Electroaddressing of Cell Populations by Co‐Deposition with Calcium Alginate Hydrogels

Abstract

Electroaddressing of biological components at specific device addresses is attractive because it enlists the capabilities of electronics to provide spatiotemporally controlled electrical signals. Here, the electrodeposition of calcium alginate hydrogels at specific electrode addresses is reported. The method employs the low pH generated at the anode to locally solubilize calcium ions from insoluble calcium carbonate. The solubilized Ca2+ can then bind alginate to induce this polysaccharide to undergo a localized sol‐gel transition. Calcium alginate gel formation is shown to be spatially controlled in the normal and lateral dimensions. The deposition method is sufficiently benign that it can be used to entrap the bacteria E. coli. The entrapped cells are able to grow and respond to chemical inducers in their environment. Also, the entrapped cells can be liberated from the gel network by adding sodium citrate that can compete with alginate for Ca2+ binding. The capabilities of calcium alginate electrodeposition is illustrated by entrapping reporter cells that can recognize the quorum sensing autoinducer 2 (AI‐2) signaling molecule. These reporter cells were observed to recognize and respond to AI‐2 generated from an external bacterial population. Thus, calcium alginate electrodeposition provides a programmable method for the spatiotemporally controllable assembly of cell populations for cell‐based biosensing and for studying cell‐cell signaling.

Light-addressable electrodeposition of cell-encapsulated alginate hydrogels for a cellular microarray using a digital micromirror device

“…[2][3][4][5][6][7][8][9][10][11][12] Among these methods, an acidic polysaccharide of sodium alginate, which can form a calcium alginate gel in the presence of calcium ions (Ca 2þ ), is widely used to entrap and immobilize prokaryotes and eukaryotic cells, such as alginate beads, [6][7][8] fibers/tubes, 9,10 and a three-dimensional (3D) cellular microarray. 11,12 Electroaddressing is an attractive technique for depositing calcium alginate gel [13][14][15] or pH-responsive chitosan 16,17 at specific addresses and in specific shapes on the preformed metal thin-film electrode surfaces that can generate protons or hydroxide ions by electrolysis on the anodes or cathodes of the electrodes. This technique is used for the assembly of cells within polysaccharide hydrogels at specific addresses with a controllable pattern.…”

Light-Directed Self-Assembly of Robust Alginate Gels at Precise Locations in Microfluidic Channels

“…66,67 For this application, we used the same fluid composition as above, and we prepared two batches of the fluid with red-and green-fluorescent microbeads, respectively. The microbeads are a model for a payload to be deposited at specific sites.…”

Light-Addressable Electrodeposition of Magnetically-Guided Cells Encapsulated in Alginate Hydrogels for Three-Dimensional Cell Patterning

“…Recently, a biocompatible polysaccharide of sodium alginate, which can form a calcium alginate gel in the presence of calcium ions (Ca 2+ ), is widely used to entrap and immobilize prokaryotes and eukaryotic cells in 3D hydrogel structures [3][4][5]. Among these fabrication methods to form alginate hydrogels, electroaddressing is an attractive technique due to its ability to deposit alginate hydrogels [6][7][8][9][10][11][12][13] at specific addresses and in specific shapes with a controllable pattern on the preformed metal thin-film electrode surfaces. Payne et al [8,11] reported the electroaddressing of calcium alginate hydrogels, with the ability to entrap viable cell populations within the electrodeposited films.…”

“…Among these fabrication methods to form alginate hydrogels, electroaddressing is an attractive technique due to its ability to deposit alginate hydrogels [6][7][8][9][10][11][12][13] at specific addresses and in specific shapes with a controllable pattern on the preformed metal thin-film electrode surfaces. Payne et al [8,11] reported the electroaddressing of calcium alginate hydrogels, with the ability to entrap viable cell populations within the electrodeposited films. However, gel patterns involving locations, shapes and dimensions are completely subject to pre-defined configurations of microelectrodes.…”