Biosynthesis of inorganic nanomaterials using microbial cells and bacteriophages

Making Cells as a "Nirvana Phoenix": Precise Coupling of Precursors Prior to ROS Bursts for Intracellular Synthesis of Quantum Dots

Rationally coupling natural biochemical reactions for live-cell synthesis of inorganic nanocrystals with fluorescence, such as quantum dots (QDs) especially near-infrared (NIR), holds significant potential for in situ labeling and bioimaging. However, the introduced exogenous reactants and intracellularly produced species, e.g., reactive oxygen species (ROS), often cause cell damage, decreasing the fluorescence of the QDs. Herein, we have found that cell-adaptable selenocystine ((Cys-Se)2) can be reduced to biocompatible low-valence Se precursors, which could be subsequently hijacked by timely added Ag-glutathione (AgSG) to be transformed into NIR Ag2Se QDs. Such a comprehensive control strategy can inhibit the production of cytotoxic Se species and ROS bursts, significantly increasing the cell viability from 4 to 80% and enhancing the fluorescence of intracellularly synthesized Ag2Se QDs by over 8.7 times. Notably, the proliferative and in vivo tumorigenic capacities of the cells with strong NIR fluorescence-emitting functions could be maintained, enabling long-term tracking of cell division and disease progression. This work has provided new insights into fully excavating the potential of cells for the synthesis of inorganic nanocrystals by designing biocompatible precursors and also opened a new window for conventional synthetic biology from organic to inorganic.

Unraveling the genetic basis of microbial metal resistance: Shift from mendelian to systems biology

Microbial metal resistance, a trait that enables microorganisms to withstand high levels of toxic metals, has been studied for over a century. The significance of uncovering these mechanisms goes beyond basic science as they have implications for human health through their connection to microbial pathogenesis, metal bioremediation, and biomining. Recent advances in analytical chemistry and molecular biology have accelerated the discovery and understanding of genetic mechanisms underlying microbial metal resistance, identifying specific metal resistance genes and their operons. The emergence of omics tools has further propelled research towards a comprehensive understanding of how cells respond to metal stress at the systemic level, revealing the complex regulatory networks and evolutionary dynamics that drive microbial adaptation to metal-rich environments. In this article, we present a historical overview of the evolving understanding of the genetic determinants of metal resistance in microbes. Through multiple narrative threads, we illustrate how our knowledge of microbial metal resistance and genetics has interacted with genetic tools and concept development. This review also discusses how our understanding of microbial metal resistance has progressed from the Mendelian perspective to the current systems biology viewpoint, particularly as omics approaches have considerably enhanced our understanding. This system-level understanding has opened new possibilities for genetically engineered microorganisms to regulate metal homeostasis.

Direct Visualization of Self-Mineralized Biohybrid-Triggered Apoptosis-Ferroptosis Synergistic Tumor Therapy by Cryo-Soft X-ray Tomography

Bionano robots have been recognized as a tumor-selective and effective platform for therapeutic outcomes as they synergize the merits of living organisms and nanoparticles. Here, we construct a self-mineralized system (denoted as SO@FeS) by employing the facultative anaerobic bacterium Shewanella oneidensis MR-1 to biosynthesize FeS NPs for effective cancer therapy with dual cell death pathways. Biogenic FeS NPs are embedded into the cell surface with inherent photothermal conversion ability and low crystallinity and tend to simultaneously release Fe2+ and hydrogen sulfide (H2S) in an acidic environment. As a result, the obtained SO@FeS hybrid can couple the versatility of the nanoparticles with the respiration and tumor-targeting capacities of bacterium, ultimately leading to the collaborative clearance of tumor cells. Specifically, cryo-soft X-ray tomography (cryo-SXT) is a near-native 3D imaging modality that directly displays the trafficking pathway of SO@FeS in cancer cells. More importantly, cryo-SXT captures the 3D maps of SO@FeS-initiated ferroptosis and apoptosis, as evidenced by the remodeling of cytoplasmic organelles. This work offers valuable theoretical insights from the perspective of organelle morphology, links subcellular reorganization and cell death pathways, and facilitates the design of living nanoplatforms that integrate multiple therapies.

Dynamic synthesis and transport of phenazine-1-carboxylic acid to boost extracellular electron transfer rate

Electron shuttle plays a decisive role in extracellular electron transfer (EET) of exoelectrogens. However, neither identifying the most efficient electron shuttle molecule nor programming its optimal synthesis level that boosts EET has been established. Here, the phenazine-1-carboxylic acid (PCA) biosynthesis pathway is first constructed to synthesize PCA at an optimal level for EET in Shewanella oneidensis MR-1. To facilitate PCA transport, the porin OprF is expressed to improve cell membrane permeability, the cytotoxicity of which, however, impaired cell growth. To mitigate cytotoxicity, PCA biosensor is designed to dynamically decouple PCA biosynthesis and transport, resulting in the maximum output power density reaching 2.85 ± 0.10 W m-2, 33.75-fold higher than wild-type strain. Moreover, extensive analyses of cellular electrophysiology, metabolism, and behaviors reveal PCA shuttles electrons from cell to electrode, which is the dominant mechanism underlying PCA-boosted EET. We conclude dynamic synthesis and transport of PCA is an efficient strategy for enhancing EET.

Recombinant Escherichia coli Utilizes Mild Hydrogen Sources for the Targeted Intracellular Synthesis of Palladium Nanoparticles and Whole-Cell-Catalyzed Aromatic Aldehyde Hydrogenation

Metal-enzyme cascade catalysis effectively combines the broad reactivity of chemical catalysis with the high selectivity of biocatalysis, improving reaction efficiency and simplifying the process flow through multiple sequential reactions in the same system. The introduction of exogenous palladium nanoparticles (Pd NPs) into Escherichia coli (E. coli) cells can significantly broaden the range of catalytic reactions facilitated by biological enzymes. Additionally, the targeted cytoplasmic synthesis of Pd NPs enhances their utilization efficiency in intracellular catalytic reactions while also eliminating the need for separating and purifying metals and enzymes. However, current methods largely enable the intracellular synthesis of Pd NPs in the periplasmic space and outer membrane. Moreover, the hydrogen sources commonly used in these methods─such as hydrogen (H2) and sodium borohydride (NaBH4)─carry safety risks. In this study, the mechanism of targeted synthesis of Pd NPs on the cytoplasmic side and its process were deeply investigated using a mild hydrogen source, sodium formate, in combination with genetic engineering and preparation conditions. And the constructed functional cell (Pd@E. coli) could catalyze benzaldehyde hydrogenation, with a conversion rate of 41.41% and benzyl alcohol yield of 17.68%, demonstrating considerable catalytic and loading stability. This study provides a reference for constructing catalytic systems for intracellular metal-enzyme cascades. Thus, it could bolster the development opportunities in the areas of non-natural products and drug development and provide ideas for addressing the drawbacks of existing biosynthetic technologies.

The Role of Anode Potential in Electromicrobiology

Electroactive microorganisms are capable of exchanging electrons with electrodes and thus have potential applications in many fields, including bioenergy production, microbial electrochemical synthesis of chemicals, environmental protection, and microbial electrochemical sensors. Due to the limitations of low electron transfer efficiency and poor stability, the application of electroactive microorganisms in industry is still confronted with significant challenges. In recent years, many studies have demonstrated that modulating anode potential is one of the effective strategies to enhance electron transfer efficiency. In this review, we have summarized approximately 100 relevant studies sourced from PubMed and Web of Science over the past two decades. We present the classification of electroactive microorganisms and their electron transfer mechanisms and elucidate the impact of anode potential on the bioelectricity behavior and physiology of electroactive microorganisms. Our review provides a scientific basis for researchers, especially those who are new to this field, to choose suitable anode potential conditions for practical applications to optimize the electron transfer efficiency of electroactive microorganisms, thus contributing to the application of electroactive microorganisms in industry.

SynBioNanoDesign: pioneering targeted drug delivery with engineered nanomaterials

Synthetic biology and nanotechnology fusion represent a transformative approach promoting fundamental and clinical biomedical science development. In SynBioNanoDesign, biological systems are reimagined as dynamic and programmable materials to yield engineered nanomaterials with emerging and specific functionalities. This review elucidates a comprehensive examination of synthetic biology's pivotal role in advancing engineered nanomaterials for targeted drug delivery systems. It begins with exploring the fundamental synergy between synthetic biology and nanotechnology, then highlights the current landscape of nanomaterials in targeted drug delivery applications. Subsequently, the review discusses the design of novel nanomaterials informed by biological principles, focusing on expounding the synthetic biology tools and the potential for developing advanced nanomaterials. Afterward, the research advances of innovative materials design through synthetic biology were systematically summarized, emphasizing the integration of genetic circuitry to program nanomaterial responses. Furthermore, the challenges, current weaknesses and opportunities, prospective directions, and ethical and societal implications of SynBioNanoDesign in drug delivery are elucidated. Finally, the review summarizes the transformative impact that synthetic biology may have on drug-delivery technologies in the future.

Near-Native Imaging of Metal Ion-Initiated Cell State Transition

Metal ions are indispensable to life, as they can serve as essential enzyme cofactors to drive fundamental biochemical reactions, yet paradoxically, excess is highly toxic. Higher-order cells have evolved functionally distinct organelles that separate and coordinate sophisticated biochemical processes to maintain cellular homeostasis upon metal ion stimuli. Here, we uncover the remodeling of subcellular architecture and organellar interactome in yeast initiated by several metal ion stimulations, relying on near-native three-dimensional imaging, cryo-soft X-ray tomography. The three-dimensional architecture of intact yeast directly shows that iron or manganese triggers a hormesis-like effect that promotes cell proliferation. This process leads to the reorganization of organelles in the preparation for division, characterized by the polar distribution of mitochondria, an increased number of lipid droplets (LDs), volume shrinkage, and the formation of a hollow structure. Additionally, vesicle-like structures that detach from the vacuole are observed. Oppositely, cadmium or mercury causes stress-associated phenotypes, including mitochondrial fragmentation, LD swelling, and autophagosome formation. Notably, the organellar interactome, encompassing the interactions between mitochondria and LDs and those between the nuclear envelope and LDs, is quantified and exhibits alteration with multifaceted features in response to different metal ions. More importantly, the dynamics of organellar architecture render them more sensitive biomarkers than traditional approaches for assessing the cell state. Strikingly, yeast has a powerful depuration capacity to isolate and transform the overaccumulated cadmium in the vacuole, mitochondria, and cytoplasm as a high-value product, quantum dots. This work presents the possibility of discovering fundamental links between organellar morphological characteristics and the cell state.

In vivo synthesis of semiconductor nanoparticles in Azotobacter vinelandii for light-driven ammonia production

Ammonia (NH3) is an important commodity chemical used as an agricultural fertilizer and hydrogen-storage material. There has recently been much interest in developing an environmentally benign process for NH3 synthesis. Here, we report enhanced production of ammonia from diazotrophs under light irradiation using hybrid composites of inorganic nanoparticles (NPs) and bacterial cells. The primary focus of this study lies in the intracellular biosynthesis of semiconductor NPs within Azotobacter vinelandii, a diazotroph, when bacterial cells are cultured in a medium containing precursor molecules. For example, enzymes in bacterial cells, such as cysteine desulfurase, convert cysteine (Cys) into precursors for cadmium sulfide (CdS) synthesis when supplied with CdCl2. Photoexcited charge carriers in the biosynthesized NPs are transferred to nitrogen fixation enzymes, e.g., nitrogenase, facilitating the production of ammonium ions. Notably, the intracellular biosynthesis approach minimizes cell toxicity compared to extracellular synthesis due to the diminished generation of reactive oxygen species. The biohybrid system based on the in vivo approach results in a fivefold increase in ammonia production (0.45 mg gDCW-1 h-1) compared to the case of diazotroph cells only (0.09 mg gDCW-1 h-1).

A one-step route for the conversion of Cd waste into CdS quantum dots by Acidithiobacillus sp. via unique biosynthesis pathways

Microorganisms serve as biological factories for the synthesis of nanomaterials such as CdS quantum dots. Based on the uniqueness of Acidithiobacillus sp., a one-step route was explored to directly convert cadmium waste into CdS QDs using these bacteria. First, an exhaustive study was conducted to reveal the specific pathways involved in the biosynthesis of CdS QDs. The widely known homologous enzyme, cysteine desulfhydrase, which catalyzes the synthesis of CdS QDs from a cysteine substrate, is also present in Acidithiobacillus sp. and is referred to as the OSH enzyme. The structure of the OSH enzyme was determined through X-ray crystallography. Moreover, we identified two new pathways. One involved the SQR enzyme in Acidithiobacillus sp., which catalyzed the formation of sulfur globules and subsequently catalyzed further reactions with GSH to release H2S; subsequently, a CdS QD biosynthesis pathway was successfully constructed. The other pathway involved extracellular polyphosphate, a bacterial metabolic product, which with the addition of GSH and Cd2+, resulted in the formation of water-soluble fluorescent CdS QDs in the supernatant. Based on the above-described mechanism, after the bioleaching of Cd2+ from cadmium waste by Acidithiobacillus sp., CdS QDs were directly obtained from the bacterial culture supernatants. This work provides important insights into cleaner production and cadmium bioremediation with potential industrial applications.

Biosynthesis of trimetallic nanoparticles and their biological applications: a recent review

Trimetallic nanoparticles (TMNPs) have emerged as a pivotal area of research due to their unique properties and diverse applications across medicine, agriculture, and environmental sciences. This review provides several novel contributions that distinguish it from existing literature on trimetallic nanoparticles (TMNPs). Firstly, it offers a focused exploration of TMNPs, specifically addressing their unique properties and applications, which have been less examined compared to other multimetallic nanoparticles. This targeted analysis fills a significant gap in current research. Secondly, the review emphasizes innovative biosynthesis methods utilizing microorganisms and plant extracts, positioning these green synthesis approaches as environmentally friendly alternatives to traditional chemical methods. This focus aligns with the increasing demand for sustainable practices in nanotechnology. Furthermore, the review integrates discussions on both medical and agricultural applications of TMNPs, highlighting their multifunctional potential across diverse fields. This comprehensive perspective enhances our understanding of how TMNPs can address various challenges. Additionally, the review explores the synergistic effects among the different metals in TMNPs, providing insights into how these interactions can be harnessed to optimize their properties for specific applications. Such discussions are often overlooked in existing studies. Moreover, this review identifies critical research gaps and challenges within the field, outlining future directions that encourage further investigation and innovation in TMNP development. By doing so, it proactively contributes to advancing the field. Finally, the review advocates for interdisciplinary collaboration among material scientists, biologists, and environmental scientists, emphasizing the importance of diverse expertise in enhancing the research and application of TMNPs.

Advancements in magnetic catalysts: Preparation, modification, and applications in photocatalytic and environmental remediation

Owing to their widely available source materials, simple magnetic separation, and low cost, magnetic catalysts have demonstrated considerable application potential in modern photocatalysis technologies and environmental remediation. This review summarizes the synthesis and modification methods of magnetic catalysts and describes recent advances using different synthesis methods. Several key problems still need to be solved in the existing progress, such as the fact that the catalytic activity of magnetic catalysts decreases over time. Under an external magnetic field, magnetic catalysts exhibit satisfactory energy bandgaps and charge transfer rates for photocatalysis, enabling wide and comprehensive photocatalytic applications. In addition, they are strong candidate materials for wastewater treatment and new-energy applications. In summary, the review provides future directions for the development of novel magnetic catalysts, contaminant removal, and even large-scale practical applications.

Leveraging bacteria-inspired nanomaterials for targeted controlling biofilm and virulence properties of Pseudomonas aeruginosa

Pseudomonas aeruginosa is an opportunistic pathogen designated as a high-priority pathogen because of its role in major healthcare-associated and nosocomial infections. Biofilm production by these bacteria is one of the adaptive resistance mechanisms to traditional antibiotics, making treatment challenging, especially for immunocompromised patients. P. aeruginosa also produces a variety of virulence factors, which aid in invasion, adhesion, persistence, and immune system protection. Recent advances in nanotechnology-based therapy, notably the application of bioinspired metal and metal-oxide nanomaterials, have been seen as a viable way to control P. aeruginosa biofilm and virulence. Because of its ease of growth and culture, synthesizing metal and metal-oxide nanomaterials using bacterial species has become one of the most environmentally benign green synthesis options. The application of bacterial-inspired nanomaterials is particularly successful for targeted control of P. aeruginosa infection due to interactions with cell membrane components and transport systems. This paper delves into and provides a complete overview of the application of bacterial-inspired metal and metal-oxide nanomaterials to treat P. aeruginosa infection by targeting biofilm and virulence characteristics. The review focused on synthesizing and applying gold, silver, copper, iron, magnetite, and zinc oxide nanomaterials to mitigate P. aeruginosa biofilm and virulence. The underlying mechanism of these metal and metal-oxide nanoparticles in relation to biofilm and virulence features has also been thoroughly discussed. The current review introduces novel approaches to treating and controlling drug-resistant P. aeruginosa using bacterial-inspired nanomaterials as a targeted therapeutic strategy.

Recent advances in carbon quantum dots for gene delivery: A comprehensive review

Gene therapy is a revolutionary technology in healthcare that provides novel therapeutic options and has immense potential in addressing genetic illnesses, malignancies, and viral infections. Nevertheless, other obstacles still need to be addressed regarding safety, ethical implications, and technological enhancement. Nanotechnology and gene therapy fields have shown significant promise in transforming medical treatments by improving accuracy, effectiveness, and personalization. This review assesses the possible uses of gene therapy, its obstacles, and future research areas, specifically emphasizing the creative combination of gene therapy and nanotechnology. Nanotechnology is essential for gene delivery as it allows for the development of nano-scale carriers, such as carbon quantum dots (CQDs), which may effectively transport therapeutic genes into specific cells. CQDs exhibit distinctive physicochemical characteristics such as small size, excellent stability, and minimal toxicity, which render them highly favorable for gene therapy applications. The objective of this study is to review and describe the current advancements in the utilization of CQDs for gene delivery. Additionally, it intends to assess existing research, explore novel applications, and identify future opportunities and obstacles. This study offers a thorough summary of the current state and future possibilities of using CQDs for gene delivery. Combining recent research findings highlights the potential of CQDs to revolutionize gene therapy and its delivery methods.

Updated Review of Metal Nanoparticles Fabricated by Green Chemistry Using Natural Extracts: Biosynthesis, Mechanisms, and Applications

Metallic nanoparticles have found wide applications due to their unique physical and chemical properties. Green biosynthesis using plants, microbes, and plant/microbial extracts provides an environmentally friendly approach for nanoparticle synthesis. This review discusses the mechanisms and factors governing the biosynthesis of metallic nanoparticles such as silver, gold, and zinc using various plant extracts and microorganisms, including bacteria, fungi, and algae. The phytochemicals and biomolecules responsible for reducing metal ions and stabilizing nanoparticles are discussed. Key process parameters like pH, temperature, and precursor concentration affecting particle size are highlighted. Characterization techniques for confirming the formation and properties of nanoparticles are also mentioned. Applications of biosynthesized nanoparticles in areas such as antibacterial delivery, cancer therapy, biosensors, and environmental remediation are reviewed. Challenges in scaling up production and regulating nanoparticle properties are addressed. Power Point 365 was used for creating graphics. Overall, green biosynthesis is an emerging field with opportunities for developing eco-friendly nanomanufacturing platforms using abundant natural resources. Further work on optimizing conditions, standardizing protocols, and exploring new biosources is needed to realize the full potential of this approach.

Biometabolically Derived Selenium Nanoparticles Armed with Protein Protective Suit toward High-Performance Li-Se Batteries

Selenium (Se) serves as a burgeoning high-energy-density cathode material in lithium-ion batteries. However, the development of Se cathode is strictly limited by low Se utilization and inferior cycling stability arising from intrinsic volume expansion and notorious shuttle effect. Herein, a microbial metabolism strategy is developed to prepare "functional vesicle-like" Se globules via Bacillus subtilis subsp. from selenite in sewage, in which Se nanoparticles are armed with a natural biological protein membrane with rich nitrogen and phosphorus, achieving the eco-efficient conversion of trash into treasure (selenite, SeO3 2- → Selenium, Se). The appealing-design "functional vesicle-like" Se globules are beneficial to accommodate volume changes of Se in electrochemical reactions, confining polyselenides via chemisorption, and enhancing mechanical strength of electrode by associated bacteria debris, realizing comprehensive utilization of microorganism. By conceptualizing "functional vesicle-like" Se globules, rather than artificial Se-host composites, as cathode for lithium-selenium batteries, it exhibits outstanding cycling stability and improved rate performance. This strategy opens the door to design smart electrode materials with unattainable structure that cannot be achieved by traditional approaches, achieving eco-efficient conversion of pollutants into energy-storage nanomaterials, which will be a promising research field for interdisciplinary of energy, biology, and environment.

Advancements in Functional Nanomaterials Inspired by Viral Particles

Virus-like particles (VLPs) are nanostructures composed of one or more structural proteins, exhibiting stable and symmetrical structures. Their precise compositions and dimensions provide versatile opportunities for modifications, enhancing their functionality. Consequently, VLP-based nanomaterials have gained widespread adoption across diverse domains. This review focuses on three key aspects: the mechanisms of viral capsid protein self-assembly into VLPs, design methods for constructing multifunctional VLPs, and strategies for synthesizing multidimensional nanomaterials using VLPs. It provides a comprehensive overview of the advancements in virus-inspired functional nanomaterials, encompassing VLP assembly, functionalization, and the synthesis of multidimensional nanomaterials. Additionally, this review explores future directions, opportunities, and challenges in the field of VLP-based nanomaterials, aiming to shed light on potential advancements and prospects in this exciting area of research.

Understanding Nanoscale Interactions between Minerals and Microbes: Opportunities for Green Remediation of Contaminated Sites

In situ contaminant degradation and detoxification mediated by microbes and minerals is an important element of green remediation. Improved understanding of microbe-mineral interactions on the nanoscale offers promising opportunities to further minimize the environmental and energy footprints of site remediation. In this Perspective, we describe new methodologies that take advantage of an array of multidisciplinary tools─including multiomics-based analysis, bioinformatics, machine learning, gene editing, real-time spectroscopic and microscopic analysis, and computational simulations─to identify the key microbial drivers in the real environments, and to characterize in situ the dynamic interplay between minerals and microbes with high spatiotemporal resolutions. We then reflect on how the knowledge gained can be exploited to modulate the binding, electron transfer, and metabolic activities at the microbe-mineral interfaces, to develop new in situ contaminant degradation and detoxication technologies with combined merits of high efficacy, material longevity, and low environmental impacts. Two main strategies are proposed to maximize the synergy between minerals and microbes, including using mineral nanoparticles to enhance the versatility of microorganisms (e.g., tolerance to environmental stresses, growth and metabolism, directed migration, selectivity, and electron transfer), and using microbes to synthesize and regenerate highly dispersed nanostructures with desired structural/surface properties and reactivity.

Phage-based delivery systems: engineering, applications, and challenges in nanomedicines

Bacteriophages (phages) represent a unique category of viruses with a remarkable ability to selectively infect host bacteria, characterized by their assembly from proteins and nucleic acids. Leveraging their exceptional biological properties and modifiable characteristics, phages emerge as innovative, safe, and efficient delivery vectors. The potential drawbacks associated with conventional nanocarriers in the realms of drug and gene delivery include a lack of cell-specific targeting, cytotoxicity, and diminished in vivo transfection efficiency. In contrast, engineered phages, when employed as cargo delivery vectors, hold the promise to surmount these limitations and attain enhanced delivery efficacy. This review comprehensively outlines current strategies for the engineering of phages, delineates the principal types of phages utilized as nanocarriers in drug and gene delivery, and explores the application of phage-based delivery systems in disease therapy. Additionally, an incisive analysis is provided, critically examining the challenges confronted by phage-based delivery systems within the domain of nanotechnology. The primary objective of this article is to furnish a theoretical reference that contributes to the reasoned design and development of potent phage-based delivery systems.

The use of phages for the biosynthesis of metal nanoparticles and their biological applications: A review

Nowadays, the use of biological methods of synthesis of nanoparticles as substitutes for methods that use high energy and consumption of expensive and dangerous materials is of interest to researchers all over the world. Biological methods of synthesising metal nanoparticles are very important because they are easy, affordable, safe, environmentally friendly and able to control the size and shape of nanoparticles. One of the methods that is of interest today is the use of bacteriophages as the most abundant organisms in nature in the synthesis of metal nanoparticles. Nanomaterials biosynthesized from phages have shown various clinical applications, including antimicrobial activities, biomedical sensors, drug and gene delivery systems, cancer treatment and tissue regeneration. Therefore, the purpose of this review is to investigate the biosynthesis of metal nanoparticles with phages and their biomedical applications.

Biosynthesis of photostable CdS quantum dots by UV-resistant psychrotolerant bacteria isolated from Union Glacier, Antarctica

BACKGROUND

Quantum Dots (QDs) are fluorescent nanoparticles with exceptional optical and optoelectronic properties, finding widespread utility in diverse industrial applications. Presently, chemically synthesized QDs are employed in solar cells, bioimaging, and various technological domains. However, many applications demand QDs with prolonged lifespans under conditions of high-energy radiation. Over the past decade, microbial biosynthesis of nanomaterials has emerged as a sustainable and cost-effective process. In this context, the utilization of extremophile microorganisms for synthesizing QDs with unique properties has recently been reported.

RESULTS

In this study, UV-resistant bacteria were isolated from one of the most extreme environments in Antarctica, Union Glacier at the Ellsworth Mountains. Bacterial isolates, identified through 16 S sequencing, belong to the genera Rhodococcus, Pseudarthrobacter, and Arthrobacter. Notably, Rhodococcus sp. (EXRC-4 A-4), Pseudarthrobacter sp. (RC-2-3), and Arthrobacter sp. (EH-1B-1) tolerate UV-C radiation doses ≥ 120 J/m². Isolated UV-resistant bacteria biosynthesized CdS QDs with fluorescence intensities 4 to 8 times higher than those biosynthesized by E. coli, a mesophilic organism tolerating low doses of UV radiation. Transmission electron microscopy (TEM) analysis determined QD sizes ranging from 6 to 23 nm, and Fourier-transform infrared (FTIR) analysis demonstrated the presence of biomolecules. QDs produced by UV-resistant Antarctic bacteria exhibit high photostability after exposure to UV-B radiation, particularly in comparison to those biosynthesized by E. coli. Interestingly, red fluorescence-emitting QDs biosynthesized by Rhodococcus sp. (EXRC-4 A-4) and Arthrobacter sp. (EH-1B-1) increased their fluorescence emission after irradiation. Analysis of methylene blue degradation after exposure to irradiated QDs biosynthesized by UV-resistant bacteria, indicates that the QDs transfer their electrons to O2 for the formation of reactive oxygen species (ROS) at different levels.

CONCLUSIONS

UV-resistant Antarctic bacteria represent a novel alternative for the sustainable generation of nanostructures with increased radiation tolerance-two characteristics favoring their potential application in technologies requiring continuous exposure to high-energy radiation.

Self-Assembly of Heterogeneous Ferritin Nanocages for Tumor Uptake and Penetration

Well-defined nanostructures are crucial for precisely understanding nano-bio interactions. However, nanoparticles (NPs) fabricated through conventional synthesis approaches often lack poor controllability and reproducibility. Herein, a synthetic biology-based strategy is introduced to fabricate uniformly reproducible protein-based NPs, achieving precise control over heterogeneous components of the NPs. Specifically, a ferritin assembly toolbox system is developed that enables intracellular assembly of ferritin subunits/variants in Escherichia coli. Using this strategy, a proof-of-concept study is provided to explore the interplay between ligand density of NPs and their tumor targets/penetration. Various ferritin hybrid nanocages (FHn) containing human ferritin heavy chains (FH) and light chains are accurately assembled, leveraging their intrinsic binding with tumor cells and prolonged circulation time in blood, respectively. Further studies reveal that tumor cell uptake is FH density-dependent through active binding with transferrin receptor 1, whereas in vivo tumor accumulation and tissue penetration are found to be correlated to heterogeneous assembly of FHn and vascular permeability of tumors. Densities of 3.7 FH/100 nm2 on the nanoparticle surface exhibit the highest degree of tumor accumulation and penetration, particularly in tumors with high permeability compared to those with low permeability. This study underscores the significance of nanoparticle heterogeneity in determining particle fate in biological systems.

Metallic nanomaterials - targeted drug delivery approaches for improved bioavailability, reduced side toxicity, and enhanced patient outcomes

This paper explores the integral role of metallic nanomaterials in drug delivery, specifically focusing on their unique characteristics and applications. Exhibiting unique size, shape, and surface features, metallic nanoparticles (MNPs) (e.g., gold, iron oxide, and silver NPs) present possibilities for improving medication efficacy while minimizing side effects. Their demonstrated success in improving drug solubility, bioavailability, and targeted release makes them promising carriers for treating a variety of diseases, including inflammation and cancer, which has one of the highest rates of mortality in the world. Furthermore, it is crucial to acknowledge some limitations of MNPs in drug delivery before successfully incorporating them into standard medical procedures. Thus, challenges such as potential toxicity, issues related to long-term safety, and the need for standardized production methods will also be addressed.

Peptide nanovaccine in melanoma immunotherapy

Melanoma is an especially fatal neoplasm resistant to traditional treatment. The advancement of novel therapeutical approaches has gained attention in recent years by shedding light on the molecular mechanisms of melanoma tumorigenesis and their powerful interplay with the immune system. The presence of many mutations in melanoma cells results in the production of a varied array of antigens. These antigens can be recognized by the immune system, thereby enabling it to distinguish between tumors and healthy cells. In the context of peptide cancer vaccines, generally, they are designed based on tumor antigens that stimulate immunity through antigen-presenting cells (APCs). As naked peptides often have low potential in eliciting a desirable immune reaction, immunization with such compounds usually necessitates adjuvants and nanocarriers. Actually, nanoparticles (NPs) can provide a robust immune response to peptide-based melanoma vaccines. They improve the directing of peptide vaccines to APCs and induce the secretion of cytokines to get maximum immune response. This review provides an overview of the current knowledge of the utilization of nanotechnology in peptide vaccines emphasizing melanoma, as well as highlights the significance of physicochemical properties in determining the fate of these nanovaccines in vivo, including their drainage to lymph nodes, cellular uptake, and influence on immune responses.

Biological upcycling of nickel and sulfate as electrocatalyst from electroplating wastewater

Upcycling nickel (Ni) to useful catalyst is an appealing route to realize low-carbon treatment of electroplating wastewater and simultaneously recovering Ni resource, but has been restricted by the needs for costly membranes or consumption of large amount of chemicals in the existing upcycling processes. Herein, a biological upcycling route for synchronous recovery of Ni and sulfate as electrocatalysts, with certain amount of ferric salt (Fe3+) added to tune the product composition, is proposed. Efficient biosynthesis of bio-NiFeS nanoparticles from electroplating wastewater was achieved by harnessing the sulfate reduction and metal detoxification ability of Desulfovibrio vulgaris. The optimal bio-NiFeS, after further annealing at 300 °C, served as an efficient oxygen evolution electrocatalyst, achieving a current density of 10 mA·cm-1 at an overpotential of 247 mV and a Tafel slope of 60.2 mV·dec-1. It exhibited comparable electrocatalytic activity with the chemically-synthesized counterparts and outperformed the commercial RuO2. The feasibility of the biological upcycling approach for treating real Ni-containing electroplating wastewater was also demonstrated, achieving 99.5 % Ni2+removal and 41.0 % SO42- removal and enabling low-cost fabrication of electrocatalyst. Our work paves a new path for sustainable treatment of Ni-containing wastewater and may inspire technology innovations in recycling/ removal of various metal ions.

Bacterially synthesized superfine tellurium nanoneedles as an antibacterial and solar-thermal still for efficient purification of polluted water

Bacterial biosynthesis of nanomaterials has several advantages (e.g., reduced energy inputs, lower cost, negligible environmental pollution) compared with traditional approaches. Various nanomaterials have been produced by bacteria. However, reports on using the bacterial biosynthesis of nanomaterials for applications with solar-thermal agents are scarce due to their narrow optical absorption. Herein, for the first time, we proposed a bacterial biosynthesis of broad-absorbing tellurium nanoneedles and demonstrated their effectiveness for solar-thermal evaporation and antibacterial applications. By simple biosynthesis within bacteria (Shewanella oneidensis MR-1), tellurium nanoneedles achieved a superfine configuration with a length-to-diameter ratio of nearly 20 and broad-spectrum absorbance. After integrating tellurium nanoneedles into a porous polyvinyl-alcohol scaffold, a solar-thermal still named TSAS-3 realized a high evaporation rate of 2.25 kg m-2 h-1 and solar-thermal conversion efficiency of 81% upon 1-Sun illumination. Based on these unique properties, the scaffold displayed good performances in seawater desalination, multiple wastewater treatment, and antibacterial applications. This work provides a simple and feasible strategy for the use of microbial-synthesized nanomaterials in solar-driven water purification and antibacterial applications.

Living Materials Based Dynamic Information Encryption via Light-Inducible Bacterial Biosynthesis of Quantum Dots

Microbial biosynthesis, as an alternative method for producing quantum dots (QDs), has gained attention because it can be conducted under mild and environmentally friendly conditions, distinguishing it from conventional chemical and physical synthesis approaches. However, there is currently no method to selectively control this biosynthesis process in a subset of microbes within a population using external stimuli. In this study, we have attained precise and selective control over the microbial biosynthesis of QDs through the utilization of an optogenetically engineered Escherichia coli (E. coli). The recombinant E. coli is designed to express smCSE enzyme, under the regulation of eLightOn system, which can be activated by blue light. The smCSE enzymes use L-cysteine and Cd2+ as substrates to form CdS QDs. This system enables light-inducible bacterial biosynthesis of QDs in precise patterns within a hydrogel for information encryption. As the biosynthesis progresses, the optical characteristics of the QDs change, allowing living materials containing the recombinant E. coli to display time-dependent patterns that self-destruct after reading. Compared to static encryption using fluorescent QD inks, dynamic information encryption based on living materials offers enhanced security.

Biogenic engineered nanomaterials for enhancing bioavailability via developing nano-iron-fortified smart foods: advances, insight, and prospects of nanobionics in fortification of food

Iron deficiency is a significant cause of iron deficiency anemia (IDA). Treatment of IDA is challenging due to several challenges, including low target bioavailability, low palatability, poor pharmacokinetics, and extended therapeutic regimes. Nanotechnology holds the promise of revolutionizing the management and treatment of IDA. Smart biogenic engineered nanomaterials (BENMs) such as lipids, protein, carbohydrates, and complex nanomaterials have been the subject of extensive research and opened new avenues for people and the planet due to their enhanced physicochemical, rheological, optoelectronic, thermomechanical, biological, magnetic, and nutritional properties. Additionally, they show eco-sustainability, low biotoxicity, active targeting, enhanced permeation and retention, and stimuli-responsive characteristics. We examine the opportunities offered by emerging smart BENMs for the treatment of iron deficiency anemia by utilizing iron-fortified smart foods. We review the progress made so far and other future directions to maximize the impact of smart nanofortification on the global population. The toxicity effects are also discussed with commercialization challenges.

Preparation and usage of nanomaterials in biomedicine

Nanotechnology is one of the most promising and decisive technologies in the world. Nanomaterials, as the primary research aspect of nanotechnology, are quite different from macroscopic materials because of their unique optical, electrical, magnetic, thermal properties, and more robust mechanical properties, which make them play an essential role in the field of materials science, biomedical field, aerospace field, and environmental energy. Different preparation methods for nanomaterials have various physical and chemical properties and are widely used in different areas. In this review, we focused on the preparation methods, including chemical, physical, and biological methods due to the properties of nanomaterials. We mainly clarified the characteristics, advantages, and disadvantages of different preparation methods. Then, we focused on the applications of nanomaterials in biomedicine, including biological detection, tumor diagnosis, and disease treatment, which provide a development trend and promising prospects for nanomaterials.

A State-of-the-Art Systemic Review on Selenium Nanoparticles: Mechanisms and Factors Influencing Biogenesis and Its Potential Applications

Selenium is a trace element required for the active function of numerous enzymes and various physiological processes. In recent years, selenium nanoparticles draw the attention of scientists and researchers because of its multifaceted uses. The process involved in chemically synthesized SeNPs has been found to be hazardous in nature, which has paved the way for safe and ecofriendly SeNPs to be developed in order to achieve sustainability. In comparison to chemical synthesis, SeNPs can be synthesized more safely and with greater flexibility utilizing bacteria, fungi, and plants. This review focused on the synthesis of SeNPs utilizing bacteria, fungi, and plants; the mechanisms involved in SeNP synthesis; and the effect of various abiotic factors on SeNP synthesis and morphological characteristics. This article discusses the synergies of SeNP synthesis via biological routes, which can help future researchers to synthesize SeNPs with more precision and employ them in desired fields.

Exploring novel strategies to improve anti-tumour efficiency: The potential for targeting reactive oxygen species

The cellular milieu in which malignant growths or cancer stem cells reside is known as the tumour microenvironment (TME). It is the consequence of the interactivity amongst malignant and non-malignant cells and directly affects cancer development and progression. Reactive oxygen species (ROS) are chemically reactive molecules that contain oxygen, they are generated because of numerous endogenous and external factors. Endogenous ROS produced from mitochondria is known to significantly increase intracellular oxidative stress. In addition to playing a key role in several biological processes both in healthy and malignant cells, ROS function as secondary messengers in cell signalling. At low to moderate concentrations, ROS serves as signalling transducers to promote cancer cell motility, invasion, angiogenesis, and treatment resistance. At high concentrations, ROS can induce oxidative stress, leading to DNA damage, lipid peroxidation and protein oxidation. These effects can result in cell death or trigger signalling pathways that lead to apoptosis. The creation of innovative therapies and cancer management techniques has been aided by a thorough understanding of the TME. At present, surgery, chemotherapy, and radiotherapy, occasionally in combination, are the most often used methods for tumour treatment. The current challenge that these therapies face is the lack of spatiotemporal application specifically at the lesion which results in toxic effects on healthy cells associated with off-target drug delivery and undesirably high doses. Nanotechnology can be used to specifically deliver various chemicals via nanocarriers to target tumour cells, thereby increasing the accumulation of ROS-inducing agents at the site of the tumour. Nanoparticles can be engineered to release ROS-inducing agents in a controlled manner to the TME that will in turn react with the ROS to either increase or decrease it, thereby improving antitumour efficiency. Nano-delivery systems such as liposomes, nanocapsules, solid lipid nanoparticles and nanostructured lipid carriers were explored for the up/down-regulation of ROS. This review will discuss the use of nanotechnology in targeting and altering the ROS in the TME.

Applications of drug delivery systems, organic, and inorganic nanomaterials in wound healing

The skin is known to be the largest organ in the human body, while also being exposed to environmental elements. This indicates that skin is highly susceptible to physical infliction, as well as damage resulting from medical conditions such as obesity and diabetes. The wound management costs in hospitals and clinics are expected to rise globally over the coming years, which provides pressure for more wound healing aids readily available in the market. Recently, nanomaterials have been gaining traction for their potential applications in various fields, including wound healing. Here, we discuss various inorganic nanoparticles such as silver, titanium dioxide, copper oxide, cerium oxide, MXenes, PLGA, PEG, and silica nanoparticles with their respective roles in improving wound healing progression. In addition, organic nanomaterials for wound healing such as collagen, chitosan, curcumin, dendrimers, graphene and its derivative graphene oxide were also further discussed. Various forms of nanoparticle drug delivery systems like nanohydrogels, nanoliposomes, nanofilms, and nanoemulsions were discussed in their function to deliver therapeutic agents to wound sites in a controlled manner.

Long-Term Continuous Test of H2-Induced Denitrification Catalyzed by Palladium Nanoparticles in a Biofilm Matrix

Pd0 catalysis and microbially catalyzed reduction of nitrate (NO3--N) were combined as a strategy to increase the kinetics of NO3- reduction and control selectivity to N2 gas versus ammonium (NH4+). Two H2-based membrane biofilm reactors (MBfRs) were tested in continuous mode: one with a biofilm alone (H2-MBfR) and the other with biogenic Pd0 nanoparticles (Pd0NPs) deposited in the biofilm (Pd-H2-MBfR). Solid-state characterizations of Pd0NPs in Pd-H2-MBfR documented that the Pd0NPs were uniformly located along the outer surfaces of the bacteria in the biofilm. Pd-H2-MBfR had a higher rate of NO3- reduction compared to H2-MBfR, especially when the influent NO3- concentration was high (28 mg-N/L versus 14 mg-N/L). Pd-H2-MBfR enriched denitrifiers of Dechloromonas, Azospira, Pseudomonas, and Stenotrophomonas in the microbial community and also increased abundances of genes affiliated with NO3--N reductases, which reflected that the denitrifying bacteria could channel their respiratory electron flow to NO3- reduction to NO2-. N2 selectivity in Pd-H2-MBfR was regulated by the H2/NO3- flux ratio: 100% selectivity to N2 was achieved when the ratio was less than 1.3 e- equiv of H2/e- equiv N, while the selectivity toward NH4+ occurred with larger H2/NO3- flux ratios. Thus, the results with Pd-H2-MBfR revealed two advantages of it over the H2-MBfR: faster kinetics for NO3- removal and controllable selectivity toward N2 versus NH4+. By being able to regulate the H2/NO3- flux ratio, Pd-H2-MBfR has significant implications for improving the efficiency and effectiveness of the NO3- reduction processes, ultimately leading to more environmentally benign wastewater treatment.

Cancer phototherapy with nano-bacteria biohybrids

The utilization of light for therapeutic interventions, also known as phototherapy, has been extensively employed in the treatment of a wide range of illnesses, including cancer. Despite the benefits of its non-invasive nature, phototherapy still faces challenges pertaining to the delivery of phototherapeutic agents, phototoxicity, and light delivery. The incorporation of nanomaterials and bacteria in phototherapy has emerged as a promising approach that leverages the unique properties of each component. The resulting nano-bacteria biohybrids exhibit enhanced therapeutic efficacy when compared to either component individually. In this review, we summarize and discuss the various strategies for assembling nano-bacteria biohybrids and their applications in phototherapy. We provide a comprehensive overview of the properties and functionalities of nanomaterials and cells in the biohybrids. Notably, we highlight the roles of bacteria beyond their function as drug vehicles, particularly their capacity to produce bioactive molecules. Despite being in its early stage, the integration of photoelectric nanomaterials and genetically engineered bacteria holds promise as an effective biosystem for antitumor phototherapy. The utilization of nano-bacteria biohybrids in phototherapy is a promising avenue for future investigation, with the potential to enhance treatment outcomes for cancer patients.

The Construction of a Microbial Synthesis System for Rare Earth Enrichment and Material Applications

Rare earth materials play an irreplaceable role in biomedical and high technology fields. However, typical mining and extraction approaches to rare earth elements (REEs) often lead to severe environmental problems and resource wastage due to the involvement of hazardous chemicals. Although biomining shows elegant alternatives, there are still grand challenges to sustainably isolate and recover REEs in nature because of insufficient metal-extracting microbes and RE-scavenging macromolecular tools. To obtain high-performance rare earth materials directly from rare earth ore, a new generation of biological synthesis strategies needs to be developed for the efficient preparation of REEs. The microbial synthesis system established here has achieved active biomanufacturing of high-purity rare earth products. Further, through employing robust affinity columns bioconjugated with structurally engineered proteins, outstanding separation of Eu/Lu and Dy/La is acquired with the purity of 99.9% (Eu), 97.1% (La), and 92.7% (Dy). More importantly, in situ one-pot synthesis of lanthanide-dependent methanol dehydrogenase is well harnessed and exclusively adsorbs La, Ce, Pr, and Nd in RE tailing for advanced biocatalysis, indicating high value-added application. Therefore, this novel biosynthetic platform provides an insightful roadmap to expand the scope of chassis engineering in terms of biofoundry and to manufacture valuable bioproducts related to REEs.

Recent progress of micro/nanomotors to overcome physiological barriers in the gastrointestinal tract

Oral administration is a convenient administration route for gastrointestinal disease therapy with good patient compliance. But the nonspecific distribution of the oral drugs may cause serious side effects. In recent years, oral drug delivery systems (ODDS) have been applied to deliver the drugs to the gastrointestinal disease sites with decreased side effects. However, the delivery efficiency of ODDS is tremendously limited by physiological barriers in the gastrointestinal sites, such as the long and complex gastrointestinal tract, mucus layer, and epithelial barrier. Micro/nanomotors (MNMs) are micro/nanoscale devices that transfer various energy sources into autonomous motion. The outstanding motion characteristics of MNMs inspired the development of targeted drug delivery, especially the oral drug delivery. However, a comprehensive review of oral MNMs for the gastrointestinal diseases therapy is still lacking. Herein, the physiological barriers of ODDS were comprehensively reviewed. Afterward, the applications of MNMs in ODDS for overcoming the physiological barriers in the past 5 years were highlighted. Finally, future perspectives and challenges of MNMs in ODDS are discussed as well. This review will provide inspiration and direction of MNMs for the therapy of gastrointestinal diseases, pushing forward the clinical application of MNMs in oral drug delivery.

Biosynthesis, Spectrophotometric Follow-Up, Characterization, and Variable Antimicrobial Activities of Ag Nanoparticles Prepared by Edible Macrofungi

The biosynthesis of silver nanoparticles (Ag NPs) could play a significant role in the development of commercial antimicrobials. Herein, the biosynthesis of Ag NPs was studied using the edible mushroom Pleurotus floridanus, and following its formation, spectrophotometry was used to detect the best mushroom content, pH, temperature, and silver concentration. After that, the morphology was described via transmission electron microscopy (TEM), and nanoscale-size particles were found ranging from 11 to 13 nm. The best conditions of Ag content and pH were found at 1.0 mM and 11.0, respectively. In addition, the best mushroom extract concentration was found at 30 g/L. According to XRD analysis, the crystal structure of the formed amorphous Ag NPs is cubic with a space group of fm-3m and a space group number of 225. After that, the function groups at the surface of the prepared Ag NPs were studied via FTIR analysis, which indicated the presence of C=O, C-H, and O-H groups. These groups could indicate the presence of mushroom traces in the Ag NPs, which was confirmed via the amorphous characteristics of Ag NPs from the XRD analysis. The prepared Ag NPs have a high impact against different microorganisms, which could be attributed to the ability of Ag NPs to penetrate the cell bacterial wall.

Detection and discrimination of pathogenic bacteria with nanomaterials-based optical biosensors: A review

Pathogenic bacteria can pose a great threat to food safety and human health. It is therefore imperative to develop a rapid, portable, and sensitive determination and discrimination method for pathogenic bacteria. Over the past few years, various nanomaterials (NMs) have been employed as desirable nanoprobes because they possess extraordinary properties that can be used for optical signal enabled detection and identification of bacteria. By means of modification, NMs can, depending on different mechanisms, sense targets directly or indirectly, which then provides an essential support for the detection and differentiation of pathogenic bacteria. In this review, recent application of NMs-based optical biosensors for food safety bacterial detection and discrimination is performed, mainly in but not limited to noble metal NMs, fluorescent NMs, and point-of-care testing (POCT). This review also focuses on future trends in bacterial detection and discrimination, and machine learning in performing intelligent rapid detection and multiple accurate identification of bacteria.

Sunlight-driven intimately coupled photocatalysis and biodegradation (SDICPB): A sustainable approach for enhanced detoxification of triclosan

Triclosan is considered as recalcitrant contaminant difficult to degrade from the contaminated wastewater. Thus, promising, and sustainable treatment method is necessary to remove triclosan from the wastewater. Intimately coupled photocatalysis and biodegradation (ICPB) is an emerging, low-cost, efficient, and eco-friendly method for the removal of recalcitrant pollutants. In this study BiOI photocatalyst coated bacterial biofilm developed at carbon felt for efficient degradation and mineralization of triclosan was studied. Based on the characterization of BiOI prepared using methanol had lower band gap 1.85 eV which favors lower recombination of electron-hole pair and higher charge separation which ascribed to enhanced photocatalytic activity. ICPB exhibits 89% of triclosan degradation under direct sunlight exposure. The results showed that production of reactive oxygen species hydroxyl radical and superoxide radical anion played crucial role in the degradation of triclosan into biodegradable metabolites further the bacterial communities mineralized the biodegradable metabolites into water and carbon dioxide. The confocal laser scanning electron microscope results emphasized that interior of the biocarrier shows a large number of live bacterial cells existing in the photocatalyst-coated carrier, where the little toxic effect on bacterial biofilm occurred on the exterior of the carrier. The extracellular polymeric substances characterization result remarkable confirms that which could act as sacrificial agent of photoholes further helped by preventing the toxicity to the bacterial biofilm from the reactive oxygen species and triclosan. Hence, this promising approach can be a possible alternative method for the wastewater treatment polluted with triclosan.

Biogenic Copper Selenide Nanoparticles for Near-Infrared Photothermal Therapy Application

Near-infrared (NIR) photothermal therapy (PTT) is attractive for cancer treatment but is currently restricted by limited availability and insufficient NIR-II photoactivity of photothermal agents, for which artificial nanomaterials are usually used. Here, we report the first use of biogenic nanomaterials for PTT application. A fine-controlled extracellular biosynthesis of copper selenide nanoparticles (bio-Cu_2-xSe) by Shewanella oneidensis MR-1 was realized. The resulting bio-Cu_2-xSe, with fine sizes (∼35.5 nm) and high product purity, exhibited 76.9% photothermal conversion efficiency under 1064 nm laser irradiation, outperforming almost all the existing counterparts. The protein capping also imparted good biocompatibility to bio-Cu_2-xSe to favor a safe PTT application. The in vivo PTT with injected bio-Cu_2-xSe in mice (without extraction nor further modification) showed 87% tumor ablation without impairing the normal organisms. Our work not only opens a green route to synthesize the NIR-II photothermal nanomaterial but may also lay a basis for the development of bacteria-nanomaterial hybrid therapy technologies.

Direct Visualization and Restoration of Metallic Ion-Induced Subcellular Ultrastructural Remodeling

Analysis of cellular ultrastructure dynamics and metal ions' fate can provide insights into the interaction between living organisms and metal ions. Here, we directly visualize the distribution of biogenic metallic aggregates, ion-induced subcellular reorganization, and the corresponding regulation effect in yeast by the near-native 3D imaging approach, cryo-soft X-ray tomography (cryo-SXT). By comparative 3D morphometric assessment, we observe the gold ions disrupting cellular organelle homeostasis, resulting in noticeable distortion and folding of vacuoles, apparent fragmentation of mitochondria, extreme swelling of lipid droplets, and formation of vesicles. The reconstructed 3D architecture of treated yeast demonstrates ∼65% of Au-rich sites in the periplasm, a comprehensive quantitative assessment unobtained by TEM. We also observe some AuNPs in rarely identified subcellular sites, namely, mitochondria and vesicles. Interestingly, the amount of gold deposition is positively correlated with the volume of lipid droplets. Shifting the external starting pH to near-neutral results in the reversion of changes in organelle architectures, boosting the amount of biogenic Au nanoparticles, and increasing cell viability. This study provides a strategy to analyze the metal ions-living organism interaction from subcellular architecture and spatial localization perspectives.

Biosynthesis, characterization and optimization of TiO2 nanoparticles by novel marine halophilic Halomonas sp. RAM2: application of natural dye-sensitized solar cells

BACKGROUND

Metal oxide nanoparticles (NPs) are becoming valuable due to their novel applications. The green synthesis of TiO2 NPs is more popular as a flexible and eco-friendly method compared to traditional chemical synthesis methods. TiO2 NPs are the most commonly used semiconductor in dye-sensitized solar cells (DSSCs).

RESULTS

The biogenic TiO2 NPs were produced extracellularly by the marine halophilic bacterium Halomonas sp. RAM2. Response surface methodology (RSM) was used to optimize the biosynthesis process, resulting in a starting TiO2 concentration of 0.031 M and a pH of 5 for 92 min (⁓15 nm). TiO2 NPs were well-characterized after the calcination process at different temperatures of 500, 600, 700 and 800 °C. Anatase TiO2 NPs (calcined at 500 °C) with a smaller surface area and a wider bandgap were nominated for use in natural dye-sensitized solar cells (NDSSCs). The natural dye used as a photosensitizer is a mixture of three carotenoids extracted from the marine bacterium Kocuria sp. RAM1. NDSSCs were evaluated under standard illumination. After optimization of the counter electrode, NDSSCBio(10) (10 layers) demonstrated the highest photoelectric conversion efficiency (η) of 0.44%, which was almost as good as NDSSCP25 (0.55%).

CONCLUSION

The obtained results confirmed the successful green synthesis of TiO2 NPs and suggested a novel use in combination with bacterial carotenoids in DSSC fabrication, which represents an initial step for further efficiency enhancement studies.

Engineered Escherichia coli as a Controlled-Release Biocarrier for Electrochemical Immunoassay

Micro/nanocarriers hold great potential in bioanalysis for molecular recognition and signal amplification but are frequently hampered by harsh synthesis conditions and time-consuming labeling processes. Herein, we demonstrate that Escherichia coli (Ec) can be engineered as an efficient biocarrier for electrochemical immunoassay, which can load ultrahigh amounts of redox indicators and simultaneously be decorated with detection antibodies via a facile polydopamine (PDA)-mediated coating approach. Compared with conventional carrier materials, the entire preparation of the Ec biocarrier is simple, highly sustainable, and reproducible. Moreover, immune recognition and electrochemical transduction are performed independently, which eliminates the accumulation of biological interference on the electrode and simplifies electrode fabrication. Using human epidermal growth factor receptor 2 (HER2) as the model target, the proposed immunosensor exhibits excellent analytical performance with a low detection limit of 35 pg/mL. The successful design and deployment of Ec biocarrier may provide new guidance for developing biohybrids in biosensing applications.

A Dual-Biomineralized Yeast Micro-/Nanorobot with Self-Driving Penetration for Gastritis Therapy and Motility Recovery

Micro-/nanorobots have attracted great interest in the field of drug delivery and treatment, while preparations for biocompatible robots are extremely challenging. Here, a self-driving yeast micro-/nanorobot (Cur@CaY-robot) is designed via dual biomineralization and acid catalysis of calcium carbonate (CaCO₃). Inner nano-CaCO₃ inside yeast cells (CaY) is biomineralized through cell respiration and provides nanoscaffolds for highly encapsulating curcumin (Cur). Meanwhile, the CaCO₃ crystals outside yeast cells (outer-CaCO₃) through uniaxial growth offer an asymmetric power source for self-propelled motility. The Cur@CaY-robot displays an efficient motion in gastric acid, with the potential for deep penetration to the thick gastric mucus, which significantly improves the accumulation of drug agents in the stomach wall tissue for robust gastritis therapy. More importantly, Ca²⁺ cations released from the Cur@CaY-robot also synergistically repair the gastric motility of gastritis mice. Such yeast micro-/nanorobots exhibit desirable biocompatibility and biodegradability with a good loading capacity for drugs. This work provides an idea for the design of micro-/nanorobots through an environmentally friendly biosynthesis strategy for active drug delivery and precise therapy.

CRISPR-induced DNA reorganization for multiplexed nucleic acid detection

Nucleic acid sensing powered by the sequence recognition of CRIPSR technologies has enabled major advancement toward rapid, accurate and deployable diagnostics. While exciting, there are still many challenges facing their practical implementation, such as the widespread need for a PAM sequence in the targeted nucleic acid, labile RNA inputs, and limited multiplexing. Here we report FACT (Functionalized Amplification CRISPR Tracing), a CRISPR-based nucleic acid barcoding technology compatible with Cas12a and Cas13a, enabling diagnostic outputs based on cis- and trans-cleavage from any sequence. Furthermore, we link the activation of CRISPR-Cas12a to the expression of proteins through a Reprogrammable PAIRing system (RePAIR). We then combine FACT and RePAIR to create FACTOR (FACT on RePAIR), a CRISPR-based diagnostic, that we use to detect infectious disease in an agricultural use case: honey bee viral infection. With high specificity and accuracy, we demonstrate the potential of FACTOR to be applied to the sensing of any nucleic acid of interest.

Heavy-metal resistant bio-hybrid with biogenic ferrous sulfide nanoparticles: pH-regulated self-assembly and wastewater treatment application

Self-assembled bio-hybrids with biogenic ferrous sulfide nanoparticles (bio-FeS) on the cell surface are attractive for reduction of toxic heavy metals due to higher activity than bare bacteria, but they still suffer from slow synthesis and regeneration of bio-FeS and bacterial activity decay for removal of high-concentration heavy metals. A further optimization of the bio-FeS synthesis process and properties is of vital importance to address this challenge. Herein, we present a simple pH-regulation strategy to enhance bio-FeS synthesis and elucidated the underlying regulatory mechanisms. Slightly raising the pH from 7.4 to 8.3 led to 1.5-fold higher sulfide generation rate due to upregulated expression of thiosulfate reduction-related genes, and triggered the formation of fine-sized bio-FeS (29.4 ± 6.1 nm). The resulting bio-hybrid exhibited significantly improved extracellular reduction activity and was successfully used for treatment of high-concentration chromium -containing wastewater (Cr(VI), 80 mg/L) at satisfactory efficiency and stability. Its feasibility for bio-augmented treatment of real Cr(VI)-rich electroplating wastewater was also demonstrated, showing no obvious activity decline during 7-day operation. Overall, our work provides new insights into the environmental-responses of bio-hybrid self-assembly process, and may have important implications for optimized application of bio-hybrid for wastewater treatment and environmental remediation.