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Biocementation is an exciting biomanufacturing alternative to common cement, which is a significant contributor of CO₂greenhouse gas production. In nature biocementation processes are usually modulated via ureolytic microbes, such asSporosarcina pasteurii,precipitating calcium carbonate to cement particles together, but these ureolytic reactions also produce ammonium and carbonate byproducts, which may have detrimental effects on the environment. As an alternative approach, this work examines biosilicification via surface-displayed silicatein-α in bio-engineeredE. colias anin vivobiocementation strategy. The surface-display of silicatein-α with ice nucleation protein is a novel protein fusion combination that effectively enables biosilicification, which is the polymerization of silica species in solution, from the surface ofE. colibacterial cells. Biosilicification with silicatein-α produces biocementation products with comparable compressive strength asS. pasteurii.This biosilicification approach takes advantage of the high silica content found naturally in sand and does not produce the ammonium and carbonate byproducts of ureolytic bacteria, making this a more environmentally friendly biocementation strategy. 

Life exists at an interface. One of the key characteristics of biological cells is compartmentalization, which is facilitated by lipids that create a water-impenetrable barrier to control transport of materials across the hydrophilic-hydrophobic interface. Microbial systems utilize a rich diversity of surfactants beyond lipids to adapt to an environmental niche, modify the properties of an interface, facilitate solubilization of nutrients for metabolism and as antimicrobials. As such, they are a fascinating class of biomolecules to study in terms of how effectiveness in an application or niche environment depends on sequence, structure and chemical properties. Moreover, there is increasing appreciation of the negative health and environmental impacts petrochemical-based surfactants can have, such as soil erosion and toxicity to plants and aquatic life, as well as the carbon footprint and associated greenhouse gas emissions associated with petrochemical surfactant manufacturing. In this review, we discuss the properties of biosurfactants and applications, and highlight key glycolipid-, protein- and peptide-based surfactants described in literature as examples of biosurfactants with unique potential and applications. As society looks towards the transition to a circular bioeconomy, we are excited by the potential of synthetic biology to develop new materials such as biosurfactants to facilitate this important transition. 

Silicatein is an enzyme that mineralizes environmental precursors to patterned nanomaterials and is found naturally orchestrating the complex and beautiful exoskeletons of marine sponges. To harness this activity for nanomaterial biomanufacturing, enzyme solubility and stability have been widely studied. We address the enzyme's solubility challenge via protein fusion tags: enhanced green fluorescent protein (eGFP), monomeric superfolder GFP (msGFP2), and trigger factor (TF). All three silicatein fusion proteins form oligomers to varying degrees, that are partially modulated by disulfide bridges. Biomineralization activity was assessed with silica and nanoceria, showing comparable yields for eGFP-silicatein and TF-silicatein, as well as identical composition of mineralized products regardless of disulfide bridge reduction, shown via XRD characterization of silicatein's nanocrystalline product. This implies that solubility has only minor effects on silicatein activity and that continued improvement in this area is currently inessential. Furthermore, these results suggest that silicatein biomineralization activity is inherent to the enzyme itself. Thus, future studies should be aimed at understanding silicatein's kinetic mechanisms. 

If hydrogen evolution photocatalysis are to be deployed at industrial scale, the synthesis of these photocatalytic materials must be both economically and environmentally scalable. This suggests that we must move towards green synthesis of earth-abundant photocatalysts while also maintaining high catalytic performance. Herein, we present the enzymatically driven, aqueous phase, low temperature, synthesis of an earth-abundant nickel sulfide (Ni x S y ) hydrogen evolution cocatalyst, and its integration into a CdS/Ni x S y heterostructured photocatalyst. This resulting photocatalyst provides hydrogen evolution rates (10 500 μmol h −1 g −1 ) comparable to photocatalysts prepared by more traditional routes. Furthermore, the Ni x S y is demonstrated to provide similar activity enhancement to the more traditional, but also more expensive platinum cocatalysts. To achieve this result, we carefully studied and engineered the synthesis environment to maintain enzyme activity towards HS − production while sustaining a sufficient concentration of free Ni 2+ in solution to enable reaction and formation of Ni x S y . Ultimately, this work provides a methodology to control the coordination of metal precursors in low temperature, aqueous systems to allow for precipitation of catalytically active materials and demonstrates the viability of green synthesis pathways for photocatalysts. 

The development of high quality, non-toxic ( i.e. , heavy-metal-free), and functional quantum dots (QDs) via ‘green’ and scalable synthesis routes is critical for realizing truly sustainable QD-based solutions to diverse technological challenges. Herein, we demonstrate the low-temperature all-aqueous-phase synthesis of silver indium sulfide/zinc (AIS/Zn) QDs with a process initiated by the biomineralization of highly crystalline indium sulfide nanocrystals, and followed by the sequential staging of Ag + cation exchange and Zn 2+ addition directly within the biomineralization media without any intermediate product purification. Therein, we exploit solution phase cation concentration, the duration of incubation in the presence of In 2 S 3 precursor nanocrystals, and the subsequent addition of Zn 2+ as facile handles under biomineralization conditions for controlling QD composition, tuning optical properties, and improving the photoluminescence quantum yield of the AIS/Zn product. We demonstrate how engineering biomineralization for the synthesis of intrinsically hydrophilic and thus readily functionalizable AIS/Zn QDs with a quantum yield of 18% offers a ‘green’ and non-toxic materials platform for targeted bioimaging in sensitive cellular systems. Ultimately, the decoupling of synthetic steps helps unravel the complexities of ion exchange-based synthesis within the biomineralization platform, enabling its adaptation for the sustainable synthesis of ‘green’, compositionally diverse QDs.