Microbial Nanotechnology: Challenges and Prospects for Green Biocatalytic Synthesis of Nanoscale Materials for Sensoristic and Biomedical Applications

Soil Biodegradation Resistance of Cotton Fiber Doped with Interior and Exterior Silver Nanoparticles

Engineering fibers with nanomaterials is an effective way to modify their properties and responses to external stimuli. In this study, we doped cotton fibers with silver nanoparticles, both on the surface (126 ± 17 nm) and throughout the fiber cross section (18 ± 4 nm), and examined the resistance to soil biodegradation. A reagent-free one-pot treatment of a raw cotton fabric, where noncellulosic constituents of the raw cotton fiber and starch sizing served as reducing agents, produced silver nanoparticles with a total concentration of 11 g/kg. In a soil burial study spanning 16 weeks, untreated cotton underwent a sequential degradation process-fibrillation, fractionation, and merging-corresponding to the length of the soil burial period, whereas treated cotton did not exhibit significant degradation. The remarkable biodegradation resistance of the treated cotton was attributed to the antimicrobial properties of silver nanoparticles, as demonstrated through a test involving the soil-borne fungus Aspergillus flavus. The nonlinear loss behavior of silver from the treated cotton suggests that nanoparticle depletion in the soil depends on their location, with interior nanoparticles proving durable against environmental exposure.

Exploring synthesis and applications of green nanoparticles and the role of nanotechnology in wastewater treatment

Current research endeavours are progressively focussing towards discovering sustainable methods for synthesising eco-friendly materials. In this environment, nanotechnology has emerged as a key frontier, especially in bioremediation and biotechnology. A few areas of nanotechnology including membrane technology, sophisticated oxidation processes, and biosensors. It is possible to create nanoparticles (NPs) via physical, chemical, or biological pathways in a variety of sizes and forms. These days, the investigation of plants as substitutes for NP synthesis methods has drawn a lot of interest. Toxic water contaminants such as methyl blue have been shown to be removed upto 70% by nanoparticles. In our article, we aimed at focussing the environmental sustainability and cost-effectiveness towards the green synthesis of nanoparticles. Furthermore it offers a comprehensive thorough summary of green NP synthesis methods which can be distinguished by their ease of use, financial sustainability, and environmentally favourable utilization of plant extracts. This study highlights how green synthesis methods have the potential to transform manufacturing of NPs while adhering to environmental stewardship principles and resource efficiency.

Impedance nanobiosensor based on enzyme-conjugated biosynthesized gold nanoparticles for the detection of Gram-positive bacteria

In this report, gold nanoparticles (GNPS) were synthesized using cell-free extracts of seven different isolates, namely, Pseudomonas aerogenosa CEBP2, Pseudomonas sp. CEBP1, Pseudomonas pseudoalcaligenes CEB1G, Acinetobactor baumani CEBS1, Cuprividus sp. CEB3, Micrococcus luteus CUB12, and Pandoraea sp. CUB2S. The spectroscopic (UV-vis, FTIR, DLS, XRD, EDS) and microscopic (FESEM, TEM) results confirm the reduction of Au3+ to Au0 in the presence of biomolecules having reducing as well as self-stabilizing activity. In this green synthesis approach, the average particle size of biosynthesized GNPS might vary (4-60 nm) depending on the bacterial species, pH of the media, incubation time, and temperature. In this study, GSH-modified BSGNPs (Au-GSH) have shown antimicrobial activity with better stability against Gram-positive bacteria. After conjugation of lysozyme with Au-GSH (lyso@Au-GSH), the zone of inhibition was enhanced from 12 to 23 mm (Au-GSH). The TEM study shows the spherical GNP (16.65 ± 2.84) turns into a flower-shaped GNP (22.22 ± 3.12) after conjugation with lysozyme due to the formation of the protein corona. Furthermore, the nanobioconjugate (lyso@Au-GSH) was immobilized with Nafion on a glassy carbon electrode to fabricate a label-free impedance biosensor that is highly sensitive to monitor changes in the transducer surface due to biomolecular interactions. The uniquely designed biosensor could selectively detect Gram-positive bacteria in the linear range of 3.0 × 101-3 × 1010 cfu mL-1 with RE <5%. The proposed simplest biosensor exhibited good reproducibility (RSD = 3.1%) and excellent correlation (R2 = 0.999) with the standard plate count method, making it suitable for monitoring Gram-positive bacterial contamination in biofluids, food, and environmental samples.

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.

Special Issue: Microbial Nanotechnology

Microbial nanotechnology (MN), or microbial nanobiotechnology, is a rapidly expanding research area with the potential to transform various fields, including bioremediation, energy production, medicine, and agriculture [...].

Bacterial nano-factories as a tool for the biosynthesis of TiO2 nanoparticles: characterization and potential application in wastewater treatment

The development of reliable and eco-conscious processes for nanoparticle synthesis constitutes a significant element in nanotechnology. TiO2 nanoparticles (NPs) are becoming essential due to their potential uses in dentistry, surgery, agriculture, and pharmacy. This leads to the development of various procedures for producing TiO2 NPs using various physicochemical methods. Still, the drawbacks of these conventional methods are associated with the emission of toxic chemicals into the atmosphere and high energy demands in production, hence endangering the health and the environment. Problems issued are solved by green nanotechnology, which offers tools as nano-factories by utilizing biological sources to subside the improper effects of conventional methods and produces nanoparticles through synthesis methods that are clean, safe, energy-efficient, and cost-effective. Among the biogenic sources, microbial cells such as bacteria possess intrinsic pathways of converting metallic salt to nanoparticles due to their ability to produce reductase enzymes. Also, they can offer features to products such as high dispersity and produce sustainable nanoparticles at a large scale. Biosynthesized TiO2 NPs have high oxidizing potential and a wide range of applications, specifically as photosensitizers and antimicrobial agents. This review will address bacterial nano-factories that can be utilized for the biosynthesis of TiO2 NPs, the characterization of biosynthesized nanoparticles, and their potential application in wastewater treatment.

Possible Molecular Targeting of Biofilm-Associated Genes by Nano-Ag in Candida albicans

The treatment of candidiasis infections is hindered by the presence of biofilms. Here, we report the biofilm-associated genes as potential molecular targets by silver nanoparticles (nano-Ag) in Candida albicans. Nano-Ag was biosynthesized using Bacillus licheniformis, Bacillus cereus, and Fusarium oxysporum. The physicochemical properties of the microbial-synthesized of nano-Ag are widely characterized by visual observation, ultraviolet-visible spectroscopy, scanning electron microscopy, X-ray diffraction spectroscopy, and Fourier transform infrared spectroscopy. Characterization results revealed the formation of nano-Ag. Antiplanktonic cells and antibiofilm activities of nano-Ag were also demonstrated by minimum inhibition concentrations (MIC), minimum fungicidal concentration (MFC), MFC/MIC ratio, crystal violet staining, 2,3-bis (2-methoxy-4-nitro-5 sulfophenyl)-5-[(phenylamino) carbonyl]-2H-tetrazolium hydroxide (XTT), and microscopic image analysis. We have analyzed the expressions of biofilm-associated genes in C. albicans treated with different concentrations of nano-Ag based on MIC. The expression profile of BCR1, ALS1, ALS3, HWP1, and ECE1 showed downregulated genes involved in these pathways by the treatment with nanoparticles. Negative regulators, TUP1, NRG1, and TOR1, were upregulated by the treatment of nano-Ag. Our study suggests that nano-Ag affects gene expression and may subsequently decrease the pathogenesis of C. albicans by inhibiting biofilm formation. Molecular targeting of biofilm-associated genes involved in biofilm formation by nano-Ag may be an effective treatment strategy for candidiasis infections.

Antibacterial and Anti-Biofilm Activities of Microbial Synthesized Silver and Magnetic Iron Oxide Nanoparticles Against Pseudomonas aeruginosa

Pseudomonas aeruginosa is a human bacterial pathogen causing devastating diseases and equipped with various virulence factors like biofilm formation. Common antibiotic treatment has limited efficacy for the P. aeruginosa present in biofilms because of the increased resistance. In this study, we focused our attention on the antibacterial and anti-biofilm activities of various microbial synthesized silver (nano-Ag) and magnetic iron oxide (nano-Fe3O4) nanoparticles against clinical isolates of P. aeruginosa that displayed ceftazidime resistance. The nano-Ag and nano-Fe3O4 represented great antibacterial properties. Nano-Ag and nano-Fe3O4 exhibited a reduction in the biofilm formation by P. aeruginosa reference strain as determined by crystal violet and XTT assays and light microscopy method. Among all, nano-Ag-2 and 7 owing to inherent attributes and mechanisms of resistance in the bacterial biofilm, exhibited anti-biofilm efficacy against ceftazidime resistance clinical isolate of P. aeruginosa. Moreover, nano-Ag and nano-Fe3O4 changed the relative expression of biofilm-associated genes, PELA and PSLA in a concentration dependent manner by P. aeruginosa reference strain. As revealed by qRT-PCR, the expression levels of biofilm-associated genes were downregulated in P. aeruginosa biofilms treated with nano-Ag, while selected biofilm-associated genes were low expressed under treated with nano-Fe3O4. Results of the study demonstrate the potential of microbial synthesized nano-Ag-2 and 7 to act as anti-biofilm agents against ceftazidime resistance clinical isolate of P. aeruginosa. Molecular targeting of biofilm-associated genes by nano-Ag and nano-Fe3O4 may be candidate for new therapeutics against P. aeruginosa diseases.

A novel approach for enhancing the color and antimicrobial properties of pine and beech wood using Se-NPs

Pine wood (PW) and beech wood (BW) are the most used wood in furniture and other applications owing to their unique characteristics and low machining cost. However, their biodegradability and varied moisture content limit their wider use and durability. Therefore, in this study, nanotechnology was used as a novel eco-friendly approach to enhance the durability, antimicrobial properties, and color of wood. Selenium nanoparticles (Se-NPs) were prepared in spherical shape at varied concentrations (25 and 50 mM) using an eco-friendly method in the range of 35-80 and 40-155 nm, respectively. Se-NPs formation at the nanoscale was confirmed using UV/Vis analysis, transmission electron microscopy (TEM), and X-ray diffraction (XRD). The prepared Se-NPs were then impregnated into PW and BW for different periods ranging from 2 h to 1 week. The treated wood were then leached in distilled water for 14 days to eliminate excess Se-NPs from the wood surface. The treated wood surfaces were examined using energy-dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM). In addition, the depth of Se-NPs penetration into the treated wood at both tangential and radial sides was determined. Se-NPs impacts on the color properties, density, moisture content and antimicrobial activities of the treated wood were evaluated. PW treated with Se-NPs showed better antimicrobial and color characteristics than treated BW. PW samples immersed in 50 mM Se-NPs for 2 h showed the highest K/S values, whereas the highest antimicrobial values were obtained for those immersed at the same concentration for 2 days, and 1 week.

Impact of Biogenic and Chemogenic Selenium Nanoparticles on Model Eukaryotic Lipid Membranes

Microbial nanotechnology is an expanding research area devoted to producing biogenic metal and metalloid nanomaterials (NMs) using microorganisms. Often, biogenic NMs are explored as antimicrobial, anticancer, or antioxidant agents. Yet, most studies focus on their applications rather than the underlying mechanism of action or toxicity. Here, we evaluate the toxicity of our well-characterized biogenic selenium nanoparticles (bSeNPs) produced by the Stenotrophomonas maltophilia strain SeITE02 against the model yeast Saccharomyces cerevisiae comparing it with chemogenic SeNPs (cSeNPs). Knowing from previous studies that the biogenic extract contained bSeNPs in an organic material (OM) and supported here by Fourier transform infrared spectroscopy, we removed and incubated it with cSeNPs (cSeNPs_OM) to assess its influence on the toxicity of these formulations. Specifically, we focused on the first stages of the eukaryotic cell exposure to these samples─i.e., their interaction with the cell lipid membrane, which was mimicked by preparing vesicles from yeast polar lipid extract or phosphatidylcholine lipids. Fluidity changes derived from biogenic and chemogenic samples revealed that the bSeNP extract mediated the overall rigidification of lipid vesicles, while cSeNPs showed negligible effects. The OM and cSeNPs_OM induced similar modifications to the bSeNP extract, reiterating the need to consider the OM influence on the physical-chemical and biological properties of bSeNP extracts.

An update on the biological effects of quantum dots: From environmental fate to risk assessment based on multiple biological models

Quantum dots (QDs) are zero-dimension nanomaterials with excellent physical and chemical properties, which have been widely used in environmental science and biomedicine. Therefore, QDs are potential to cause toxicity to the environment and enter organisms through migration and bioenrichment effects. This review aims to provide a comprehensive and systematic analysis on the adverse effects of QDs in different organisms based on recently available data. Following PRISMA guidelines, this study searched PubMed database according to the pre-set keywords, and included 206 studies according to the inclusion and elimination criteria. CiteSpace software was firstly used to analyze the keywords of included literatures, search for breaking points of former studies, and summarize the classification, characterization and dosage of QDs. The environment fate of QDs in the ecosystems were then analyzed, followed with comprehensively summarized toxicity outcomes at individual, system, cell, subcellular and molecular levels. After migration and degradation in the environment, aquatic plants, bacteria, fungi as well as invertebrates and vertebrates have been found to be suffered from toxic effects caused by QDs. Aside from systemic effects, toxicity of intrinsic QDs targeting to specific organs, including respiratory system, cardiovascular system, hepatorenal system, nervous system and immune system were confirmed in multiple animal models. Moreover, QDs could be taken up by cells and disturb the organelles, which resulted in cellular inflammation and cell death, including autophagy, apoptosis, necrosis, pyroptosis and ferroptosis. Recently, several innovative technologies, like organoids have been applied in the risk assessment of QDs to promote the surgical interventions of preventing QDs' toxicity. This review not only aimed at updating the research progress on the biological effects of QDs from environmental fate to risk assessment, but also overcame the limitations of available reviews on basic toxicity of nanomaterials by interdisciplinarity and provided new insights for better applications of QDs.

Draft genome sequence of potato crop bacterial isolates and nanoparticles-intervention for the induction of secondary metabolites biosynthesis

Introduction

Insights about the effects of gold nanoparticles (AuNPs) on the biosynthetic manipulation of unknown microbe secondary metabolites could be a promising technique for prospective research on nano-biotechnology.

Aim

In this research, we aimed to isolate a fresh, non-domesticated unknown bacterium strain from a common scab of potato crop located in Saudi Arabia and study the metabolic profile.

Methodology

This was achieved through genomic DNA (gDNA) sequencing using Oxford Nanopore Technology. The genomic data were subjected to several bioinformatics tools, including canu-1.9 software, Prokka, DFAST, Geneious Prime, and AntiSMASH. We exposed the culture of the bacterial isolate with different concentrations of AuNPs and investigated the effects of AuNPs on secondary metabolites biosynthesis using several analytical techniques. Furthermore, Tandem-mass spectrometric (MS/MS) technique was optimized for the characterization of several significant sub-classes.

Results

The genomic draft sequence assembly, alignment, and annotation have verified the bacterial isolate as Priestia megaterium. This bacterium has secondary metabolites related to different biosynthetic gene clusters. AuNPs intervention showed an increase in the production of compounds with the molecular weights of 254 and 270 Da in a direct-dependent manner with the increase of the AuNPs concentrations.

Conclusion

The increase in the yields of compound 1 and 2 concomitantly with the increase in the concentration of the added AuNPs provide evidences about the effects of nanoparticles on the biosynthesis of the secondary metabolites. It contributes to the discovery of genes involved in different biosynthetic gene clusters (BGCs) and prediction of the structures of the natural products.

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.

Enhanced anaerobic hydrogen production from cotton straws assisted by copper molybdate

Hydrogen production from dark fermentation has potential application due to its environmental friendliness, low production cost, and sustainability. However, there is still an obstacle to improving the efficiency of bioH₂ production to meet the requirements in practical applications. In this research, copper molybdates are synthesized under different pH conditions as additives to study their different influence processes during anaerobic hydrogen production from cotton straws with the pure cultural system. A series of results indicate that CuMoO₄ with appropriate experimental conditions has the highest H₂ yield at 191.3 mL/g straws at 37 °C, which is 236% higher than the control group. It can be shown that O. ethanolica 8KG-4 has an obvious accompanying with high stability and low cytotoxicity for this clean energy production system as well as the improvement of metabolic pathway. These results extend new thinking of obtaining higher H₂ yield as a biofuel in future production.

New aspects of lipopeptide-incorporated nanoparticle synthesis and recent advancements in biomedical and environmental sciences: a review

The toxicity of metal nanoparticles has introduced promising research in the current scenario since an enormous number of people have been potentially facing this problem in the world. The extensive attention on green nanoparticle synthesis has been focussed on as a vital step in bio-nanotechnology to improve biocompatibility, biodegradability, eco-friendliness, and huge potential utilization in various environmental and clinical assessments. Inherent influence on the study of green nanoparticles plays a key role to synthesize the controlled and surface-influenced molecule by altering the physical, chemical, and biological assets with the provision of various precursors, templating/co-templating agents, and supporting solvents. However, in this article, the dominant characteristics of several kinds of lipopeptide biosurfactants are discussed to execute a critical study of factors affecting synthesis procedure and applications. The recent approaches of metal, metal oxide, and composite nanomaterial synthesis have been deliberated as well as the elucidation of the reaction mechanism. Furthermore, this approach shows remarkable boosts in the production of nanoparticles with the very less employed harsh and hazardous processes as compared to chemical or physical method-based nanoparticle synthesis. This study also shows that the advances in strain selection for green nanoparticle production could be a worthwhile and strong economical approach in futuristic medical science research.

A MALDI-MS-based impact assessment of ZnO nanoparticles, nanorods and quantum dots on the lipid profile of bacterial pathogens

MALDI-MS was used for studying the impact of zinc oxide (ZnO) nanomaterials on Pseudomonas aeruginosa and Staphylococcus aureus. The growth patterns of both these bacterial pathogens in the presence of the ZnO nanomaterials and the subsequent lipidomic changes were assessed using an optimized simple, rapid MALDI-MS based methodology. All three nanostructures tested exhibited differential bactericidal activity unique to P. aeruginosa and S. aureus. The results indicated that the ZnO nanomaterials were highly inhibitory to S. aureus even at 70 mg L^-1, while in the case of P. aeruginosa, the ZnO nanomaterials were compatible for up to 10 h and beyond 10 h only marginal growth inhibition was observed. The results proved that the shapes of the ZnO nanomaterials did not affect their toxicity properties. MALDI-MS was applied to study the lipidomic changes of P. aeruginosa and S. aureus after nanomaterial treatment, in order to throw light on the mechanism of growth inhibition. The results from the MALDI-MS studies showed that the ZnO nanostructures exhibited only marginal changes in the lipidomic profile both in the case of P. aeruginosa and S. aureus. These preliminary results indicate that the mechanism of growth inhibition by the ZnO nanomaterial is not through lipid-based interactions, but apparently more so via protein inhibitions.

Self-induced transformation of raw cotton to a nanostructured primary cell wall for a renewable antimicrobial surface

Herein, raw cotton is shown to undergo self-induced transformation into a nanostructured primary cell wall. This process generates a metal nanoparticle-mediated antimicrobial surface that is regenerable through multiple washings. Raw cotton, without being scoured and bleached, contains noncellulosic constituents including pectin, sugars, and hemicellulose in its primary cell wall. These noncellulosic components provide definitive active binding sites for the in situ synthesis of silver nanoparticles (Ag NPs). Facile heating in an aqueous solution of AgNO₃ activated raw cotton to produce Ag NPs (ca. 28 nm in diameter and 2261 mg kg^-1 in concentration). Compared with scoured and bleached cotton, raw cotton requires lower concentrations of AgNO₃-ten times lower for Klebsiella pneumonia and two times lower for Staphylococcus aureus-to achieve 99.9% reductions of both Gram-positive and Gram-negative bacteria. The Ag NPs embedded in the primary cell wall, which was confirmed via transmission electron microscopy images of the fiber cross-sections, are immobilized, exhibiting resistance to leaching as judged by continuous laundering. A remarkable percentage (74%) of the total Ag NPs remained in the raw cotton after 50 laundering cycles.

Ginsenoside compound K-loaded gold nanoparticles synthesized from Curtobacterium proimmune K3 exerts anti-gastric cancer effect via promoting PI3K/Akt-mediated apoptosis

Background

Compound K (CK) is the minor ginsenoside present in fermented Panax ginseng extract. Despite the pharmacological efficacy of CK, its industrial use has been restricted due to its low water solubility and poor permeability. To overcome this defect, our study was to synthesize gold nanoparticles from CK (CK-AuNPs) to investigate their potential as anticancer candidates.

Methods

To biologically synthesize CK-AuNPs, a novel strain, Curtobacterium proimmune K3, was isolated from fermented ginseng beverage, then combined with CK and gold salts to biosynthesize gold nanoparticles (CurtoCK-AuNPs). Their physicochemical characteristics were evaluated using UV–Vis spectrometry, FE-TEM, EDX, elemental mapping, XRD, SAED, DLS and TGA.

Results

CurtoCK-AuNPs exerted significant selective cytotoxic effects on AGS human gastric cancer cells. Fluorescence staining with Hoechst, propidium iodide, and MitoTracker demonstrated that CurtoCK-AuNPs induce apoptosis and mitochondrial damage, respectively. Quantitative real-time PCR and western blotting analyses showed that cytotoxic effect of CurtoCK-AuNPs were involved in apoptosis, based on their activation of Bax/Bcl-2, cytochrome c, caspase 9, and caspase 3, as well as their suppression of PI3K–Akt signaling.

Conclusion

Our findings provide data for understanding the molecular mechanisms of nanoparticles; thus, providing insight into the development of alternative medications based on gold nanoparticles of ginseng-derived CK.

Classification, Synthetic, and Characterization Approaches to Nanoparticles, and Their Applications in Various Fields of Nanotechnology: A Review

Nanoparticles typically have dimensions of less than 100 nm. Scientists around the world have recently become interested in nanotechnology because of its potential applications in a wide range of fields, including catalysis, gas sensing, renewable energy, electronics, medicine, diagnostics, medication delivery, cosmetics, the construction industry, and the food industry. The sizes and forms of nanoparticles (NPs) are the primary determinants of their properties. Nanoparticles’ unique characteristics may be explored for use in electronics (transistors, LEDs, reusable catalysts), energy (oil recovery), medicine (imaging, tumor detection, drug administration), and more. For the aforementioned applications, the synthesis of nanoparticles with an appropriate size, structure, monodispersity, and morphology is essential. New procedures have been developed in nanotechnology that are safe for the environment and can be used to reliably create nanoparticles and nanomaterials. This research aims to illustrate top-down and bottom-up strategies for nanomaterial production, and numerous characterization methodologies, nanoparticle features, and sector-specific applications of nanotechnology.

Microbes-mediated synthesis strategies of metal nanoparticles and their potential role in cancer therapeutics

Past few years have seen a paradigm shift towards ecofriendly, green and biological fabrication of metal nanoparticles (MNPs) for diverse nanomedicinal applications especially in cancer nanotheranostics. Besides, the well-known green synthesis methods of plant materials, the potential of the microbial world (bacteria, fungi, alga, etc.) in biofabrication is equally realized. Biomolecules and enzymes in the microbial cells are capable of catalyzing the biosynthesis process. These microbial derived inorganic nanoparticles have been frequently evaluated as potential agents in cancer therapies revealing exciting results. Through, cellular and molecular pathways, these microbial derived nanoparticles are capable of killing the cancer cells. Considering the recent developments in the anticancer applications of microbial derived inorganic MNPs, a dire need was felt to bring the available information to a single document. This manuscript reviews not only the mechanistic aspects of the microbial derived MNPs but also include the diverse mechanisms that governs their anticancer potential. Besides, an updated literature review is presented that includes studies of 2019-onwards.

Size and Shape Directed Novel Green Synthesis of Plasmonic Nanoparticles Using Bacterial Metabolites and Their Anticancer Effects

The growing need for developing new synthesis methods of plasmonic nanoparticles (PNPs) stems from their various applications in nanotechnology. As a result, a variety of protocols have been developed for the synthesis of PNPs of different shapes, sizes, and compositions. Though widely practiced, the chemical synthesis of PNPs demands stringent control over the experimental conditions, often employs environmentally hazardous chemicals for surface stabilization, and is frequently energy-intensive. Additionally, chemically obtained PNPs require subsequent surface engineering steps for various optoelectronic and biomedicine applications to minimize the toxic effects and render them useful for targeted drug delivery, sensing, and imaging. Considering the pressing need to develop environmentally-friendly technology solutions, “greener” methods of nanoparticle synthesis are gaining importance. Here, we report on the biological synthesis of plasmonic nanoparticles using bacterial metabolites. A peptide-based siderophore pyoverdine and a blue-green pigment pyocyanin obtained from a marine strain of Pseudomonas aeruginosa rapidly produced plasmonic nanoparticles of gold and silver in an aqueous environment. The morphology of plasmonic nanoparticles could be modulated by tuning the concentration of these metabolites and the reaction time. The exposure of pyoverdine to chloroauric acid resulted in anisotropic gold nanoparticles. On the other hand, pyocyanin produced a highly monodispersed population of gold nanoparticles and anisotropic silver nanoparticles. Biologically obtained gold and silver nanoparticles retained pyoverdine and pyocyanin on the nanoparticle surface and were stable for an extended period of time. The biologically obtained gold and silver plasmonic nanoparticles displayed potent anticancer activities against metastatic lung cancer cells. Biogenic nanoparticles were rapidly internalized by cancer cells in high quantity to affect the cellular organization, and karyoplasmic ratio, indicating the potential of these nanoparticles for cancer nanomedicine.

Current status of microbes involved in the degradation of pharmaceutical and personal care products (PPCPs) pollutants in the aquatic ecosystem

Contamination of aquatic systems with pharmaceuticals, personal care products, steroid hormones, and agrochemicals has been an immense problem for the earth's ecosystem and health impacts. The environmental issues of well-known persistence pollutants, their metabolites, and other micro-pollutants in diverse aquatic systems around the world were collated and exposed in this review assessment. Waste Water Treatment Plant (WWTP) influents and effluents, as well as industrial, hospital, and residential effluents, include detectable concentrations of known and undiscovered persistence pollutants and metabolites. These components have been found in surface water, groundwater, drinking water, and natural water reservoirs receiving treated and untreated effluents. Several studies have found that these persistence pollutants, and also similar recalcitrant pollutants, are hazardous to a variety of non-targeted creatures in the environment. In human and animals, they can also have severe and persistent harmful consequences. Because these pollutants are harmful to aquatic organisms, microbial degradation of these persistence pollutants had the least efficiency. Fortunately, only a few wild and Genetically Modified (GMOs) microbial species have the ability to degrade these PPCPs contaminants. Hence, researchers have been studying the degradation competence of microbial communities in persistence pollutants of Pharmaceutical and Personal Care Products (PPCPs) and respective metabolites for decades, as well as possible degradation processes in various aquatic systems. As a result, this review provides comprehensive information about environmental issues and the degradation of PPCPs and their metabolites, as well as other micro-pollutants, in aquatic systems.

Green route for recycling of low-cost waste resources for the biosynthesis of nanoparticles (NPs) and nanomaterials (NMs)-A review

Nowadays, nanoparticles (NPs) and nanomaterials (NMs) are used extensively in various streams such as medical science, solar energy, drug delivery, water treatment, and detection of persistent pollutants. Intensive synthesis of NPs/NMs carried out via physico-chemical technologies is deteriorating the environment globally. Therefore, an urgent need to adopt cost-effective and green technologies to synthesize NPs/NMs by recycling of secondary waste resources is highly required. Environmental wastes such as metallurgical slag, electronics (e-waste), and acid mine drainage (AMD) are rich sources of metals to produce NPs. This concept can remediate the environment on the one hand and the other hand, it can provide a future roadmap for economic benefits at industrial scale operations. The waste-derived NPs will reduce the industrial consumption of limited primary resources. In this review article, green emerging technologies involving lignocellulosic waste to synthesize the NPs from the waste streams and the role of potential microorganisms such as microalgae, fungi, yeast, bacteria for the synthesis of NPs have been discussed. A critical insight is also given on use of recycling technologies and the incorporation of NMs in the membrane bioreactors (MBRs) to improve membrane functioning and process performance. Finally, this study aims to mitigate various persisting scientific and technological challenges for the safe disposal and recycling of organic and inorganic waste for future use in the circular economy.

Green Synthesis of Gold Nanoparticles: An Eco-Friendly Approach

By virtue of their unique physicochemical properties, gold nanoparticles (AuNPs) have gained significant interest in a broad range of biomedical applications such as sensors, diagnosis, and therapy. AuNPs are generally synthesized via different conventional physical and chemical methods, which often use harmful chemicals that induce health hazards and pollute the environment. To overcome these issues, green synthesis techniques have evolved as alternative and eco-friendly approaches to the synthesis of environmentally safe and less-expensive nanoparticles using naturally available metabolites from plants and microorganisms such as bacteria, fungi, and algae. This review provides an overview of the advances in the synthesis of AuNPs using different biological resources with examples, and their profound applications in biomedicine. A special focus on the biosynthesis of AuNPs using different medicinal plants and their multifunctional applications in antibacterial, anti-inflammatory, and immune responses are featured. Additionally, the applications of AuNPs in cancer theranostics, including contrast imaging, drug delivery, hyperthermia, and cancer therapeutics, are comprehensively discussed. Moreover, this review will shed light on the importance of the green synthesis approach, and discuss the advantages, challenges, and prospects in this field.

Mutual impacts and interactions of antibiotic resistance genes, microcystin synthetase genes, graphene oxide, and Microcystis aeruginosa in synthetic wastewater

The physiological impacts and interactions of antibiotic resistance gene (ARG) abundance, microcystin synthetase gene expression, graphene oxide (GO), and Microcystis aeruginosa in synthetic wastewater were investigated. The results demonstrated that the absolute abundance of sul1, sul2, tetW, and tetM in synthetic wastewater dramatically increased to 365.2%, 427.1%, 375.2%, and 231.7%, respectively, when the GO concentration was 0.01 mg/L. Even more interesting is that the sum gene copy numbers of mcyA-J also increased to 243.2%. The appearance of GO made the significant correlation exist between ARGs abundance and mcyA-J expression. Furthermore, M. aeruginosa displayed better photosynthetic performance and more MCs production at 0.01 mg/L GO. There were 65 pairs of positive correlations between the intracellular differential metabolites of M. aeruginosa and the abundance of sul1, sul2, tetM, and tetW with various GO concentrations. The GO will impact the metabolites and metabolic pathway in M. aeruginosa. The metabolic changes impacted the ARGs, microcystin synthetase genes, and physiological characters in algal cells. Furthermore, there were complex correlations among sul1, sul2, tetM, tetW, mcyA-J, MCs, photosynthetic performance parameters, and ROS. The different concentration of GO will aggravate the hazards of M. aeruginosa by promoting the expression of mcyA-J, producing more MCs; simultaneously, it may cause the spread of ARGs.

Why Does Not Nanotechnology Go Green? Bioprocess Simulation and Economics for Bacterial-Origin Magnetite Nanoparticles

Nanotechnological developments, including fabrication and use of magnetic nanomaterials, are growing at a fast pace. Magnetic nanoparticles are exciting tools for use in healthcare, biological sensors, and environmental remediation. Due to better control over final-product characteristics and cleaner production, biogenic nanomagnets are preferable over synthetic ones for technological use. In this sense, the technical requirements and economic factors for setting up industrial production of magnetotactic bacteria (MTB)-derived nanomagnets were studied in the present work. Magnetite fabrication costs in a single-stage fed-batch and a semicontinuous process were US$ 10,372 and US$ 11,169 per kilogram, respectively. Depending on the variations of the production process, the minimum selling price for biogenic nanomagnets ranged between US$ 21 and US$ 120 per gram. Because these prices are consistently below commercial values for synthetic nanoparticles, we suggest that microbial production is competitive and constitutes an attractive alternative for a greener manufacturing of magnetic nanoparticles nanotools with versatile applicability.

Recent trends in microbial nanoparticle synthesis and potential application in environmental technology: a comprehensive review

Microbial technology comprising environment in various aspects of pollution monitoring, treatment of pollutants, and energy generation has been put forth by the researchers worldwide in an eco-friendly manner. During the past few decades, this revolution has pronounced microbial cells in green nanotechnology, extending the scope, efficiency, and investment capita at research institutes, industries, and global markets. In the present review, initially, the source for the microbial synthesis of nanoparticles will be discussed involving bacteria, fungi, actinomycetes, microalgae, and viruses. Further, the mechanism and bio-components of microbial cells such as enzymes, proteins, peptides, amino-acids, exopolysaccharides, and others involved in the bio-reduction of metal ions to corresponding metal nanoparticles will be emphasized. The biosynthesized nanoparticles physicochemical properties and bio-reduction methods' advantages compared with synthetic methods will be detailed. To understand the suitability of biosynthesized nanoparticles in a wide range of applications, an overview of its blend of medicine, agriculture, and electronics will be discussed. This will be geared up with its applications specific to environmental aspects such as bioremediation, wastewater treatment, green-energy production, and pollution monitoring. Towards the end of the review, nano-waste management and limitations, i.e., void gaps that tend to impede the application of biosynthesized nanoparticles and microbial-based nanoparticles' prospects, will be deliberated. Thus, the review would claim to be worthy of unwrapping microorganisms sustainability in the emerging field of green nanotechnology.

A state of the art review on the synthesis, antibacterial, antioxidant, antidiabetic and tissue regeneration activities of zinc oxide nanoparticles

Recently, zinc oxide nanoparticles (ZnONPs) are gaining much interest of nanobiotechnologists due to their profound biomedical applications. ZnONPs are used as antibacterial agents, which cause both gram-positive and negative bacterial cell death through the generation of reactive free radicals as well as membrane rupture. ZnONPs show excellent antioxidant properties in normal mammalian cells via the scavenging of reactive free radicals and up-regulation of antioxidant enzyme activities. Besides, it also shows hypoglycaemic effect in diabetic animals via pancreatic β-cells mediated increased insulin secretion and glucose uptake by liver, skeletal muscles and adipose tissues. Among the other potential applications, ZnONPs-induced bone and soft-tissue regeneration open a new horizon in the field of tissue engineering. Here, first we reviewed the complete synthesis routes of ZnONPs by physical, chemical, and biological pathways as well as outlined the advantages and disadvantages of the techniques. Further, we discussed the several important aspects of physicochemical analysis of ZnONPs. Additionally, we extensively reviewed the important biomedical applications of ZnONPs as antibacterial, antioxidant, and antidiabetic agents, and in the field of tissue engineering with special emphasis on their mechanisms of actions. Furthermore, the future perspectives of the ZnONPs are also discussed.

Silver Nanoparticles Biosynthesis, Characterization, Antimicrobial Activities, Applications, Cytotoxicity and Safety Issues: An Updated Review

Rapid advances in nanotechnology have led to its emergence as a tool for the development of green synthesized noble metal nanoparticles, especially silver nanoparticles (AgNPs), for applications in diverse fields such as human health, the environment and industry. The importance of AgNPs is because of their unique physicochemical and antimicrobial properties, with a myriad of activities that are applicable in various fields, including the pharmaceutical industry. Countries with high biodiversity require the collection and transformation of information about biological assets into processes, associations, methods and tools that must be combined with the sustainable utilization of biological diversity. Therefore, this review paper discusses the applicable studies of the biosynthesis of AgNPs and their antimicrobial activities towards microorganisms in different areas viz. medicine and agriculture. The confirmed antiviral properties of AgNPs promote their applicability for SARS-CoV-2 treatment, based on assimilating the virus’ activities with those of similar viruses via in vivo studies. In this review, an insight into the cytotoxicity and safety issues of AgNPs, along with their future prospects, is also provided.

Sewage Treatment through Constructed Wetland System Tailed by Nanocomposite Clay Filter: A Clean Green Initiative

Sewage treatment through constructed wetland is an ecofriendly and sustainable approach proven effective worldwide. Constructed wetland with appropriate species is capable of eliminating all pollutants in sewage, except pathogen removal. An additional polishing treatment is required to eliminate pathogen. Optimization of HLR in CWS was executed by applying first order kinetics. Nanocomposite clay filter with economically viable materials was synthesized and disinfection ability was evaluated. A novel approach integrating constructed wetland system tailed by nanocomposite clay filter was designed. Control was setup with constructed wetland system devoid of plants integrated with clay filter devoid of nanoparticles. The constructed wetland system devoid of plants was used as plants play a vital role in the removal of pollutants. The quality of the influent for (n=20) BOD, COD, TKN, TP, TSS, TDS, SO4, Cl, lead and iron were 248, 345, 26, 4.8, 350, 450, 50, 48, 0.2, 5 mg/L respectively. The quality of effluent in the control was 145, 225, 18, 3.8, 185, 345, 31, 30, 0.6, 2 mg/L for BOD,COD, TKN, TP, TSS, TDS, SO4, Cl, lead and iron respectively. While in the test, 10, 30, 2, 1, 30, 128, 13, 12, BDL, BDL mg/L for BOD, COD, TKN, TP,TSS, TDS, SO4, Cl, lead and iron respectively. The inlet concentration of T.C, F.C and E.coli were 42.1x106-6.3x108, 4.9x105-14.4x106 and 7.8x103-3.8x105 respectively. The pathogen reduction in log removal for test and control units were 5.4 and 1.1 for T.C, 4.4 and 1.2 for F.C and 3 and 1 for E.coli.  Thus it is a clean green initiative combating the limitations of disinfection surpassing the existing barriers.

Sewage Treatment through Constructed Wetland System Tailed by Nanocomposite Clay Filter: A Clean Green Initiative

Sewage treatment through constructed wetland is an ecofriendly and sustainable approach proven effective worldwide. Constructed wetland with appropriate species is capable of eliminating all pollutants in sewage, except pathogen removal. An additional polishing treatment is required to eliminate pathogen. Optimization of HLR in CWS was executed by applying first order kinetics. Nanocomposite clay filter with economically viable materials was synthesized and disinfection ability was evaluated. A novel approach integrating constructed wetland system tailed by nanocomposite clay filter was designed. Control was setup with constructed wetland system devoid of plants integrated with clay filter devoid of nanoparticles. The constructed wetland system devoid of plants was used as plants play a vital role in the removal of pollutants. The quality of the influent for (n=20) BOD, COD, TKN, TP, TSS, TDS, SO4, Cl, lead and iron were 248, 345, 26, 4.8, 350, 450, 50, 48, 0.2, 5 mg/L respectively. The quality of effluent in the control was 145, 225, 18, 3.8, 185, 345, 31, 30, 0.6, 2 mg/L for BOD,COD, TKN, TP, TSS, TDS, SO4, Cl, lead and iron respectively. While in the test, 10, 30, 2, 1, 30, 128, 13, 12, BDL, BDL mg/L for BOD, COD, TKN, TP,TSS, TDS, SO4, Cl, lead and iron respectively. The inlet concentration of T.C, F.C and E.coli were 42.1x106-6.3x108, 4.9x105-14.4x106 and 7.8x103-3.8x105 respectively. The pathogen reduction in log removal for test and control units were 5.4 and 1.1 for T.C, 4.4 and 1.2 for F.C and 3 and 1 for E.coli.  Thus it is a clean green initiative combating the limitations of disinfection surpassing the existing barriers.

Microbial biomanufacture of metal/metallic nanomaterials and metabolic engineering: design strategies, fundamental mechanisms, and future opportunities

Biomanufacturing metal/metallic nanomaterials with ordered micro/nanostructures and controllable functions is of great importance in both fundamental studies and practical applications due to their low toxicity, lower pollution production, and energy conservation. Microorganisms, as efficient biofactories, have a significant ability to biomineralize and bioreduce metal ions that can be obtained as nanocrystals of varying morphologies and sizes. The development of nanoparticle biosynthesis maximizes the safety and sustainability of the nanoparticle preparation. Significant efforts and progress have been made to develop new green and environmentally friendly methods for biocompatible metal/metallic nanomaterials. In this review, we mainly focus on the microbial biomanufacture of different metal/metallic nanomaterials due to their unique advantages of wide availability, environmental acceptability, low cost, and circular sustainability. Specifically, we summarize recent and important advances in the synthesis strategies and mechanisms for different types of metal/metallic nanomaterials using different microorganisms. Finally, we highlight the current challenges and future research directions in this growing multidisciplinary field of biomaterials science, nanoscience, and nanobiotechnology.

Bactericidal and Virucidal Activities of Biogenic Metal-Based Nanoparticles: Advances and Perspectives

Much progress has been achieved in the preparation and application of engineered nanoparticles (NPs) in the field of medicine, mainly for antibacterial and antiviral applications. In the war against bacteria and viruses, besides traditional antibiotics and antiviral drugs, metal-based nanoparticles, such as silver (AgNPs), copper (CuNPs), copper oxides (CuO-NPs), iron oxide (FeO-NPs), zinc oxide (ZnO-NPs), and titanium oxide (TiO2-NPs) have been used as potent antimicrobial agents. These nanoparticles can be synthesized by traditional methods, such as chemical and physical routes, or more recently by biogenic processes. A great variety of macro and microorganisms can be successfully used as reducing agents of metal salt precursors in the biogenic synthesis of metal-based NPs for antimicrobial activity. Depending on the nature of the biological agent, NPs with different sizes, aggregation states, morphology, surface coatings and charges can be obtained, leading to different antimicrobial effects. Considering the drug resistance to traditional therapies, the development of versatile nanomaterials with potent antimicrobial effects is under intensive investigation. In this sense, this review presents and discusses the recent progress in the preparation and application of metal-based nanoparticles biogenically synthesized for antibacterial and antivirus applications. The strength and limitations are critically discussed.

Microbe-Mediated Biosynthesis of Nanoparticles: Applications and Future Prospects

Nanotechnology is the science of nano-sized particles/structures (~100 nm) having a high surface-to-volume ratio that can modulate the physical, chemical and biological properties of the chemical compositions. In last few decades, nanoscience has attracted the attention of the scientific community worldwide due to its potential uses in the pharmacy, medical diagnostics and disease treatment, energy, electronics, agriculture, chemical and space industries. The properties of nanoparticles (NPs) are size and shape dependent. These characteristic features of nanoparticles can be explored for various other applications such as computer transistors, chemical sensors, electrometers, memory schemes, reusable catalysts, biosensing, antimicrobial activity, nanocomposites, medical imaging, tumor detection and drug delivery. Therefore, synthesizing nanoparticles of desired size, structure, monodispersity and morphology is crucial for the aforementioned applications. Recent advancements in nanotechnology aim at the synthesis of nanoparticles/materials using reliable, innoxious and novel ecofriendly techniques. In contrast to the traditional methods, the biosynthesis of nanoparticles of a desired nature and structure using the microbial machinery is not only quicker and safer but more environmentally friendly. Various microbes, including bacteria, actinobacteria, fungi, yeast, microalgae and viruses, have recently been explored for the synthesis of metal, metal oxide and other important NPs through intracellular and extracellular processes. Some bacteria and microalgae possess specific potential to fabricate distinctive nanomaterials such as exopolysaccharides, nanocellulose, nanoplates and nanowires. Moreover, their ability to synthesize nanoparticles can be enhanced using genetic engineering approaches. Thus, the use of microorganisms for synthesis of nanoparticles is unique and has a promising future. The present review provides explicit information on different strategies for the synthesis of nanoparticles using microbial cells; their applications in bioremediation, agriculture, medicine and diagnostics; and their future prospects.

Green Synthesis: An Eco-friendly Route for the Synthesis of Iron Oxide Nanoparticles

Green approach has received major attention for the synthesis of metal oxide nanoparticles. One such metal oxide nanoparticles are iron oxide nanoparticles (IONPs). IONPs have fetched a great deal of interest in recent era because of their magnetic nature, as they can be easily recovered from the reaction mixture by applying an external magnetic field. Although, a variety of chemical and physical methods of synthesis are known, green synthesis is safer, sustainable and biologically acceptable. Plants and microbes are the main biological materials used for the green synthesis. In present review, the synthesis of IONPs by using plants, bacteria, fungi and algae have been highlighted. IONPs produced by plants, fungi, bacteria and algae usually falls in 1–100 nm range and are of distinct shapes like cubic, tetragonal crystalline, spherical, cylindrical, elliptical, octahedral, orthorhombic, hexagonal rods, nanosphere and quasi spherical. Furthermore, these biomaterials play role of reducing, capping, stabilizing and fabricating agents in green synthesis of nanoparticles. The review put forward a comprehensive report of various routes used for synthesizing IONP, biologically. Intuition into the procedures for synthesis of nanoparticles will help to nourish our learning in the area of nanotechnology.

Desertifilum sp. EAZ03 cell extract as a novel natural source for the biosynthesis of zinc oxide nanoparticles and antibacterial, anticancer and antibiofilm characteristics of synthesized zinc oxide nanoparticles

AIMS

The use of cyanobacterial cell extracts for the synthesis of zinc oxide nanoparticles (ZnO NPs) seems to be superior to other methods of synthesis because of its a green, environmentally friendly and low-cost approach. In this study, the cell extract of a newly characterized cyanobacterial strain Desertifilum sp. EAZ03 was used for the biosynthesis of ZnO NPs. The antimicrobial, antibiofilm and anticancer activities of the biosynthesized ZnO NPs (hereinafter referred to as CED-ZnO NPs) were examined as well.

METHODS AND RESULTS

UV-Vis spectroscopy analysis of CED-ZnO NPs showed an absorbance band at 364 nm, and powder X-ray diffraction analysis confirmed the purity of the synthesized nanoparticles. The analyses of scanning electron microscopy and transmission electron microscopy images revealed that CED-ZnO NPs were rod-shaped with a size of 88 nm. The study of the biological features of CED-ZnO NPs showed a significant antimicrobial potential against the bacterial strains tested. CED-ZnO NPs were able to impede the biofilm formation by Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa up to 80%, 89% and 85%, respectively. The nanoparticles also showed 69%, 70% and 62% degrading activity against S. aureus, E. coli and P. aeruginosa 1-day-old biofilms, respectively. The antibiofilm activity of the synthesized nanoparticles was investigated by confocal laser scanning microscopy. The MTT assay showed that CED-ZnO NPs, at a concentration of 100 μg/ml, had less cytotoxicity towards normal lung (MRC-5) cells, at the half, compared to cancerous lung alveolar epithelial (A549) cells. The minimum inhibitory concentration and minimum bactericidal concentration values of CED-ZnO NPs against E. coli, P. aeruginosa and S. aureus were 1500, 2000 and 32 μg/ml, and 2500, 3500 and 64 μg/ml, respectively.

CONCLUSIONS

The multifunctional CED-ZnO NPs seem to be promising for possible applications in the therapeutic and pharmaceutical industries.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study proposes a new approach for the biosynthesis of zinc oxide nanoparticles using a newly characterized cyanobacterial strain Desertifilum sp. EAZ03. The considerable antimicrobial, antibiofilm and anticancer activities of the biosynthesized zinc oxide nanoparticles further emphasize the emerging role of microbial systems in the green synthesis of metal oxide nanoparticles.

Endophytic Nanotechnology: An Approach to Study Scope and Potential Applications

Nanotechnology has become a very advanced and popular form of technology with huge potentials. Nanotechnology has been very well explored in the fields of electronics, automobiles, construction, medicine, and cosmetics, but the exploration of nanotecnology's use in agriculture is still limited. Due to climate change, each year around 40% of crops face abiotic and biotic stress; with the global demand for food increasing, nanotechnology is seen as the best method to mitigate challenges in disease management in crops by reducing the use of chemical inputs such as herbicides, pesticides, and fungicides. The use of these toxic chemicals is potentially harmful to humans and the environment. Therefore, using NPs as fungicides/ bactericides or as nanofertilizers, due to their small size and high surface area with high reactivity, reduces the problems in plant disease management. There are several methods that have been used to synthesize NPs, such as physical and chemical methods. Specially, we need ecofriendly and nontoxic methods for the synthesis of NPs. Some biological organisms like plants, algae, yeast, bacteria, actinomycetes, and fungi have emerged as superlative candidates for the biological synthesis of NPs (also considered as green synthesis). Among these biological methods, endophytic microorganisms have been widely used to synthesize NPs with low metallic ions, which opens a new possibility on the edge of biological nanotechnology. In this review, we will have discussed the different methods of synthesis of NPs, such as top-down, bottom-up, and green synthesis (specially including endophytic microorganisms) methods, their mechanisms, different forms of NPs, such as magnesium oxide nanoparticles (MgO-NPs), copper nanoparticles (Cu-NPs), chitosan nanoparticles (CS-NPs), β-d-glucan nanoparticles (GNPs), and engineered nanoparticles (quantum dots, metalloids, nonmetals, carbon nanomaterials, dendrimers, and liposomes), and their molecular approaches in various aspects. At the molecular level, nanoparticles, such as mesoporous silica nanoparticles (MSN) and RNA-interference molecules, can also be used as molecular tools to carry genetic material during genetic engineering of plants. In plant disease management, NPs can be used as biosensors to diagnose the disease.

Microbial Fabricated Nanosystems: Applications in Drug Delivery and Targeting

The emergence of nanosystems for different biomedical and drug delivery applications has drawn the attention of researchers worldwide. The likeness of microorganisms including bacteria, yeast, algae, fungi, and even viruses toward metals is well-known. Higher tolerance to toxic metals has opened up new avenues of designing microbial fabricated nanomaterials. Their synthesis, characterization and applications in bioremediation, biomineralization, and as a chelating agent has been well-documented and reviewed. Further, these materials, due to their ability to get functionalized, can also be used as theranostics i.e., both therapeutic as well as diagnostic agents in a single unit. Current article attempts to focus particularly on the application of such microbially derived nanoformulations as a drug delivery and targeting agent. Besides metal-based nanoparticles, there is enough evidence wherein nanoparticles have been formulated using only the organic component of microorganisms. Enzymes, peptides, polysaccharides, polyhydroxyalkanoate (PHA), poly-(amino acids) are amongst the most used biomolecules for guiding crystal growth and as a capping/reducing agent in the fabrication of nanoparticles. This has promulgated the idea of complete green chemistry biosynthesis of nano-organics that are most sought after in terms of their biocompatibility and bioavailability.

Synthesis of intracellular and extracellular gold nanoparticles with a green machine and its antifungal activity

Green synthesis method is being increasingly used in the development of safe, stable, and eco-friendly nanostructures with biological resources. In this study, extracellular and intracellular synthesis of gold nanoparticles (AuNPs) was carried out using green algae Chlorella sorokiniana Shihira & R.W. Fresh algae were isolated and identified from Musaözü Pond located in the province of Eskişehir and then extraction process were performed. Optimization studies were studied using pH value, metal salt concentration, and time parameters for extracellular synthesis and using only time parameter for intrasellular synthesis. Since more controlled and optimum conditions can be achieved in the production of AuNPs by extracellular synthesis, these nanoparticles (NPs) were used for characterization and antifungal activity studies. Optical, physical, and chemical properties of synthesized NPs were characterized by UV visible spectrophotometer (UV-Vis), dynamic light scattering (DLS), Zetasizer, X-Ray diffraction (XRD), Fourier transform ınfrared spectroscopy (FTIR), field emission scanning electron microscope (FE-SEM), ınductively coupled plasma mass spectrometer (ICP-MS) and transmission electron microscope (TEM) analysis. The optimum conditions for AuNPs synthesis were determined as 1 mM for HauCl₄ concentration, 6 for pH value, and 60th min for time. AuNPs obtained from extracellular synthesis from C. sorokiniana extract are 5–15 nm in size and spherical shape. TEM images of extracellular synthesis show noticeable cell wall and membrane damages, cytoplasma dissolutions, and irregularities. AuNPs obtained by intracellular synthesis are in 20–40 nm size and localized in the cell wall and cytoplasm. These NPs exhibited significant antifungal activity against C. tropicalis, C. glabrata, and C. albicans isolates. AuNPs obtained by algae-mediated green synthesis have a significant potential for medical and industrial use, and this eco-friendly synthesis method can be easily scaled for future studies.

The Emerging Trend of Bio-Engineering Approaches for Microbial Nanomaterial Synthesis and Its Applications

Micro-organisms colonized the world before the multi-cellular organisms evolved. With the advent of microscopy, their existence became evident to the mankind and also the vast processes they regulate, that are in direct interest of the human beings. One such process that intrigued the researchers is the ability to grow in presence of toxic metals. The process seemed to be simple with the metal ions being sequestrated into the inclusion bodies or cell surfaces enabling the conversion into nontoxic nanostructures. However, the discovery of genome sequencing techniques highlighted the genetic makeup of these microbes as a quintessential aspect of these phenomena. The findings of metal resistance genes (MRG) in these microbes showed a rather complex regulation of these processes. Since most of these MRGs are plasmid encoded they can be transferred horizontally. With the discovery of nanoparticles and their many applications from polymer chemistry to drug delivery, the demand for innovative techniques of nanoparticle synthesis increased dramatically. It is now established that microbial synthesis of nanoparticles provides numerous advantages over the existing chemical methods. However, it is the explicit use of biotechnology, molecular biology, metabolic engineering, synthetic biology, and genetic engineering tools that revolutionized the world of microbial nanotechnology. Detailed study of the micro and even nanolevel assembly of microbial life also intrigued biologists and engineers to generate molecular motors that mimic bacterial flagellar motor. In this review, we highlight the importance and tremendous hidden potential of bio-engineering tools in exploiting the area of microbial nanoparticle synthesis. We also highlight the application oriented specific modulations that can be done in the stages involved in the synthesis of these nanoparticles. Finally, the role of these nanoparticles in the natural ecosystem is also addressed.

Biogenic Nanoparticles: Synthesis, Characterisation and Applications

Nanotechnology plays a big part in our modern daily lives, ranging from the biomedical sector to the energy sector. There are different physicochemical and biological methods to synthesise nanoparticles towards multiple applications. Biogenic production of nanoparticles through the utilisation of microorganisms provides great advantages over other techniques and is increasingly being explored. This review examines the process of the biogenic synthesis of nanoparticles mediated by microorganisms such as bacteria, fungi and algae, and their applications. Microorganisms offer a disparate environment for nanoparticle synthesis. Optimum production and minimum time to obtain the desired size and shape, to improve the stability of nanoparticles and to optimise specific microorganisms for specific applications are the challenges to address, however. Numerous applications of biogenic nanoparticles in medicine, environment, drug delivery and biochemical sensors are discussed.

Biocompatibility of nanomaterials and their immunological properties

Nanomaterials (NMs) have revolutionized multiple aspects of medicine by enabling novel sensing, diagnostic, and therapeutic approaches. Advancements in processing and fabrication have also allowed significant expansion in the applications of the major classes of NMs based on polymer, metal/metal oxide, carbon, liposome, or multi-scale macro-nano bulk materials. Concomitantly, concerns regarding the nanotoxicity and overall biocompatibility of NMs have been raised. These involve putative negative effects on both patients and those subjected to occupational exposure during manufacturing. In this review, we describe the current state of testing of NMs including those that are in clinical use, in clinical trials, or under development. We also discuss the cellular and molecular interactions that dictate their toxicity and biocompatibility. Specifically, we focus on the reciprocal interactions between NMs and host proteins, lipids, and sugars and how these induce responses in immune and other cell types leading to topical and/or systemic effects.