Further progress in the applications of self-assembled nanostructures critically depends on developing a fundamental understanding of the relation between the properties of nanoparticle ensembles and their time-dependent structural characteristics. Following dynamic generation of hot-spots in the self-assembled chains of gold nanorods, we established a direct correlation between ensemble-averaged surface-enhanced Raman scattering and extinction properties of the chains. Experimental results were supported with comprehensive finite-difference time-domain simulations. The established relationship between the structure of nanorod ensembles and their optical properties provides the basis for creating dynamic, solution-based, plasmonic platforms that can be utilized in applications ranging from sensing to nanoelectronics.

We report a microfluidic approach to generating capsules of biopolymer hydrogels. Droplets of an aqueous solution of a biopolymer were emulsified in an organic phase comprising a cross-linking agent. Polymer gelation was achieved in situ (on a microfluidic chip) by diffusion-controlled ionic cross-linking of the biopolymer, following the transfer of the cross-linking agent from the continuous phase to the droplets. Gelation was quenched by collecting particles in a large pool of cross-linking agent-free liquid. The structure of microgels (from capsules to gradient microgels to particles with a uniform structure) was controlled by varying the time of residence of droplets on the microfluidic chip and the concentration of the cross-linking agent in the continuous phase. We demonstrated the encapsulation of a controlled number of polystyrene beads in the microgel capsules. The described approach was applied to the preparation of capsules of several polysaccharides such as alginate, kappa-carrageenan, and carboxymethylcellulose.

In this Concept article, recent advances in microfluidic platforms for the generation of cell-laden hydrogel particles (microgels) are reported. Advances in the continuous microfluidic encapsulation of cells in droplets and microgels are critically reviewed, and currently used methods for the encapsulation of cells in polymer microgels are discussed. An outlook on current applications and future directions in this field of research are also presented. This article will be of interest to chemists, materials scientists, cell biologists, bioengineers, and pharmacologists.

In this tutorial review we discuss recent advances in the application of microfluidics for the generation of microgels from synthetic and biological polymers. We summarize advantages and drawbacks of the current methods used in microfluidic synthesis and assembly of polymer microgels. Continuous microfluidic encapsulation of cells is discussed as an exemplary application of the microgels. The article is finalized with a perspective on future research in the field. The article will be of interest to chemists, cell biologists, pharmacologists, and medicinal chemists.

Polymer microgels in the size range from several micrometers to hundreds of micrometers are used in the pharmaceutical, cosmetics, nutrition, pesticide, and food industries, as well as in the encapsulation of cells. To date, a broad range of strategies for the generation of polymer microgels exist, however, these methods involve multistage processes, do not utilize biocompatible components or do not allow precise control of the dimensions and internal structure of the microgels. Recently, microfluidic strategies for the production of polymer particles have offered precise control over the shapes, morphologies, and size distributions of polymer colloids. This paper discusses the most recent results obtained by the authors in the area of the microfluidic production of biopolymer microgels. It provides a brief review of the microfluidic methods for the continuous synthesis and fabrication of microgels, sets the criteria for the successful microfluidic generation of biomicrogels, and describes two methods for the preparation of microgels by microfluidic means. The article concludes with a summary and an outlook.magnified image