{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,28]],"date-time":"2026-03-28T09:23:59Z","timestamp":1774689839223,"version":"3.50.1"},"reference-count":49,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2020,4,18]],"date-time":"2020-04-18T00:00:00Z","timestamp":1587168000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","doi-asserted-by":"publisher","award":["UIDB\/50006\/2020"],"award-info":[{"award-number":["UIDB\/50006\/2020"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","doi-asserted-by":"publisher","award":["PD\/BD\/128398\/2017"],"award-info":[{"award-number":["PD\/BD\/128398\/2017"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","doi-asserted-by":"publisher","award":["SFRH\/BD\/97540\/2013"],"award-info":[{"award-number":["SFRH\/BD\/97540\/2013"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","doi-asserted-by":"publisher","award":["SFRH\/BD\/130948\/2017"],"award-info":[{"award-number":["SFRH\/BD\/130948\/2017"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","doi-asserted-by":"publisher","award":["UID\/AMB\/50017\/2019"],"award-info":[{"award-number":["UID\/AMB\/50017\/2019"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001871","name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia","doi-asserted-by":"publisher","award":["LISBOA-01-0145-FEDER-402-022125"],"award-info":[{"award-number":["LISBOA-01-0145-FEDER-402-022125"]}],"id":[{"id":"10.13039\/501100001871","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia and Minist\u00e9rio da Ci\u00eancia","award":["CEECIND\/01620\/2017"],"award-info":[{"award-number":["CEECIND\/01620\/2017"]}]},{"name":"Funda\u00e7\u00e3o para a Ci\u00eancia e a Tecnologia and Minist\u00e9rio da Ci\u00eancia","award":["UID\/QUI\/00062\/2019"],"award-info":[{"award-number":["UID\/QUI\/00062\/2019"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>The evaluation of encapsulation efficiency is a regulatory requirement for the characterization of drug delivery systems. However, the difficulties in efficiently separating nanomedicines from the free drug may compromise the achievement of accurate determinations. Herein, ultrafiltration was exploited as a separative strategy towards the evaluation of methotrexate (MTX) encapsulation efficiency in nanostructured lipid carriers and polymeric nanoparticles. The effect of experimental conditions such as pH and the amount of surfactant present in the ultrafiltration media was addressed aiming at the selection of suitable conditions for the effective purification of nanocarriers. MTX-loaded nanoparticles were then submitted to ultrafiltration and the portions remaining in the upper compartment of the filtering device and in the ultrafiltrate were collected and analyzed by HPLC-UV using a reversed-phase (C18) monolithic column. A short centrifugation time (5 min) was suitable for establishing the amount of encapsulated MTX in nanostructured lipid carriers, based on the assumption that the free MTX concentration was the same in the upper compartment and in the ultrafiltrate. The defined conditions allowed the efficient separation of nanocarriers from the free drug, with recoveries of &gt;85% even when nanoparticles were present in cell culture media and in pig skin surrogate from permeation assays.<\/jats:p>","DOI":"10.3390\/molecules25081879","type":"journal-article","created":{"date-parts":[[2020,4,21]],"date-time":"2020-04-21T05:48:52Z","timestamp":1587448132000},"page":"1879","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":33,"title":["Insights on Ultrafiltration-Based Separation for the Purification and Quantification of Methotrexate in Nanocarriers"],"prefix":"10.3390","volume":"25","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-4386-850X","authenticated-orcid":false,"given":"Sara S.","family":"Marques","sequence":"first","affiliation":[{"name":"LAQV, REQUIMTE, Departamento de Ci\u00eancias Qu\u00edmicas, Faculdade de Farm\u00e1cia, Universidade do Porto, Rua de Jorge Viterbo Ferreira n 228, 4050-313 Porto, Portugal"}]},{"given":"In\u00eas I.","family":"Ramos","sequence":"additional","affiliation":[{"name":"LAQV, REQUIMTE, Departamento de Ci\u00eancias Qu\u00edmicas, Faculdade de Farm\u00e1cia, Universidade do Porto, Rua de Jorge Viterbo Ferreira n 228, 4050-313 Porto, Portugal"}]},{"given":"Sara R.","family":"Fernandes","sequence":"additional","affiliation":[{"name":"LAQV, REQUIMTE, Departamento de Ci\u00eancias Qu\u00edmicas, Faculdade de Farm\u00e1cia, Universidade do Porto, Rua de Jorge Viterbo Ferreira n 228, 4050-313 Porto, Portugal"},{"name":"Escola Superior de Sa\u00fade, Instituto Polit\u00e9cnico do Porto, 4200-072 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3481-5809","authenticated-orcid":false,"given":"Luisa","family":"Barreiros","sequence":"additional","affiliation":[{"name":"LAQV, REQUIMTE, Departamento de Ci\u00eancias Qu\u00edmicas, Faculdade de Farm\u00e1cia, Universidade do Porto, Rua de Jorge Viterbo Ferreira n 228, 4050-313 Porto, Portugal"},{"name":"Escola Superior de Sa\u00fade, Instituto Polit\u00e9cnico do Porto, 4200-072 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8777-5877","authenticated-orcid":false,"given":"Sofia A. C.","family":"Lima","sequence":"additional","affiliation":[{"name":"LAQV, REQUIMTE, Departamento de Ci\u00eancias Qu\u00edmicas, Faculdade de Farm\u00e1cia, Universidade do Porto, Rua de Jorge Viterbo Ferreira n 228, 4050-313 Porto, Portugal"}]},{"given":"Salette","family":"Reis","sequence":"additional","affiliation":[{"name":"LAQV, REQUIMTE, Departamento de Ci\u00eancias Qu\u00edmicas, Faculdade de Farm\u00e1cia, Universidade do Porto, Rua de Jorge Viterbo Ferreira n 228, 4050-313 Porto, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5357-3601","authenticated-orcid":false,"given":"M. Ros\u00e1rio M.","family":"Domingues","sequence":"additional","affiliation":[{"name":"Centro de Espetrometria de Massa, Departamento de Qu\u00edmica &amp; QOPNA, Universidade de Aveiro, Campus Universit\u00e1rio de Santiago, 3810-193 Aveiro, Portugal"},{"name":"Departamento de Qu\u00edmica &amp; CESAM &amp; ECOMARE, Universidade de Aveiro, Campus Universit\u00e1rio de Santiago, 3810-193 Aveiro, Portugal"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2938-0214","authenticated-orcid":false,"given":"Marcela A.","family":"Segundo","sequence":"additional","affiliation":[{"name":"LAQV, REQUIMTE, Departamento de Ci\u00eancias Qu\u00edmicas, Faculdade de Farm\u00e1cia, Universidade do Porto, Rua de Jorge Viterbo Ferreira n 228, 4050-313 Porto, Portugal"}]}],"member":"1968","published-online":{"date-parts":[[2020,4,18]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"263","DOI":"10.1016\/j.ijpharm.2018.01.016","article-title":"Recent trends of nanomedicinal approaches in clinics","volume":"538","author":"Dilnawaz","year":"2018","journal-title":"Int. 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