11.2.1 Size/Diameter

Development of bacterial biofilms is a notable procedure, which makes these

deleterious pathogens immune to traditional antibiotic treatment therapies. However,

bacterial adhesion is the underlying phenomenon, which firmly substantiates the

growth of these. Recent studies highlighted the fact that the size plays a notable

effect on the therapeutic interventional property of the nanoparticulate system.

Esfandiari et al. in a novel approach designed Ag-functionalized TiO2 nanotubes,

and the efficacy of this versatile nanostructured system was tested against E. coli

(Esfandiari et al. 2014). The study clearly pointed toward a size-dependent bacteri-

cidal effect of the developed nanoparticulate system. It was found that the nanotubes

having a smaller opening diameter (~100 nm) and AgNPs (~20 nm) produced a

significantly pronounced effect than their larger counterparts.

In another study planned by Pan et al., three nano-Mg (OH)2 slurries of different

morphologies were utilized, and their antibacterial properties were tested on model

E. coli bacteria (Pan et al. 2013). The fact, which came into light from this study, was

the establishment of an inverse relationship between the NPs size and bactericidal

effect. The smaller-sized slurries tend to have a comparatively higher antibacterial

property, while a vice versa phenomenon was observed in case of larger-sized

slurries. The TEM analysis showed no evidence of cellular co-localization of NPs;

however, a breach in cell wall integrity was noticed (Pan et al. 2013). Both the

studies clearly demarcated the importance of particle size in determining the extent

and mechanism of antibacterial property. This size-dependent toxicity can be

explained by the fact that a smaller-sized particle offers a greater surface area to

the volume ratio. This aids in establishing an enhanced contact among the NPs and

bacterial cell wall also as such smaller particles can swiftly translocate themselves

Fig. 11.1 Graphical representation showing varied physicochemical parameters of nanoparticle

and their influence on the bacterial cell

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A. Parmar and S. Sharma