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Elastic forces give rise to unusual phase transformations in polyelectrolyte gels: A Raman microscopy study
Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för läkemedelskemi. (Pharmaceutical Physical Chemistry)
Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Tekniska sektionen, Institutionen för materialvetenskap, Fasta tillståndets fysik.ORCID-id: 0000-0003-2759-7356
Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Farmaceutiska fakulteten, Institutionen för läkemedelskemi. (Pharmaceutical Physical Chemistry)
(engelsk)Manuskript (preprint) (Annet vitenskapelig)
HSV kategori
Forskningsprogram
Farmaceutisk fysikalisk kemi; Farmaceutisk vetenskap; Galenisk farmaci
Identifikatorer
URN: urn:nbn:se:uu:diva-472817OAI: oai:DiVA.org:uu-472817DiVA, id: diva2:1652294
Tilgjengelig fra: 2022-04-18 Laget: 2022-04-18 Sist oppdatert: 2022-04-18
Inngår i avhandling
1. Microgels as drug delivery vehicles: loading and release of amphiphilic drugs
Åpne denne publikasjonen i ny fane eller vindu >>Microgels as drug delivery vehicles: loading and release of amphiphilic drugs
2022 (engelsk)Doktoravhandling, med artikler (Annet vitenskapelig)
Abstract [en]

Polyelectrolyte microgels are used as delivery vehicles for amphiphilic drugs in, e.g., treatments of liver cancer by a method called trans-arterial chemoembolization. The thesis deals with fundamental properties of such delivery systems related to the self-assembling properties of the drug molecules and their interaction with the charged polymer network of the microgel. The main objective was to establish mechanistic models describing the loading and release of drugs under relevant conditions. For that purpose experimental techniques providing thermodynamic, compositional and microstructural information were used to elucidate how the kinetics depend on the stability of the drug self-assemblies and the volume response of the microgels. Micromanipulator-assisted microscopy studies showed that negatively charged microgels phase separated during loading and release of cationic amphiphilic drugs. At intermediate loading levels the drug aggregates and part of the network formed a collapsed phase coexisting with a swollen, drug-lean phase. In particular, during release in a medium of physiological ionic strength, the drug-lean phase formed a depletion layer (shell) surrounding a drug-rich core. Investigations of a series of drugs with different molecular architectures showed that the drug release rate was determined mainly by the stability of the drug aggregates in the core and the diffusive mass transport of drug molecules through the shell. Detailed studies of polyacrylate microgels interacting with amitriptyline hydrochloride showed that swelling of the shell network greatly influenced the release rate. Furthermore, experiments with a specially constructed microscopy cell was used to establish that the collapsed and swollen phases could coexist in equilibrium, and that the swelling of the network in the swollen phase depended on the proportion between them when present in the same microgel. The latter effect was related to the elastic coupling between the phases. Confocal Raman microscopy was employed to demonstrate, for the first time, the related elastic effect, that the concentration of amitriptyline in the swollen phase decreased with increasing proportion of the collapsed phase. Small-angle X-ray scattering showed that the collapsed phase had a disordered microstructure of drug micelles with ellipsoidal shape. The aggregation number increased with increasing concentration of drug in the microgel, most likely by incorporating the uncharged base form. By providing detailed information about thermodynamic properties and microstructures, the results of the thesis provide a basis for rational design of microgel drug delivery systems.

sted, utgiver, år, opplag, sider
Uppsala: Acta Universitatis Upsaliensis, 2022. s. 61
Serie
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Pharmacy, ISSN 1651-6192 ; 312
Emneord
microgel, amphiphilic drug, phase separation, micropipette, Raman microscopy, controlled release, drug delivery, SAXS
HSV kategori
Forskningsprogram
Farmaceutisk fysikalisk kemi
Identifikatorer
urn:nbn:se:uu:diva-472818 (URN)978-91-513-1502-7 (ISBN)
Disputas
2022-06-14, Room A1:111a, BMC, Husargatan 3, Uppsala, 09:15 (engelsk)
Opponent
Veileder
Tilgjengelig fra: 2022-05-17 Laget: 2022-04-18 Sist oppdatert: 2022-06-15

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