Toward Practical Applications of Engineered Living Materials with Advanced Fabrication Techniques

Electrochemical manipulation of the insulin secretion from pancreatic beta cells directly cultured on a PEDOT:PSS electrode

The development of cell-based devices using mammalian cells is becoming increasingly feasible. To remotely control such sophisticated devices, an interface between digital computer/internet networks and cellular/organ networks is essential. This study explores the electrochemical manipulation of insulin secretion-a regulatory hormone for the control of blood sugar levels-using pancreatic β cells as a model. iGL cells, expressing insulin fused with Gaussia Luciferase (INS-GLase), were directly cultured on a custom-made cell culture device coated with a transparent poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) electrode. Luminescence imaging was employed to evaluate insulin secretion in response to applied potentials. Results showed that insulin secretion could be induced by regulating membrane potential through an applied potential. The addition of nicardipine, an L-type voltage-dependent Ca2+ channel inhibitor, suppressed insulin secretion, suggesting the involvement of Ca2+ channels in this electrochemical system. Additionally, changes in membrane potential were directly visualized with the membrane potential-sensitive dye FluoVolt™, which confirmed both the forced depolarization and the forced restoration of the membrane potential to its non-excited state upon potential application to the electrode. The reported electrochemical technique, in which cells are directly cultured on an electrode, offers significant promise for designing advanced bio-hybrid systems that integrate cellular functions with digital networks.

Advances in in vitro cultivation techniques for comprehensive analysis of human gut microbiome

The role of gut microbiota in human health and disease is becoming increasingly recognized. Historically, the impact of human gut microbiota on health has been studied using clinical trials and animal models. However, clinical studies often struggle with controlling variables and pinpointing disease-causing factors, while animal models fall short of accurately replicating the human gut environment. Additionally, continuous sample collection for gut microbiota analysis in vivo presents significant ethical and technical challenges. To address these limitations, in vitro fermentation models have emerged as promising alternatives. These models aim to simulate the structural and functional characteristics of the human gut in a controlled setting, offering valuable insights into microbial behavior. This review highlights current knowledge and technological advances in in vitro cultivation systems for human gut microbiota, focusing on key elements such as three-dimensional scaffolds, culture media, fermentation systems, and analytical techniques. By examining these components, the review establishes a framework for improving methods to cultivate and study human gut microbiota, enhancing research methodologies for better understanding microbial interactions, behavior, and adaptation in diverse environments.

Extracellular Bacterial Production of DNA Hydrogels-Toward Engineered Living Materials

Engineered Living Materials (ELMs) combine synthetic biology with artificial materials to create biohybrid living systems capable of replicating, self-repairing, and responding to external stimuli. Due to their self-optimization abilities, these systems hold great potential for biotechnological applications. This study is a first step toward ELMs based on DNA hydrogels, focusing on the production of biohybrid materials using the exoelectrogenic bacterium Shewanella oneidensis. To equip the bacterium with the functionality needed for building DNA hydrogels, inducible cell surface anchors are developed, which can bind exogenous polymerase via the SpyCatcher/SpyTag (SC/ST) technology. The process parameters for in situ production of DNA hydrogels are established, enabling the development of these materials in the context of living bacteria for the first time. Using an extracellular nuclease-deficient S. oneidensis strain, stable biohybrid biofilms are generated directly on the surface of bioelectrochemical systems, showing the current generation. Given the high programmability and functionalization potential of DNA hydrogels, it is believed that this study represents a significant step toward establishing dynamic biohybrid material systems that exhibit both conductivity and metabolic activity.

Modulating Microbial Materials - Engineering Bacterial Cellulose with Synthetic Biology

The fusion of synthetic biology and materials science offers exciting opportunities to produce sustainable materials that can perform programmed biological functions such as sensing and responding or enhance material properties through biological means. Bacterial cellulose (BC) is a unique material for this challenge due to its high-performance material properties and ease of production from culturable microbes. Research in the past decade has focused on expanding the benefits and applications of BC through many approaches. Here, we explore how the current landscape of BC-based biomaterials is being shaped by progress in synthetic biology. As well as discussing how it can aid production of more BC and BC with tailored material properties, we place special emphasis on the potential of using BC for engineered living materials (ELMs); materials of a biological nature designed to carry out specific tasks. We also explore the role of 3D bioprinting being used for BC-based ELMs and highlight specific opportunities that this can bring. As synthetic biology continues to advance, it will drive further innovation in BC-based materials and ELMs, enabling many new applications that can help address problems in the modern world, in both biomedicine and many other application fields.