{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,27]],"date-time":"2026-04-27T21:58:59Z","timestamp":1777327139167,"version":"3.51.4"},"reference-count":45,"publisher":"MDPI AG","issue":"5","license":[{"start":{"date-parts":[[2022,4,30]],"date-time":"2022-04-30T00:00:00Z","timestamp":1651276800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"MICRODIGEST project","award":["no. 037716"],"award-info":[{"award-number":["no. 037716"]}]},{"name":"MICRODIGEST project","award":["no. 101003440"],"award-info":[{"award-number":["no. 101003440"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Micromachines"],"abstract":"<jats:p>Polydimethylsiloxane (PDMS) is ubiquitously used in microfluidics. However, PDMS is porous and hydrophobic, potentially leading to small molecule partitioning. Although many studies addressed this issue and suggested surface\/bulk modifications to overcome it, most were not quantitative, did not address which variables besides hydrophobicity governed molecule absorption, and no modification has been shown to completely obviate it. We evaluated qualitatively (confocal microscopy) and quantitatively (fluorescence spectroscopy) the effects of solute\/solvent pairings, concentration, and residence time on molecule partitioning into PDMS. Additionally, we tested previously reported surface\/bulk modifications, aiming to determine whether reduced PDMS hydrophobicity was stable and hindered molecule partitioning. Partitioning was more significant at lower concentrations, with the relative concentration of rhodamine-B at 20 \u00b5M remaining around 90% vs. 10% at 1 \u00b5M. Solute\/solvent pairings were demonstrated to be determinant by the dramatically higher partitioning of Nile-red in a PBS-based solvent as opposed to ethanol. A paraffin coating slightly decreased the partitioning of Nile-red, and a sol\u2013gel modification hindered the rhodamine-B diffusion into the PDMS bulk. However, there was no direct correlation between reduced surface hydrophobicity and molecule partitioning. This work highlighted the need for pre-assessing the absorption of test molecules into the microfluidic substrates and considering alternative materials for fabrication.<\/jats:p>","DOI":"10.3390\/mi13050713","type":"journal-article","created":{"date-parts":[[2022,4,30]],"date-time":"2022-04-30T05:44:07Z","timestamp":1651297447000},"page":"713","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":23,"title":["Partitioning of Small Hydrophobic Molecules into Polydimethylsiloxane in Microfluidic Analytical Devices"],"prefix":"10.3390","volume":"13","author":[{"given":"Patr\u00edcia M.","family":"Rodrigues","sequence":"first","affiliation":[{"name":"International Iberian Nanotechnology Laboratory, Avenida Mestre Jos\u00e9 Veiga, 4715-330 Braga, Portugal"},{"name":"University of Minho, Gualtar Campus, 4710-057 Braga, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0447-5439","authenticated-orcid":false,"given":"Miguel","family":"Xavier","sequence":"additional","affiliation":[{"name":"International Iberian Nanotechnology Laboratory, Avenida Mestre Jos\u00e9 Veiga, 4715-330 Braga, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8971-7301","authenticated-orcid":false,"given":"Victor","family":"Calero","sequence":"additional","affiliation":[{"name":"International Iberian Nanotechnology Laboratory, Avenida Mestre Jos\u00e9 Veiga, 4715-330 Braga, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6637-3462","authenticated-orcid":false,"given":"Lorenzo","family":"Pastrana","sequence":"additional","affiliation":[{"name":"International Iberian Nanotechnology Laboratory, Avenida Mestre Jos\u00e9 Veiga, 4715-330 Braga, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7121-6875","authenticated-orcid":false,"given":"Catarina","family":"Gon\u00e7alves","sequence":"additional","affiliation":[{"name":"International Iberian Nanotechnology Laboratory, Avenida Mestre Jos\u00e9 Veiga, 4715-330 Braga, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2022,4,30]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1224","DOI":"10.1039\/c2lc20982a","article-title":"Engineers are from PDMS-land, Biologists are from Polystyrenia","volume":"12","author":"Berthier","year":"2012","journal-title":"Lab Chip"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"396","DOI":"10.1016\/S0165-9936(99)00176-4","article-title":"Fabrication techniques and materials commonly used for the production of microreactors and micro total analytical systems","volume":"19","author":"McCreedy","year":"2000","journal-title":"TrAC Trends Anal. 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