Low Discrimination of Charged Silica Particles at T4 Phage Surfaces
- Corresponding Author:
- Brook MA
Department of Chemistry
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Received Date: June 19, 2015; Accepted Date: September 07, 2015; Published Date: September 09, 2015
Citation: Khan MF, Dong H, Chen Y, Brook MA (2015) Low Discrimination of Charged Silica Particles at T4 Phage Surfaces. Biosens J 4:125. doi:10.4172/2090-4967.1000125
Copyright: © 2015 Khan MF, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Bacteriophages have a variety of interesting properties that can be exploited in biological assays, including high binding specificity for the identification of bioactive molecules, and particularly, their capacity to propagate via bacterial lysis. However, the development of phage-based assays and disinfection devices is hampered by ineffective methods to stabilize and orient the phage in active form. For example, T4 phage, which has an anionic head and cationic tail, binds targets using its tail fibers, hence the adsorption of their tails to a substrate during immobilization, limits the ability of T4 to bind targets. Previously, we demonstrated that T4 phage retains infectivity despite adsorption to large silica particles of anionic or cationic charge. In an effort to better understand this phenomenon, we have instead used silica nanoparticles – much smaller than the phage – to probe the locus of preferential adsorption. Silica nanoparticles (NPs) (10 and 30 nm) were synthesized from tetraethoxysilane (TEOS) using the Stöber process. Charged particles were prepared by mixing appropriate silica dispersions with the cationic polyelectrolyte (PDADMAC), leading to both negative (zeta potential (ζ < -10) and positively charged (ζ > +10) silica surfaces. These particles were mixed with 1.5 × 1010 pfu/ mL T4 (model) phage and analyzed by transmission electron microscopy (TEM). Results show that regardless of the particle concentration, both positively and negatively charged 30 nm particles bind effectively to both head and tail, with a slight preference for the head. No difference between NP associations to head or tail was seen with 10 nm particles, possibly because of their lower charge surface density and smaller size, which can accommodate small features on the phage surface better. The high hydrophilicity of silica facilitates maintenance of phage hydration and, likely, phage mobility, such that orientation is less important for bacterial binding in this system.