Reversible Social Self-Sorting of Colloidal Cell-Mimics with Blue Light Switchable Proteins

Abstract

Toward the bottom-up assembly of synthetic cells from molecular building blocks, it is an ongoing challenge to assemble micrometer sized compartments that host different processes into precise multicompartmental assemblies, also called prototissues. The difficulty lies in controlling interactions between different compartments dynamically both in space and time, as these interactions determine how they organize with respect to each other and how they work together. In this study, we have been able to control the self-assembly and social self-sorting of four different types of colloids, which we use as a model for synthetic cells, into two separate families with visible light. For this purpose we used two photoswitchable protein pairs (iLID/Nano and nHagHigh/pMagHigh) that both reversibly heterodimerize upon blue light exposure and dissociate from each other in the dark. These photoswitchable proteins provide noninvasive, dynamic, and reversible remote control under biocompatible conditions over the self-assembly process with unprecedented spatial and temporal precision. In addition, each protein pair brings together specifically two different types of colloids. The orthogonality of the two protein pairs enables social self-sorting of a four component mixture into two distinct families of colloidal aggregates with controlled arrangements. These results will ultimately pave the way for the bottom-up assembly of multicompartment synthetic prototissues of a higher complexity, enabling us to control precisely and dynamically the organization of different compartments in space and time.

Independent Blue and Red Light Triggered Narcissistic Self‐Sorting Self‐Assembly of Colloidal Particles

“…It should also be noted that as soon as particles were decorated with proteins some aggregation was observed even for nonactivated samples and from the very beginning ( t = 0 min), possibly due to the unspecific protein interactions and the sticky nature of proteins. A comparable contribution of nonspecific interactions independent of photoactivation has also been between beads that were functionalized with other photoswitchable proteins . While at the molecular level, the proteins VVDHigh and Cph1 undergo light induced conformational changes, which expose the specific homodimerization interphases, within seconds the assembly processes are much slower.…”

“…A comparable contribution of nonspecific interactions independent of photoactivation has also been between beads that were functionalized with other photoswitchable proteins. [32] While at the molecular level, the proteins VVDHigh and Cph1 undergo light induced conformational changes, which expose the specific homodimerization interphases, within seconds the assembly processes are much slower. This indicates that the rate-limiting step is two colloidal particles coming into proximity and not the photoswitching of the proteins.…”

“…Self‐sorting of a mixture of different colloidal particles into distinct assemblies is far more challenging, as it requires multiple and orthogonal interactions to drive the assembly and sorting. Previous examples achieved the pairwise sorting of four different colloids, also known as social self‐sorting, by implementing two pairs of orthogonal heterodimerization partners on the colloid surface . The sorting of two different colloids into discrete clusters, also known as narcissistic or asocial self‐sorting, has not been realized with colloidal systems but is what is observed during embryo development and colony segregation in bacteria .…”

“…Previous examples achieved the pairwise sorting of four different colloids, also known as social self-sorting, by implementing two pairs of orthogonal heterodimerization partners on the colloid surface. [32,33] The sorting of two different colloids into discrete clusters, also known as narcissistic or asocial self-sorting, has not been realized with colloidal systems but is what is observed during embryo development and colony segregation in bacteria. [2][3][4] Furthermore, within a self-sorted mixture dynamically switching different assembly types with orthogonal stimuli would provide a valuable model to create adaptive smart materials.Here, we describe how in a mixture of two types of colloids each type orthogonally self-assembles either under blue or red light and self-sorts into separate clusters.…”

The Many Ways to Assemble Nanoparticles Using Light

“…Alternating the exposure to UV and visible light led to reversible dissociation and reformation of the inclusion complexes, and therefore of the aggregates. In other recent notable examples of light‐controlled self‐assembly of microparticles, Wegner and co‐workers demonstrated light‐induced narcissistic and social self‐sorting of 2 µm polystyrene beads decorated with photoswitchable proteins, whereas Fan and co‐workers developed dual‐responsive colloids by coating magnetic Fe 3 O 4 particles with monolayers of spiropyran molecules …”