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KTH, School of Chemical Science and Engineering (CHE).
2011 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesisAlternative title
Nya miceller för läkemedelsfrisättning (Swedish)
Abstract [en]

In this study, two families of amphiphilic block copolymers were synthesized with different block length. The polymer copolymers are PVP-PCL and PEG-PCL. For each family three copolymers were made with variation in the length of the PCL block, thus the length ratios were label using the following composition: 1-2000-2000 g/mol, 2-2000-4000 g/mol and 3-2000-6000 g/mol. In the synthesis of PVP-PCL copolymers, PVP end-capped in ε-Caprolactone was synthesized by free radical polymerization; then the copolymer was synthesized by ring opening polymerization of ε-Caprolactone using BuLi as initiator. In the case of PEG-PCL copolymers, mPEG (Mn=2000 g/mol) was used as a co-monomer and the process was done by ring opening polymerization of ε-Caprolactone in the presence of Sn(Otc)2.The copolymers were characterized by SEC and the molecular structure confirmed using 1H-NMR. Knowing that amphiphilic block copolymers can form micelles at certain concentration, micellization study was performed by UV-vis spectroscopy. All the copolymers showed micelles formation in deionized water. The micellization process was also tested in buffer solutions with difference in pH, where only PVP-PCL copolymers showed micellar formation. The micelles formation was confirmed by SEM after lyophilization process. Also the size of the micelles was measure by Zetasizer, showing a range size between 100 nm and 500 nm. After studied the micelles features given by all the copolymers, one polymer of each family was chosen for drug loading and further study of release kinetics, based on the efficiency of the formulation. The copolymer chosen were the ones with the highest length of the hydrophobic block. The drug loading was done by direct dissolution method. Two types of drugs were used, SBA and Diflunisal. The drug loading content was 20 % w/w and 50 % w/w. Micelles from the PEG-PCL copolymer could achieve retention till 50 % w/w of drug loaded, whereas micelles from PVP-PCL copolymer only achieved retention of 20 % w/w of the drug. The micelles formation was again confirm by SEM and the micelles size was measure by Zetasizer. The size of the loaded micelles was smaller than the unloaded micelles. The delivery kinetics was study by UV-vis. After lyophilization process, the compound polymer-drug was immersed in PBS to perform the study, examining the delivery of both drugs in each copolymer selected. In the case of micelles from PVP-PCL copolymer, the large amount of drug was release after 9 h in PBS for both Pas. The micelles from PEG-PCL copolymer, showed a difference in release rate for both drugs, 9 h for Diflunisal and 3 h for SBA; the nature of the drug play a role in drug release and thus in drug loading efficiency. Finally, the families investigated seemed to be promising carriers for controlled drug release. In addition, they appeared to be promising formulations as injectable DDS.

Place, publisher, year, edition, pages
Keyword [en]
polymer technology, micelles, drug delivery, copolymers, PCL
National Category
Polymer Technologies
URN: urn:nbn:se:kth:diva-90694OAI: diva2:506052
Subject / course
Polymer Technology
Physics, Chemistry, Mathematics
Available from: 2012-02-27 Created: 2012-02-27 Last updated: 2012-02-27Bibliographically approved

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