A new design for living cell-based biosensors: Microgels with a selectively permeable shell that can harbor bacterial species

• Published in: Sensors and actuators. B, Chemical Vol. 334; p. 129648
• Main Authors: Zhao, Sibo, Wen, Huilin, Ou, Yangteng, Li, Minhui, Wang, Lancheng, Zhou, Huimin, Di, Bin, Yu, Ziyi, Hu, Chi
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 01-05-2021; Elsevier Science Ltd
• Subjects: Beads; Bioinspired silica; Biosensors; Cell encapsulation; Cells (biology); E coli; Encapsulation; Gel-shell beads; Genetic engineering; Hydrogels; Living cell-based biosensors; Microfluidics; Microgels; Microorganisms; Nutrients; Pseudomonas aeruginosa; Quorum sensing; Synthetic environments; Water supply; Bioinspired silica; Quorum sensing; Gel-shell beads; Living cell-based biosensors; Cell encapsulation
• ISSN: 0925-4005; 1873-3077
• DOI: 10.1016/j.snb.2021.129648

•Gel-shell beads (GSBs) were prepared as robust living cell-based biosensors.•Bioinspired silica coating prevents bacterial leakage while allows fast diffusion of signal molecules.•Biosensor performance was demonstrated by encapsulating quorum sensing reporter cells into GSBs.•The encapsulated reporter cells exhibit high real-time sensitivity detection to target analyte, protection from ex vivo environment, and high viability/activity.•Upon exposure to human pathogen P. aeruginosa, a strong bioluminescent signal localized inside GSBs was observed.
Biosensors integrating genetically programmed living cells into hostile and synthetic environments (e.g., devices or matrices) provide powerful tools for scientific research and enable new technological applications. However, it remains a challenge to maintain the viability and functionality of the living components exposed to different chemical, physiological or mechanical conditions in specific applications. To this end, we report herein a microfluidic approach to encapsulate microorganisms in gel-shell beads (GSBs) as a novel kind of biosensor. Inspired by biosilicification, hydrogel beads are coated with a mesoporous shell that can prevent cell leakage and afford mechanical stability, with the porous hydrogel structure naturally providing sustained supplies of water and nutrients to the embedded microorganisms. Communications between compartmentalized bacterial strains and the environment is achieved through the diffusion of signalling molecules across the mesoporous shell. Application of GSBs as living cell-based sensors is exemplified in a quorum sensing system, where genetically engineered Escherichia coli cells are encapsulated in GSBs and can respond to autoinducer concentrations ranging from 10−6 to 10−7 mol/L as secreted by human pathogen Pseudomonas aeruginosa in the infection site.