Chemical Modification Of M13 Bacteriophage And Its Applications

In comparison to conventional synthetic particles, viruses have received particular attention for the development of nanotechnology for the following reasons:(1) they represent robust and well-organized architectures with a broad selection of sizes in the nanometer scale from 10 nm to 200 nm; (2) their three dimensional structures can be resolved at atomic or near-atomic levels; (3) the composition and surface properties of the viruses can be controlled using molecular biology; (4) large scale purification of these viruses was inexpensive; (5) they have propensity to self-assemble into monodisperse nanoparticles of discrete shape and sizes. Benefits by these virtues, viruses have been widely used as scaffolds in the development of novel nanomaterials and medical applications. As the most studied virus, researches about M13 bacteriophage were concentrated on selecting new mutations which have good binding affinity and specificity for essentially any target analyte through a technique called phage display. Based on this technology, a great number of M13 mutations was selected for many interesting applications, such as high-power phage batteries, tissue regenerating materials, metal nanowire catalysts, biological sensors, gene transfer vectors, and targeted cancer therapies. Although phage display is a powerful technology, it relies entirely on peptide expressions and selection. If the needed functionalities were beyond peptides, the genetic tool would fail to address the requirements.Orthogonal bioconjugation techniques have permeated fundamental virus chemistry, decorating addressable amino acids with a variety of molecules ranging from small molecules, such as fluorescent dyes, to large particles, such as quantum dots. In this thesis, M13 bacteriophage was employed as a template for chemical modification studies. In addition, the special applications of modified phage particles have also been addressed. Researches were focused on:1. The stability of M13 bacteriophage in different solvent/water mixtures is monitored, and it is found that in some, non-natural harsh conditions the virus also remained intact. Using M13 bacteriophage as a building block, combining theoretical computation method along with bioconjugation techniques, we have carefully studied the chemical reactivity of three different groups (amine, carboxylic acid, and tyrosine residues) which located on the external surface. Furthermore, the regioselectivity of each reaction was investigated by MALDI-TOF and HPLC-MS-MS. 2. Hundreds of fluorescent moieties and cell targeting motifs such as folic acid could be attached on the external surface of M13 bacteriophage. Such dual-modified M13 particles showed very good binding affinity to human cancer cells, which demonstrated the potential applications of M13 bacteriophage in bioimaging. Furthermore, core-shell nanoparticles could be synthesized by the assembly of Doxorubicin (DOX), poly(2-vinylpyridine-b-caprolactone) (PCL-P2VP) and folate-conjugated M13. The DOX-loaded composite nanoparticles had an average diameter of approximately 220 nm. The release of DOX from the nanoparticle under acidic conditions was shown to be significantly higher than that observed at physiological pH.3. Fibrillar M13 bacteriophages were used as basic building blocks to generate thin films with aligned nanogrooves, which, upon chemical grafting with RGD peptides, guide cell alignment and orient the cell outgrowth along defined directions.