Mariana Guilger

Biogenic silver nanoparticles (AgNPs) are investigated for their antimicrobial activity and reduced toxicity associated with metabolite-derived surface coatings. Their stability and biological activity are enhanced by metabolite-derived coatings produced by the synthesizing organism. This study develops hybrid nanocarriers by combining biogenic AgNPs synthesized from Penicillium chrysogenum with poloxamer micelles. Subsequently, the AgNPs were incorporated into poloxamer-based micelles (PL188 and PL407), yielding the nanocarriers AgNPs_PL407 and AgNPs_PL188. Physicochemical characterization was performed using dynamic light scattering (DLS) to determine hydrodynamic diameter (Dh), polydispersity index (PDI), and zeta potential (ζ). Antimicrobial activity was evaluated through disk-diffusion assays, minimum inhibitory concentration (MIC), and bacterial growth kinetics. Cell viability was assessed using trypan blue exclusion and MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assays. Biogenic AgNPs exhibited a Dh of 277.20 ± 112.16 nm, a PDI of 0.271, and a ζ potential of −9.40 ± 0.54 mV. Pure poloxamers showed ζ potentials close to zero (0.03 ± 0.07 mV and −0.01 ± 0.06 mV, respectively). Incorporation resulted in AgNPs_PL407 nanocarriers, characterized by greater heterogeneity, with a Dh of 555.60 ± 268.40 nm and a PDI of 1.000, and in AgNPs_PL188 nanocarriers, characterized by greater homogeneity, with a Dh of 301.63 ± 106.11 nm and a PDI of 0.349. Both hybrid systems exhibited ζ potentials near zero (−0.02 ± 0.00 mV for AgNPs_PL407 and −0.00 ± 0.00 mV for AgNPs_PL188), indicating the possible colloidal stabilization conferred by the poloxamers. Both the AgNPs and the hybrid nanocarriers demonstrated antimicrobial activity across the tested combinations, supporting their broad antimicrobial potential. Importantly, most antimicrobial MIC values were below the cytotoxicity threshold determined for HaCaT cells (IC50 = 2.29 × 1010 NPs/mL), particularly those obtained for the hybrid nanocarriers. However, free AgNPs against E. coli showed an MIC of 2.65 × 1010 NPs/mL, slightly exceeding the HaCaT IC50, indicating that the apparent therapeutic window was formulation- and microorganism-dependent. Cytotoxicity assays also confirmed high cell viability at biologically active concentrations, particularly for the hybrid systems. AgNPs_PL188 showed the most promising overall profile, combining favorable antibacterial performance with low apparent cytotoxicity. Overall, these results suggest that incorporating biogenic AgNPs into poloxamer micelles may improve their apparent antimicrobial selectivity over cytotoxicity, highlighting their potential for developing antimicrobial formulations, particularly for oral inhalation administration. However, further studies are needed to optimize the system and ensure product safety.

Biogenic silicon dioxide nanoparticles (SiO₂–NPs_bio) synthesized using Fusarium oxysporum were combined with Beauveria bassiana in a Pickering emulsion to enhance fungal bioavailability and insecticidal efficacy. The biogenic nanoparticles exhibited larger diameters (324 ± 3 nm) and lower ζ-potential (−23 ± 0.2 mV) than commercial SiO₂–NPs, while showing no significant cytotoxicity in HaCat and 3T3 cell lines. Encapsulation markedly improved fungal performance, resulting in 100% mortality of Spodoptera frugiperda, S. cosmioides, and Chrysodeixis includens, and 86% mortality of Rachiplusia nu, significantly higher than isolated nanoparticles or fungus. The nanoformulation also protected B. bassiana against UV radiation and showed no phytotoxic effects. This study demonstrates, for the first time, a sustainable biogenic SiO₂-based Pickering emulsion as an effective carrier for entomopathogenic fungi in pest control.

BACKGROUND: Biogenic metallic and oxide metal nanoparticles have potential as alternatives for several current problems in agriculture, such as the control of caterpillars which cause huge losses in the production of important crops. In the present study, capped and uncapped silver, iron oxide and titanium dioxide nanoparticles were synthesized from the filtrate of Beauveria bassiana and evaluated in regard to physico‐chemical characteristics, capping composition, cytotoxicity, genotoxicity and biological activity on Helicoverpa armigera and Spodoptera frugiperda caterpillars.RESULTS: A difference in the physico‐chemical parameters of the capped and uncapped nanoparticles was observed, with larger aggregation and lower stability of the uncapped. In regard to the study of the capping, the presence of functional groups of biomolecules as well as the activity of B. bassiana hydrolytic enzymes were observed. Cytotoxic effects on the tested cell lines were not observed and DNA damage levels increased with more intense effects of the uncapped nanoparticles. In regard to the biological activity against Noctuidae pests, the uncapped and capped iron oxide, and uncapped titanium dioxide nanoparticles occasioned higher mortality (76%, 60% and 51%, respectively) but no differences in LC₅₀ were recorded. Moreover, sublethal effects were reported on Helicoverpa armigera whereas Spodoptera frugiperda showed low susceptibility to the nanoparticles.CONCLUSION: The results demonstrate that biogenic metallic and oxide metal nanoparticles might show promising effects for the control of caterpillars which cause damage on important agricultural crops. Further investigations are necessary to understand the mechanisms of action and optimize the biological activity of these new nanomaterials. © 2023 Society of Chemical Industry.

The supply of food derived from aquaculture has increased significantly in recent years. The aim of this industrial sector is to produce sustainable products to meet the needs of consumers, providing food security and nutritional benefits. The development of aquaculture has faced challenges including disease outbreaks that can cause substantial economic losses. These diseases can be controlled using chemicals such as antibiotics. However, the indiscriminate use of these substances can have major negative impacts on human health and the environment with the additional risk of the emergence of resistant organisms. The present manuscript describes the use of phytotherapy in association with nanotechnology in order to obtain a more effective and less harmful system for the control of bacterial diseases in fish. Zein nanoparticles associated with eugenol and garlic essential oil were prepared through antisolvent precipitation and characterized. Zein nanoparticles are promising carrier systems as zein proteins are biodegradable and biocompatible and, in this way, good candidates for encapsulation of active ingredients. The system presented good physicochemical properties with an average particle diameter of approximately 150 nm, a polydispersity index lower than 0.2, and a zeta potential of approximately 30 mV. High encapsulation efficiency was obtained for the active compounds with values higher than 90%, and the compounds were protected against degradation during storage (90 days). The nanoparticle formulations containing the botanical compounds also showed less toxicity in the tests performed with a biomarker (Artemia salina). In addition, the systems showed bactericidal activity against the important fish pathogenic bacteria Aeromonas hydrophila, Edwardsiella tarda, and Streptococcus iniaein vitro. The present study opens new perspectives for the use of botanical compounds in combination with nanotechnology to treat fish diseases caused by bacteria, contributing to a more sustainable fish chain production.

The use of fungi as reducing and stabilizing agents in the biogenic synthesis of silver nanoparticles is attractive due to the production of large quantities of proteins, high yields, easy handling, and low toxicity of the residues. Furthermore, this synthesis process coats the nanoparticles with biomolecules derived from the fungus, which can improve stability and may confer biological activity. The aim of this review is to describe studies in which silver nanoparticles were synthesized using fungi as reducing agents, discussing the mechanisms and optimization of the synthesis, as well as the applications. The literature shows that various species of fungus have potential for use in biogenic synthesis, enabling the production of nanoparticles with different characteristics, considering aspects such as their size, surface charge, and morphology. The synthesis mechanisms have not yet been fully elucidated, although it is believed that fungal biomolecules are mainly responsible for the process. The synthesis can be optimized by adjusting parameters such as temperature, pH, silver precursor concentration, biomass amount, and fungus cultivation time. Silver nanoparticles synthesized using fungi enable the control of pathogens, with low toxicity and good biocompatibility. These findings open perspectives for future investigations concerning the use of these nanoparticles as antimicrobials in the areas of health and agriculture.

Biogenic synthesis of silver nanoparticles employing fungi offers advantages, including the formation of a capping from fungal biomolecules, which provides stability and can contribute to biological activity. In this work, silver nanoparticles were synthesized usingTrichoderma harzianumcultivated with (AgNP-TS) and without enzymatic stimulation (AgNP-T) by the cell wall ofSclerotinia sclerotiorum. The nanoparticles were evaluated for the control ofS.sclerotiorum. The specific activity of theT.harzianumhydrolytic enzymes were determined in the filtrates and nanoparticles. Cytotoxicity and genotoxicity were also evaluated. Both the nanoparticles exhibited inhibitory activity towardsS.sclerotiorum, with no new sclerotia development, however AgNP-TS was more effective against mycelial growth. Both the filtrates and the nanoparticles showed specific enzymatic activity. Low levels of cytotoxicity and genotoxicity were observed. This study opens perspectives for further exploration of fungal biogenic nanoparticles, indicating their use for the control ofS.sclerotiorumand other agricultural pests.

Silver nanoparticles (AgNPs) are known mainly because of their bactericidal properties. Among the different types of synthesis, there is the biogenic synthesis, which allows the synergy between the nanocomposites and substances from the organism employed for the synthesis. This study describes the synthesis of AgNPs using infusion of roots (AgNpR) and extract (AgNpE) of the plant Althaea officinalis. After the synthesis through reduction of silver nitrate with compounds of A. officinalis, physico-chemical analyzes were performed by UV-Vis spectroscopy, nanoparticles tracking analysis (NTA), dynamic light scattering (DLS) and scanning electron microscopy (SEM). Toxicity was evaluated through Allium cepa assay, comet test with cell lines, cell viability by mitochondrial activity and image cytometry and minimal inhibitory concentration on pathogenic microorganisms. Biochemical analyzes (CAT - catalase, GPx - glutathione peroxidase e GST - glutationa S-transferase) and genotoxicity evaluation in vivo on Zebrafish were also performed. AgNpE and AgNpR showed size of 157 ± 11 nm and 293 ± 12 nm, polydispersity of 0.47 ± 0.08 and 0.25 ± 0.01, and zeta potential of 20.4 ± 1.4 and 26.5 ± 1.2 mV, respectively. With regard to toxicity, the AgNpE were the most toxic when compared with AgNpR. Biochemical analyzes on fish showed increase of CAT activity in most of the organs, whereas GPx showed few changes and the activity of GST decreased. Also regarding to bactericidal activity, both nanoparticles were effective, however AgNpR showed greater activity. Althaea officinalis can be employed as reducing agent for the synthesis of silver nanoparticles, although it is necessary to consider its potential toxicity and ecotoxicity.

Fungi of the Trichoderma spp. genus, notably Trichoderma harzianum, are commonly used for biological management of deleterious seed‐ and soil‐borne pathogens. The global biopesticides market is booming with a major share of various commercial formulations of T. harzianum. However, there are some major drawbacks associated with these commercial formulations including short shelf life, low on‐field stability and irregular performance in different agro‐climatic regions. For effectively resolving these issues, new strategies are urgently required for efficient management of pathogens. The present review provides an overview of the use of Trichoderma spp., with special emphasis on T. harzianum, and discusses future trends for biological control. Technologies are described for the microencapsulation of fungi and for the biogenic synthesis of nanoparticles, with the aim of improving the biological control of pathogens and contributing to sustainable agricultural practices. © 2018 Society of Chemical Industry