":"2014","journal-title":"J. Mech. Behav. Biomed. Mater."},{"key":"2026072810100767300_cit17","doi-asserted-by":"publisher","first-page":"1837","DOI":"10.3390\/pharmaceutics13111837","article-title":"Optimization of\nPrinting Parameters for Digital Light Processing 3D Printing of Hollow\nMicroneedle Arrays","volume":"13","author":"Mathew","year":"2021","journal-title":"Pharmaceutics"},{"key":"2026072810100767300_cit18","doi-asserted-by":"publisher","first-page":"034101","DOI":"10.1088\/1758-5090\/aac00c","article-title":"Bio-resin\nfor high resolution lithography-based\nbiofabrication of complex cell-laden constructs","volume":"10","author":"Lim","year":"2018","journal-title":"Biofabrication"},{"key":"2026072810100767300_cit19","doi-asserted-by":"publisher","first-page":"531","DOI":"10.3390\/gels8090531","article-title":"Fabrication\nof Thermo-Responsive\nControllable Shape-Changing Hydrogel","volume":"8","author":"Luo","year":"2022","journal-title":"Gels"},{"key":"2026072810100767300_cit20","doi-asserted-by":"publisher","first-page":"1459","DOI":"10.1002\/app.31677","article-title":"Rheological behaviors\nof PVA\/H2O solutions of high-polymer concentration","volume":"116","author":"Gao","year":"2010","journal-title":"J. Appl. Polym. Sci."},{"key":"2026072810100767300_cit21","doi-asserted-by":"publisher","first-page":"2439","DOI":"10.1021\/bm049654g","article-title":"Study of Gelling\nBehavior of Poly(vinyl alcohol)-Methacrylate for Potential Utilizations\nin Tissue Replacement and Drug Delivery","volume":"5","author":"Cavalieri","year":"2004","journal-title":"Biomacromolecules"},{"key":"2026072810100767300_cit22","doi-asserted-by":"publisher","first-page":"1157","DOI":"10.3390\/mi14061157","article-title":"The Effect of 3D Printing Tilt Angle on the Penetration\nof 3D-Printed Microneedle Arrays","volume":"14","author":"Razzaghi","year":"2023","journal-title":"Micromachines"},{"key":"2026072810100767300_cit23","doi-asserted-by":"publisher","first-page":"1971","DOI":"10.1016\/j.tiv.2010.08.012","article-title":"Effects of microneedle length, density, insertion time\nand multiple applications on human skin barrier function: Assessments\nby transepidermal water loss","volume":"24","author":"Gomaa","year":"2010","journal-title":"Toxicol. In Vitro"},{"key":"2026072810100767300_cit24","unstructured":"Ebrahiminejad, V.\n          \n          Design and\nfabrication of microneedle patches, microblades and featured insertion\napplicator for optimising transdermal drug delivery. Ph.D.\nThesis, University of Southern Queensland, Toowoomba, Australia, 2023."},{"key":"2026072810100767300_cit25","doi-asserted-by":"publisher","first-page":"2101856","DOI":"10.1002\/admi.202101856","article-title":"Microneedle\nArrays for Drug Delivery and Diagnostics: Toward an Optimized Design,\nReliable Insertion, and Penetration","volume":"9","author":"Ebrahiminejad","year":"2022","journal-title":"Adv. Mater.\nInterfaces"},{"key":"2026072810100767300_cit26","doi-asserted-by":"publisher","first-page":"1155","DOI":"10.1016\/j.jbiomech.2003.12.010","article-title":"Insertion\nof microneedles into skin: measurement and prediction of insertion\nforce and needle fracture force","volume":"37","author":"Davis","year":"2004","journal-title":"J. Biomech."},{"key":"2026072810100767300_cit27","doi-asserted-by":"publisher","first-page":"1426","DOI":"10.3390\/polym13091426","article-title":"Study on\nStructure, Thermal Behavior, and Viscoelastic Properties of Nanodiamond-Reinforced\nPoly (vinyl alcohol) Nanocomposites","volume":"13","author":"Remis\u030c","year":"2021","journal-title":"Polymers"},{"key":"2026072810100767300_cit28","doi-asserted-by":"publisher","first-page":"826","DOI":"10.1039\/C2SM26763B","article-title":"The role of crystallization and phase\nseparation in the formation of physically cross-linked PVA hydrogels","volume":"9","author":"Holloway","year":"2013","journal-title":"Soft Matter"},{"key":"2026072810100767300_cit29","doi-asserted-by":"publisher","first-page":"295","DOI":"10.3390\/jcs8080295","article-title":"Effect of\nPhoto-Crosslinking Conditions on Thermal Conductivity of Photo-Curable\nLadder-like Polysilsesquioxane\u2013Al2O3 Nanocomposites","volume":"8","author":"Romeo","year":"2024","journal-title":"J. Compos. Sci."},{"key":"2026072810100767300_cit30","doi-asserted-by":"publisher","first-page":"2300214","DOI":"10.1002\/marc.202300214","article-title":"Initiator-Free\nPhotocuring 3D-Printable PVA-Based Hydrogel\nwith Tunable Mechanical Properties and Cell Compatibility","volume":"44","author":"Li","year":"2023","journal-title":"Macromol. Rapid Commun."},{"key":"2026072810100767300_cit31","doi-asserted-by":"crossref","unstructured":"Scheiger, J. M., Levkin, P. A.\n          Hydrogels with\nPreprogrammable Lifetime via UV-Induced Polymerization and Degradation\n2020. https:\/\/advanced.onlinelibrary.wiley.com\/doi\/full\/10.1002\/adfm.201909800 (accessed February 21, 2026).","DOI":"10.1002\/adfm.201909800"},{"key":"2026072810100767300_cit32","doi-asserted-by":"publisher","first-page":"3986","DOI":"10.1007\/s13346-025-01888-8","article-title":"Assessing the integrity\nand mechanical properties of commercial microneedles: innovation or\nfad?","volume":"15","author":"Lee","year":"2025","journal-title":"Drug Delivery Transl. Res."},{"key":"2026072810100767300_cit33","doi-asserted-by":"publisher","first-page":"2439","DOI":"10.1021\/bm049654g","article-title":"Study of Gelling\nBehavior of Poly(vinyl alcohol)-Methacrylate for Potential Utilizations\nin Tissue Replacement and Drug Delivery","volume":"5","author":"Cavalieri","year":"2004","journal-title":"Biomacromolecules"},{"key":"2026072810100767300_cit34","doi-asserted-by":"publisher","first-page":"3","DOI":"10.1038\/s41378-024-00850-x","article-title":"Micro-vibration assisted dual-layer spiral microneedles\nto rapidly extract dermal interstitial fluid for minimally invasive\ndetection of glucose","volume":"11","author":"Saifullah","year":"2025","journal-title":"Microsyst. Nanoeng."},{"key":"2026072810100767300_cit35","doi-asserted-by":"publisher","first-page":"1322","DOI":"10.3390\/mi16121322","article-title":"Pump-Free Insulin Delivery via an\nSLA-Printed Hollow Microneedle\nPatch with an Integrated Self-Sealing Reservoir","volume":"16","author":"Smith","year":"2025","journal-title":"Micromachines"}],"container-title":["ACS Omega"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/pubs.acs.org\/doi\/pdf\/10.1021\/acsomega.6c04499","content-type":"application\/pdf","content-version":"vor","intended-application":"unspecified"},{"URL":"https:\/\/pubs.acs.org\/acsodf\/article-pdf\/11\/29\/44284\/65901577\/acsomega.6c04499.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/pubs.acs.org\/acsodf\/article-pdf\/11\/29\/44284\/65901577\/acsomega.6c04499.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,7,28]],"date-time":"2026-07-28T14:40:54Z","timestamp":1785249654000},"score":1,"resource":{"primary":{"URL":"https:\/\/pubs.acs.org\/acsodf\/article\/11\/29\/44284\/5207825\/Influence-of-Light-Exposure-Time-on-the-Vat"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,7,14]]},"references-count":35,"journal-issue":{"issue":"29","published-online":{"date-parts":[[2026,7,14]]},"published-print":{"date-parts":[[2026,7,28]]}},"URL":"https:\/\/doi.org\/10.1021\/acsomega.6c04499","relation":{},"ISSN":["2470-1343"],"issn-type":[{"value":"2470-1343","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,7,14]]}}}