Inhibition of growth and biofilm formation of clinical bacterial isolates by NiO nanoparticles synthesized from Eucalyptus globulus plants

Green nanotechnology in phytosynthesis and its efficiency in inhibiting bacterial biofilm formation: implications for medicine

Nanotechnology is used in several biomedical applications, including antimicrobial and antibiofilm applications using nanomaterials. Bacterial biofilm varies according to the strain; the matrix is very strong and resistant. In this sense, phytosynthesis is an important method for combating bacterial biofilms through the use of metallic nanoparticles (silver, gold, or copper) with increased marketing and technical-scientific potential. In this review, we seek to gather the leading publications on the use of phytosynthesized metallic nanoparticles against bacterial biofilms. Furthermore, this study aims to understand the main characteristics and parameters of these nanomaterials, their antibiofilm efficiency, and the presence or absence of cytotoxicity in these developed technologies.

Kinetics analysis of PAHs degradation using SiO2-ZnO nanoparticles and evaluating their antibacterial and antibiofilm efficacy

The adsorption of Polycyclic aromatic hydrocarbons (PAHs) using nanoparticles is gaining significant attention due to the rapid removal or treatment rates. In this study, Silicon Dioxide-Zinc Oxide nanoparticles (SiO2-ZnO NPs) were synthesized to adsorb pyrene. Physicochemical characterization of SiO2-ZnO NPs showed plasmon resonance at 323 nm, agglomeration, irregular dispersion, and diameters of 90-100 nm. FT-IR analysis identified major functional groups on SiO2-ZnO NPs, including alkyne, amine, and isothiocyanate. SiO2-ZnO NPs demonstrated significant pyrene adsorption at pH 5, with 10 μg/mL of SiO2-ZnO NPs and 2 μg/mL of PAHs, performing better under UV irradiation. Two isotherm models, adsorption isotherm and kinetics adsorption, were used to analyze the PAHs adsorption by SiO2-ZnO NPs. Additionally, SiO2-ZnO NPs were tested for antibacterial and antibiofilm activities against both Gram-negative and Gram-positive bacteria. At a concentration of 150 μg/mL, SiO2-ZnO NPs produced inhibition zones of 21.57 mm, 20.30 mm, 19.30 mm, and 11.30 mm against Staphylococcus aureus, Escherichia coli, Bacillus subtilis, and Klebsiella pneumoniae, respectively. They also inhibited and disrupted biofilms of Micrococcus luteus and Acinetobacter baumannii. Furthermore, SiO2-ZnO NPs exhibited photocatalytic degradation of lead, achieving 68.24% degradation within 5 h of treatment. Therefore, SiO2-ZnO NPs are efficient candidates for multiple applications, including pyrene adsorption, bacterial biofilm disruption, and lead degradation under sunlight.

Combating bacterial biofilms and related drug resistance: Role of phyto-derived adjuvant and nanomaterials

The emergence of antimicrobial resistance (AMR) in clinical microbes has led to a search for novel antibiotics for combating bacterial infections. The treatment of bacterial infections becomes more challenging with the onset of biofilm formation. AMR is further accelerated by biofilm physiology and differential gene expression in bacteria with an inherent resistance to conventional antibiotics. In the search for innovative strategies to control the spread of AMR in clinical isolates, plant-derived therapeutic metabolites can be repurposed to control biofilm-associated drug resistance. Unlike antibiotics, designed to act on a single cellular process, phytochemicals can simultaneously target multiple cellular components. Furthermore, they can disrupt biofilm formation and inhibit quorum sensing, offering a comprehensive approach to combat bacterial infections. In bacterial biofilms, the first line of AMR is due to biofilms associated with the extracellular matrix, diffusion barriers, quorum sensing, and persister cells. These extracellular barriers can be overcome using phytochemical-based antibiotic adjuvants to increase the efficacy of antibiotic treatment and restrict the spread of AMR. Furthermore, phytochemicals can be used to target bacterial intracellular machinery such as DNA replication, protein synthesis, efflux pumps, and degrading enzymes. In parallel with pristine phytochemicals, phyto-derived nanomaterials have emerged as an effective means of fighting bacterial biofilms. These nanomaterials can be formulated to cross the biofilm barriers and function on cellular targets. This review focuses on the synergistic effects of phytochemicals and phyto-derived nanomaterials in controlling the progression of biofilm-related AMR. IT provides comprehensive insights into recent advancements and the underlying mechanisms of the use of phyto-derived adjuvants and nanomaterials.

Characteristics of Metallic Nanoparticles (Especially Silver Nanoparticles) as Anti-Biofilm Agents

Biofilm-associated infections account for a large proportion of chronic diseases and pose a major health challenge. Metal nanoparticles offer a new way to address this problem, by impairing microbial growth and biofilm formation and by causing degradation of existing biofilms. This review of metal nanoparticles with antimicrobial actions included an analysis of 20 years of journal papers and patent applications, highlighting the progress over that time. A network analysis of relevant publications showed a major focus on the eradication of single-species biofilms formed under laboratory conditions, while a bibliometric analysis showed growing interest in combining different types of metal nanoparticles with one another or with antibiotics. The analysis of patent applications showed considerable growth over time, but with relatively few patents progressing to be granted. Overall, this profile shows that intense interest in metal nanoparticles as anti-biofilm agents is progressing beyond the confines of simple laboratory biofilm models and coming closer to clinical application. Looking to the future, metal nanoparticles may provide a sustainable approach to combatting biofilms of drug-resistant bacteria.

Nanomaterial in controlling biofilms and virulence of microbial pathogens

The escalating threat of antimicrobial resistance (AMR) poses a grave concern to global public health, exacerbated by the alarming shortage of effective antibiotics in the pipeline. Biofilms, intricate populations of bacteria encased in self-produced matrices, pose a significant challenge to treatment, as they enhance resistance to antibiotics and contribute to the persistence of organisms. Amid these challenges, nanotechnology emerges as a promising domain in the fight against biofilms. Nanomaterials, with their unique properties at the nanoscale, offer innovative antibacterial modalities not present in traditional defensive mechanisms. This comprehensive review focuses on the potential of nanotechnology in combating biofilms, focusing on green-synthesized nanoparticles and their associated anti-biofilm potential. The review encompasses various aspects of nanoparticle-mediated biofilm inhibition, including mechanisms of action. The diverse mechanisms of action of green-synthesized nanoparticles offer valuable insights into their potential applications in addressing AMR and improving treatment outcomes, highlighting novel strategies in the ongoing battle against infectious diseases.

Metal-based nanoparticles: an alternative treatment for biofilm infection in hard-to-heal wounds

Metal-based nanoparticles (MNPs) are promoted as effective compounds in the treatment of bacterial infections and as possible alternatives to antibiotics. These MNPs are known to affect a broad spectrum of microorganisms using a multitude of strategies, including the induction of reactive oxygen species and interaction with the inner structures of the bacterial cells. The aim of this review was to summarise the latest studies about the effect of metal-based nanoparticles on pathogenic bacterial biofilm formed in wounds, using the examples of Gram-positive bacterium Staphylococcus aureus and Gram-negative bacterium Pseudomonas aeruginosa, as well as provide an overview of possible clinical applications.

Silver and gold nanoparticles: Eco-friendly synthesis, antibiofilm, antiviral, and anticancer bioactivities

For the first time in this study, silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) were green synthesized by the cost-effective and eco-friendly procedure using Cotton seed meal and Fodder yeast extracts. The biosynthesized NPs were characterized by UV-Vis spectroscopy, dynamic light scattering analysis (DLS), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and fourier-transform infrared (FTIR) spectroscopy. Furthermore, the biosynthesized NPs were tested in vitro against biofilm formation by some pathogenic negative bacteria (Escherichia coli, Proteus mirabilis, Klebsiella sp., Salmonella sp., and Pseudomonas aeruginosa) and negative bacteria (staphylococcus aureus) as well as against human denovirus serotype 5 (HAdV-5) and anticancer activity using HepG2 hepatocarcinoma cells. UV-Vis absorption spectra of reaction mixture of AgNPs and AuNPs exhibited maximum absorbance at 440 nm and 540 nm, respectively. This finding was confirmed by DLS measurements that the highest intensity of the AgNPs and AuNPs were 84 nm and 73.9 nm, respectively. FTIR measurements identified some functional groups detected in Cotton seed meal and Fodder yeast extracts that could be responsible for reduction of silver and gold ions to metallic silver and gold. The morphologies and particle size of AgNPs and AuNPs were confirmed by the TEM and SAED pattern analysis. Biosynthesized AgNPs and AuNPs showed good inhibitory effects against biofilms produced by Escherichia coli, Proteus mirabilis, Klebsiella sp., Salmonella sp., Pseudomonas aeruginosa, and Staphylococcus aureus. In addition, they showed anticancer activities against hepatocellular carcinoma (HepG-2) and antiviral activity against human adenovirus serotype 5 infection in vitro. Finally, the results of this study is expected to be extremely helpful to nano-biotechnology, pharmaceutical, and food packing applications through developing antimicrobial and/or an anticancer drugs from ecofriendly and inexpensive nanoparticles with multi-potentiality.

Assessing silver nanoparticle and antimicrobial combinations for antibacterial activity and biofilm prevention on surgical sutures

AIMS

To evaluate the effect of silver nanoparticles alone and in combination with Triclosan, and trans-cinnamaldehyde against Staphylococcus aureus and Escherichia coli biofilms on sutures to improve patients' outcomes.

METHODS AND RESULTS

Silver nanoparticles were prepared by chemical method and characterized by UV-visible spectrophotometer and dynamic light scattering. The minimum inhibitory concentration was assessed by the Microdilution assay. The antibiofilm activity was determined using crystal violet assay. A checkerboard assay using the fractional inhibitory concentration index and time-kill curve was used to investigate the synergistic effect of silver nanoparticle combinations. The hemolytic activity was determined using an erythrocyte hemolytic assay. Our results revealed that silver nanoparticles, Triclosan, and trans-cinnamaldehyde (TCA) inhibited S.aureus and E.coli biofilms. Silver nanoparticles with TCA showed a synergistic effect (FICI values 0.35 and 0.45 against S. aureus and E. coli biofilms, respectively), and silver nanoparticles with Triclosan showed complete inhibition of S. aureus biofilm. The hemolytic activity was <2.50% for the combinations.

Green synthesis of nanomaterials by using plant extracts as reducing and capping agents

An alternative method to conventional synthesis is examined in this review by the use of plant extracts as reducing and capping agents. The use of plant extracts represents an economically viable and environmentally friendly alternative to conventional synthesis. In contrast to previous reviews, this review focuses on the synthesis of nano-compounds utilizing plant extracts, which lack comprehensive reports. In order to synthesize diverse nanostructures, researchers have discovered a sustainable and cost-effective method of harnessing functional groups in plant extracts. Each plant extract is discussed in detail, along with its potential applications, demonstrating the remarkable morphological diversity achieved by using these green synthesis approaches. A reduction and capping agent made from plant extracts is aligned with the principles of green chemistry and offers economic advantages as well as paving the way for industrial applications. In this review, it is discussed the significance of using plant extracts to synthesize nano-compounds, emphasizing their potential to shape the future of nanomaterials in a sustainable and ecologically friendly manner.

Phytosynthesis of Nickel Oxide Nanoparticles and Their Antioxidant and Antibacterial Efficacy Studies

INTRODUCTION

 Multidrug-resistant (MDR) bacteria are widely acknowledged as a significant and pressing public health concern. Tribulus terrestris has been used as a health tonic in traditional medicine since ancient Vedic times. It was also utilized to synthesize small, well-dispersed metal nanoparticles (NPs). The biosynthesized nickel oxide nanoparticles (NiO-NPs) have a broad spectrum of biomedical uses.

OBJECTIVE

 The objective of the research was to utilize a green synthesis method to synthesize NiO-NPs using Tribulus terrestris, subsequently characterize, and this study aimed to assess the antioxidant and antibacterial effectiveness of these NPs against wound isolates that are resistant to multiple drugs.

MATERIALS AND METHODS

 The synthesis of NiO-NPs was achieved through the titration method, which is a green synthesis approach, and it was characterized by using techniques such as ultraviolet-visible spectroscopy (UV), Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis, and energy dispersive X-ray (EDX). The antioxidant activity of the NPs was evaluated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, and antibacterial activity was done using the agar well diffusion method. IBM SPSS Statistics for Windows, Version 21 (Released 2012; IBM Corp., Armonk, New York, United States) is used for statistical analysis.

RESULTS

 The biosynthesized NiO-NPs exhibited a color change from dark brown to dark green, indicating the successful reduction of the NPs. UV analysis peaks were observed at 310-350 nm, while FT-IR analysis showed the peaks at various wavelengths such as 629.31cm-1 (halo compound; C-Br stretching), 957.80cm-1(aromatic phosphates; P-O-C stretch), 1004.65cm-1 (aliphatic phosphates; P-O-C stretch), 1094.93cm-1 (organic siloxane or silicone; Si-O-Si), 1328.38cm-1 (dialkyl/aryl sulfones), 1604.88cm-1 (open-chain azo-N=N-), 2928.68cm-1 (methylene C-H asym/sym stretch), 3268.65cm-1 (normal polymeric "OH" stretch). The crystallinity of the NPs was determined to be 24.7%, while the remaining 75.6% exhibited an amorphous structure. The SEM image revealed a spherically agglomerated structure of the nano-ranged size NiO-NPs. The EDX analysis indicated the presence of elemental compositions Ni (7.4%), O (39.4%), and C (53.3%) in the biosynthesized NiO-NPs. These NPs demonstrated significant antibacterial activity against Pseudomonas aeruginosa and Klebsiella pneumoniae, moderate antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA), and the lowest antibacterial activity against Enterococcus faecalis.

CONCLUSION

 Our in vitro results demonstrate that the biosynthesized NiO-NPs exhibit significant antioxidant and antibacterial activity. These NPs can be used as a future antimicrobial medication, particularly against MDR clinical wound isolates of K. pneumoniae, P. aeruginosa, and MRSA.

Synergistic antibacterial effects of exopolysaccharides/nickel-nanoparticles composites against multidrug-resistant bacteria

The need for an alternative treatment to fight infectious diseases caused by antibiotic-resistant bacteria is increasing. A possible way to overcome bacterial resistance to antibiotics is by reintroducing commonly used antibiotics with a sensitizer capable of enhancing their antimicrobial effect in resistant bacteria. Here, we use a composite composed of exopolysaccharide capped-NiO NPs, with antimicrobial effects against antibiotic-resistant Gram-positive and Gram-negative bacteria. It potentiated the antimicrobial effects of four different antibiotics (ampicillin, kanamycin, chloramphenicol, and ciprofloxacin) at lower concentrations than their minimal inhibitory concentrations. We observed that the Ni-composite synergistically enhanced, fourfold, the antibacterial effect of kanamycin and chloramphenicol against multidrug-resistant Staphylococcus aureus and Pseudomonas aeruginosa, as well as ampicillin against multidrug-resistant Staphylococcus aureus, and ciprofloxacin against multidrug-resistant Pseudomonas aeruginosa by eightfold. We also found that Ni-composite could not inhibit biofilm synthesis on the tested bacterial strains. Our results demonstrated the possibility of using metal nanoparticles, like NiO, as a sensitizer to overcome bacterial antibiotic resistance.

Using biologically synthesized TiO2 nanoparticles as potential remedy against multiple drug resistant Staphylococcus aureus of bovine mastitis

Presently, there is considerable emphasis on biological synthesis of nanoparticles containing bioactive reducing compounds with an aim to mitigate the harmful effects of pollutants. The approach under study is simple and ideal for the production of durable antimicrobial nanomaterials by novel single-step green synthesis of TiO2 metal oxide nanostructures using ginger and garlic crude aqueous extracts with bactericidal and catalytic activity. A variety of experimental techniques were used to characterize the synthesized nanomaterials. As demonstrated using x-ray diffraction and ultra-violet visible spectroscopy, the produced nanoparticles exhibited high absorption at 318 nm with size varying between 23.38 nm for ginger and 58.64 nm for garlic in biologically-reduced TiO2. At increasing concentrations (500, 1000 µg/50 µl), nanoparticles reduced with garlic exhibited enhanced bactericidal efficacy against multiple drug-resistant S. aureus and effectively decomposed toxic methylene blue (MB) dye. In conclusion, biologically-reduced TiO2 nanoparticles may prove an effective tool in the fight against microbial illnesses and drug resistance.

Application of nanomaterials as potential quorum quenchers for disease: Recent advances and challenges

Chemical signal molecules are used by bacteria to interact with one another. Small hormone-like molecules known as autoinducers are produced, released, detected, and responded to during chemical communication. Quorum Sensing (QS) is the word for this procedure; it allows bacterial populations to communicate and coordinate group behavior. Several research has been conducted on using inhibitors to prevent QS and minimize the detrimental consequences. Through the enzymatic breakdown of the autoinducer component, by preventing the formation of autoinducers, or by blocking their reception by adding some compounds (inhibitors) that can mimic the autoinducers, a technique known as "quorum quenching" (QQ) disrupts microbial communication. Numerous techniques, including colorimetry, electrochemistry, bioluminescence, chemiluminescence, fluorescence, chromatography-mass spectroscopy, and many more, can be used to test QS/QQ. They all permit quantitative and qualitative measurements of QS/QQ molecules. The mechanism of QS and QQ, as well as the use of QQ in the prevention of biofilms, are all elaborated upon in this writing, along with the fundamental study of nanoparticle (NP)in QQ. Q.

Zingiber officinale rhizome extracts mediated ni nanoparticles and its promising biomedical and environmental applications

BACKGROUND

Zingiber officinale, generally known as ginger, contains bioactive phytochemicals, including gingerols and shogaols, that may function as reducing agents and stabilizers for the formation of nickel nanoparticles (Ni-NPs). Ginger extract-mediated nickel nanoparticles were synthesized using an eco-friendly method, and their antibacterial, antioxidant, antiparasitic, antidiabetic, anticancer, dye degrading, and biocompatibility properties were investigated.

METHODS

UV-visible spectroscopy, fourier transform infrared spectroscopy, X-ray powder diffraction, energy-dispersive X-ray spectroscopy, and scanning electron microscopy were used to validate and characterize the synthesis of Ni-NPs. Agar well diffusion assay, alpha-amylase and glucosidase inhibitory assay, free radical scavenging assay, biocompatibility assay, and MTT assay were used to analyse the biomedical importance of Ni-NPs.

RESULTS

SEM micrograph examinations revealed almost aggregates of Ni-NPs; certain particles were monodispersed and spherical, with an average grain size of 74.85 ± 2.5 nm. Ni-NPs have successfully inhibited the growth of Pseudomonas aeruginosa, Escherichia coli, and Proteus vulgaris by inducing membrane damage, as shown by the absorbance at 260 nm (A260). DPPH (2,2-diphenyl-1-picrylhydrazyl) free radicals were successfully scavenged by Ni-NPs at an inhibition rate of 69.35 ± 0.81% at 800 µg/mL. A dose-dependent cytotoxicity of Ni-NPs was observed against amastigote and promastigote forms of Leishmania tropica, with significant mortality rates of 94.23 ± 1.10 and 92.27 ± 1.20% at 1.0 mg/mL, respectively. Biocompatibility studies revealed the biosafe nature of Ni-NPs by showing RBC hemolysis up to 1.53 ± 0.81% at 400 µg/mL, which is considered safe according to the American Society for Materials and Testing (ASTM). Furthermore, Ni-NPs showed antidiabetic activity by inhibiting α-amylase and α-glucosidase enzymes at an inhibition rate of 22.70 ± 0.16% and 31.23 ± 0.64% at 200 µg/mL, respectively. Ni-NPs have shown significant cytotoxic activity by inhibiting MCF-7 cancerous cells up to 68.82 ± 1.82% at a concentration of 400 µg/mL. The IC50 for Ni-NPs was almost 190 µg/mL. Ni-NPs also degraded crystal violet dye up to 86.1% at 2 h of exposure.

CONCLUSIONS

In conclusion, Zingiber officinale extract was found successful in producing stable nanoparticles. Ni-NPs have shown substantial biomedical activities, and as a result, we believe these nanoparticles have potential as a powerful therapeutic agent for use in nanomedicine.

The bioaccessibility of adsorped heavy metals on biofilm-coated microplastics and their implication for the progression of neurodegenerative diseases

Microplastic (MP) tiny fragments (< 5 mm) of conventional and specialized industrial polymers are persistent and ubiquitous in both aquatic and terrestrial ecosystem. Breathing, ingestion, consumption of food stuffs, potable water, and skin are possible routes of MP exposure that pose potential human health risk. Various microorganisms including bacteria, cyanobacteria, and microalgae rapidly colonized on MP surfaces which initiate biofilm formation. It gradually changed the MP surface chemistry and polymer properties that attract environmental metals. Physicochemical and environmental parameters like polymer type, dissolved organic matter (DOM), pH, salinity, ion concentrations, and microbial community compositions regulate metal adsorption on MP biofilm surface. A set of highly conserved proteins tightly regulates metal uptake, subcellular distribution, storage, and transport to maintain cellular homeostasis. Exposure of metal-MP biofilm can disrupt that cellular homeostasis to induce toxicities. Imbalances in metal concentrations therefore led to neuronal network dysfunction, ROS, mitochondrial damage in diseases like Alzheimer's disease (AD), Parkinson's disease (PD), and Prion disorder. This review focuses on the biofilm development on MP surfaces, factors controlling the growth of MP biofilm which triggered metal accumulation to induce neurotoxicological consequences in human body and stategies to reestablish the homeostasis. Thus, the present study gives a new approach on the health risks of heavy metals associated with MP biofilm in which biofilms trigger metal accumulation and MPs serve as a vector for those accumulated metals causing metal dysbiosis in human body.

Exploring the potential of metal and metal oxide nanomaterials for sustainable water and wastewater treatment: A review of their antimicrobial properties

Metallic nanoparticles (NPs) are of particular interest as antimicrobial agents in water and wastewater treatment due to their broad suppressive range against bacteria, viruses, and fungi commonly found in these environments. This review explores the potential of different types of metallic NPs, including zinc oxide, gold, copper oxide, and titanium oxide, for use as effective antimicrobial agents in water and wastewater treatment. This is due to the fact that metallic NPs possess a broad suppressive range against bacteria, viruses, as well as fungus. In addition to that, NPs are becoming an increasingly popular alternative to antibiotics for treating bacterial infections. Despite the fact that most research has been focused on silver NPs because of the antibacterial qualities that are known to be associated with them, curiosity about other metallic NPs as potential antimicrobial agents has been growing. Zinc oxide, gold, copper oxide, and titanium oxide NPs are included in this category since it has been demonstrated that these elements have antibacterial properties. Inducing oxidative stress, damage to the cellular membranes, and breakdowns throughout the protein and DNA chains are some of the ways that metallic NPs can have an influence on microbial cells. The purpose of this review was to engage in an in-depth conversation about the current state of the art regarding the utilization of the most important categories of metallic NPs that are used as antimicrobial agents. Several approaches for the synthesis of metal-based NPs were reviewed, including physical and chemical methods as well as "green synthesis" approaches, which are synthesis procedures that do not involve the employment of any chemical agents. Moreover, additional pharmacokinetics, physicochemical properties, and the toxicological hazard associated with the application of silver NPs as antimicrobial agents were discussed.

Biomedical Applications of Biosynthesized Nickel Oxide Nanoparticles

Nickel oxide nanoparticles have gained tremendous attention recently in a variety of scientific domains thanks to their characteristic chemical, physical, optical, and biological properties. Due to the diversity of applications in various fields, different physicochemical methods have been used to synthesize nickel oxide nanoparticles. However, most conventional methods use hazardous chemicals during synthesis and become liable for potential health risks, while others are expensive and require a lot of energy to synthesize nanoparticles. As a result, the nanoparticles become less biocompatible and biologically inefficient. Biogenic synthesis of nanoparticles is currently proposed as a valuable alternative to the physical and chemical methods, as it is a simple, non-toxic, cheap, green and facile approach. This synthetic method uses biological substrates such as plant extracts, microorganisms, and other biological products to synthesize nickel oxide nanoparticles. The various phytochemicals from plant extracts, enzymes or proteins from microorganisms, and other biological derivatives play as reducing, stabilizing, and capping agents to provide bioactive and biocompatible nickel oxide nanoscale material. This review discusses current findings and trends in the biogenic synthesis of nickel oxide nanoparticles and their biological activities such as antibacterial, antifungal, antileishmanial, and anticancer, with an emphasis on antimicrobial and anticancer activity along with their mechanistic elucidation. Overall, this thorough study provides insight into the possibilities for the future development of green nickel oxide nanoparticles as therapeutic agents for a variety of ailments.

Eucalyptus globulus Mediated Green Synthesis of Environmentally Benign Metal Based Nanostructures: A Review

The progress in nanotechnology has effectively tackled and overcome numerous global issues, including climate change, environmental contamination, and various lethal diseases. The nanostructures being a vital part of nanotechnology have been synthesized employing different physicochemical methods. However, these methods are expensive, polluting, eco-unfriendly, and produce toxic byproducts. Green chemistry having exceptional attributes, such as cost-effectiveness, non-toxicity, higher stability, environment friendliness, ability to control size and shape, and superior performance, has emerged as a promising alternative to address the drawbacks of conventional approaches. Plant extracts are recognized as the best option for the biosynthesis of nanoparticles due to adherence to the environmentally benign route and sustainability agenda 2030 of the United Nations. In recent decades, phytosynthesized nanoparticles have gained much attention for different scientific applications. Eucalyptus globulus (blue gum) is an evergreen plant belonging to the family Myrtaceae, which is the targeted point of this review article. Herein, we mainly focus on the fabrication of nanoparticles, such as zinc oxide, copper oxide, iron oxide, lanthanum oxide, titanium dioxide, magnesium oxide, lead oxide, nickel oxide, gold, silver, and zirconium oxide, by utilizing Eucalyptus globulus extract and its essential oils. This review article aims to provide an overview of the synthesis, characterization results, and biomedical applications of nanoparticles synthesized using Eucalyptus globulus. The present study will be a better contribution to the readers and the students of environmental research.

Antibiofilm Effect of Biogenic Silver Nanoparticles Combined with Oregano Derivatives against Carbapenem-Resistant Klebsiella pneumoniae

Resistant bacteria may kill more people than COVID-19, so the development of new antibacterials is essential, especially against microbial biofilms that are reservoirs of resistant cells. Silver nanoparticles (bioAgNP), biogenically synthesized using Fusarium oxysporum, combined with oregano derivatives, present a strategic antibacterial mechanism and prevent the emergence of resistance against planktonic microorganisms. Antibiofilm activity of four binary combinations was tested against enteroaggregative Escherichia coli (EAEC) and Klebsiella pneumoniae carbapenemase-producing K. pneumoniae (KPC): oregano essential oil (OEO) plus bioAgNP, carvacrol (Car) plus bioAgNP, thymol (Thy) plus bioAgNP, and Car plus Thy. The antibiofilm effect was accessed using crystal violet, MTT, scanning electron microscopy, and Chromobacterium violaceum anti-quorum-sensing assays. All binary combinations acted against preformed biofilm and prevented its formation; they showed improved antibiofilm activity compared to antimicrobials individually by reducing sessile minimal inhibitory concentration up to 87.5% or further decreasing biofilm metabolic activity and total biomass. Thy plus bioAgNP extensively inhibited the growth of biofilm in polystyrene and glass surfaces, disrupted three-dimensional biofilm structure, and quorum-sensing inhibition may be involved in its antibiofilm activity. For the first time, it is shown that bioAgNP combined with oregano has antibiofilm effect against bacteria for which antimicrobials are urgently needed, such as KPC.

Future of Nanotechnology in Food Industry: Challenges in Processing, Packaging, and Food Safety

Over the course of the last several decades, nanotechnology has garnered a growing amount of attention as a potentially valuable technology that has significantly impacted the food industry. Nanotechnology helps in enhancing the properties of materials and structures that are used in various fields such as agriculture, food, pharmacy, and so on. Applications of nanotechnology in the food market have included the encapsulation and distribution of materials to specific locations, the improvement of flavor, the introduction of antibacterial nanoparticles into food, the betterment of prolonged storage, the detection of pollutants, enhanced storage facilities, locating, identifying, as well as consumer awareness. Labeling food goods with nano barcodes helps ensure their security and may also be used to track their distribution. This review article presents a discussion about current advances in nanotechnology along with its applications in the field of food-tech, food packaging, food security, enhancing life of food products, etc. A detailed description is provided about various synthesis routes of nanomaterials, that is, chemical, physical, and biological methods. Nanotechnology is a rapidly improving the field of food packaging and the future holds great opportunities for more enhancement via the development of new nanomaterials and nanosensors.

Catalytic and antimicrobial potential of green synthesized Au and Au@Ag core-shell nanoparticles

It has been a never-ending quest to design a safe, cost-effective, and environmentally acceptable technology for eliminating contaminants from water and countering antibiotic resistance. Herein, a waste leaf extract from the abundant and renewable plant, Brassica oleracea var. gongylodes, is introduced as a cost-effective and sustainable means to generate gold (Au) and Au@Ag core-shell nanoparticles (NPs). In comparison to the bare Au NPs, bimetallic NPs demonstrated improved catalytic and antibacterial capabilities. The reduction process conforms to the pseudo-first-order kinetic, and apparent rate constant (k_app) was calculated to be 0.46 min^-1, according to the kinetic analysis. With both microbial pathogens, E. coli (Gram-negative) and B. subtilis (Gram-positive), an increment of Au and Au@Ag NPs lead to a considerable improvement in the zone of clearance. The present outcome is a step forward in the establishment of a viable and cost-effective catalytic and antibacterial platform based on bimetallic NPs that could be generated in an inexpensive and eco-friendly manner.

Effect of Mo doping in NiO nanoparticles for structural modification and its efficiency for antioxidant, antibacterial applications

Novel molybdenum (Mo)-doped nickel oxide (NiO) Nanoparticles (NPs) were synthesized by using a simple sonochemical methodology and the synthesized NPs were investigated for antioxidant, and antibacterial applications. The X-ray diffraction (XRD) analysis revealed that the crystal systems of rhombohedral (21.34 nm) and monoclinic (17.76 nm) were observed for pure NiO and Mo-doped NiO NPs respectively. The scanning electron microscopy (SEM) results show that the pure NiO NPs possess irregular spherical shape with an average particle size of 93.89 nm while the Mo-doped NiO NPs exhibit spherical morphology with an average particle size of 85.48 nm. The ultraviolet-visible (UV-Vis) spectrum further indicated that the pure and Mo-doped NiO NPs exhibited strong absorption band at the wavelengths of 365 and 349 nm, respectively. The free radical scavenging activity of NiO and Mo-doped NiO NPs was also investigated by utilizing several biochemical assays. The Mo-doped NiO NPs showed better antioxidant activity (84.2%) towards ABTS. + at 200 µg/mL in comparison to their pure counterpart which confirmed that not only antioxidant potency of the doped NPs was better than pure NPs but this efficacy was also concentration dependant as well. The NiO and Mo-doped NiO NPs were further evaluated for their antibacterial activity against gram-positive (Staphylococcus aureus and Bacillus subtilis) and gram-negative (Pseudomonas aeruginosa and Escherichia coli) bacterial strains. The Mo-doped NiO NPs displayed better antibacterial activity (25 mm) against E. coli in comparison to the pure NPs. The synthesized NPs exhibited excellent aptitude for multi-dimensional applications.

Phyto-interactive impact of green synthesized iron oxide nanoparticles and Rhizobium pusense on morpho-physiological and yield components of greengram

The iron oxide nanoparticles (IONPs) prepared by green synthesis method using Syzigium cumini leaf extract was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The XRD confirmed the crystalline structure of green synthesized NPs measuring around 33 nm while SEM revealed its nearly spherical shape. Rhizobium species recovered from greengram nodules, identified by 16s rRNA gene sequencing as Rhizobium pusense produced 30% more exopolysaccharides (EPS) in basal medium treated with 1000 μg IONPs/ml. Compositional variation in EPS was observed by Fourier-transform infrared spectroscopy (FTIR). There was no reduction in rhizobial viability and no damage to bacterial membrane was observed under SEM and confocal laser scanning microscopy (CLSM), respectively. Effects of IONPs and R. pusense, used alone and in combination on the growth and development of greengram plants varied considerably. Plants grown with IONPs and R. pusence, used alone and in combination, showed a significant increase in seed germination rate, length and dry biomass of plant organs and seed components compared to controls. The IONPs in the presence of rhizobial strain further increased seed germination, plant growth, seed protein and pigments. Greater protein content (442 mg/g) was observed in seeds at 250 mg/kg of IONPs compared to control. Plants raised with mixture of IONPs plus R. pusense had maximum chlorophyll content (39.2 mg/g FW) while proline content decreased by 53% relative to controls. This study confirms that the green synthesis of IONPs from S. cumini leaf possess useful plant growth promoting effects and could be developed as a nano-biofertilizer for optimizing legume production.

Metal nanoparticles produced by plants with antibacterial properties against Staphylococcus aureus

Staphylococcus aureus (S. aureus) is a pathogenic bacteria that causes a variety of potentially fatal infections. The emergence of antibiotic-resistant strains of S. aureus has made treatment even more difficult. In recent years, nanoparticles have been used as an alternative therapeutic agent for S. aureus infections. Among various methods for the synthesis of nanoparticles, the method utilizing plant extracts from different parts of a plant, such as root, stem, leaf, flower, seeds, etc. is gaining widespread usage. Phytochemicals present in plant extract are an inexpensive, eco-friendly, natural material that act as reducing and stabilization agent for the nanoparticle synthesis. The utilization of plant-fabricated nanoparticles against S. aureus is currently in trend. The current review discusses recent findings in the therapeutic application of phytofabricated metal-based nanoparticles against Staphylococcus aureus.

Facile Green Synthesis of Ni(OH)2@Mn3O4 Cactus-Type Nanocomposite: Characterization and Cytotoxicity Properties

In the present work, the facile eco-friendly synthesis and evaluation of the anti-tumor activity of Ni(OH)₂@Mn₃O₄ nanocomposite were carried out. The synthesis of Ni(OH)₂@Mn₃O₄ nanocomposite from chia-seed extract was mediated by sonication. The obtained materials were characterized by different spectroscopic techniques such as transmission electron microscopy (TEM), scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), ultraviolet-visible (UV-Vis), and Fourier transform infrared (FT-IR) spectroscopies. The results of XRD, SEM, EDS, TEM, FT-IR, and UV-Vis analysis indicate the successful manufacturing of a crystalline, cactus-type Ni(OH)₂@Mn₃O₄ nanocomposite of 10.10 nm average particle size. XPS analysis confirms that the synthesized materials consist mainly of Ni²⁺, Mn²⁺, and Mn³⁺. The antitumor activity of the nanocomposite was tested against a breast cancer (MCF-7) cell line. The results showed Ni(OH)₂@Mn₃O₄ nanocomposite possesses insignificant cytotoxicity. The cell-death percentage was 34% at a 100 ppm concentration of Ni(OH)₂@Mn₃O₄ nanocomposite. The obtained results imply that the synthesized nanocomposite could be suitable and safe for drug delivery and water treatment.

Antibacterial activity of nano zinc oxide green-synthesised from Gardenia thailandica triveng. Leaves against Pseudomonas aeruginosa clinical isolates: in vitro and in vivo study

The increasing emergence of bacterial resistance is a challenge for the research community, thus novel antibacterial agents should be developed. Metal nanoparticles are promising antibacterial agents and could solve the problem of antibiotic resistance. Herein, we used Gardenia thailandica methanol extract (GTME) to biogenically synthesise zinc oxide nanoparticles (ZnO-NPs). The characterisation of ZnO-NPs was performed by UV spectroscopy, FTIR, scanning and transmission electron microscopes, dynamic light scattering, and X-ray diffraction. The antibacterial activity of ZnO-NPs was studied both in vitro and in vivo against Pseudomonas aeruginosa clinical isolates. Its minimum inhibitory concentration values ranged from 2 to 64 µg/mL, and it significantly decreased the membrane integrity and resulted in a significant increase in the inner and outer membrane permeability. Also, the ZnO-NPs treated cells possessed a distorted and deformed shape when examined by scanning electron microscope. The in vivo study (biochemical parameters and histological investigation) was conducted and it revealed a protective effect of ZnO-NPs against the deleterious influences of P. aeruginosa bacteria on lung, liver, and kidney tissues. LC-ESI-MS/MS revealed a phytochemical tentative identification of 57 compounds for the first time. We propose that GTME is a useful source for ZnO-NPs which has a promising antibacterial activity.

Nickel Nanoparticles: Applications and Antimicrobial Role against Methicillin-Resistant Staphylococcus aureus Infections

Methicillin-resistant Staphylococcus aureus (MRSA) has evolved vast antibiotic resistance. These strains contain numerous virulence factors facilitating the development of severe infections. Considering the costs, side effects, and time duration needed for the synthesis of novel drugs, seeking efficient alternative approaches for the eradication of drug-resistant bacterial agents seems to be an unmet requirement. Nickel nanoparticles (NiNPs) have been applied as prognostic and therapeutic cheap agents to various aspects of biomedical sciences. Their antibacterial effects are exerted via the disruption of the cell membrane, the deformation of proteins, and the inhibition of DNA replication. NiNPs proper traits include high-level chemical stability and binding affinity, ferromagnetic properties, ecofriendliness, and cost-effectiveness. They have outlined pleomorphic and cubic structures. The combined application of NiNPs with CuO, ZnO, and CdO has enhanced their anti-MRSA effects. The NiNPs at an approximate size of around 50 nm have exerted efficient anti-MRSA effects, particularly at higher concentrations. NiNPs have conferred higher antibacterial effects against MRSA than other nosocomial bacterial pathogens. The application of green synthesis and low-cost materials such as albumin and chitosan enhance the efficacy of NPs for therapeutic purposes.

Rhamnolipid-Coated Iron Oxide Nanoparticles as a Novel Multitarget Candidate against Major Foodborne E. coli Serotypes and Methicillin-Resistant S. aureus

Surface-growing antibiotic-resistant pathogenic bacteria such as Escherichia coli and Staphylococcus aureus are emerging as a global health challenge due to dilemmas in clinical treatment. Furthermore, their pathogenesis, including increasingly serious antimicrobial resistance and biofilm formation, makes them challenging to treat by conventional therapy. Therefore, the development of novel antivirulence strategies will undoubtedly provide a path forward in combatting these resistant bacterial infections. In this regard, we developed novel biosurfactant-coated nanoparticles to combine the antiadhesive/antibiofilm properties of rhamnolipid (RHL)-coated Fe3O4 nanoparticles (NPs) with each of the p-coumaric acid (p-CoA) and gallic acid (GA) antimicrobial drugs by using the most available polymer common coatings (PVA) to expand the range of effective antibacterial drugs, as well as a mechanism for their synergistic effect via a simple method of preparation. Mechanistically, the average size of bare Fe3O4 NPs was ~15 nm, while RHL-coated Fe3O4@PVA@p-CoA/GA was about ~254 nm, with a drop in zeta potential from -18.7 mV to -34.3 mV, which helped increase stability. Our data show that RHL-Fe3O4@PVA@p-CoA/GA biosurfactant NPs can remarkably interfere with bacterial growth and significantly inhibited biofilm formation to more than 50% via downregulating IcaABCD and CsgBAC operons, which are responsible for slime layer formation and curli fimbriae production in S. aureus and E. coli, respectively. The novelty regarding the activity of RHL-Fe3O4@PVA@p-CoA/GA biosurfactant NPs reveals their potential effect as an alternative multitarget antivirulence candidate to minimize infection severity by inhibiting biofilm development. Therefore, they could be used in antibacterial coatings and wound dressings in the future. IMPORTANCE Antimicrobial resistance poses a great threat and challenge to humanity. Therefore, the search for alternative ways to target and eliminate microbes from plant, animal, and marine microorganisms is one of the world's concerns today. Furthermore, the extraordinary capacity of S. aureus and E. coli to resist standard antibacterial drugs is the dilemma of all currently used remedies. Methicillin-resistant S. aureus (MRSA) and vancomycin-resistant S. aureus (VRSA) have become widespread, leading to no remedies being able to treat these threatening pathogens. The most widely recognized serotypes that cause severe foodborne illness are E. coli O157:H7, O26:H11, and O78:H10, and they display increasing antimicrobial resistance rates. Therefore, there is an urgent need for an effective therapy that has dual action to inhibit biofilm formation and decrease bacterial growth. In this study, the synthesized RHL-Fe3O4@PVA@p-CoA/GA biosurfactant NPs have interesting properties, making them excellent candidates for targeted drug delivery by inhibiting bacterial growth and downregulating biofilm-associated IcaABCD and CsgBAC gene loci.

Recent advances in biobased and biodegradable polymer nanocomposites, nanoparticles, and natural antioxidants for antibacterial and antioxidant food packaging applications

Inorganic nanoparticles (NPs) and natural antioxidant compounds are an emerging trend in the food industry. Incorporating these substances in biobased and biodegradable matrices as polysaccharides (e.g., starch, cellulose, and chitosan) and proteins has highlighted the potential in active food packaging applications due to more significant antimicrobial, antioxidant, UV blocking, oxygen scavenging, water vapor permeability effects, and low environmental impact. In recent years, the migration of metal NPs and metal oxides in food contact packaging and their toxicological potential have raised concerns about the safety of the nanomaterials. In this review, we provide a comprehensive overview of the main biobased and biodegradable polymer nanocomposites, inorganic NPs, natural antioxidants, and their potential use in active food packaging. The intrinsic properties of NPs and natural antioxidant actives in packaging materials are evaluated to extend shelf-life, safety, and food quality. Toxicological and safety aspects of inorganic NPs are highlighted to understand the current controversy on applying some nanomaterials in food packaging. The synergism of inorganic NPs and plant-derived natural antioxidant actives (e.g., vitamins, polyphenols, and carotenoids) and essential oils (EOs) potentiated the antibacterial and antioxidant properties of biodegradable nanocomposite films. Biodegradable packaging films based on green NPs-this is biosynthesized from plant extracts-showed suitable mechanical and barrier properties and had a lower environmental impact and offered efficient food protection. Furthermore, AgNPs and TiO₂ NPs released metal ions from packaging into contents insufficiently to cause harm to human cells, which could be helpful to understanding critical gaps and provide progress in the packaging field.

Sonochemical-Assisted Biogenic Synthesis of Theophrasite β-Ni(OH)2 Nanocluster Using Chia Seeds Extract: Characterization and Anticancer Activity

Theophrasite β-Ni(OH)₂ nanocluster were fabricated via the sonochemical-assisted biogenic method using chia seeds extract as a reducing and stabilizing agent. The optical and morphological feature of the synthesized nanocluster was characterized using UV-Vis, FTIR, FE-SEM-EDS, HR-TEM, DLS, XPS, and XRD analysis. According to FE-SEM and HR-TEM images of the synthesized materials, β-Ni(OH)₂ nanocluster illustrates the hexagonal particle shape with an average size of 5.8 nm, while the EDS results confirm the high purity of the synthesized nanocluster. Moreover, the XRD pattern of the synthesized materials shows typical peaks that match the reference pattern of the Theophrasite form of β-Ni(OH)₂ with a hexagonal crystal system. The XPS analysis illustrates that the prepared samples exhibit both Ni²⁺ and Ni³⁺ with the predominance of Ni²⁺ species. Additionally the in-vitro cytotoxic activity of β-Ni(OH)₂ nanocluster is tested against the MCF7 cell lines (breast cancer cells). The MTT assay results proved that the synthesized β-Ni(OH)₂ nanocluster has potent cytotoxic activity against breast cancer cell lines (IC₅₀: 62.7 μg/mL).

In vitro embryotoxicity and mode of antibacterial mechanistic study of gold and copper nanoparticles synthesized from Angelica keiskei (Miq.) Koidz. leaves extract

The present study demonstrated the in vitro embryotoxicity assessment of gold nanoparticles (AuNPs) and copper nanoparticles (CuNPs) prepared from the leaves extract of Angelica keiskei (Miq.) Koidz. and addressed their mode of antibacterial mechanisms. Both AuNPs and CuNPs were rapidly synthesized and the formations were observed within 1 h and 24 h, respectively. Further the morphological images of the nanoparticles were confirmed through transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM). The high-resolution X-ray diffraction (HR-XRD) analysis of the biosynthesized AuNPs and CuNPs were matched with joint committee on powder diffraction standards (JCPDS) file no of 04-0784 and 89-5899, respectively. A strong prominent Au and Cu signals were observed through energy dispersive spectroscopy (EDS) analysis. Fourier transform infrared spectroscopy (FT-IR) analysis confirmed the responsible phytochemicals for the synthesis of AuNPs and CuNPs. In order to assess the toxic effects of AuNPs and CuNPs, bactericidal activity was performed against few of the test pathogens in which the effective inhibition was observed against Gram-negative bacteria than the Gram-positive bacteria. The mode of action and interaction of nanoparticles were performed on the bacterial pathogens and the results concluded that the interaction of nanoparticles initially initiated on the surface of the cell wall adherence followed by ruptured the cells and caused the cell death. In addition to the antibacterial activity, in vitro embryotoxicity studies were performed against zebrafish embryos and the results confirmed that 200 µg/ml concentration of AuNPs showed the embryotoxicity, whereas 2 µg/ml of CuNPs resulted the embryotoxicity. Furthermore, the morphological anomalies of zebrafish embryos revealed the toxic nature of the synthesized nanoparticles.

Recent Advances and Mechanistic Insights into Antibacterial Activity, Antibiofilm Activity, and Cytotoxicity of Silver Nanoparticles

The substantial increase in multidrug-resistant (MDR) pathogenic bacteria is a major threat to global health. Recently, the Centers for Disease Control and Prevention reported possibilities of greater deaths due to bacterial infections than cancer. Nanomaterials, especially small-sized (size ≤10 nm) silver nanoparticles (AgNPs), can be employed to combat these deadly bacterial diseases. However, high reactivity, instability, susceptibility to fast oxidation, and cytotoxicity remain crucial shortcomings for their uptake and clinical application. In this review, we discuss various AgNPs-based approaches to eradicate bacterial infections and provide comprehensive mechanistic insights and recent advances in antibacterial activity, antibiofilm activity, and cytotoxicity (both in vitro and in vivo) of AgNPs. The mechanistic of antimicrobial activity involves four steps: (i) adhesion of AgNPs to cell wall/membrane and its disruption; (ii) intracellular penetration and damage; (iii) oxidative stress; and (iv) modulation of signal transduction pathways. Numerous factors affecting the bactericidal activity of AgNPs such as shape, size, crystallinity, pH, and surface coating/charge have also been described in detail. The review also sheds light on antimicrobial photodynamic therapy and the role of AgNPs versus Ag⁺ ions release in bactericidal activities. In addition, different methods of synthesis of AgNPs have been discussed in brief.

Nano-Antibacterials Using Medicinal Plant Components: An Overview

Gradual emergence of new bacterial strains, resistant to one or more antibiotics, necessitates development of new antibacterials to prevent us from newly evolved disease-causing, drug-resistant, pathogenic bacteria. Different inorganic and organic compounds have been synthesized as antibacterials, but with the problem of toxicity. Other alternatives of using green products, i.e., the medicinal plant extracts with biocompatible and potent antibacterial characteristics, also had limitation because of their low aqueous solubility and therefore less bioavailability. Use of nanotechnological strategy appears to be a savior, where phytochemicals are nanonized through encapsulation or entrapment within inorganic or organic hydrophilic capping agents. Nanonization of such products not only makes them water soluble but also helps to attain high surface to volume ratio and therefore high reaction area of the nanonized products with better therapeutic potential, over that of the equivalent amount of raw bulk products. Medicinal plant extracts, whose prime components are flavonoids, alkaloids, terpenoids, polyphenolic compounds, and essential oils, are in one hand nanonized (capped and stabilized) by polymers, lipids, or clay materials for developing nanodrugs; on the other hand, high antioxidant activity of those plant extracts is also used to reduce various metal salts to produce metallic nanoparticles. In this review, five medicinal plants, viz., tulsi (Ocimum sanctum), turmeric (Curcuma longa), aloe vera (Aloe vera), oregano (Oregano vulgare), and eucalyptus (Eucalyptus globulus), with promising antibacterial potential and the nanoformulations associated with the plants' crude extracts and their respective major components (eugenol, curcumin, anthraquinone, carvacrol, eucalyptus oil) have been discussed with respect to their antibacterial potency.

Versatile polymer-based strategies for antibacterial drug delivery systems and antibacterial coatings

Human health damage and economic losses due to bacterial infections are very serious worldwide. Excessive use of antibiotics has caused an increase in bacterial resistance. Fortunately, various non-antibiotic antibacterial materials...

Past and Current Progress in the Development of Antiviral/Antimicrobial Polymer Coating towards COVID-19 Prevention: A Review

The astonishing outbreak of SARS-CoV-2 coronavirus, known as COVID-19, has attracted numerous research interests, particularly regarding fabricating antimicrobial surface coatings. This initiative is aimed at overcoming and minimizing viral and bacterial transmission to the human. When contaminated droplets from an infected individual land onto common surfaces, SARS-CoV-2 coronavirus is able to survive on various surfaces for up to 9 days. Thus, the possibility of virus transmission increases after touching or being in contact with contaminated surfaces. Herein, we aim to provide overviews of various types of antiviral and antimicrobial coating agents, such as antimicrobial polymer-based coating, metal-based coating, functional nanomaterial, and nanocomposite-based coating. The action mode for each type of antimicrobial agent against pathogens is elaborated. In addition, surface properties of the designed antiviral and antimicrobial polymer coating with their influencing factors are discussed in this review. This paper also exhibits several techniques on surface modification to improve surface properties. Various developed research on the development of antiviral/antimicrobial polymer coating to curb the COVID-19 pandemic are also presented in this review.

Ecofriendly and low-cost synthesis of ZnO nanoparticles from Acremonium potronii for the photocatalytic degradation of azo dyes

Nanoparticles (NPs) have enormous applications in every field of science by their particular size, diverse morphology, and higher surface-ratio, which provide them for unique properties. Nanosized materials can be used to overcome almost every challenge in science. The development of nanoscience, metal or metal oxide NPs have emerged as promising materials. Especially, zinc oxide nanoparticles (ZnO NPs) have remarkable applications in diverse fields including cosmetic, optical, and electrical fields, biomedicine, and catalysis. Several cost-effective strategies using different chemicals, plants, and microbes mediated ZnO NPs are reported in several studies, among which fungal-mediated approaches have gained tremendous interest due to their eco-friendly and simple protocols. In this study, we report the formation of ZnO NPs with sizes ranging between 13 and 15 nm using Acremonium potronii, a new fungal species found in fruits, soil, and marine environments. The obtained ZnO NPs are characterized by several analytical techniques, and their catalytic activity in the degradation of methylene blue dye is investigated, including a kinetic study to investigate the rate of degradation process. The ZnO NPs can degrade about 93% of the dye. This work demonstrates the potential of the synthesized ZnO NPs as dye removal catalysts and offers a platform for the application of A. potronii.

Phyto-fabricated Nanoparticles and Their Anti-biofilm Activity: Progress and Current Status

Biofilm is the self-synthesized, mucus-like extracellular polymeric matrix that acts as a key virulence factor in various pathogenic microorganisms, thereby posing a serious threat to human health. It has been estimated that around 80% of hospital-acquired infections are associated with biofilms which are found to be present on both biotic and abiotic surfaces. Antibiotics, the current mainstream treatment strategy for biofilms are often found to be futile in the eradication of these complex structures, and to date, there is no effective therapeutic strategy established against biofilm infections. In this regard, nanotechnology can provide a potential platform for the alleviation of this problem owing to its unique size-dependent properties. Accordingly, various novel strategies are being developed for the synthesis of different types of nanoparticles. Bio-nanotechnology is a division of nanotechnology which is gaining significant attention due to its ability to synthesize nanoparticles of various compositions and sizes using biotic sources. It utilizes the rich biodiversity of various biological components which are biocompatible for the synthesis of nanoparticles. Additionally, the biogenic nanoparticles are eco-friendly, cost-effective, and relatively less toxic when compared to chemically or physically synthesized alternatives. Biogenic synthesis of nanoparticles is a bottom-top methodology in which the nanoparticles are formed due to the presence of biological components (plant extract and microbial enzymes) which act as stabilizing and reducing agents. These biosynthesized nanoparticles exhibit anti-biofilm activity via various mechanisms such as ROS production, inhibiting quorum sensing, inhibiting EPS production, etc. This review will provide an insight into the application of various biogenic sources for nanoparticle synthesis. Furthermore, we have highlighted the potential of phytosynthesized nanoparticles as a promising antibiofilm agent as well as elucidated their antibacterial and antibiofilm mechanism.

Titanium Dioxide Nanoparticles Induce Inhibitory Effects against Planktonic Cells and Biofilms of Human Oral Cavity Isolates of Rothia mucilaginosa, Georgenia sp. and Staphylococcus saprophyticus

Multi-drug resistant (MDR) bacterial cells embedded in biofilm matrices can lead to the development of chronic cariogenesis. Here, we isolated and identified three Gram-positive MDR oral cocci, (1) SJM-04, (2) SJM-38, and (3) SJM-65, and characterized them morphologically, biochemically, and by 16S rRNA gene-based phylogenetic analysis as Georgenia sp., Staphylococcus saprophyticus, and Rothia mucilaginosa, respectively. These three oral isolates exhibited antibiotic-resistance against nalidixic acid, tetracycline, cefuroxime, methicillin, and ceftazidime. Furthermore, these Gram positive MDR oral cocci showed significant (p < 0.05) variations in their biofilm forming ability under different physicochemical conditions, that is, at temperatures of 28, 30, and 42 °C, pH of 6.4, 7.4, and 8.4, and NaCl concentrations from 200 to 1000 µg/mL. Exposure of oral isolates to TiO2NPs (14.7 nm) significantly (p < 0.05) reduced planktonic cell viability and biofilm formation in a concentration-dependent manner, which was confirmed by observing biofilm architecture by scanning electron microscopy (SEM) and optical microscopy. Overall, these results have important implications for the use of tetragonal anatase phase TiO2NPs (size range 5-25 nm, crystalline size 13.7 nm, and spherical shape) as an oral antibiofilm agent against Gram positive cocci infections. We suggest that TiO2NPs pave the way for further applications in oral mouthwash formulations and antibiofilm dental coatings.

The fate and long-term toxic effects of NiO nanoparticles at environmental concentration in constructed wetland: Enzyme activity, microbial property, metabolic pathway and functional genes

Although the potential threats of metallic oxide nanoparticles (MNPs) to constructed wetland (CW) have been broadly reported, limited information is available regarding the long-term impact of nickel oxide nanoparticles (NiO NPs) on CWs at the environmentally relevant concentrations. Here, we comprehensively elucidated the responses in the treatment performance, enzyme activities, microbial properties, metabolic pathways and functional genes of CWs to chronic exposure of NiO NPs (0.1 and 1 mg/L) for 120 days, with a quantitative analysis on the fate and migration of NiO NPs within CWs. Nitrogen removal evidently declined under the long-term exposure to NiO NPs. Besides, NiO NPs induced a deterioration in phosphorus removal, but gradually restored over time. The activities of dehydrogenase (DHA), phosphatase (PST), urease (URE), ammonia oxygenase (AMO) and nitrate reductase (NAR) were inhibited to some extent under NiO NPs stress. Furthermore, NiO NPs exposure reduced bacterial diversity, shifted microbial composition and obviously inhibited the transcription of the ammonia oxidizing and denitrifying functional genes. The results of nickel mass balance indicated that the major removal mechanism of NiO NPs in CWs was through substrate adsorption and plants uptake. Thus, the ecological impacts of prolonged NiO NPs exposure at environmental concentrations should not be neglected.

Impact of Bi Doping into Boron Nitride Nanosheets on Electronic and Optical Properties Using Theoretical Calculations and Experiments

In the present work, boron nitride (BN) nanosheets were prepared through bulk BN liquid phase exfoliation while various wt. ratios (2.5, 5, 7.5 and 10) of bismuth (Bi) were incorporated as dopant using hydrothermal technique. Our findings exhibit that the optical investigation showed absorption spectra in near UV region. Density functional theory calculations indicate that Bi doping has led to various modifications in the electronic structures of BN nanosheet by inducing new localized gap states around the Fermi level. It was found that bandgap energy decrease with the increase of Bi dopant concentrations. Therefore, in analysis of the calculated absorption spectra, a redshift has been observed in the absorption edges, which is consistent with the experimental observation. Additionally, host and Bi-doped BN nanosheets were assessed for their catalytic and antibacterial potential. Catalytic activity of doped free and doped BN nanosheets was evaluated by assessing their performance in dye reduction/degradation process. Bactericidal activity of Bi-doped BN nanosheets resulted in enhanced efficiency measured at 0-33.8% and 43.4-60% against S. aureus and 0-38.8% and 50.5-85.8% against E. coli, respectively. Furthermore, In silico molecular docking predictions were in good agreement with in-vitro bactericidal activity. Bi-doped BN nanosheets showed good binding score against DHFR of E. coli (- 11.971 kcal/mol) and S. aureus (- 8.526 kcal/mol) while binding score for DNA gyrase from E. coli (- 6.782 kcal/mol) and S. aureus (- 7.819 kcal/mol) suggested these selected enzymes as possible target.