Cell shape recognition by colloidal cell imprints: energy of the cell-imprint interaction.

Josef Borovička,Vesselin N Paunov,Simeon D Stoyanov

doi:10.1103/physreve.92.032730

Abstract

The results presented in this study are aimed at the theoretical estimate of the interactions between a spherical microbial cell and the colloidal cell imprints in terms of the Derjaguin, Landau, Vervey, and Overbeek (DLVO) surface forces. We adapted the Derjaguin approximation to take into account the geometry factor in the colloidal interaction between a spherical target particle and a hemispherical shell at two different orientations with respect to each other. We took into account only classical DLVO surface forces, i.e., the van der Waals and the electric double layer forces, in the interaction of a spherical target cell and a hemispherical shell as a function of their size ratio, mutual orientation, distance between their surfaces, their respective surface potentials, and the ionic strength of the aqueous solution. We found that the calculated interaction energies are several orders higher when match and recognition between the target cell and the target cell imprint is achieved. Our analysis revealed that the recognition effect of the hemispherical shell towards the target microsphere comes from the greatly increased surface contact area when a full match of their size and shape is produced. When the interaction between the surfaces of the hemishell and the target cell is attractive, the recognition greatly amplifies the attraction and this increases the likelihood of them to bind strongly. However, if the surface interaction between the cell and the imprint is repulsive, the shape and size match makes this interaction even more repulsive and thus decreases the likelihood of binding. These results show that the surface chemistry of the target cells and their colloidal imprints is very important in controlling the outcome of the interaction, while the shape recognition only amplifies the interaction. In the case of nonmonotonous surface-to-surface interaction we discovered some interesting interplay between the effects of shape match and surface chemistry which is discussed in the paper. The results from this study establish the theoretical basis of cell shape recognition by colloidal cell imprints which, combined with cell killing strategies, could lead to an alternative class of cell shape selective antimicrobials, antiviral, and potentially anticancer therapies.

Highlights

Shape-specific recognition of microbial cells has recently been established as a new and growing field with numerous applications, including microbial detection [1,2] and extraction [3] as well as alternative types of colloidal antibodies [4]
We develop a theoretical analysis which represents an extension of the Derjaguin, Landau, Vervey, and Overbeek (DLVO) theory [8,9] which considers the van der Waals and the electric double layer interactions, adapted for the geometry of a spherical target cell interacting with its hemispherical-shell replica
We explored the influence of the ionic strength of the aqueous medium in which the target particles are incubated with the hemishells, and the role of their surface potentials and the separation between them, as well as the size ratio and the orientation of the hemishell and the target cell

Summary

Introduction

Shape-specific recognition of microbial cells has recently been established as a new and growing field with numerous applications, including microbial detection [1,2] and extraction [3] as well as alternative types of colloidal antibodies [4]. Dickert and Hayden [1] used shape recognition of microbes to produce a bioanalytical tool based on patterned solid surfaces with polyurethane and a sol-gel process which imprint the surface of various genera of yeast. A similar approach of immobilizing microbial organisms onto solid surfaces containing the sol-gel imprints was employed by Cohen et al [2] The same principle was used for extraction of bacterial spores on the surfaces of patterned microbeads [3]. We created colloidal particles which are partial imprints of microbial cells [4,7] This was achieved by templating silica on the surface of the target cells followed by their fragmentation and subsequent cell removal by bleaching.

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Conclusion