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Proceedings Paper

MS2 bacteriophage as a delivery vessel of porphyrins for photodynamic therapy
Author(s): Brian A. Cohen; Alain E. Kaloyeros; Magnus Bergkvist
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Paper Abstract

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.

Paper Details

Date Published: 10 February 2011
PDF: 7 pages
Proc. SPIE 7886, Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XX, 788614 (10 February 2011); doi: 10.1117/12.875202
Show Author Affiliations
Brian A. Cohen, Univ. at Albany (United States)
Alain E. Kaloyeros, Univ. at Albany (United States)
Magnus Bergkvist, Univ. at Albany (United States)

Published in SPIE Proceedings Vol. 7886:
Optical Methods for Tumor Treatment and Detection: Mechanisms and Techniques in Photodynamic Therapy XX
David H. Kessel; Tayyaba Hasan, Editor(s)

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