(204b) Directed Co-Assembly of Live Cells and Colloidal Particles Into Biocomposites with Engineered Structure and Functionality

We will overview strategies for engineered biocolloidal assembly of live cells and synthetic micro- and nanoparticles. Such directed co-assembly could result in biomaterials, where the functionality of the cells is supplemented by the one of the particles. In the first part of the talk we will discuss how controlled drying of liquid suspensions in thin menisci driven on surfaces can be used for efficient deposition of thin particle-cell coatings. The organization of the particles and/or cells is a result of the combined action of convective transport and capillary forces at the liquid/air interface. The live cell and cell-particle films deposited by the convective assembly process can find applications in hydrogen generating devices, self-cleaning coatings and test beds for toxicity evaluation. The second part of the talk will be focused on more complex and precise methods for biocomposite assembly by electric fields. The process is based on dielectrophoresis (DEP), mobility and interaction of particles in AC fields. We will demonstrate how on-chip dielectrophoresis can be used to assemble chains and membranes of latex spheres and cells such as Baker’s yeast, or mouse fibroblasts. Experimental observations and electrostatic simulations of the DEP co-assembly dynamics showed that particles smaller in size than the cells were drawn and captured into the cell junctions by the electric field. The arrays can be bound into permanent biocomposites by using lectin-conjugated spheres as biocolloidal binders. Binding by particles with magnetic cores yielded live cell membranes and chains that could be manipulated by magnetic field and interfaced with on-chip electrodes. Such cell-particle assemblies may find applications in sensors, microassays, microsurgery, or in responsive biomaterials.