# Rod-Like Virus-Based Multiarm Colloidal Molecules

## TL;DR

This paper demonstrates the construction of multiarm colloidal molecules using tip-linking filamentous bacteriophages, with a focus on functionalization, stability, and controlled valency, supported by experimental and theoretical analysis.

## Contribution

It introduces a novel method for creating virus-based multiarm colloidal structures with tunable valency and provides a comprehensive theoretical model matching experimental results.

## Key findings

- Successful formation of stable virus-based colloidal molecules
- Valency controlled by molar excess of components
- Real-time visualization of assembly dynamics

## Abstract

We report on the construction of multiarm colloidal molecules by tip-linking filamentous bacteriophages, functionalized either by biological engineering or chemical conjugation. The affinity for streptavidin of a genetically modified vector phage displaying Strep-tags fused to one end of the viral particle is measured by determining the dissociation constant, Kd. In order to improve both the colloidal stability and the efficiency of the self-assembly process, a biotinylation protocol having a chemical yield higher than 90% is presented to regioselectively functionalize the cystein residues located at one end of the bacteriophages. For both viral systems, a theoretical comparison is performed by developing a quantitative model of the self-assembly and interaction of the modified viruses with streptavidin compounds, which accurately accounts for our experimental results. Multiarm colloidal structures of different valencies are then produced by conjugation of these tip-functionalized viruses with streptavidin activated nanoparticles. We succeed to form stable virus based colloidal molecules, whose number of arms, called valency, is solely controlled by tuning the molar excess. Thanks to a fluorescent labeling of the viral arms, the dynamics of such systems is also presented in real time by fluorescence microscopy.