Constructing Synthetic Ecosystems with Biopolymer Fluitrodes

Abstract

the relationships within microbiomes and the interactions between microbiome and host in a well-controlled and spatially analogous manner is of great interest in microbiome engineering and developing new biological technologies. [4] Microfluidic platforms have been of great interest for cellular studies in the last two decades. Recent transition from two dimensional (2D) to three dimensional (3D) cell culture in microfluidics provides the ability to control and monitor in vitro interactions between cells and extracellular matrix, establish stable chemical gradients and stimuli, deliver oxygen and nutrients, and to remove metabolites and reduce shear stress by laminar flows. [5] For example, natural and synthetic calcium alginate hydrogels were assembled into 3D geometries with high aspect ratio and curvature by combination of laser ablation and sacrificial molding technique. [4b,c] Calcium alginate with target cells was electrodeposited on electrodes or flow-assembled in microfluidics to model biofilms or construct synthetic ecosystems with spatiotemporal programmability. [6] Great advances have been made in organ-on-a-chip systems and synthetic systems that enable spatially controlled cocultures of cells and model various biological events including cancer metastasis and vascular functions. [7] The vast majority of microbial models or the microbehost systems, however, are limited to mixed or binary cultures that either are challenging if not impossible to track changes occurring in individual populations, or lack the compatibility to deliver different nutrients for different species. Challenges remain in culturing cells with a spatial resolution that can be used to study complex interactions between multiple species within microbial communities.This study presents, for the first time, the concept of fluitrodes to conveniently embed multiple cell populations in 3D hydrogels in microfluidics with a spatial resolution of biological relevance. The fluitrodes are freestanding biopolymer membranes that, like electrodes in transmitting electrons, transmit ions and small molecules with spatiotemporal programmability. Since biology information is mainly transmitted via ions and small molecules rather than electrons, the fluitrodes provide a novel platform to communicate with cell populations through ions and molecules in aqueous condition complementary to the communication in solids through an electrode. The spatially patterned cell populations were assembled either side by side or layer by layer in Modeling the complex interactions among organisms found within microbiomes is of great interest for the development of new biological technologies. Challenges remain in culturing cells of multiple species with spatial resolutions similar to microbial communities. Here, a fluitrode concept in microfluidics using biofabrication of functional biopolymers is demonstrated to efficiently assemble multiple cell populations in 3D hydrogels of spatial and biological relevance. The fluitrodes are freestanding biopolymer membranes...

Oral mucosa-on-a-chip to assess layer-specific responses to bacteria and dental materials

“…First, multispecies bacterial culture on the mucosal chip may be achieved by compartmentalizing the mucosal and bacterial culture spaces on the chip, while still retaining soluble communication. 51 Second, artificial saliva 52 rather than nutrient media may be used to bathe the apical channel containing both keratinocytes and bacteria.…”

Microfluidic and mathematical modeling of aquatic microbial communities

“…To decouple the physically and chemically mediated interactions among microbials of different types, a number of microfluidic platforms have been developed in which a permeable interface is introduced to prevent physical contact, while allowing for chemical exchange. Examples of permeable interface are microsieves [33], narrow connecting channels [34], and permeable membranes [35][36][37]. To control the physical distance of various cell types, clever spatial arrangements have been developed, controlling the relative position and distance between individual strains via careful design of the microchamber layout [35].…”

Chemotropism among populations of yeast cells with spatiotemporal resolution in a biofabricated microfluidic platform

“…The polydimethylsiloxane (PDMS) microchannels were made with the common soft lithography process. 22,23 Briefly, Sylgard 184 and its curing agent were mixed at 10:1 ratio, degassed, poured into the SU-8 molds in a home-made aluminum foil container, and cured at 65 °C on a hot plate for 120 min. The solidified PDMS was then delaminated from the molds and cut into desired pieces.…”

“…Chitosan membranes were biofabricated following a recently reported procedure by steering air bubbles in PDMS microchannels with an add-on vacuuming layer when needed. 22,23 Briefly, the positively charged chitosan solution ( pH 5.8) was pumped with a Genie syringe pump (Kent Scientific, CT) into the middle microchannel, while the negative charged alginate solutions ( pH 11.5) were pumped into the two-side microchannel, at the flow rate of 0.5 μl/min in all three channels. The flows were stopped after air bubbles were trapped in the apertures due to the natural hydrophobicity of PDMS.…”