{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,20]],"date-time":"2025-10-20T10:04:23Z","timestamp":1760954663368},"reference-count":33,"publisher":"Wiley","issue":"8","license":[{"start":{"date-parts":[[2004,8,9]],"date-time":"2004-08-09T00:00:00Z","timestamp":1092009600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Macromolecular Bioscience"],"published-print":{"date-parts":[[2004,8,9]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:p><jats:bold>Summary:<\/jats:bold> The aim of this study was to design new soy protein\u2010based bi\u2010layered co\u2010injection moulded matrix systems aimed to achieve controlled drug delivery. The devices consisted of a drug\u2010free outer layer (skin) and a drug\u2010containing core. The systems overcame the inherent disadvantage of non\u2010linear release associated with diffusion\u2010controlled single\u2010layer matrix devices by providing additional releasing area with time to compensate for the decreasing release rate. As expected, the bi\u2010layer devices presented a significant decrease in drug release rate when compared with a correspondent single layer matrix system. The skin thickness and the degree of crosslinking of the core appeared to be very important tools to tailor the release patterns. Furthermore, due to the amphoteric nature of the soy protein, the developed devices evidenced a pH\u2010dependent behaviour. The mechanisms of drug release were also elucidated at two different pH values: i) pH 5.0, near the isoelectric point of soy (low matrix solubility); and ii) pH 7.4, physiological pH (high matrix solubility). Consequently, changing the release medium from pH 5.0 to pH 7.4 after two hours, led to an abrupt increase in drug release and the devices presented a typical controlled drug delivery profile: slow release\/fast release. These evidences may provide for the development of individual systems with different release onsets that in combination may exhibit drug releases at predetermined times in a pre\u2010programmed way. Another possibility is the production of three\u2010layer devices presenting bimodal release profiles (fast release\/slow release\/fast release) by similar technologies.<\/jats:p><jats:p><jats:boxed-text content-type=\"graphic\" position=\"anchor\"><jats:caption><jats:p>Scanning electron micrograph of a developed bi\u2010layer device.<\/jats:p><\/jats:caption><jats:graphic xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" mimetype=\"image\/jpeg\" position=\"anchor\" specific-use=\"enlarged-web-image\" xlink:href=\"graphic\/mgra001.jpg\"><jats:alt-text>magnified image<\/jats:alt-text><jats:caption><jats:p>Scanning electron micrograph of a developed bi\u2010layer device.<\/jats:p><\/jats:caption><\/jats:graphic><\/jats:boxed-text>\n<\/jats:p>","DOI":"10.1002\/mabi.200300060","type":"journal-article","created":{"date-parts":[[2004,8,9]],"date-time":"2004-08-09T23:05:50Z","timestamp":1092092750000},"page":"795-801","source":"Crossref","is-referenced-by-count":10,"title":["Controlled Delivery Achieved with Bi\u2010Layer Matrix Devices Produced by Co\u2010Injection Moulding"],"prefix":"10.1002","volume":"4","author":[{"given":"Cl\u00e1udia M.","family":"Vaz","sequence":"first","affiliation":[]},{"given":"Patrick F. 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