Phenotypically complex living materials containing engineered cyanobacteria

Advances in 3D bioprinting for environmental remediation and hazardous materials treatment

The high-throughput method based on the micron-level structure that 3D bioprinting technology offers for various environmental microbiological engineering applications is made possible by its several printing paths and precision programming control. This versatility makes it an on-demand manufacturing technology. A novel 3D manufacturing technique called 3D bioprinting may be used to precisely uptake and disperse bacteria to create microbial active substances with a variety of intricate functionalities for environmental applications. The technological challenges that the current 3D bioprinting technology must face include the mechanical properties of materials, the creation of specific bioinks to adapt to different strains, and the exploration of 4D bioprinting for intelligent applications. Therefore, this analysis delves deeply into the core technological ideas of 3D bioprinting, bioink materials, and their environmental applications. It also offers recommendations about the challenges and opportunities associated with 3D bioprinting. Combined with the present advancements in microbe enhancement technology, 3D bioprinting will provide an enabling platform for multifunctional microorganisms and facilitate the management of in situ directional responses in the environmental domain. This review highlights the applications of 3D bioprinting in the environmental monitoring and bioremediation. 3D printing in solid waste management is also discussed in detail.

Sonosynthetic Cyanobacteria Oxygenation for Self-Enhanced Tumor-Specific Treatment

Photosynthesis, essential for life on earth, sustains diverse processes by providing nutrition in plants and microorganisms. Especially, photosynthesis is increasingly applied in disease treatments, but its efficacy is substantially limited by the well-known low penetration depth of external light. Here, ultrasound-mediated photosynthesis is reported for enhanced sonodynamic tumor therapy using organic sonoafterglow (ultrasound-induced afterglow) nanoparticles combined with cyanobacteria, demonstrating the proof-of-concept sonosynthesis (sonoafterglow-induced photosynthesis) in cancer therapy. Chlorin e6, a typical small-molecule chlorine, is formulated into nanoparticles to stimulate cyanobacteria for sonosynthesis, which serves three roles, i.e., overcoming the tissue-penetration limitations of external light sources, reducing hypoxia, and acting as a sonosensitizer for in vivo tumor suppression. Furthermore, sonosynthetic oxygenation suppresses the expression of hypoxia-inducible factor 1α, leading to reduced stability of downstream SLC7A11 mRNA, which results in glutathione depletion and inactivation of glutathione peroxidase 4, thereby inducing ferroptosis of cancer cells. This study not only broadens the scope of microbial nanomedicine but also offers a distinct direction for sonosynthesis.

Extrusion-based 3D printing of soft active materials

Active materials are capable of responding to external stimuli, as observed in both natural and synthetic systems, from sensitive plants to temperature-responsive hydrogels. Extrusion-based 3D printing of soft active materials facilitates the fabrication of intricate geometries with spatially programmed compositions and architectures at various scales, further enhancing the functionality of materials. This Feature Article summarizes recent advances in extrusion-based 3D printing of active materials in both non-living (i.e., synthetic) and living systems. It highlights emerging ink formulations and architectural designs that enable programmable properties, with a focus on complex shape morphing and controllable light-emitting patterns. The article also spotlights strategies for engineering living materials that can produce genetically encoded material responses and react to a variety of environmental stimuli. Lastly, it discusses the challenges and prospects for advancements in both synthetic and living composite materials from the perspectives of chemistry, modeling, and integration.

Influence of Critical Parameters on the Extraction of Concentrated C-PE from Thermotolerant Cyanobacteria

This work aimed to identify the influence of pH, molarity, w/v fraction, extraction time, agitation, and either a sodium (Na2HPO4·7H2O-NaH2PO4·H2O) or potassium buffer (K2HPO4-KH2PO4) used in the extraction of C-phycoerythrin (C-PE) from a thermotolerant strain of Potamosiphon sp. An experimental design (Minimum Run Resolution V Factorial Design) and a Central Composite Design (CCD) were used. According to the statistical results of the first design, the K-PO4 buffer, pH, molarity, and w/v fraction are vital factors that enhance the extractability of C-PE. The construction of a CCD design of the experiments suggests that the potassium phosphate buffer at pH 5.8, longer extraction times (50 min), and minimal extraction speed (1000 rpm) are ideal for maximizing C-PE concentration, while purity is unaffected by the design conditions. This optimization improves extraction yields and maintains the desired bright purple color of the phycobiliprotein.

Light management by algal aggregates in living photosynthetic hydrogels

Rapid progress in algal biotechnology has triggered a growing interest in hydrogel-encapsulated microalgal cultivation, especially for the engineering of functional photosynthetic materials and biomass production. An overlooked characteristic of gel-encapsulated cultures is the emergence of cell aggregates, which are the result of the mechanical confinement of the cells. Such aggregates have a dramatic effect on the light management of gel-encapsulated photobioreactors and hence strongly affect the photosynthetic outcome. To evaluate such an effect, we experimentally studied the optical response of hydrogels containing algal aggregates and developed optical simulations to study the resultant light intensity profiles. The simulations are validated experimentally via transmittance measurements using an integrating sphere and aggregate volume analysis with confocal microscopy. Specifically, the heterogeneous distribution of cell aggregates in a hydrogel matrix can increase light penetration while alleviating photoinhibition more effectively than in a flat biofilm. Finally, we demonstrate that light harvesting efficiency can be further enhanced with the introduction of scattering particles within the hydrogel matrix, leading to a fourfold increase in biomass growth. Our study, therefore, highlights a strategy for the design of spatially efficient photosynthetic living materials that have important implications for the engineering of future algal cultivation systems.

Synthetic biology advances towards a bio-based society in the era of artificial intelligence

Synthetic biology is a rapidly emerging field with broad underlying applications in health, industry, agriculture, or environment, enabling sustainable solutions for unmet needs of modern society. With the very recent addition of artificial intelligence (AI) approaches, this field is now growing at a rate that can help reach the envisioned goals of bio-based society within the next few decades. Integrating AI with plant-based technologies, such as protein engineering, phytochemicals production, plant system engineering, or microbiome engineering, potentially disruptive applications have already been reported. These include enzymatic synthesis of new-to-nature molecules, bioelectricity generation, or biomass applications as construction material. Thus, in the not-so-distant future, synthetic biologists will help attain the overarching goal of a sustainable yet efficient production system for every aspect of society.

Engineered Living Structures with Shape-Morphing Capability Enabled by 4D Printing with Functional Bacteria

Engineered living structures with the incorporation of functional bacteria have been explored extensively in recent years and have shown promising potential applications in biosensing, environmental remediation, and biomedicine. However, it is still rare and challenging to achieve multifunctional capabilities such as material production, shape transformation, and sensing in a single-engineered living structure. In this study, we demonstrate bifunctional living structures by synergistically integrating cellulose-generating bacteria with pH-responsive hydrogels, and the entire structures can be precisely fabricated by three-dimensional (3D) printing. Such 3D-printed bifunctional living structures produce cellulose nanofibers in ambient conditions and have reversible and controlled shape-morphing properties (usually referred to as four-dimensional printing). Those functionalities make them biomimetic versions of silkworms in the sense that both can generate nanofibers and have body motion. We systematically investigate the processing-structure-property relationship of the bifunctional living structures. The on-demand separation of 3D cellulose structures from the hydrogel template and the living nature of the bacteria after processing and shape transformation are also demonstrated.

Engineered Living Material Bioreactors with Tunable Mechanical Properties using Vat Photopolymerization

3D-printed engineered living materials (ELM) are promising bioproduction platforms for agriculture, biotechnology, sustainable energy, and green technology applications. However, the design of these platforms faces several challenges, such as the processability of these materials into complex form factors and control over their mechanical properties. Herein, ELM are presented as 3D-printed bioreactors with arbitrary shape geometries and tunable mechanical properties (moduli and toughness). Poly(ethylene glycol) diacrylate (PEGDA) is used as the precursor to create polymer networks that encapsulate the microorganisms during the vat photopolymerization process. A major limitation of PEGDA networks is their propensity to swell and fracture when submerged in water. The authors overcame this issue by adding glycerol to the resin formulation to 3D print mechanically tough ELM hydrogels. While polymer concentration affects the modulus and reduces bioproduction, ELM bioreactors still maintain their metabolic activity regardless of polymer concentration. These ELM bioreactors have the potential to be used in different applications for sustainable architecture, food production, and biomedical devices that require different mechanical properties from soft to stiff.

Growth, Distribution, and Photosynthesis of Chlamydomonas Reinhardtii in 3D Hydrogels

Engineered living materials (ELMs) are a novel class of functional materials that typically feature spatial confinement of living components within an inert polymer matrix to recreate biological functions. Understanding the growth and spatial configuration of cellular populations within a matrix is crucial to predicting and improving their responsive potential and functionality. Here, this work investigates the growth, spatial distribution, and photosynthetic productivity of eukaryotic microalga Chlamydomonas reinhardtii (C. reinhardtii) in three-dimensionally shaped hydrogels in dependence of geometry and size. The embedded C. reinhardtii cells photosynthesize and form confined cell clusters, which grow faster when located close to the ELM periphery due to favorable gas exchange and light conditions. Taking advantage of location-specific growth patterns, this work successfully designs and prints photosynthetic ELMs with increased CO2 capturing rate, featuring high surface to volume ratio. This strategy to control cell growth for higher productivity of ELMs resembles the already established adaptations found in multicellular plant leaves.