Bacteriophage t4 nanoparticles as materials in sensor applications: variables that influence their organization and assembly on surfaces

Abstract

Bacteriophage T4 nanoparticles possess characteristics that make them ideal candidates as materials for sensors, particularly as sensor probes. Their surface can be modified, either through genetic engineering or direct chemical conjugation to display functional moieties such as antibodies or other proteins to recognize a specific target. However, in order for T4 nanoparticles to be utilized as a sensor probe, it is necessary to understand and control the variables that determine their assembly and organization on a surface. The aim of this work is to discuss some of variables that we have identified as influencing the behavior of T4 nanoparticles on surfaces. The effect of pH, ionic strength, substrate characteristics, nanoparticle concentration and charge was addressed qualitatively using atomic force microscopy (AFM).

Keywords: atomic force microscopy; bacteriophage T4; sensors.

Figure 1.

Schematic representation of A) bacteriophage T4 with all its native structures (capsid, tail, whiskers and tail fibers) and B) the non-infectious functional T4 nanoparticle decorated with a capture moiety resulting from genetic engineering of the wild type bacteriophage T4.

Figure 2.

Schematic representation of a sensor surface which utilizes functional T4 nanoparticles as biorecognition elements. The detection of the target could be done through optical or electrical transduction.

Figure 3.

Atomic force microscopy (AFM) topographical images of T4 nanoparticles deposited on aminosilanized glass. In each case a 1:50 dilution from the stock solution was made in 10 mM Tris-HCl at pH a) 5.6, b) 7.5 and c) 8.8.

Figure 4.

Atomic force microscopy (AFM) topographical images of T4 nanoparticles deposited at a 1:10 dilution in 10 mM Tris-HCl at pH 8.8 on a) bare (clean) glass, b) aminosilanized glass and c) freshly cleaved mica.

Figure 5.

Atomic force microscopy (AFM) topographical images of T4 nanoparticles deposited on aminosilanized glass with a) no dilution, b) 1:1 dilution in 10 mM Tris-HCl at pH 8.8 and c) 1:50 dilution in 10 mM Tris-HCl at pH 8.8.

Figure 6.

Atomic force microscopy (AFM) topographical images of poly(ethylene glycol) (PEG) derivatized (a and c) and a reference unmodified T4 nanoparticles on mica (b and d). The same nanoparticles concentration was used in both conditions.