Metal Nanoparticles as Novel Antifungal Agents for Sustainable Agriculture: Current Advances and Future Directions

Mercaptoimidazole-capped gold nanoparticles as a potent agent against plant pathogenic fungi

Plant pathogenic fungi pose a substantial challenge to agricultural production, but the conventional fungicide-based approaches are losing importance. As agents with broad-spectrum antibacterial effects, gold nanoparticles (Au NPs) are found to have antifungal effects; however, no study has examined their application in agriculture as fungicides. Accordingly, this study investigates the activity of 2-mercaptoimidazole-capped Au NPs (MI-Au NPs) against the 'top' plant pathogenic fungi, finding that they could inhibit Magnaporthe oryzae, Botrytis cinerea, Fusarium pseudograminearum and Colletotrichum destructivum by inducing cytoplasmic leakage. Moreover, MI-Au NPs are found to protect plants from infection by B. cinerea. Specifically, pot experiments demonstrate that MI-Au NPs decrease the incidence rate of B. cinerea infection in Arabidopsis thaliana from 74.6% to 6.2% and in Solanum lycopersicum from 100% to 10.9%, outperforming those achieved by imazalil. Furthermore, the biosafety assays reveal that MI-Au NPs cannot penetrate the cuticle of plant cells or negatively influence plant growth, and it is safe to mammalian cells. In summary, the findings of this study will support the development of NP-based antifungal agents for use in agriculture.

Advancements in the nanodelivery of azole-based fungicides to control oil palm pathogenic fungi

The cultivation of oil palms is of great importance in the global agricultural industry due to its role as a primary source of vegetable oil with a wide range of applications. However, the sustainability of this industry is threatened by the presence of pathogenic fungi, particularly Ganoderma spp., which cause detrimental oil palm disease known as basal stem rot (BSR). This unfavorable condition eventually leads to significant productivity losses in the harvest, with reported yield reductions of 50-80 % in severely affected plantations. Azole-based fungicides offer potential solutions to control BSR, but their efficacy is hampered by limited solubility, penetration, distribution, and bioavailability. Recent advances in nanotechnology have paved the way for the development of nanosized delivery systems. These systems enable effective fungicide delivery to target pathogens and enhance the bioavailability of azole fungicides while minimising environmental and human health risks. In field trials, the application of azole-based nanofungicides resulted in up to 75 % reduction in disease incidence compared to conventional fungicide treatments. These innovations offer opportunities for the development of sustainable agricultural practices. This review highlights the importance of oil palm cultivation concerning the ongoing challenges posed by pathogenic fungi and examines the potential of azole-based fungicides for disease control. It also reviews recent advances in nanotechnology for fungicide delivery, explores the mechanisms behind these nanodelivery systems, and emphasises the opportunities and challenges associated with azole-based nanofungicides. Hence, this review provides valuable insights for future nanofungicide development in effective oil palm disease control.

Nanomaterials for Plant Disease Diagnosis and Treatment: A Review

Currently, the excessive use of pesticides has generated environmental pollution and harmful effects on human health. The controlled release of active ingredients through the use of nanomaterials (NMs) appears to reduce human exposure and ecosystem alteration. Although the use of NMs can offer an alternative to traditional methods of disease diagnosis and control, it is necessary to review the current approach to the application of these NMs. This review describes the most recent and significant advances in using NMs for diagnosing and treating plant diseases (bacteria, phytopathogenic fungi, viruses, and phytopathogenic nematodes) in cultivated plants. Most studies have focused on reducing, delaying, or eliminating bacteria, fungi, viruses, and nematodes in plants. Both metallic (including metal oxides) and organic nanoparticles (NPs) and composites are widely used in diagnosing and controlling plant diseases due to their biocompatibility and ease of synthesis. Few studies have been carried out with regard to carbon-based NPs due to their toxicity, so future studies should address the development of detection tools, ecological and economic impacts, and human health. The synergistic effect of NMs as fertilizers and pesticides opens new areas of knowledge on the mechanisms of action (plant-pathogen-NMs interaction), the interaction of NMs with nutrients, the effects on plant metabolism, and the traceability of NMs to implement sustainable approaches. More studies are needed involving in vivo models under international regulations to ensure their safety. There is still controversy in the release of NMs into the environment because they could threaten the stability and functioning of biological systems, so research in this area needs to be improved.

Potential antifungal applications of heterometallic silica nanohybrids: A synergistic activity

An estimated 1.7 million fatalities and 150 million cases worldwide are attributed to fungal infections annually, that are in rise due to immunocompromised patient population. The challenges posed by traditional treatments can be addressed with the help of nanotechnology advancements. In this study, Co, Cu, and Ag-were doped into silica nanoparticles. Then the synthesized monometallic silica nanohybrids were combined to formulate heterometallic silica nanohybrids, characterized structurally and morphologically, compared, and evaluated for antifungal activity based on their individual and synergistic activity. The antifungal assays were conducted by using ATCC cultures of Candida albicans and QC samples of Trichophyton rubrum, Microsporum gypseum, and Aspergillus niger. The MIC (ranging from 49.00 to 1560.00 μg/mL), MFC (ranging from 197.00 to 3125.00 μg/mL), IC50 values (ranging from 31.10 to 400.80 μg/mL), and FICI of nanohybrids were determined and compared. Moreover, well diffusion assay was performed. ABTS assay and DPPH assay were conducted to investigate the radical scavenging activity (RSA) of nanohybrids. SEM analysis clearly evidenced the structural deformations of each fungal cells and spores due to the treatment with trimetallic nanohybrid. According to the results, the trimetallic silica nanohybrids exhibited the most powerful synergistic RSA and the most effective antifungal activity, compared to the bimetallic silica nanohybrids.

Polygonum bistorta Linn. as a green source for synthesis of biocompatible selenium nanoparticles with potent antimicrobial and antioxidant properties

Here, we report for the first time, green-synthesized selenium nanoparticles (SeNPs) using pharmacologically potent herb of Polygonum bistorta Linn. for multiple biomedical applications. In the study, a facile and an eco-friendly approach is utilized for synthesis of SeNPs using an aqueous roots extract of P. bistorta Linn. followed by extensive characterization via Fourier transform infrared spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Energy Dispersive X-Ray (EDX) analysis. The XRD and FTIR data determine the phase composition and successful capping of plant extract onto the surface of NPs while SEM and TEM micrographic examination reveals the elliptical and spherical morphology of the particles with a mean size of 69 ± 23 nm. After comprehensive characterization, the NPs are investigated for antifungal, antibacterial, antileishmanial, antioxidant, and biocompatibility properties. The study reveals that Polygonum bistorta Linn. synthesized SeNPs exhibit significant antibacterial and antifungal activities with Staphylococcus aureus and Fusarium oxysporum inducing the highest zone of inhibition of 14 ± 1.0 mm and 20 ± 1.2 mm, respectively at the concentration of 40 mg/mL. The NPs are also found to have antiparasitic potential against promastigote and amastigote forms of Leishmania tropica. Furthermore, the NPs are discovered to have excellent potential in neutralizing harmful free radicals thus exhibiting considerable antioxidant potential. Most importantly, Polygonum bistorta Linn. synthesized SeNPs showed substantial compatibility against blood cells in vitro studies, which signifies the nontoxic nature of the NPs. The study thus concludes that medicinally important Polygonum bistorta Linn. roots can be utilized as an eco-friendly, sustainable, and green source for the synthesis of pharmacologically potent selenium nanoparticles.

Aflatoxins in Peanut (Arachis hypogaea): Prevalence, Global Health Concern, and Management from an Innovative Nanotechnology Approach: A Mechanistic Repertoire and Future Direction

Arachis hypogaea is the most significant oilseed nutritious legume crop in agricultural trade across the world. It is recognized as a valued crop for its contributions to nourishing food, as a cooking oil, and for meeting the protein needs of people who are unable to afford animal protein. Currently, its production, marketability, and consumption are hindered because of Aspergillus species infection that consequently contaminates the kernels with aflatoxins. Regarding health concerns, humans and animals are affected by acute and chronic aflatoxin toxicity and millions of people are at high risk of chronic levels. Most methods used to store peanuts are traditional and serve effectively for short-term storage. Now the question for long-term storage has been raised, and this promptly finds potential approaches to the issue. It is imperative to reduce the aflatoxin levels in peanuts to a permissible level by introducing detoxifying innovations. Most of the detoxification reports mention physical, chemical, and biological techniques. However, many current approaches are impractical because of time consumption, loss of nutritional quality, or weak detoxifying efficiency. Therefore, it is crucial to investigate practical, economical, and green methods to control Aspergillus flavus that address current global food security problems. Herein, a green and economically revolutionary way is a nanotechnology that has demonstrated its potential to connect farmers to markets, elevate international marketability, improve human and animal health conditions, and enhance food quality and safety by the management of fungal diseases. Due to the antimicrobial potential of nanoparticles, they act as nanofungicides and have an incredible role in the control of aflatoxins. Nanoparticles have ultrasmall sizes and therefore penetrate the fungal body and invade the pathogen machinery, leading to fungal cell death by ROS production, mutation in DNA, disruption of organelles, and membrane leakage. This is the first mechanistic overview that unveils a comprehensive insight into aflatoxin contamination in peanuts, its prevalence, health effects, and management in addition to nanotechnological interventions that serve as a triple defense approach to detoxify aflatoxins. The optimum use of nanofungicides ensures food safety and the development of goals, especially "zero hunger".

Evaluation of ALA-capped silver, copper, and silver-copper nanoparticles for controlling fungal plant pathogens

Phytopathogenic fungi significantly threaten global food security, causing substantial yield and quality losses. Sustainable solutions are urgently needed to combat these agricultural pathogens. This study explored the potential of silver (Ag), copper (Cu), and combined Ag/Cu nanoparticles capped with aminolevulinic acid (ALA) as antifungal agents. The nanoparticles (ALAAg, ALACu, and ALAAgCu) were synthesized via photoreduction and characterized using various techniques (UV-Vis, TEM, XRD, Zeta potential). Their antifungal activity against four key plant pathogens (Alternaria grandis, Colletotrichum truncatum, Corynespora cassiicola, and Fusarium oxysporum) was evaluated using poisoned food techniques. Notably, ALAAgCuNPs demonstrated superior antifungal activity compared to a conventional fungicide against two fungal strains. Even at lower concentrations, ALAAgCuNPs exhibited fungistatic effects comparable to those of the control. These promising results suggest the potential of ALAAgCu NPs as a broad-spectrum, potentially eco-friendly alternative for fungal control in plants and seeds. This approach is crucial for ensuring crop health, harvest quality, and food safety.

Advances in the Optimization of Fe Nanoparticles: Unlocking Antifungal Properties for Biomedical Applications

In recent years, nanotechnology has achieved a remarkable status in shaping the future of biological applications, especially in combating fungal diseases. Owing to excellence in nanotechnology, iron nanoparticles (Fe NPs) have gained enormous attention in recent years. In this review, we have provided a comprehensive overview of Fe NPs covering key synthesis approaches and underlying working principles, the factors that influence their properties, essential characterization techniques, and the optimization of their antifungal potential. In addition, the diverse kinds of Fe NP delivery platforms that command highly effective release, with fewer toxic effects on patients, are of great significance in the medical field. The issues of biocompatibility, toxicity profiles, and applications of optimized Fe NPs in the field of biomedicine have also been described because these are the most significant factors determining their inclusion in clinical use. Besides this, the difficulties and regulations that exist in the transition from laboratory to experimental clinical studies (toxicity, specific standards, and safety concerns) of Fe NPs-based antifungal agents have been also summarized.

A review on metal/metal oxide nanoparticles in food processing and packaging

Consuming hygienic and secure food has become challenging for everyone. The preservation of excess food without negatively affecting its nutritional values, shelf life, freshness, or effectiveness would undoubtedly strengthen the food industry. Nanotechnology is a new and intriguing technology that is currently being implemented in the food industry. Metal-based nanomaterials have considerable potential for use in packaging and food processing. These materials have many advanced physical and chemical characteristics. Since these materials are increasingly being used in food applications, there are certain negative health consequences related to their toxicity when swallowed through food. In this article, we have addressed the introduction and applications of metal/metal oxide nanoparticles (MNPs), food processing and food packaging, applications of MNPs-based materials in food processing and food packaging, health hazards, and future perspectives.

Antifungal Properties of Bio-AgNPs against D. pinodes and F. avenaceum Infection of Pea (Pisum sativum L.) Seedlings

Ascochyta blight and Fusarium root rot are the most serious fungal diseases of pea, caused by D. pinodes and F. avenaceum, respectively. Due to the lack of fully resistant cultivars, we proposed the use of biologically synthesized silver nanoparticles (bio-AgNPs) as a novel protecting agent. In this study, we evaluated the antifungal properties and effectiveness of bio-AgNPs, in in vitro (poisoned food technique; resazurin assay) and in vivo (seedlings infection) experiments, against D. pinodes and F. avenaceum. Moreover, the effects of diseases on changes in the seedlings' metabolic profiles were analyzed. The MIC for spores of both fungi was 125 mg/L, and bio-AgNPs at 200 mg/L most effectively inhibited the mycelium growth of D. pinodes and F. avenaceum (by 45 and 26%, respectively, measured on the 14th day of incubation). The treatment of seedlings with bio-AgNPs or fungicides before inoculation prevented the development of infection. Bio-AgNPs at concentrations of 200 mg/L for D. pinodes and 100 mg/L for F. avenaceum effectively inhibited infections' spread. The comparison of changes in polar metabolites' profiles revealed disturbances in carbon and nitrogen metabolism in pea seedlings by both pathogenic fungi. The involvement of bio-AgNPs in the mobilization of plant metabolism in response to fungal infection is also discussed.

Bimetallic nanoparticles and biochar produced by Adansonia Digitata shell and their effect against tomato pathogenic fungi

Adansonia digitata L. is a royal tree that is highly valued in Africa for its medicinal and nutritional properties. The objective of this study was to use its fruit shell extract to develop new, powerful mono and bimetallic nanoparticles (NPs) and biochar (BC) using an eco-friendly approach. Silver (Ag), iron oxide (FeO), the bimetallic Ag-FeO NPs, as well as (BC) were fabricated by A. digitata fruit shell extract through a reduction process and biomass pyrolysis, respectively, and their activity against tomato pathogenic fungi Alternaria sp., Sclerotinia sclerotiorum, Fusarium equiseti, and Fusarium venenatum were detected by agar dilution method. The Ag, FeO, Ag-FeONPs, and BC were characterized using a range of powerful analytical techniques such as ultraviolet-visible (UV-Vis) spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier Transform-Infra Red (FT-IR), dynamic light scatter (DLS), and zeta potential analysis. The fabricated Ag, FeO and Ag-FeO NPs have demonstrated a remarkable level of effectiveness in combating fungal strains. UV-Vis spectra ofAg, FeO, Ag-FeONPs, and BC show broad exhibits peaks at 338, 352, 418, and 480 nm, respectively. The monometallic, bimetallic NPs, and biochar have indicated the presence in various forms mostly in Spherical-shaped. Their size varied from 102.3 to 183.5 nm and the corresponding FTIR spectra suggested that the specific organic functional groups from the plant extract played a significant role in the bio-reduction process. Ag and Ag-FeO NPs exhibited excellent antifungal activity against pathogenic fungi Alternaria sp., S. sclerotiorum, F. equiseti, and F. venenatum. The current study could be a significant achievement in the field of antifungal agents since has the potential to develop new approaches for treating fungal infections.

Tiny but mighty: metal nanoparticles as effective antimicrobial agents for plant pathogen control

Metal nanoparticles (MNPs) have gained significant attention in recent years for their potential use as effective antimicrobial agents for controlling plant pathogens. This review article summarizes the recent advances in the role of MNPs in the control of plant pathogens, focusing on their mechanisms of action, applications, and limitations. MNPs can act as a broad-spectrum antimicrobial agent against various plant pathogens, including bacteria, fungi, and viruses. Different types of MNPs, such as silver, copper, zinc, iron, and gold, have been studied for their antimicrobial properties. The unique physicochemical properties of MNPs, such as their small size, large surface area, and high reactivity, allow them to interact with plant pathogens at the molecular level, leading to disruption of the cell membrane, inhibition of cellular respiration, and generation of reactive oxygen species. The use of MNPs in plant pathogen control has several advantages, including their low toxicity, selectivity, and biodegradability. However, their effectiveness can be influenced by several factors, including the type of MNP, concentration, and mode of application. This review highlights the current state of knowledge on the use of MNPs in plant pathogen control and discusses the future prospects and challenges in the field. Overall, the review provides insight into the potential of MNPs as a promising alternative to conventional chemical agents for controlling plant pathogens.

Bioinspired silver nanoparticle-based nanocomposites for effective control of plant pathogens: A review

Plant pathogens, including bacteria, fungi, and viruses, pose significant challenges to the farming community due to their extensive diversity, the rapidly evolving phenomenon of multi-drug resistance (MDR), and the limited availability of effective control measures. Amid mounting global pressure, particularly from the World Health Organization, to limit the use of antibiotics in agriculture and livestock management, there is increasing consideration of engineered nanomaterials (ENMs) as promising alternatives for antimicrobial applications. Studies focusing on the application of ENMs in the fight against MDR pathogens are receiving increasing attention, driven by significant losses in agriculture and critical knowledge gaps in this crucial field. In this review, we explore the potential contributions of silver nanoparticles (AgNPs) and their nanocomposites in combating plant diseases, within the emerging interdisciplinary arena of nano-phytopathology. AgNPs and their nanocomposites are increasingly acknowledged as promising countermeasures against plant pathogens, owing to their unique physicochemical characteristics and inherent antimicrobial properties. This review explores recent advancements in engineered nanocomposites, highlights their diverse mechanisms for pathogen control, and draws attention to their potential in antibacterial, antifungal, and antiviral applications. In the discussion, we briefly address three crucial dimensions of combating plant pathogens: green synthesis approaches, toxicity-environmental concerns, and factors influencing antimicrobial efficacy. Finally, we outline recent advancements, existing challenges, and prospects in scholarly research to facilitate the integration of nanotechnology across interdisciplinary fields for more effective treatment and prevention of plant diseases.

Spectroscopic and thermodynamic characterization of the interaction between sugar-stabilised silver nanoparticles and wheat germ agglutinin (WGA), a chitin binding lectin

Nanomaterials have lately been investigated in agriculture as eco-friendly and effective antifungal agents. Many nanomaterials, notably metal nanoparticles, have strong antifungal properties. Among metal nanoparticles, Ag nanoparticles have received the most attention as antifungal agents. Many plant lectins have been identified as antifungal agents. Conjugating AgNPs with antifungal lectins is thus expected to improve Ag nanoparticle antifungal efficacy. Understanding the molecular interactions and physical features of lectin-sugar-stabilised nanoparticle conjugates is critical for future applications. WGA has traditionally been used as an anti-tumor and antifungal agent. To investigate the prospect of developing an effective biocompatible antifungal system with applications in medicine and agriculture, fluorescence spectroscopy was used to investigate the interaction between sugar-stabilised silver nanoparticles and WGA. During the association, protein intrinsic fluorescence emission is suppressed by about ∼15 % at saturation, with no significant shift in fluorescence emission maxima. Binding tests reveal a strong bond. Stern-Volmer analysis of the quenching data indicates that the interaction happens via a static quenching process that induces complex formation. The study of hemagglutination activity and interaction experiments in the presence of particular sugar shows that the lectin's sugar-binding site is separate from the nanoparticle-binding site, and cell recognition is conserved in the lectin-nanoparticle complex. The Van't Hoff plot thermodynamic parameters suggest that the contact is hydrophobic. The fact that ΔGo is negative shows that the binding is a spontaneous process. CD spectroscopy experiments reveal that the lectin's secondary structure is not affected while binding to the nanoparticle. Our findings suggest that a stable WGA-silver nanoparticle combination may emerge for a variety of applications.

Metallic Nanoparticles: A Promising Arsenal against Antimicrobial Resistance-Unraveling Mechanisms and Enhancing Medication Efficacy

The misuse of antibiotics and antimycotics accelerates the emergence of antimicrobial resistance, prompting the need for novel strategies to combat this global issue. Metallic nanoparticles have emerged as effective tools for combating various resistant microbes. Numerous studies have highlighted their potential in addressing antibiotic-resistant fungi and bacterial strains. Understanding the mechanisms of action of these nanoparticles, including iron-oxide, gold, zinc oxide, and silver is a central focus of research within the life science community. Various hypotheses have been proposed regarding how nanoparticles exert their effects. Some suggest direct targeting of microbial cell membranes, while others emphasize the release of ions from nanoparticles. The most compelling proposed antimicrobial mechanism of nanoparticles involves oxidative damage caused by nanoparticles-generated reactive oxygen species. This review aims to consolidate knowledge, discuss the properties and mechanisms of action of metallic nanoparticles, and underscore their potential as alternatives to enhance the efficacy of existing medications against infections caused by antimicrobial-resistant pathogens.

Nanotechnology-Based Strategies to Combat Multidrug-Resistant Candida auris Infections

An emerging multidrug-resistant pathogenic yeast called Candida auris has a high potential to spread quickly among hospitalized patients and immunodeficient patients causing nosocomial outbreaks. It has the potential to cause pandemic outbreaks in about 45 nations with high mortality rates. Additionally, the fungus has become resistant to decontamination techniques and can survive for weeks in a hospital environment. Nanoparticles might be a good substitute to treat illnesses brought on by this newly discovered pathogen. Nanoparticles have become a trend and hot topic in recent years to combat this fatal fungus. This review gives a general insight into the epidemiology of C. auris and infection. It discusses the current conventional therapy and mechanism of resistance development. Furthermore, it focuses on nanoparticles, their different types, and up-to-date trials to evaluate the promising efficacy of nanoparticles with respect to C. auris.

Myco-synthesized copper oxide nanoparticles using harnessing metabolites of endophytic fungal strain Aspergillus terreus: an insight into antibacterial, anti-Candida, biocompatibility, anticancer, and antioxidant activities

BACKGROUND

The overuse of antibiotics leads to the emergence of antibiotic-resistant microbes which causes high mortality worldwide. Therefore, the synthesis of new active compounds has multifunctional activities are the main challenge. Nanotechnology provides a solution for this issue.

METHOD

The endophytic fungal strain Aspergillus terreus BR.1 was isolated from the healthy root of Allium sativum and identified using internal transcribed spacer (ITS) sequence analysis. The copper oxide nanoparticles (CuO-NPs) were synthesized by harnessing the metabolites of the endophytic fungal strain. The UV-Visble spectroscopy, Fourier-transform infrared spectroscopy (FT-IR), Transmission electron micrscopy (TEM), Energy dispersive X-ray (EDX), X-ray diffraction (XRD), Dynamic light scattering (DLS), and zeta potential (ζ) were used for the characterization of synthesized CuO-NPs. The activity against different pathogenic bacteria and Candida species were investigated by agar well-diffusion method. The biocombatibility and anticancer activity were assessed by MTT assay method. The scavenging of DPPH was used to investigate the antioxidant activity of synthesized CuO-NPs.

RESULTS

Data showed the successful formation of crystalline nature and spherical shape CuO-NPs with sizes in the ranges of 15-55 nm. The EDX reveals that the as-formed sample contains ions of C, O, Cl, and Cu with weight percentages of 18.7, 23.82, 11.31, and 46.17%, respectively. The DLS and ζ-potential showed high homogeneity and high stability of synthesized CuO-NPs with a polydispersity index (PDI) of 0.362 and ζ-value of - 26.6 mV. The synthesized CuO-NPs exhibited promising antibacterial and anti-Candida activity (concentration-dependent) with minimum inhibitory concentration (MIC) values in the ranges of 25-50 µg mL^-1. Moreover, the fungal mediated-CuO-NPs targeted cancer cells of MCF7 and PC3 at low IC₅₀ concentrations of 159.2 ± 4.5 and 116.2 ± 3.6 µg mL^-1, respectively as compared to normal cells (Vero and Wi38 with IC₅₀ value of 220.6 ± 3.7 and 229.5 ± 2.1 µg mL^-1, respectively). The biosynthesized CuO-NPs showed antioxidant activity as detected by the DPPH method with scavenging percentages of 80.5 ± 1.2% at a concentration of 1000 µg mL^-1 and decreased to 20.4 ± 4.2% at 1.9 µg mL^-1 as compared to ascorbic acid (control) with scavenging activity of 97.3 ± 0.2 and 37.5 ± 1.3% at the same concentrations, respectively.

CONCLUSION

The fungal mediated-CuO-NPs exhibited promising activity and can be integrated into various biomedical and theraputic applications.

Metal Nanomaterials and Hydrolytic Enzyme-Based Formulations for Improved Antifungal Activity

Active research of metal-containing compounds and enzymes as effective antifungal agents is currently being conducted due to the growing antifungal resistance problem. Metals are attracting special attention due to the wide variety of ligands that can be used for them, including chemically synthesized and naturally obtained variants as a result of the so-called "green synthesis". The main mechanism of the antifungal action of metals is the triggering of the generation and accumulation of reactive oxygen species (ROS). Further action of ROS on various biomolecules is nonspecific. Various hydrolytic enzymes (glucanases and proteases), in turn, exhibit antifungal properties by affecting the structural elements of fungal cells (cell walls, membranes), fungal quorum sensing molecules, fungal own protective agents (mycotoxins and antibiotics), and proteins responsible for the adhesion and formation of stable, highly concentrated populations in the form of biofilms. A wide substrate range of enzymes allows the use of various mechanisms of their antifungal actions. In this review, we discuss the prospects of combining two different types of antifungal agents (metals and enzymes) against mycelial fungi and yeast cells. Special attention is paid to the possible influence of metals on the activity of the enzymes and the possible effects of proteins on the antifungal activity of metal-containing compounds.

Chitosan: Properties and Its Application in Agriculture in Context of Molecular Weight

Chitosan is a naturally occurring compound that can be obtained from deacetylated chitin, which is obtained from various sources such as fungi, crustaceans, and insects. Commercially, chitosan is produced from crustaceans. Based on the range of its molecular weight, chitosan can be classified into three different types, namely, high molecular weight chitosan (HMWC, >700 kDa), medium molecular weight chitosan (MMWC, 150-700 kDa), and low molecular weight chitosan (LMWC, less than 150 kDa). Chitosan shows several properties that can be applied in horticultural crops, such as plant root growth enhancer, antimicrobial, antifungal, and antiviral activities. Nevertheless, these properties depend on its molecular weight (MW) and acetylation degree (DD). Therefore, this article seeks to extensively review the properties of chitosan applied in the agricultural sector, classifying them in relation to chitosan's MW, and its use as a material for sustainable agriculture.

Engineered Metal Oxide Nanoparticles as Fungicides for Plant Disease Control

Metal oxide nanoparticles are considered to be good alternatives as fungicides for plant disease control. To date, numerous metal oxide nanoparticles have been produced and evaluated as promising antifungal agents. Consequently, a detailed and critical review on the use of mono-, bi-, and tri-metal oxide nanoparticles for controlling phytopathogenic fungi is presented. Among the studied metal oxide nanoparticles, mono-metal oxide nanoparticles-particularly ZnO nanoparticles, followed by CuO nanoparticles -are the most investigated for controlling phytopathogenic fungi. Limited studies have investigated the use of bi- and tri-metal oxide nanoparticles for controlling phytopathogenic fungi. Therefore, more studies on these nanoparticles are required. Most of the evaluations have been carried out under in vitro conditions. Thus, it is necessary to develop more detailed studies under in vivo conditions. Interestingly, biological synthesis of nanoparticles has been established as a good alternative to produce metal oxide nanoparticles for controlling phytopathogenic fungi. Although there have been great advances in the use of metal oxide nanoparticles as novel antifungal agents for sustainable agriculture, there are still areas that require further improvement.

Special Issue: Fungal Nanotechnology 2

Fungal nanotechnology provides techniques useful for molecular and cell biology, medicine, biotechnology, agriculture, veterinary physiology, and reproduction. This technology also has exciting potential applications in pathogen identification and treatment, as well as impressive outcomes in the animal and food systems. Myconanotechnology is a viable option for the synthesis of green nanoparticles because it is simple, affordable, and more environmentally friendly to use fungal resources. Mycosynthesis nanoparticles can be used for various purposes, such as pathogen detection and diagnosis, control, wound healing, drug delivery, cosmetics, food preservation, and textile fabrics, among other applications. They can be applied to a variety of industries, such as agriculture, manufacturing, and medicine. Gaining deeper comprehension of the molecular biology and genetic components underlying the fungal nanobiosynthetic processes is becoming increasingly important. This Special Issue aims to showcase recent advancements in invasive fungal diseases caused by human, animal, plant, and entomopathogenic fungi that are being identified, treated, and treated using antifungal nanotherapy. Utilizing fungus in nanotechnology has several benefits, such as their capacity to create nanoparticles with distinctive characteristics. As an illustration, some fungi can create nanoparticles that are highly stable, biocompatible, and have antibacterial capabilities. Fungal nanoparticles may be used in a variety of industries, including biomedicine, environmental cleanup, and food preservation. Fungal nanotechnology is also a sustainable and environmentally beneficial method. Fungi are an appealing alternative to conventional chemical methods of creating nanoparticles because they are simple to cultivate using affordable substrates and may be cultivated under diverse conditions.

Nanomaterial-Reinforced Portland-Cement-Based Materials: A Review

Portland cement (PC) is a material that is indispensable for satisfying recent urban requirements, which demands infrastructure with adequate mechanical and durable properties. In this context, building construction has employed nanomaterials (e.g., oxide metals, carbon, and industrial/agro-industrial waste) as partial replacements for PC to obtain construction materials with better performance than those manufactured using only PC. Therefore, in this study, the properties of fresh and hardened states of nanomaterial-reinforced PC-based materials are reviewed and analyzed in detail. The partial replacement of PC by nanomaterials increases their mechanical properties at early ages and significantly improves their durability against several adverse agents and conditions. Owing to the advantages of nanomaterials as a partial replacement for PC, studies on the mechanical and durability properties for a long-term period are highly necessary.

Fighting Phytopathogens with Engineered Inorganic-Based Nanoparticles

The development of effective and ecofriendly agrochemicals, including bactericides, fungicides, insecticides, and nematicides, to control pests and prevent plant diseases remains a key challenge. Nanotechnology has provided opportunities for the use of nanomaterials as components in the development of anti-phytopathogenic agents. Indeed, inorganic-based nanoparticles (INPs) are among the promising ones. They may play an effective role in targeting and killing microbes via diverse mechanisms, such as deposition on the microbe surface, destabilization of cell walls and membranes by released metal ions, and the induction of a toxic mechanism mediated by the production of reactive oxygen species. Considering the lack of new agrochemicals with novel mechanisms of action, it is of particular interest to determine and precisely depict which types of INPs are able to induce antimicrobial activity with no phytotoxicity effects, and which microbe species are affected. Therefore, this review aims to provide an update on the latest advances in research focusing on the study of several types of engineered INPs, that are well characterized (size, shape, composition, and surface features) and show promising reactivity against assorted species (bacteria, fungus, virus). Since effective strategies for plant protection and plant disease management are urgently needed, INPs can be an excellent alternative to chemical agrochemical agents as indicated by the present studies.

Biocontrol of Fusarium equiseti using chitosan nanoparticles combined with Trichoderma longibrachiatum and Penicillium polonicum

A safe and ecofriendly biocontrol of pathogenic Fusarium equiseti was developed based on chitosan nanoparticles (CNPs) combined with Trichoderma longibrachiatum and Penicillium polonicum. Two strains of F. equiseti which were isolated from wilting tomato plant as well as three antagonistic fungi including Trichoderma longibrachiatum and two strains of Penicillium polonicum were isolated from the surrounding soil. All the isolated pathogenic and antagonistic fungi were identified using genomic DNA sequences. The antifungal activity of the three antagonistic fungi were studied against the two strains of F. equiseti. Also, CNPs which were prepared according to the ionic gelation method using sodium tripolyphosphate anions in acetic acid solution were used to enhance the antifungal activity of the three antagonistic fungi. The results exhibit that, combination of T. longibrachiatum with CNPs and P. polonicum with CNPs achieve high antifungal activity against F. equiseti by an inhibition rate equal to 71.05% and 66.7%, respectively.

Trichoderma-Mediated ZnO Nanoparticles and Their Antibiofilm and Antibacterial Activities

Antimicrobial resistance is a major global health concern and one of the gravest challenges to humanity today. Antibiotic resistance has been acquired by certain bacterial strains. As a result, new antibacterial drugs are urgently required to combat resistant microorganisms. Species of Trichoderma are known to produce a wide range of enzymes and secondary metabolites that can be exploited for the synthesis of nanoparticles. In the present study, Trichoderma asperellum was isolated from rhizosphere soil and used for the biosynthesis of ZnO NPs. To examine the antibacterial activity of ZnO NPs against human pathogens, Escherichia coli and Staphylococcus aureus were used. The obtained antibacterial results show that the biosynthesized ZnO NPs were efficient antibacterial agents against the pathogens E. coli and S. aureus, with an inhibition zone of 3-9 mm. The ZnO NPs were also effective in the prevention of S. aureus biofilm formation and adherence. The current work shows that the MIC dosages of ZnO NPs (25, 50, and 75 μg/mL) have effective antibacterial activity and antibiofilm action against S. aureus. As a result, ZnO NPs can be used as a part of combination therapy for drug-resistant S. aureus infections, where biofilm development is critical for disease progression.

The potential of lactic acid bacteria in mediating the control of plant diseases and plant growth stimulation in crop production - A mini review

The microbial diseases cause significant damage in agriculture, resulting in major yield and quality losses. To control microbiological damage and promote plant growth, a number of chemical control agents such as pesticides, herbicides, and insecticides are available. However, the rising prevalence of chemical control agents has led to unintended consequences for agricultural quality, environmental devastation, and human health. Chemical agents are not naturally broken down by microbes and can be found in the soil and environment long after natural decomposition has occurred. As an alternative to chemical agents, biocontrol agents are employed to manage phytopathogens. Interest in lactic acid bacteria (LAB) research as another class of potentially useful bacteria against phytopathogens has increased in recent years. Due to the high level of biosafety, they possess and the processes they employ to stimulate plant growth, LAB is increasingly being recognized as a viable option. This paper will review the available information on the antagonistic and plant-promoting capabilities of LAB and its mechanisms of action as well as its limitation as BCA. This review aimed at underlining the benefits and inputs from LAB as potential alternatives to chemical usage in sustaining crop productivity.

Metal Nanoparticles to Combat Candida albicans Infections: An Update

Candidiasis is an opportunistic mycosis with high annual incidence worldwide. In these infections, Candida albicans is the chief pathogen owing to its multiple virulence factors. C. albicans infections are usually treated with azoles, polyenes and echinocandins. However, these antifungals may have limitations regarding toxicity, relapse of infections, high cost, and emergence of antifungal resistance. Thus, the development of nanocarrier systems, such as metal nanoparticles, has been widely investigated. Metal nanoparticles are particulate dispersions or solid particles 10-100 nm in size, with unique physical and chemical properties that make them useful in biomedical applications. In this review, we focus on the activity of silver, gold, and iron nanoparticles against C. albicans. We discuss the use of metal nanoparticles as delivery vehicles for antifungal drugs or natural compounds to increase their biocompatibility and effectiveness. Promisingly, most of these nanoparticles exhibit potential antifungal activity through multi-target mechanisms in C. albicans cells and biofilms, which can minimize the emergence of antifungal resistance. The cytotoxicity of metal nanoparticles is a concern, and adjustments in synthesis approaches or coating techniques have been addressed to overcome these limitations, with great emphasis on green synthesis.

Antifungal Activity of Mycogenic Silver Nanoparticles on Clinical Yeasts and Phytopathogens

In this study, seven different silver nanoparticles (AgNPs) were obtained using the fungi species from the phylum Ascomycota, Aspergillus tubingensis, Aspergillus spp., Cladosporium pini-ponderosae, Fusarium proliferatum, Epicoccum nigrum, Exserohilum rostratum, and Bionectria ochroleuca, isolated from the Brazilian biodiversity, particularly from the mangrove and Caatinga biomes. The nanoparticles were coded as AgNP-AT, AgNP-Asp, AgNP-CPP, AgNP-FP, AgNP-EN, AgNP-ER, and AgNP-BO and characterized using spectrophotometry (UV-Vis), dynamic light scattering (DLS), zeta potential, transmission electron microcopy (TEM), and Fourier-transform infrared (FTIR) spectroscopy. All the AgNPs presented homogeneous size in the range from 43.4 to 120.6 nm (DLS) and from 21.8 to 35.8 nm (TEM), pH from 4.5 to 7.5, negative charge, and presence of protein coating on their surface. The antifungal activity of the AgNPs was evaluated on clinical strains of Candida albicans, and on the non-albicans species, Candida krusei, Candida glabrata, Candida parapsilosis, Candida tropicalis, and Candida guilliermondii, common in hospital infections, and against the phytopathogens Fusarium oxysporum, Fusarium phaseoli, Fusarium sacchari, Fusarium subglutinans, Fusarium verticillioides, and Curvularia lunata, which are species responsible for serious damage to agriculture production. The AgNPs were effective against the yeasts with MICs ranging from 1.25 to 40 µM and on the phytopathogens with MICs from 4 to 250 µM, indicating the promising possibility of application of these AgNPs as antifungal agents. The results indicated that the physicochemical parameters of the AgNPs, including the functional groups present on their surface, interfered with their antifungal activity. Overall, the results indicate that there is no specificity of the AgNPs for the yeasts or for the phytopathogens, which can be an advantage, increasing the possibility of application in different areas.

Biogenic silver nanoparticles as antifungal agents

In recent years, an increase in multidrug-resistant fungal strains has been observed, which, together with the limited number of clinically available antifungal agents, highlights the need for the development of new antifungal agents. Due to the proven antifungal activity of silver nanoparticles (AgNPs), there is a growing interest in their use in the treatment of fungal infections. Nanoparticles are usually synthesised through a variety of physical and chemical processes that are costly and pollute the environment. For this reason, biogenic synthesis is emerging as an environmentally friendly technology and new strategies are increasingly based on the use of biogenic AgNPs as antifungal agents for clinical use. The aim of this review is to compare the antifungal activity of different biogenic AgNPs and to summarise the current knowledge on the mechanisms of action and resistance of fungi to AgNPs. Finally, a general analysis of the toxicity of biogenic AgNPs in human and veterinary medicine is performed.

A Metal-Containing NP Approach to Treat Methicillin-Resistant Staphylococcus aureus (MRSA): Prospects and Challenges

Methicillin-resistant Staphylococcus aureus (MRSA) is an important cause of pneumonia in humans, and it is associated with high morbidity and mortality rates, especially in immunocompromised patients. Its high rate of multidrug resistance led to an exploration of novel antimicrobials. Metal nanoparticles have shown potent antibacterial activity, thus instigating their application in MRSA. This review summarizes current insights of Metal-Containing NPs in treating MRSA. This review also provides an in-depth appraisal of opportunities and challenges in utilizing metal-NPs to treat MRSA.

Nanoparticles for oral delivery: targeted therapy for inflammatory bowel disease

As a group of chronic and idiopathic gastrointestinal (GI) disorders, inflammatory bowel disease (IBD) is characterized by recurrent intestinal mucosal inflammation. Oral administration is critical for the treatment of IBD. Unfortunately, it is difficult to target the bowel located in the GI tract due to multiple physical barriers. The unique physicochemical properties of nanoparticle-based drug delivery systems (DDSs) and their enhanced permeability and retention effects in the inflamed bowel, render nanomedicines to be used to implement precise drug delivery at diseased sites in IBD therapy. In this review, we described the pathophysiological features of IBD, and designed strategies to exploit these features for intestinal targeting. In addition, we introduced the types of currently developed nano-targeted carriers, including synthetic nanoparticle-based and emerging naturally derived nanoparticles (e.g., extracellular vesicles and plant-derived nanoparticles). Moreover, recent developments in targeted oral nanoparticles for IBD therapy were also highlighted. Finally, we presented challenges associated with nanotechnology and potential directions for future IBD treatment.

Zinc nanoparticles: Mode of action and efficacy against boscalid-resistant Alternaria alternata isolates

The antifungal potential of ZnO-NPs against Alternaria alternata isolates with reduced sensitivity to the succinate dehydrogenase inhibitor (SDHI) boscalid, resulting from target site modifications, was evaluated in vitro and in vivo. ZnO-NPs could effectively inhibit mycelial growth in a dose-dependent way in both boscalid (BOSC) sensitive (BOSC-S) and resistant (BOSC-R) isolates. The fungitoxic effect of ZnO-NPs against the pathogen was significantly enhanced when combined with boscalid compared to the individual treatments in all phenotype cases (BOSC-S/R) both in vitro and in vivo. Fungitoxic effect of ZnO-NPs could be, at least partly, attributed to zinc ion release as indicated by the positive correlation between sensitivities to the nanoparticles and their ionic counterpart ZnSO₄ and the alleviation of the ZnO-NPs fungitoxic action in the presence of the strong chelating agent EDTA. The superior effectiveness of ZnO-NPs against A. alternata, compared to ZnSO_4, could be due to nanoparticle properties interfering with cellular ion homeostasis mechanisms. The observed additive action of the oxidative phosphorylation-uncoupler fluazinam (FM) against all phenotypes indicates a possible role of ATP-dependent ion efflux mechanism in the mode of action of ZnO-NPs. A potential role of ROS production in the fungitoxic action of ZnO-NPs was evident by the additive/synergistic action of salicylhydroxamate (SHAM), which blocks the alternative oxidase antioxidant action. Mixture of ZnO-NPs and boscalid, resulting in a "capping" effect for the nanoparticles and significantly reducing their mean size, probably accounted for the synergistic effect of the mixture against both sensitive and resistant A. alternata isolates. Summarizing, results indicated that ZnO-NPs can be effectively used against A. alternata both alone or in combination with boscalid, providing an effective tool for combating SDHI-resistance and reducing the environmental fingerprint of synthetic fungicides.

Mycosynthesis, Characterization, and Mosquitocidal Activity of Silver Nanoparticles Fabricated by Aspergillus niger Strain

Herein, silver nanoparticles (Ag-NPs) were synthesized using an environmentally friendly approach by harnessing the metabolites of Aspergillus niger F2. The successful formation of Ag-NPs was checked by a color change to yellowish-brown, followed by UV-Vis spectroscopy, Fourier transforms infrared (FT-IR), Transmission electron microscopy (TEM), and X-ray diffraction (XRD). Data showed the successful formation of crystalline Ag-NPs with a spherical shape at the maximum surface plasmon resonance of 420 nm with a size range of 3–13 nm. The Ag-NPs showed high toxicity against I, II, III, and IV instar larvae and pupae of Aedes aegypti with LC50 and LC90 values of 12.4–22.9 ppm and 22.4–41.4 ppm, respectively under laboratory conditions. The field assay exhibited the highest reduction in larval density due to treatment with Ag-NPs (10× LC50) with values of 59.6%, 74.7%, and 100% after 24, 48, and 72 h, respectively. The exposure of A. aegypti adults to the vapor of burning Ag-NPs-based coils caused a reduction of unfed individuals with a percentage of 81.6 ± 0.5% compared with the positive control, pyrethrin-based coils (86.1 ± 1.1%). The ovicidal activity of biosynthesized Ag-NPs caused the hatching of the eggs with percentages of 50.1 ± 0.9, 33.5 ± 1.1, 22.9 ± 1.1, and 13.7 ± 1.2% for concentrations of 5, 10, 15, and 20 ppm, whereas Ag-NPs at a concentration of 25 and 30 ppm caused complete egg mortality (100%). The obtained data confirmed the applicability of biosynthesized Ag-NPs to the biocontrol of A. aegypti at low concentrations.

Advances in Nanostructures for Antimicrobial Therapy

Microbial infections caused by a variety of drug-resistant microorganisms are more common, but there are fewer and fewer approved new antimicrobial chemotherapeutics for systemic administration capable of acting against these resistant infectious pathogens. Formulation innovations of existing drugs are gaining prominence, while the application of nanotechnologies is a useful alternative for improving/increasing the effect of existing antimicrobial drugs. Nanomaterials represent one of the possible strategies to address this unfortunate situation. This review aims to summarize the most current results of nanoformulations of antibiotics and antibacterial active nanomaterials. Nanoformulations of antimicrobial peptides, synergistic combinations of antimicrobial-active agents with nitric oxide donors or combinations of small organic molecules or polymers with metals, metal oxides or metalloids are discussed as well. The mechanisms of actions of selected nanoformulations, including systems with magnetic, photothermal or photodynamic effects, are briefly described.