Sommaire:

Self-assembly is both an advantageously spontaneous process to organize molecular or colloidal entities into functional superstructures and a key-feature of how life builds its components. However, compared to their living counterparts, synthetic materials made by self-assembly usually lack some of the interesting properties of living systems such as multicomponent character or capability to adapt, transform and evolve. In this presentation, I will describe different systems where life-like properties can emerge from self-assembled synthetic materials. First, I will show that user-defined and elaborate nanostructures (e.g., DNA origamis, nanogrids, SST assemblies) can be obtained by the isothermal self-assembly of hundreds of different DNA bricks and proteins with a unique capability to optimize, adapt, evolve and even completely transform their morphology, either spontaneously or under command [1-2]. I will also present a new DNA self-assembly principle that does not rely on base-pairing principles, showing in particular that photosensitive DNA intercalating molecules can co-assemble with DNA bases to form new extended supramolecular materials with intriguing dynamic properties. I will describe in particular the formation of photoswitchable 3D crystals with unique photoreversible growth and light-gated fluorescence [3]. Finally, I will present different colloidal self-assembly processes at air-water or liquid-liquid interfaces and explore how dynamic properties can emerge from such systems. Starting from the familiar situation of drying drop containing a colloidal suspensions, we have been interested in controlling/cancelling the so-called “coffee-ring effect” [4-7] or turning it into a low-cost yet powerful medical diagnostic tool [8]. In such systems, however, particles adsorb at the interface to form amorphous structures. This led us to invent a simple method in which bulk particles adsorb at the water-interface and directly crystallize there. Based on the use of ultralow amounts of surfactant, 2D colloidal crystals spontaneously form without any other applied force than their own weight [9]. This method allows us to crystallize a broad variety of nanometric and micrometric particles, including those made of polymers, metals or inorganic materials, and tune the characteristics of the colloidal crystals [10] that can be further deposited on solid substrates [11]. These colloidal crystals display intense structural colors as well as, under some conditions, some remarkable dynamic properties at the air/water interface. For instance, using light, we can reversibly melt/crystallize these colloidal assemblies on command, evidencing other life-like properties, such as dissipative character or living crystallization [12-13].

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[9] Anyfantakis, Langmuir 2018, 34, 15526−15536
[10] Vialetto et al., Nanoscale 2020, 12, 6279-6284
[11] Vialetto et al., Adv. Sci. 2024, 11, 2307893
[12] Vialetto et al. Angew. Chem. Int. Ed. 2019, 58, 9145-9149
[13] Vialetto et al., J. Am. Chem. Soc. 2021, 143, 11535−11543

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