Extracellular biosynthesis of biocompatible cadmium sulfide quantum dots using Trametes versicolor

Quantum dots: a next generation approach for pathogenic microbial biofilm inhibition; mechanistic insights, existing challenges, and future potential

Quantum Dots (QDs) have emerged as versatile nanomaterials with origins spanning organic, inorganic, and natural sources, revolutionizing various biomedical applications, particularly in combating pathogenic biofilm formation. Biofilms, complex structures formed by microbial communities enveloped in exopolysaccharide matrices, pose formidable challenges to traditional antibiotics due to their high tolerance and resistance, exacerbating inefficacy issues in antibiotic treatments. QDs offer a promising solution, employing physical mechanisms like photothermal or photodynamic therapy to disrupt biofilms. Their efficacy is noteworthy, with lower susceptibility to resistance development and broad-spectrum action as compared to conventional antibiotic methods. The stability and durability of QDs ensure sustained biofilm activity, even in challenging environmental conditions. This comprehensive review delves into the synthesis, properties, and applications of Carbon Quantum Dots (CQDs), most widely used QDs, showcasing groundbreaking developments that position these nanomaterials at the forefront of cutting-edge research and innovation. These nanomaterials exhibit multifaceted mechanisms, disrupting cell walls and membranes, generating reactive oxygen species (ROS), and binding to nucleic materials, effectively inhibiting microbial proliferation. This opens transformative possibilities for healthcare interventions by providing insights into biofilm dynamics. However, challenges in size control necessitate ongoing research to refine fabrication techniques, ensure defect-free surfaces, and optimize biological activity. QDs emerge as microscopic yet potent tools, promising to contribute to a brighter future where quantum wonders shape innovative solutions to persistently challenging issues posed by pathogenic biofilms. Henceforth, this review aims to explore QDs as potential agents for inhibiting pathogenic microbial biofilms, elucidating the underlying mechanisms, addressing the current challenges, and highlighting their promising future potential.

Characterization and cytotoxicity assessment of cadmium sulfide quantum dots synthesized with Fusarium oxysporum f. sp. lycopersici

The potential of CdS quantum dots for biomedical and bioimaging applications depends on their cytotoxicity, which can be modulated by coating molecules. Using sulfur as a precursor can be used along with cadmium nitrate to synthesize CdS quantum dots with the fungus Fusarium oxysporum f. sp. lycopersici. The latter replaces pure chemical sulfur as a precursor for CdS quantum dot synthesis, thus transforming waste into a value-added product, increasing sustainability, reducing the environmental impact of the process through the implementation of green synthesis techniques, and contributing to the circular economy. Therefore, we compared the cytotoxicity on HT-29 cells of biogenic, and chemical CdSQDs, synthesized by a chemical method using pure sulfur. Biogenic and chemical CdSQDs had diameters of 4.08 ± 0.07 nm and 3.2 ± 0.20 nm, Cd/S molar ratio of 43.1 and 1.1, Z-potential of - 14.77 ± 0.64 mV and - 5.52 ± 1.11 mV, and hydrodynamic diameters of 193.94 ± 3.71 nm and 152.23 ± 2.31 nm, respectively. The cell viability improved 1.61 times for biogenic CdSQDs over chemical CdSQDs, while cytotoxicity, measured as IC50, diminished 1.88-times. The lower cytotoxicity of biogenic CdSQDs was attributed to their organic coating consisting of lipids, amino acids, proteins, and nitrate groups that interacted with CdS through -OH and -SH groups. Therefore, the biogenic synthesis of CdSQDs has repurposed a pathogenic fungus, taking advantage of the biomolecules it secretes, to transform hazardous sulfur waste and metal ions into stable CdSQDs with advantageous structural and cytotoxic properties for their potential application in biomedicine and bioimaging.

Diversity of Mycogenic Oxide and Chalcogenide Nanoparticles: A Review

Oxide and chalcogenide nanoparticles have great potential for use in biomedicine, engineering, agriculture, environmental protection, and other research fields. The myco-synthesis of nanoparticles with fungal cultures, their metabolites, culture liquids, and mycelial and fruit body extracts is simple, cheap and environmentally friendly. The characteristics of nanoparticles, including their size, shape, homogeneity, stability, physical properties and biological activity, can be tuned by changing the myco-synthesis conditions. This review summarizes the data on the diversity of oxide and chalcogenide nanoparticles produced by various fungal species under different experimental conditions.

Cadmium Sulfide Nanoparticles: Preparation, Characterization, and Biomedical Applications

Cadmium sulfide nanoparticles (CdS NPs) have been employed in various fields of nanobiotechnology due to their proven biomedical properties. They are unique in their properties due to their size and shape, and they are popular in the area of biosensors, bioimaging, and antibacterial and anticancer applications. Most CdS NPs are generally synthesized through chemical, physical, or biological methods. Among these methods, biogenic synthesis has attracted more attention due to its high efficiency, environmental friendliness, and biocompatibility features. The green approach was found to be superior to other methods in terms of maintaining the structural characteristics needed for optimal biomedical applications. The size and coating components of CdS NPs play a crucial role in their biomedical activities, such as anticancer, antibacterial, bioimaging, and biosensing applications. CdS NPs have gained significant interest in bioimaging due to their desirable properties, including good dispersion, cell integrity preservation, and efficient light scattering. Despite these, further studies are necessary, particularly in vivo studies to reduce NPs' toxicity. This review discusses the different methods of synthesis, how CdS NPs are characterized, and their applications in the biomedical field.

Mycosynthesis of Zinc Oxide Nanoparticles Exhibits Fungal Species Dependent Morphological Preference

Filamentous fungi can synthesize a variety of nanoparticles (NPs), a process referred to as mycosynthesis that requires little energy input, do not require the use of harsh chemicals, occurs at near neutral pH, and do not produce toxic byproducts. While NP synthesis involves reactions between metal ions and exudates produced by the fungi, the chemical and biochemical parameters underlying this process remain poorly understood. Here, the role of fungal species and precursor salt on the mycosynthesis of zinc oxide (ZnO) NPs is investigated. This data demonstrates that all five fungal species tested are able to produce ZnO structures that can be morphologically classified into i) well-defined NPs, ii) coalesced/dissolving NPs, and iii) micron-sized square plates. Further, species-dependent preferences for these morphologies are observed, suggesting potential differences in the profile or concentration of the biochemical constituents in their individual exudates. This data also demonstrates that mycosynthesis of ZnO NPs is independent of the anion species, with nitrate, sulfate, and chloride showing no effect on NP production. These results enhance the understanding of factors controlling the mycosynthesis of ceramic NPs, supporting future studies that can enable control over the physical and chemical properties of NPs formed through this "green" synthesis method.

Ultrafast extraction of uranium from seawater using photosensitized biohybrid system with bioinspired cascaded strategy

The highly effective utilization of uranium resources in global seawater is a viable method to satisfy the rising demands for fueling nuclear energy industry. Herein, inspired by the multi-mechanisms of the marine bacteria for uranium immobilization, CdS nanoparticles are deposited on the cell of marine bacterial strain Bacillus velezensis UUS-1 to create a photosensitized biohybrid system UUS-1/CdS. This system achieves high uranium extraction efficiency using a cascaded strategy, where the bacterial cells guarantee high extraction selectivity and the photosensitive CdS nanoparticles realize cascading photoreduction of high soluble U(VI) to low soluble U(IV) to enhance extraction capacity. As one of the fastest-acting adsorbents in natural seawater, a high extraction capacity for uranium of 7.03 mg g^-1 is achieved with an ultrafast extraction speed of 4.69 mg g^-1 d^-1. The cascaded strategy promisingly improves uranium extraction performance and pioneers a new direction for the design of adsorbents to extract uranium from seawater.

Eco-Friendly Intracellular Biosynthesis of CdS Quantum Dots Using Pseudomonas aeruginosa: Evaluation of Antimicrobial Effects and DNA Cleavage Activities

BACKGROUND

Intracellular biosynthesis of Quantum Dots (QDs) based on microorganisms offers a green alternative and eco-friendly for the production of nanocrystals with superior properties. This study focused on the production of intracellular CdS QDs by stimulating the detoxification metabolism of Pseudomonas aeruginosa.

METHODS

For this aim, Pseudomonas aeruginosa ATCC 27853 strain was incubated in a solution of 1mM cadmium sulphate (CdSO4) to manipulate the detoxification mechanism. The intracellularly formed Cd-based material was extracted, and its characterization was carried out by Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD), Energy Dispersive X-ray (EDX) and dynamic light scattering (DLS) analyses and absorption-emission spectra.

RESULTS

The obtained material showed absorption peaks at 385 nm and a luminescence peak at 411 nm, and the particle sizes were measured in the range 4.63-17.54 nm. It was determined that the material was sphere-shaped, with a cubic crystalline structure, including Cd and S elements. The antibacterial and antifungal activities of CdS QDs against patent eleven bacterial (four Grampositive and seven Gram-negative) and one fungal strains were investigated by the agar disk diffusion method. It was revealed that the obtained material has antibacterial effects on both Grampositive and Gram-negative bacteria. However, cleavage activity of CdS QDs on pBR322 DNA was not detected.

CONCLUSION

As a result, it has been proposed that the stimulation of the detoxification mechanism can be an easy and effective way of producing green and cheap luminescent QDs or nanomaterial.

Light-driven bio-decolorization of triphenylmethane dyes by a Clostridium thermocellum-CdS biohybrid

Widespread application of synthetic dyes could generate colored wastewaters causing a range of serious environmental problems. Due to the complex nature of effluents from textile industries, it is difficult to obtain satisfactory treatment of dyes-contaminated wastewater using one single method. Biohybrids coupling of photocatalysts and biocatalysts have great potential in environmental purification. However, how to select suitable organisms and enhance the hybrid's catalytic activities remain challenging. Here, a novel biohybrid system (Clostridium thermocellum-CdS), created for light-driven biodecolorization under thermophilic treatment by using non-photosynthetic microorganism C. thermocellum self-photosensitized with CdS nanoparticles was established. The biohybrids exhibited remarkable decolorization effects on triphenylmethane dyes. The highest decolorization rate was 0.206 min^-1. More importantly, enhanced catalytic activities of cadmium sulfide (CdS)-based biohybrids by controlling the particle sizes of semiconductors were demonstrated. Biohybrids systems (Clostridium thermocellum-CdS) through the self-precipitation of CdS with different particle sizes not only showed dramatic changes in the optical properties but also exhibited a very different decolorization rate. This work can not only further broaden targeted applications of CdS-based biohybrids but also demonstrate a promising route for improving biohybrids corresponding photocatalytic capabilities through in situ precipitation CdS with different particle sizes.

Biogenic Sulfur-Based Chalcogenide Nanocrystals: Methods of Fabrication, Mechanistic Aspects, and Bio-Applications

Bio-nanotechnology has emerged as an efficient and competitive methodology for the production of added-value nanomaterials (NMs). This review article gathers knowledge gleaned from the literature regarding the biosynthesis of sulfur-based chalcogenide nanoparticles (S-NPs), such as CdS, ZnS and PbS NPs, using various biological resources, namely bacteria, fungi including yeast, algae, plant extracts, single biomolecules, and viruses. In addition, this work sheds light onto the hypothetical mechanistic aspects, and discusses the impact of varying the experimental parameters, such as the employed bio-entity, time, pH, and biomass concentration, on the obtained S-NPs and, consequently, on their properties. Furthermore, various bio-applications of these NMs are described. Finally, key elements regarding the whole process are summed up and some hints are provided to overcome encountered bottlenecks towards the improved and scalable production of biogenic S-NPs.

Tumor-targeting inorganic nanomaterials synthesized by living cells

Inorganic nanomaterials (NMs) have shown potential application in tumor-targeting theranostics, owing to their unique physicochemical properties. Some living cells in nature can absorb surrounding ions in the environment and then convert them into nanomaterials after a series of intracellular/extracellular biochemical reactions. Inspired by that, a variety of living cells have been used as biofactories to produce metallic/metallic alloy NMs, metalloid NMs, oxide NMs and chalcogenide NMs, which are usually automatically capped with biomolecules originating from the living cells, benefitting their tumor-targeting applications. In this review, we summarize the biosynthesis of inorganic nanomaterials in different types of living cells including bacteria, fungi, plant cells and animal cells, accompanied by their application in tumor-targeting theranostics. The mechanisms involving inorganic-ion bioreduction and detoxification as well as biomineralization are emphasized. Based on the mechanisms, we describe the size and morphology control of the products via the modulation of precursor ion concentration, pH, temperature, and incubation time, as well as cell metabolism by a genetic engineering strategy. The strengths and weaknesses of these biosynthetic processes are compared in terms of the controllability, scalability and cooperativity during applications. Future research in this area will add to the diversity of available inorganic nanomaterials as well as their quality and biosafety.

Europium sulfide nanoprobes predict antiretroviral drug delivery into HIV-1 cell and tissue reservoirs

Background: Delivery of long-acting nanoformulated antiretroviral drugs (ARVs) to human immunodeficiency virus type one cell and tissue reservoirs underlies next generation antiretroviral therapeutics. Nanotheranostics, comprised of trackable nanoparticle adjuncts, can facilitate ARV delivery through real-time drug tracking made possible through bioimaging platforms. Methods: To model HIV-1 therapeutic delivery, europium sulfide (EuS) nanoprobes were developed, characterized and then deployed to cells, tissues, and rodents. Tests were performed with nanoformulated rilpivirine (NRPV), a non-nucleoside reverse transcriptase inhibitor (NNRTI) used clinically to suppress or prevent HIV-1 infection. First, CD4+ T cells and monocyte-derived macrophages were EuS-treated with and without endocytic blockers to identify nanoprobe uptake into cells. Second, Balb/c mice were co-dosed with NRPV and EuS or lutetium177-doped EuS (177LuEuS) theranostic nanoparticles to assess NRPV biodistribution via mass spectrometry. Third, single photon emission computed tomography (SPECT-CT) and magnetic resonance imaging (MRI) bioimaging were used to determine nanotheranostic and NRPV anatomic redistribution over time. Results: EuS nanoprobes and NRPV entered cells through dynamin-dependent pathways. SPECT-CT and MRI identified biodistribution patterns within the reticuloendothelial system for EuS that was coordinate with NRPV trafficking. Conclusions: EuS nanoprobes parallel the uptake and biodistribution of NRPV. These data support their use in modeling NRPV delivery to improve treatment strategies.

Genomics Insights into Pseudomonas sp. CG01: An Antarctic Cadmium-Resistant Strain Capable of Biosynthesizing CdS Nanoparticles Using Methionine as S-Source

Here, we present the draft genome sequence of Pseudomonas sp. GC01, a cadmium-resistant Antarctic bacterium capable of biosynthesizing CdS fluorescent nanoparticles (quantum dots, QDs) employing a unique mechanism involving the production of methanethiol (MeSH) from methionine (Met). To explore the molecular/metabolic components involved in QDs biosynthesis, we conducted a comparative genomic analysis, searching for the genes related to cadmium resistance and sulfur metabolic pathways. The genome of Pseudomonas sp. GC01 has a 4,706,645 bp size with a 58.61% G+C content. Pseudomonas sp. GC01 possesses five genes related to cadmium transport/resistance, with three P-type ATPases (cadA, zntA, and pbrA) involved in Cd-secretion that could contribute to the extracellular biosynthesis of CdS QDs. Furthermore, it exhibits genes involved in sulfate assimilation, cysteine/methionine synthesis, and volatile sulfur compounds catabolic pathways. Regarding MeSH production from Met, Pseudomonas sp. GC01 lacks the genes E4.4.1.11 and megL for MeSH generation. Interestingly, despite the absence of these genes, Pseudomonas sp. GC01 produces high levels of MeSH. This is probably associated with the metC gene that also produces MeSH from Met in bacteria. This work is the first report of the potential genes involved in Cd resistance, sulfur metabolism, and the process of MeSH-dependent CdS QDs bioproduction in Pseudomonas spp. strains.

Cadmium sulfide nanoparticles-assisted intimate coupling of microbial and photoelectrochemical processes: Mechanisms and environmental applications

Intimate coupling of microbial extracellular electron transfer (EET) and photoelectrochemical processes is an emerging research area with great potential to circumvent many disadvantages associated with traditional techniques that depend on independent microbial or photocatalysis treatment. Microbial EET processes involve microorganism oxidation of extracellular electron donors for respiration and synchronous reduction of extracellular electron acceptors to form an integrated respiratory chain. Coupled microbial EET-photoelectrochemical technologies greatly improve energy conversion efficiency providing both economic and environmental benefits. Among substitutes for semiconductor photocatalysts, cadmium sulfide nanoparticles (CdS NPs) possess several attractive properties. Specifically, CdS NPs have suitable electrical conductivity, large specific surface area, visible light-driven photocatalysis capability and robust biocompatibility, enabling them to promote hybrid microbial-photoelectrochemical processes. This review highlights recent advances in intimately coupled CdS NPs-microbial extracellular electron transfer systems and examines the mechanistic pathways involved in photoelectrochemical transformations. Finally, the prospects for emerging applications utilizing hybrid CdS NPs-based microbial-photoelectrochemical technologies are assessed. As such, this review provides a rigorous fundamental analysis of electron transport dynamics for hybrid CdS NPs-microbial photoelectrochemical processes and explores the applicability of engineered CdS NPs-biohybrids for future applications, such as in environmental remediation and clean-energy production.

Superior Properties and Biomedical Applications of Microorganism-Derived Fluorescent Quantum Dots

Quantum dots (QDs) are fluorescent nanocrystals with superb photo-physical properties. Applications of QDs have been exponentially increased during the past decade. They can be employed in several disciplines, including biological, optical, biomedical, engineering, and energy applications. This review highlights the structural composition and distinctive features of QDs, such as resistance to photo-bleaching, wide range of excitations, and size-dependent light emission features. Physical and chemical preparation of QDs have prominent downsides, including high costs, regeneration of hazardous byproducts, and use of external noxious chemicals for capping and stabilization purposes. To eliminate the demerits of these methods, an emphasis on the latest progress of microbial synthesis of QDs by bacteria, yeast, and fungi is introduced. Some of the biomedical applications of QDs are overviewed as well, such as tumor and microRNA detection, drug delivery, photodynamic therapy, and microbial labeling. Challenges facing the microbial fabrication of QDs are discussed with the future prospects to fully maximize the yield of QDs by elucidating the key enzymes intermediating the nucleation and growth of QDs. Exploration of the distribution and mode of action of QDs is required to promote their biomedical applications.

In Vivo Biosynthesis of Inorganic Nanomaterials Using Eukaryotes-A Review

Bionanotechnology, the use of biological resources to produce novel, valuable nanomaterials, has witnessed tremendous developments over the past two decades. This eco-friendly and sustainable approach enables the synthesis of numerous, diverse types of useful nanomaterials for many medical, commercial, and scientific applications. Countless reviews describing the biosynthesis of nanomaterials have been published. However, to the best of our knowledge, no review has been exclusively focused on the in vivo biosynthesis of inorganic nanomaterials. Therefore, the present review is dedicated to filling this gap by describing the many different facets of the in vivo biosynthesis of nanoparticles (NPs) using living eukaryotic cells and organisms-more specifically, live plants and living biomass of several species of microalgae, yeast, fungus, mammalian cells, and animals. It also highlights the strengths and weaknesses of the synthesis methodologies and the NP characteristics, bio-applications, and proposed synthesis mechanisms. This comprehensive review also brings attention to enabling a better understanding between the living organisms themselves and the synthesis conditions that allow their exploitation as nanobiotechnological production platforms as these might serve as a robust resource to boost and expand the bio-production and use of desirable, functional inorganic nanomaterials.

Biosynthesis of CdS Quantum Dots Mediated by Volatile Sulfur Compounds Released by Antarctic Pseudomonas fragi

Previously we reported the biosynthesis of intracellular cadmium sulfide quantum dots (CdS QDs) at low temperatures by the Antarctic strain Pseudomonas fragi GC01. Here we studied the role of volatile sulfur compounds (VSCs) in the biosynthesis of CdS QDs by P. fragi GC01. The biosynthesis of nanoparticles was evaluated in the presence of sulfate, sulfite, thiosulfate, sulfide, cysteine and methionine as sole sulfur sources. Intracellular biosynthesis occurred with all sulfur sources tested. However, extracellular biosynthesis was observed only in cultures amended with cysteine (Cys) and methionine (Met). Extracellular nanoparticles were characterized by dynamic light scattering, absorption and emission spectra, energy dispersive X-ray, atomic force microscopy, transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Purified QDs correspond to cubic nanocrystals of CdS with sizes between 2 and 16 nm. The analysis of VSCs revealed that P. fragi GC01 produced hydrogen sulfide (H2S), methanethiol (MeSH) and dimethyl sulfide (DMS) in the presence of sulfate, Met or Cys. Dimethyl disulfide (DMDS) was only detected in the presence of Met. Interestingly, MeSH was the main VSC produced in this condition. In addition, MeSH was the only VSC for which the concentration decreased in the presence of cadmium (Cd) of all the sulfur sources tested, suggesting that this gas interacts with Cd to form nanoparticles. The role of MeSH and DMS on Cds QDs biosynthesis was evaluated in two mutants of the Antarctic strain Pseudomonas deceptionensis M1T: megL - (unable to produce MeSH from Met) and mddA - (unable to generate DMS from MeSH). No biosynthesis of QDs was observed in the megL - strain, confirming the importance of MeSH in QD biosynthesis. In addition, the production of QDs in the mddA - strain was not affected, indicating that DMS is not a substrate for the biosynthesis of nanoparticles. Here, we confirm a link between MeSH production and CdS QDs biosynthesis when Met is used as sole sulfur source. This work represents the first report that directly associates the production of MeSH with the bacterial synthesis of QDs, thus revealing the importance of different VSCs in the biological generation of metal sulfide nanostructures.