Self-replicating Colloidal Assemblies

Self-replication is the preeminent property of living systems and natural materials. Nature builds and repairs by self-replication. Purely synthetic materials so far lack this important ability. An indispensable prerequisite to achieve self-replication properties is the multi-directional control of orthogonal interactions between the building blocks of materials. Therefore, this proposal project has a high impact in the field of controlled colloidal assembly as it opens a new experimental research area on “self-replicating colloids”. To achieve this goal, we propose to create a new class of patchy colloidal particles bearing three patches of two different chemical functionalities.
By imparting the self-replicating property to colloidal building blocks in the course of this project, a new research area and - once successful - a technology platform for the production of sufficient quantities of simple and complex colloidal assemblies will be established, whereas well-defined or complex master-structures can nowadays only be produced and isolated in small amounts due to a difficult and tedious synthetic procedure.
The project includes the basic research that brings insights into completely new fabrication methods through self-assembly and can therefore open new avenues for the cost-effective manufacturing of novel materials and for designing ground-breaking technologies in the material science. The implementation of these new materials and methods can not only significantly improve the quality of day-to-day life but also create new work places/new industry branches as well as essentially reduce of environmental impact of industry.
The objectives of the project can be summarized as follows:
1. Synthesis of di- and tri-valent patchy particles via combined microcontact printing
2. Controlled generation of colloidal superstructures for the following self-replication process
3. Functionalize pre-assembled colloidal superstructures with replication patch
4. Proof-of-concept for colloidal self-replication process based on tri-valent patchy particles

Since beginning of the project the following results were achieved:
Silica particles of various sizes from submicrometer to several micrometer were obtained, flat and wrinkled stamps with different amplitude/period ratios were generated and di-valent particles were prepared using both wrinkled stamps and flat stamps via sandwich printing. For the polymer particles di-valent particles with two opposite chemical functionalities of patches – basic and acidic – were obtained.
Moreover, tetra- and multivalent patchy silica particles were fabricated.
A specially designed microcontact printing cell for the precise and controllable use of the centrifugal force was developed in the collaboration with the company LUM, Berlin, Germany and will be tested in the nearest future. By using this device it is possible to align the patch printing exactly on the pole position. Control of rotation speed and acceleration allow for excellent control not only over the centrifugal force applied for printing but also to define the rate of its evolution with time and thus investigate rheological phenomena during the printing procedure.
Optical microscopy was applied to quantify the formation of the particulate superstructures in the suspensions of di-valent particles in different solvents. First results are very promising, however, the yield of these superstructures has to be improved. In addition, Nanoparticle Tracking Analysis (NTA) technique (Malvern NanoSight NS300 Instrument) was applied for measurements in the suspensions of di-valent particles. This method enables simultaneously direct observation and measurement of diffusion events for each particle/particulate structure in the system.
Finally, first successful experiments on the creation of linear superstructures of di-valent particles (cyclodextrin modified magnetite nanoparticles) were carried out.

Several outputs which go beyond the current state of the art were attained:
Successful use of wrinkled stamps, especially for the generation of multi-patched morphology on microparticles; Utilization of polymeric (polyelectrolyte) inks for the generation of patches; combination of polyelectrolyte inks and release solvents for the generation of 3D-patches; loading of 3D-patches with different additives (also nanoparticulate) yielding the enhancement of accessible chemical and physical functionalities and their various combinations.
The concept of REPLICOLL, i.e. transferring material activities to artificial systems has been introduced as one of the latest research missions of Fraunhofer Gesellschaft and is also recognized by the German Ministry of Research and Education (BMBF) as agreed on in the new coalition agreement for the future German Federal Government (keyword: Biological Transformation).
Results expected until the end of the project relate to the above-mentioned project objectives. Main efforts will be directed to the creation of linear and more complicated superstructures from di- and tri-valent particles in solution and on liquid and solid templates as well as to the self-replication process using these superstructures.

Periodic Reporting for period 4 - REPLICOLL (Self-replicating Colloidal Assemblies)

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