Intracellular compartments are functional units that support the metabolism within living cells, through spatiotemporal regulation of chemical reactions and biological processes. Consequently, as a step forward in the bottom-up creation of artificial cells, building analogous intracellular architectures is essential for the expansion of cell-mimicking functionality. Herein, we report the development of a droplet laboratory platform to engineer complex emulsion-based, multicompartment artificial cells, using microfluidics and acoustic levitation. Such levitated models provide free-standing, dynamic, definable droplet networks for the compartmentalisation of chemical species. Equally, they can be remotely operated with pneumatic, heating, and magnetic elements for post-processing, including the incorporation of membrane proteins; alpha-hemolysin; and mechanosensitive channel of large-conductance. The assembly of droplet networks is three-dimensionally patterned with fluidic input configurations determining droplet contents and connectivity, whilst acoustic manipulation can be harnessed to reconfigure the droplet network in situ. The mechanosensitive channel can be repeatedly activated and deactivated in the levitated artificial cell by the application of acoustic and magnetic fields to modulate membrane tension on demand. This offers possibilities beyond one-time chemically mediated activation to provide repeated, non-contact, control of membrane protein function. Collectively, this expands our growing capability to program and operate increasingly sophisticated artificial cells as life-like materials.

(1 of 17)www.global-challenges.com robotics, have promoted the use of in vitro tumor models in high-throughput drug screenings. [2,3] High-throughput screens for anticancer drugs have been, for a long time, limited to 2D culture of tumor cells, grown as a monolayer on the bottom of a well of a microtiter plate. Compared to 2D cell cultures, 3D culture systems can more faithfully model cell-cell interactions, matrix deposition and tumor microenvironments, including more physiological flow conditions, oxygen and nutrient gradients. [4] Therefore, 3D cultures have recently begun to be incorporated into high-throughput drug screenings, with the aim of better predicting drug efficacy and improving the prioritization of candidate drugs for further in vivo testing in animals.Because of the relatively simple, reproducible, amenable to automation and scalable culture methods, single-cell type and mixed-cell tumor spheroids, known as multicellular tumor spheroids (MCTSs), are used as 3D models. [5] There exists a broad range of natural hydrogels that are compatible with microfluidics, and which provide cancer cells with mechanical cues and adhesion sites to proliferate and grow into MCTSs. [6] With the aid of microfluidics and development of more complex 3D tumor models, [7,8] and the large-scale production of tumor spheroids in hydrogels, the number of compounds that could progress to in vivo testing could be restricted, thus reducing the number of animals needed for preclinical studies.Tumor-targeted drug delivery using microparticles and liposomes is beneficial compared to conventional drug administration. This is because encapsulated drug dosages can be controlled, healthy tissues can remain unharmed during treatment and drug resistance of cancer cells may be reduced/ prevented. [9,10] Microparticles and liposomes can be tailored to specifically target tumor sites using molecular conjugates, while avoiding toxic effects. [9] This review discusses the application of droplet-based microfluidic technologies for the development of accurate in vitro tumor models and improved cancer treatment strategies. The first part of the review centers around the generation of MCTSs in natural hydrogels for a better recapitulation of the in vivo tumor microenvironment. The second section is focused on microparticle and liposomal production for tumor-targeted drug delivery. Emphases is given to microfluidic methodologies for the production of these systems, and the potential of compartmentalized artificial cells as anticancer drug screening platforms.

We simulate the movement and agglomeration of oil droplets in water under constraints, using a simplified stochastic-hydrodynamic model. We analyze both local and global properties of the networks formed by the agglomerations of droplets for various system sizes. We focus on the differences of these properties for monodisperse and polydisperse systems of droplets. For the mean degree, we obtain different values for critical exponents.

Experimentally, periodically released droplets in systems of widening pipes show clustering. This is surprising, as purely hydrodynamic interactions are repulsive so that agglomeration should be prevented. In the main part of this paper, we investigate the clustering of droplets under the influence of phenomenological hydrostatic forces and some hypothetical attraction. In two appendices, we explain why a direct numerical simulation for this system is rather more difficult (and probably not possible with current methods) than the “simple” geometry would suggest.

Intracellular compartments are functional units that support the metabolic processes within living cells, through spatiotemporal regulation of chemical reactions and biological processes. Consequently, as a step forward in the bottom-up creation of artificial cells, building analogous intracellular architectures is essential for the expansion of cell-mimicking functionality. Herein, we report the development of a droplet laboratory platform to engineer customised complex emulsion droplets as a multicompartment artificial cell chassis, using multiphase microfluidics and acoustic levitation. Such levitated constructs provide free-standing, dynamic, definable droplet networks for the encapsulation and organisation of chemical species. Equally, they can be remotely operated with pneumatic, heating, and magnetic elements for post-processing, including the incorporation of membrane proteins; alpha-hemolysin; and large-conductance mechanosensitive channel (MscL) and their activation. The assembly of droplet networks is three-dimensionally patterned with fluidic inputs configurations determining droplet contents and connectivity. Whilst acoustic manipulation can be harnessed to reconfigure the droplet network in situ. In addition, a mechanosensitive channel, MscL, can be repeatedly activated and deactivated in the levitated artificial cell by the application of acoustic and magnetic fields to modulate membrane tension on demand. This offers possibilities beyond one-time chemically mediated activation to provide repeated, non-contact control of membrane protein function. Collectively, this will expand our capability to program and operate increasingly sophisticated artificial cells as life-like materials.

Engineered artificial cells often involve phospholipid membranes in the form of vesicles or membrane mimics. Droplet interface bilayers (DIBs) constitute a commonly used membrane mimic within synthetic biology. However, these model membranes have limited accessibility due to their requirement to be surrounded by an oil environment. Here, we demonstrate in-situ bilayer manipulation of submillimeter, free-standing, encapsulated droplet interface bilayers (eDIBs) in hydrogel capsules formed by ready-to-use 3D-printed microfluidic devices. The eDIB capsules were exposed to various concentrations of membrane tension-altering lysophosphatidylcholine (LPC), in order to investigate the interaction of lysolipids with three-dimensional, droplet bilayer networks. Micellar LPC concentrations trigger the bursting of the eDIB droplets, while at concentrations below the critical micelle concentration (CMC), the encapsulated aqueous inner droplet networks endure structural changes, precisely affecting the DIB contact angles and bilayer area. Manipulation of these enclosed, 3D-orchestrated membrane mimics facilitates the exploration of readily accessible compartmentalized artificial cellular machinery. Collectively, the multi-compartmentalized capsules and the lysolipid-mediated membrane modulation introduce a chemical approach to control the properties and mechanics of artificial cellular membranes, as well as the functionalities of artificial cells, toward responsive soft material developments and drug delivery applications.