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Title: Aqueous core colloidosomes with a metal shell
Author: Sun, Qian
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2018
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Colloidosomes are microcapsules whose shells consist of colloid particles, which are coagulated by a stabiliser or fused by sintering. In recent years, they have attracted considerable attention because of their potential applications in a range of industries, such as food, bioreactors and medicine. However, traditional particulate polymer shell colloidosomes leak low molecular weight encapsulated materials due to their intrinsic shell permeability, and this problem will limit their applications in pharmaceutical industries. In this thesis, we report aqueous core colloidosomes coated with a silver or gold shell, which make the capsules impermeable. The shells can be ruptured using ultrasound. The silver shells are prepared by making an aqueous core capsule with a particulate polymer shell and then adding AgNO3, surfactant and L-ascorbic acid to form a second shell. The gold coated colloidosomes are prepared by making an aqueous core capsule with a particulate polymer shell and then adding HAuCl4, surfactant and L-ascorbic acid. We propose to use the metal coated capsules as drug carriers to load an anticancer drug, doxorubicin. After triggering by ultrasound, encapsulated drug, broken fragments and possibly some drug attached on the surface of the capsules may all kill cancer cells. For silver coated colloidosomes, at 10 capsules/cell, they have a low cytotoxicity, showing a cell viability of more than 90% during the first 24 h and more than 60% after 72 h. Increasing the number of capsules, the cytotoxicity of the silver shells increases heavily. Compared with silver ones, the gold shells show less toxicity to cells. We also used the capsules to load an antibiotic kanamycin and triggered to release the drug and kill E.coli. In addition, we set up a targeting model by modifying the colloidosomes using 4,4'-dithiodibutyric acid and attaching them with proteins - rabbit Immunoglobulin G (IgG). Label-free Surface Plasmon Resonance biosensor was used to test the specific targeting of the functional silver or gold shells with rabbit antigen. The results demonstrate that a new type of functional metal coated colloidosome with non-permeability, ultrasound sensitivity and immunoassay targeting could be applied to many medical applications.
Supervisor: Routh, Alex Sponsor: China Scholarship Council
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
Keywords: colloidosomes ; metal shell ; drug delivery