# Remodeling and self-healing of individual amyloid tactoids via multiphoton absorption

## TL;DR

This paper introduces a method to precisely control and reshape individual amyloid tactoids using light, enabling self-healing and information storage at the sub-micron level.

## Contribution

A stimuli-responsive photothermal technique for reversible structural control of colloidal tactoids at sub-micron resolution.

## Key findings

- Amyloid tactoids can be cut, ablated, and self-healed using multiphoton absorption.
- Structural information can be printed, erased, and stored within individual tactoids.
- Hybrid tactoids can be re-modeled into new structures with different functionalities.

## Abstract

Colloidal self-assembly can typically be controlled only globally, at \documentclass[12pt]{minimal}
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\begin{document}$$\ge$$\end{document}≥101 μm scale, such as in liquid-liquid crystalline phase separation (LLCPS) of anisotropic tactoidal droplets. Here, we introduce a stimuli-responsive approach allowing a fully reversible structural control of LLCPS morphologies at the individual droplet level. Using amyloid-based tactoids and multiphoton absorption with localized photothermal effect, we can cut, ablate, and self-heal individual tactoids, and -when desired- print, erase, and store structural information within at sub-micron resolution. We exploit the nematic-isotropic-nematic transition within single tactoids to locally melt the liquid crystalline (LC) order into the isotropic phase, leaving unchanged the bulk dispersion structure. The locally melted nematic field recovers its ground-state LC order within minutes after the exposure, showing both self-healing and short-term memory-storage features. Furthermore, hybrid cholesteric tactoids functionalized by guest nanoparticles can be re-modeled into new tactoids with different symmetry and functionalities, for example, featuring laser-induced fluorescent encoding. These results introduce a general strategy to direct phase separation-within-phase separation and to store, control, and engineer information at the sub-micron level in heterogeneous complex fluids.

Controlling the shape and self-assembly of anisotropic colloidal systems is essential for developing heterogeneous liquid crystalline materials with adjustable properties and functions. This study utilizes stimuli-responsive, photothermal manipulation to achieve reversible, sub-micron control of individual colloidal condensates, known as tactoids, allowing for processes such as cutting, healing, and information storage.