A study of thermogelling PCL dispersion: Towards an injectable colloidal cell delivery system

UoM administered thesis: Phd

  • Authors:
  • Nur Nabilah Shahidan

Abstract

This thesis present a study of thermo-gelling polycaprolactone (PCL) dispersion which consist of a mixture of PCL microspheres (MSs) and thermo-responsive, graft cationic copolymer. The PCL microspheres are solid or colloidosomes (hollow). This study aims toward an injectable colloidal cell delivery system. The thermo-responsive copolymer used in this study is a new family of cationic graft copolymer. The cationic graft copolymer consisted of cationic poly(N,N-dimethylaminoethyl methacrylate) backbone and poly 2-(2-methoxyethoxy) ethyl methacrylate (PMA) side chains. A series of new cationic graft copolymers were synthesized with different PMA arm length and grafting density. A representative copolymer showed good cell viabililty.The solid PCL MSs were prepared using solvent evaporation method. The MSs were mixed with the thermo-responsive graft copolymer. At room temperature the mixture were liquid-like and gelled at body temperature (37 ˚C). This indicates that the mixture systems were injectable. The injectable route offers a minimal invasive route to fill defect void inside the body. Furthermore, a porous morphology was evident for the mixed gels at 37 ˚C and the porosity could be altered using different composition of the mixed components. The mixed system showed self-healing properties for low volume fraction of PMA. The mixed system particle gel was more ductile in electrolyte but showed similar morphology to the mixed system particle gels prepared in water. This part of the study was carried out using PCL MSs prepared by cetyltrimethylammonium bromide (CTAB) as surfactant. A brief study using polyvinyl alcohol (PVA) as the surfactant showed that the PCL MSs had similar diameter and gel morphology which suggests that the model systems studied using CTAB may be applicable to the PVA system.Microencapsulation attracts interest due to its ability to deliver and control release actives and also its application in many fields. Colloidosomes are one of the microcapsules/microspheres used for microencapsulation. In this study a two step, facile and scaleable colloidosome preparation method was introduced. The PCL colloidosome shell consisted of partially fused small nanoparticles. The PCL colloidosomes were birefringence under cross polarised light due to the stress applied during solvent evaporation. A brief study showed that the mixture system of colloidosomes and thermo-responsive graft copolymer are able to gel at 37 ˚C.

Details

Original languageEnglish
Awarding Institution
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Award date1 Aug 2014