Challenges associated with photodynamic therapy (PDT) include the packaging and site-specific delivery of therapeutic
agents to the tissue of interest. Nanoscale encapsulation of PDT agents inside targeted virus capsids is a novel concept
for packaging and site-specific targeting. The icosahedral MS2 bacteriophage is one potential candidate for such a
packaging-system. MS2 has a porous capsid with an exterior diameter of ~28 nm where the pores allow small molecules
access to the capsid interior. Furthermore, MS2 presents suitable residues on the exterior capsid for conjugation of
targeting ligands. Initial work by the present investigators has successfully demonstrated RNA-based self-packaging of a
heterocyclic PDT agent (meso-tetrakis(para-N-trimethylanilinium)porphine, TMAP) into the MS2 capsid. Packaging
photoactive compounds in confined spaces could result in energy transfer between the molecules upon photoactivation,
which could in turn reduce the production of radical oxygen species (ROS). ROS are key components in photodynamic
therapy, and a reduced production could negatively impact the efficacy of PDT treatment. Here, findings are presented
from an investigation of ROS generation of TMAP encapsulated within the MS2 capsid compared to free TMAP in
solution. Monitoring of ROS production upon photoactivation via a specific singlet oxygen assay revealed the impact on
ROS generation between packaged porphyrins as compared to free porphyrin in an aqueous solution. Follow on work
will study the ability of MS2-packaged porphyrins to generate ROS in vitro and subsequent cytotoxic effects on cells in
culture.
This project comprises the development of a novel polymeric BioMEMS device capable of rapidly detecting FIV in a
minimally invasive manner. FIV severely inhibits the infected feline from mounting an immune response, and causes
susceptibility to other types of diseases. Vaccines against FIV do exist, but have some strong limitations to their
effectiveness; so early detection is the best method to combat the spread of the disease. Current testing methods look for
antibodies to the FIV protein p24 in feline blood using established Enzyme Linked ImmunoSorbent Assay (ELISA)
protocols. The focus of this research is to design and construct a device that can detect antibodies to p24 in a salivary
sample by non-intrusive electrochemical means. The device is constructed upon a silicon substrate with gold
microelectrodes coated with polypyrrole (PPy), an electrically conducting and biocompatible polymer. In the current
phase of the research, the PPy deposition process has been optimized with regards to film thickness, uniformity and
conductivity. Microfluidic channels have been fabricated using SU-8, an epoxy based polymer that enables the test
sample and other solutions to pass freely through the device. The PPy will be coated with anti-FIV p24 antibodies that
can capture FIV p24 antigens present in a salivary sample. Future research will involve the analysis of PPy/antibody
interaction and its effect on functionality. The capture of such antigens will interfere with a reduction-oxidation (redox)
reaction in a subsequently added ionic solution. This interference will change the characteristic resistance of the solution
yielding a qualitative test for the presence of the viral antigens in the sample and hence determining the occurrence of
infection.
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