Engineering M13 Bacteriophage Nanoplatforms for Diagnostic and Therapeutic Applications

M13 bacteriophage, a naturally monodisperse multifunctional nanostructure, consists of thousands of distinct protein subunits organized in a filamentous viral capsid; 900nm in length and 6nm in diameter. All M13 capsids are amenable to mutation and can be tuned for the binding and nucleation of inorganics and nanoparticles, and for the expression of ligands, functional moieties, and even enzymes. To harness these capabilities for medical imaging and therapy, the author has (i) tailored the assembly of M13 into ultra-short, ‘inho’, phage derived particles, (ii) developed a chlorotoxin (CTX) motif on the M13 p3 capsid to enable phage particle crossing of the blood-brain-barrier and homing to glioblastoma cancer cells, and (iii) built ‘inho’ phage derived transgene cassettes for phage gene delivery in mammalian cells. Tight control over the genetic sequence provided by ‘inho’ phagemids allow production of phage particles ranging in length from 25nm to over 2500nm, as dictated by the length of the packaged DNA. This length control over the phage filament is used to demonstrate the impact of the particle length on the morphology of phage templated metal nanofoams and on the in-vitro and in-vivo tissue trafficking of targeted phage nanocarrriers. An optimal length for enhancing ion transport and active material access in MnOx cathodes is described. Chlorotoxin-phages, conjugate with indocyanine green dye (ICG), are visualized in-vivo in the second window near infrared (SWIR) and home effectively to mouse brain tumor. Ultra-short, 50nm chlorotoxin-phage particles are shown to vastly improve this localization specificity. Additionally, the ‘inho’ phagemid system is engineered to produce ITR-flanked transgene cassettes. Such reporter genes packaged within targeted, cationically modified, ‘inho’ phages are able to transduce liver and brain cancer cells. The closed-ended, single-stranded ‘inho’ phage-derived cassettes have capacity up to 20 kilobases and can be delivered within phage particles as well as non-viral delivery vehicles. Ultimately, therapy or imaging agent carrying, miniaturized, chlorotoxin-targeted, M13 phage is considered here as a complete nanotheranostic platform that could augment the therapeutic efficacy of combination drugs shuttled to the site of glioma. The described multimodal, nanoplatform is re-designable for applications in nanomaterials, diagnostics, and across disease types.Ph.D