Self assembly of star shaped amphiphiles – Opportunities for drug delivery
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Date
2010-09
Authors
Aluko, O.M.
Journal Title
Journal ISSN
Volume Title
Publisher
Department of Pharmaceutics The School of Pharmacy University of London
Abstract
In order to study the influence of branching on the self-assembly of PEG amphiphiles,
polyethylene glycol (PEG)-based star-shaped have been synthesised and studied
as self-assembling systems. Palmitoyl (C16) groups were grafted to 8-armed PEG with differing
degrees of palmitoylation (P8PEG1 & P8PEG4). A novel amphiphilic linear analogue
(HDPEG) was also synthesised with hexadecyl (C16) pendant groups for comparison. These
amphiphiles were characterised using 1H Nuclear Magnetic Resonance, Fourier Transform-
Infrared and MALDI-TOF mass spectroscopy. The Pyrene probe was employed to evaluate self
assembly properties while Photon Correlation Spectroscopy was used to measure particle size
distribution. Molecular architecture and hydrophobic substitution had a profound effect on their
self-assembly behavior; as P8PEG4 with branched architecture and the greatest degree of
hydrophobic substitution had the lowest polydispersity index. Also, the critical micellar
concentration (CMC) for P8PEG4, P8PEG1 and HDPEG were 3, 8 and 15 μM respectively,
inferring greater micelle stability with branched architecture and increased hydrophobic
substitution. Particle size and morphology were confirmed by Transmission electron
microscopy as P8PEG4 and HDPEG formed mixtures of micelles and nanoparticles while a novel core-shell nano- and micro self assembly was observed for P8PEG1. Preliminary drug encapsulation studies on the amphiphiles loaded low amounts of Griseofulvin (0.04-0.09mg/ml with 5mg/ml of polymers). These resulting stable aggregates of PEG-based amphiphiles may be of benefit for drug delivery applications. However, future studies should focus on influence of polymer architecture on drug encapsulation in order to improve their encapsulation
efficiency.
Description
A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Drug Delivery, University of London
Keywords
PEG amphiphiles , Amphiphiles , Polyethylene glycol (PEG) , Encapsulation , Research Subject Categories::PHARMACY
Citation
Aluko, O.M. (2010). Self assembly of star shaped amphiphiles – Opportunities for drug delivery. A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Drug Delivery, University of London. 94p.