{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,21]],"date-time":"2026-09-21T12:06:50Z","timestamp":1789992410213,"version":"4.0.1"},"reference-count":32,"publisher":"MDPI AG","issue":"18","license":[{"start":{"date-parts":[[2026,9,20]],"date-time":"2026-09-20T00:00:00Z","timestamp":1789862400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Polymers"],"abstract":"<jats:p>Polyethylene terephthalate glycol (PETG) is a versatile thermoplastic widely used in food packaging and biomedical applications owing to its excellent mechanical properties, chemical resistance, biocompatibility, and ease of processing. Porosity is a critical design parameter that governs the biological and mechanical performance of 3D-printed PETG structures by influencing cell attachment, nutrient transport, mechanical integrity, and microbial interactions. In this study, PETG scaffolds were fabricated at five nominal infill densities (20%, 40%, 60%, 80%, and 100%) using fused deposition modelling (FDM) to investigate the influence of printing-defined architecture on mechanical performance and bacterial colonization. Tensile testing revealed that decreasing infill density resulted in a progressive reduction in ultimate tensile strength and Young\u2019s modulus, demonstrating the trade-off between reduced material density and mechanical integrity. Bacterial interactions with the scaffolds were evaluated against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermidis, and Salmonella typhimurium using optical density (OD) and ATP-based viability assays to quantify both planktonic and adherent bacterial populations. The results demonstrated that the influence of scaffold porosity was species-dependent. The results demonstrated species-dependent responses to scaffold architecture. Higher infill densities were generally associated with reduced attachment and metabolic activity for P. aeruginosa, S. epidermidis, and S. typhimurium, whereas E. coli exhibited relatively stable growth and metabolic activity across the tested infill conditions. S. aureus showed an intermediate response, with bacterial attachment and metabolic activity varying according to scaffold architecture. Overall, infill density exerted a greater influence on scaffold-associated bacteria than on planktonic populations, while simultaneously determining the mechanical performance of the printed structures. These findings demonstrate that controlling PETG infill architecture is important for balancing mechanical properties and bacterial colonization and provide design insights for future PETG-based biomedical and food-packaging applications.<\/jats:p>","DOI":"10.3390\/polym18182299","type":"journal-article","created":{"date-parts":[[2026,9,21]],"date-time":"2026-09-21T11:05:53Z","timestamp":1789988753000},"page":"2299","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Influence of Infill Density on Bacterial Colonization and Mechanical Performance of 3D-Printed PETG Scaffolds"],"prefix":"10.3390","volume":"18","author":[{"given":"Raghad A.","family":"Alabdli","sequence":"first","affiliation":[{"name":"Department of Biological Sciences, Collage of Science, University of Jeddah, Jeddah 21589, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"methodology","vocabulary":"credit"},{"role":"validation","vocabulary":"credit"},{"role":"investigation","vocabulary":"credit"},{"role":"data-curation","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8372-9117","authenticated-orcid":false,"given":"Rewaa S.","family":"Jalal","sequence":"additional","affiliation":[{"name":"Department of Biological Sciences, Collage of Science, University of Jeddah, Jeddah 21589, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"writing-review-editing","vocabulary":"credit"},{"role":"writing-original-draft","vocabulary":"credit"},{"role":"supervision","vocabulary":"credit"}]},{"given":"Abdulrahman A.","family":"Alqarni","sequence":"additional","affiliation":[{"name":"Mechanical Engineering Department, College of Engineering, King Khalid University, Abha 61421, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"methodology","vocabulary":"credit"},{"role":"data-curation","vocabulary":"credit"},{"role":"writing-original-draft","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"},{"role":"software","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0926-8321","authenticated-orcid":false,"given":"Ahmad A.","family":"Basalah","sequence":"additional","affiliation":[{"name":"Mechanical Engineering Department, Collage of Engineering and Architecture, Umm Al-Qura University, Makkah 21955, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"methodology","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"},{"role":"conceptualization","vocabulary":"credit"},{"role":"software","vocabulary":"credit"}]},{"given":"Laila A.","family":"Damiati","sequence":"additional","affiliation":[{"name":"Department of Biological Sciences, Collage of Science, University of Jeddah, Jeddah 21589, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"conceptualization","vocabulary":"credit"},{"role":"methodology","vocabulary":"credit"},{"role":"formal-analysis","vocabulary":"credit"},{"role":"data-curation","vocabulary":"credit"},{"role":"writing-original-draft","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"},{"role":"project-administration","vocabulary":"credit"},{"role":"supervision","vocabulary":"credit"},{"role":"visualization","vocabulary":"credit"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,20]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Valvez, S., Silva, A.P., and Reis, P.N.B. (2022). Optimization of Printing Parameters to Maximize the Mechanical Properties of 3D-Printed PETG-Based Parts. Polymers, 14.","DOI":"10.3390\/polym14132564"},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Hassan, M.H., Omar, A.M., Daskalakis, E., Hou, Y., Huang, B., Strashnov, I., Grieve, B.D., and B\u00e1rtolo, P. (2020). The Potential of Polyethylene Terephthalate Glycol as Biomaterial for Bone Tissue Engineering. Polymers, 12.","DOI":"10.3390\/polym12123045"},{"key":"ref_3","first-page":"45","article-title":"PETG: Applications in Modern Medicine","volume":"5","author":"Yan","year":"2024","journal-title":"Eng. Regen."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"5474","DOI":"10.1016\/j.biomaterials.2005.02.002","article-title":"Porosity of 3D biomaterial scaffolds and osteogenesis","volume":"26","author":"Karageorgiou","year":"2005","journal-title":"Biomaterials"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"485","DOI":"10.1089\/ten.teb.2012.0437","article-title":"Three-Dimensional Scaffolds for Tissue Engineering Applications: Role of Porosity and Pore Size","volume":"19","author":"Loh","year":"2013","journal-title":"Tissue Eng. Part B Rev."},{"key":"ref_6","unstructured":"Garc\u00eda, J.M., Vallejos, S., and Trigo-L\u00f3pez, M. (2024). Chapter 13\u2014Polymers in sensory and lab-on-a-chip devices. Sensory Polymers, Elsevier."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"461","DOI":"10.1016\/j.biomaterials.2009.09.063","article-title":"The effect of mean pore size on cell attachment, proliferation and migration in collagen\u2013glycosaminoglycan scaffolds for bone tissue engineering","volume":"31","author":"Murphy","year":"2010","journal-title":"Biomaterials"},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Damiati, L.A., El-Yaagoubi, M., Damiati, S.A., Kodzius, R., Sefat, F., and Damiati, S. (2022). Role of Polymers in Microfluidic Devices. Polymers, 14.","DOI":"10.3390\/polym14235132"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"1838","DOI":"10.1016\/j.matpr.2020.03.797","article-title":"Effect on infill density on mechanical properties of PETG part fabricated by fused deposition modelling","volume":"27","author":"Srinivasan","year":"2020","journal-title":"Mater. Today Proc."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"1027","DOI":"10.1177\/0022034515587690","article-title":"Effects of material properties on bacterial adhesion and biofilm formation","volume":"94","author":"Song","year":"2015","journal-title":"J. Dent. Res."},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Cheng, Y., Feng, G., and Moraru, C.I. (2019). Micro- and Nanotopography Sensitive Bacterial Attachment Mechanisms: A Review. Front. Microbiol., 10.","DOI":"10.3389\/fmicb.2019.00191"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"060801","DOI":"10.1116\/1.5054057","article-title":"Influence of surface topography on bacterial adhesion: A review (Review)","volume":"13","author":"Wu","year":"2018","journal-title":"Biointerphases"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"121263","DOI":"10.1016\/j.biomaterials.2021.121263","article-title":"Materials-driven fibronectin assembly on nanoscale topography enhances mesenchymal stem cell adhesion, protecting cells from bacterial virulence factors and preventing biofilm formation","volume":"280","author":"Damiati","year":"2022","journal-title":"Biomaterials"},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Shilov, S.Y., Rozhkova, Y.A., Markova, L.N., Tashkinov, M.A., Vindokurov, I.V., and Silberschmidt, V.V. (2022). Biocompatibility of 3D-Printed PLA, PEEK and PETG: Adhesion of Bone Marrow and Peritoneal Lavage Cells. Polymers, 14.","DOI":"10.3390\/polym14193958"},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Tektas, S., Thurnheer, T., Eliades, T., Attin, T., and Karygianni, L. (2020). Initial Bacterial Adhesion and Biofilm Formation on Aligner Materials. Antibiotics, 9.","DOI":"10.3390\/antibiotics9120908"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"518","DOI":"10.1038\/nmat1421","article-title":"Porous scaffold design for tissue engineering","volume":"4","author":"Hollister","year":"2005","journal-title":"Nat. Mater."},{"key":"ref_17","first-page":"413","article-title":"3D-printed PETG\/BC scaffolds for bone tissue repair","volume":"12","author":"Daskalakis","year":"2025","journal-title":"Int. J. Bioprint."},{"key":"ref_18","first-page":"15","article-title":"Influence of infill structure shape and density on the mechanical properties of FDM 3D-printed PETG and PETG+ CF materials","volume":"49","year":"2024","journal-title":"Adv. Technol. Mater."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"153rv10","DOI":"10.1126\/scitranslmed.3004528","article-title":"Grainger Biomaterial-associated infection: Locating the finish line in the race for the surface","volume":"4","author":"Busscher","year":"2012","journal-title":"Sci. Transl. Med."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"4368","DOI":"10.1039\/c3sm27705d","article-title":"Bacteria\u2013surface interactions","volume":"9","author":"Tuson","year":"2013","journal-title":"Soft Matter"},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"AlQurashi, R.N., Bataweel, N.M., AlQriqri, M.A., Alqahtani, S.H., Basalah, A.A., and Damiati, L.A. (2025). Three-Dimensional Printed Porous PLA Scaffolds with Dual Functionality: Cell Proliferation Enhancement and Antibacterial Properties. Polymers, 17.","DOI":"10.3390\/polym17141928"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"148","DOI":"10.1108\/13552540110395547","article-title":"Mechanical behavior of acrylonitrile butadiene styrene (ABS) fused deposition materials","volume":"7","author":"Thomas","year":"2001","journal-title":"Exp. Investig. Rapid Prototyp. J."},{"key":"ref_23","first-page":"85","article-title":"Fabrication of a PETG-Based Biocarrier Using Additive Manufacturing for Moving Bed Biofilm Reactor (MBBR) Applications","volume":"1181","author":"Widjaya","year":"2024","journal-title":"Adv. Mat. Res."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"100520","DOI":"10.1016\/j.gsd.2020.100520","article-title":"Geometry of biofilm carriers: A systematic review deciding the best shape and pore size","volume":"12","author":"Yunus","year":"2021","journal-title":"Groundw. Sustain. Dev."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"2667","DOI":"10.1007\/s00784-022-04838-7","article-title":"Surface properties and initial bacterial biofilm growth on 3D-printed oral appliances: A comparative in vitro study","volume":"27","author":"Wuersching","year":"2023","journal-title":"Clin. Oral. Investig."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"e14360","DOI":"10.1111\/1751-7915.14360","article-title":"Three dimensional printed biofilms: Fabrication, design and future biomedical and environmental applications","volume":"17","author":"Lazarus","year":"2024","journal-title":"Microb. Biotechnol."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1112","DOI":"10.1111\/1751-7915.14256","article-title":"Towards the microbial home: An overview of developments in next-generation sustainable architecture","volume":"16","author":"Armstrong","year":"2023","journal-title":"Microb. Biotechnol."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1564","DOI":"10.1021\/acssynbio.9b00192","article-title":"3D Printing for the Fabrication of Biofilm-Based Functional Living Materials","volume":"8","author":"Balasubramanian","year":"2019","journal-title":"ACS Synth. Biol."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"2997","DOI":"10.1021\/acssynbio.1c00290","article-title":"Emergent Biological Endurance Depends on Extracellular Matrix Composition of Three-Dimensionally Printed Escherichia coli Biofilms","volume":"10","author":"Balasubramanian","year":"2021","journal-title":"ACS Synth. Biol."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"881","DOI":"10.3201\/eid0809.020063","article-title":"Biofilms: Microbial life on surfaces","volume":"8","author":"Donlan","year":"2002","journal-title":"Emerg. Infect. Dis."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"8533","DOI":"10.1016\/j.biomaterials.2013.07.089","article-title":"A review of the biomaterials technologies for infection-resistant surfaces","volume":"34","author":"Campoccia","year":"2013","journal-title":"Biomaterials"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"2473","DOI":"10.1089\/ten.tea.2011.0001","article-title":"Scaffold Porosity and Oxygenation of Printed Hydrogel Constructs Affect Functionality of Embedded Osteogenic Progenitors","volume":"17","author":"Fedorovich","year":"2011","journal-title":"Tissue Eng. 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