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Bacterial biofilms are a significant problem in the food industry, as they are difficult to eradicate and represent a threat to consumer health. Currently, nanoparticles as an alternative to traditional chemical disinfectants have garnered much attention due to their broad-spectrum antibacterial activity and low toxicity. In this study, silver nanoparticles (AgNPs) were synthesized by a biological method using a Jacaranda mimosifolia flower aqueous extract and by a chemical method, and the factors affecting both syntheses were optimized. The nanoparticles were characterized by Ultraviolet-visible (UV-Vis) spectrophotometry, Fourier-transform infrared spectroscopy (FTIR), Dynamic light scattering (DLS), X-ray diffraction (XRD), and Transmission electron microscopy (TEM) with a spherical and uniform shape. The antibacterial and antibiofilm formation activity was carried out on bacterial species of Pseudomonas aeruginosa and Staphylococcus aureus with the capacity to form biofilm. The minimum inhibitory concentration was 117.5 µg/mL for the chemical and 5.3 µg/mL for the biological nanoparticles. Both types of nanoparticles showed antibiofilm activity in the qualitative Congo red test and in the quantitative microplate test. Antibiofilm activity tests on fresh lettuce showed that biological nanoparticles decreased the population of S. aureus and P. aeruginosa by 0.63 and 2.38 logarithms, respectively, while chemical nanoparticles had little microbial reduction. In conclusion, the biologically synthesized nanoparticles showed greater antibiofilm activity. Therefore, these results suggest their potential application in the formulation of sanitizing products for the food and healthcare industries.

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Nanomedicine is an interdisciplinary field where nanostructured objects are applied to treat or diagnose disease. Nanoparticles (NPs) are a special class of materials at nanometric scale that can be prepared from lipids, polymers, or noble metals through bottom-up approaches. Biological synthesis is a reliable, sustainable, and non-toxic bottom-up method that uses phytochemicals, microorganisms, and enzymes to induce the reduction of metal ions into NPs. Silver (Ag) NPs exhibit potent therapeutic properties that can be exploited to overcome the limitations of current treatment modalities for human health issues such as lung cancer (LC). Here, we review the preparation of AgNPs using biological synthesis and their application against LC using in vitro and in vivo models. An overview of the staging, diagnosis, genetic mutations, and treatment of LC, as well as its main subtypes, is presented. A summary of the reaction mechanisms of AgNPs using microbial cell cultures, plant extracts, phytochemicals, and amino acids is included. The use of capping agents in the biosynthesis of AgNPs with anticancer activity is also detailed. The history and biological activities of metal-based nanostructures synthesized with gold, copper, palladium, and platinum are considered. The possible anticancer mechanisms of AgNPs against LC models are covered. Our perspective about the future of AgNPs in LC treatment and nanomedicine is added.

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Metallic nanoparticles currently show multiple applications in the industrial, clinical and environmental fields due to their particular physicochemical characteristics. Conventional approaches for the synthesis of silver nanoparticles (AgNPs) are based on physicochemical processes which, although they show advantages such as high productivity and good monodispersity of the nanoparticles obtained, have disadvantages such as the high energy cost of the process and the use of harmful radiation or toxic chemical reagents that can generate highly polluting residues. Given the current concern about the environment and the potential cytotoxic effects of AgNPs, once they are released into the environment, a new green chemistry approach to obtain these nanoparticles called biosynthesis has emerged. This new alternative process counteracts some limitations of conventional synthesis methods, using the metabolic capabilities of living beings to manufacture nanomaterials, which have proven to be more biocompatible than their counterparts obtained by traditional methods. Among the organisms used, fungi are outstanding and are therefore being explored as potential nanofactories in an area of research known as mycosynthesis. For all the above, this paper aims to illustrate the advances in state of the art in the mycosynthesis of AgNPs, outlining the two possible mechanisms involved in the process, as well as the AgNPs stabilizing substances produced by fungi, the variables that can affect mycosynthesis at the in vitro level, the applications of AgNPs obtained by mycosynthesis, the patents generated to date in this field, and the limitations encountered by researchers in the area.

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The demand for metallic nanoparticles synthesized using green methods has increased due to their various therapeutic and clinical applications, and plant biotechnology may be a potential resource facilitating sustainable methods of AgNPs synthesis. In this study, we evaluate the capacity of extracts from Randia aculeata cell suspension culture (CSC) in the synthesis of AgNPs at different pH values, and their activity against pathogenic bacteria and cancer cells was evaluated. Using aqueous CSC extracts, AgNPs were synthesized with 10% (w/v) of fresh biomass and AgNO3 (1 mM) at a ratio of 1:1 for 24 h of incubation and constant agitation. UV-vis analysis showed a high concentration of AgNPs as the pH increased, and TEM analysis showed polydisperse nanoparticles with sizes from 10 to 90 nm. Moreover, CSC extracts produce reducing agents such as phenolic compounds (162.2 ± 27.9 mg gallic acid equivalent/100 g biomass) and flavonoids (122.07 ± 8.2 mg quercetin equivalent/100 g biomass). Notably, AgNPs had strong activity against E. coli, S. pyogenes, P. aeruginosa, S. aureus, and S. typhimurium, mainly with AgNPs at pH 6 (MIC: 1.6 to 3.9 µg/mL). AgNPs at pH 6 and 10 had a high antiproliferative effect on cancer cells (IC50 < 5.7 µg/mL). Therefore, the use of cell suspension cultures may be a sustainable option for the green synthesis of AgNPs.

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The insect Plutella xylostella is known worldwide to cause severe damage to brassica plantations because of its resistance against several groups of chemicals and pesticides. Efforts have been conducted to overcome the barrier of P. xylostella genetic resistance. Because of their easy production and effective insecticidal activity against different insect orders, silver nanoparticles are proposed as an alternative for agricultural pest control. The use of entomopathogenic fungi for nanoparticle production may offer additional advantages since fungal biomolecules may synergistically improve the nanoparticle's effectiveness. The present study aimed to synthesize silver nanoparticles using aqueous extracts of Beauveria bassiana, Metarhizium anisopliae, and Isaria fumosorosea isolates and to evaluate their insecticidal activity against P. xylostella, as innovative nano-ecofriendly pest control. The produced silver nanoparticles were evaluated by measuring the UV-vis spectrum and the mean particle size by dynamic light scattering (DLS). I. fumosorosea aqueous extract with 3-mM silver nitrate solution showed the most promising results (86-nm mean diameter and 0.37 of polydispersity). Scanning electron microscopy showed spherical nanoparticles and Fourier-Transform Infrared Spectroscopy revealed the presence of amine and amide groups, possibly responsible for nanoparticles' reduction and stabilization. The CL50 value of 0.691 mg mL-1 was determined at 72-h for the second-instar larvae of the P. xylostella, promoting a 78% of cumulative mortality rate after the entire larval stage. From our results, the synthesis of silver nanoparticles mediated by entomopathogenic fungi was successful in obtaining an efficient product for insect pest control. The I. fumosorosea was the most suitable isolate for the synthesis of silver nanoparticles contributing to the development of a green nanoproduct and the potential control of P. xylostella.

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Silver nanoparticles are widely used in the biomedical and agri-food fields due to their versatility. The use of biological methods for the synthesis of silver nanoparticles has increased considerably due to their feasibility and high biocompatibility. In general, microorganisms have been widely explored for the production of silver nanoparticles for several applications. The objective of this work was to evaluate the use of entomopathogenic fungi for the biological synthesis of silver nanoparticles, in comparison to the use of other filamentous fungi, and the possibility of using these nanoparticles as antimicrobial agents and for the control of insect pests. In addition, the in vitro methods commonly used to assess the toxicity of these materials are discussed. Several species of filamentous fungi are known to have the ability to form silver nanoparticles, but few studies have been conducted on the potential of entomopathogenic fungi to produce these materials. The investigation of the toxicity of silver nanoparticles is usually carried out in vitro through cytotoxicity/genotoxicity analyses, using well-established methodologies, such as MTT and comet assays, respectively. The use of silver nanoparticles obtained through entomopathogenic fungi against insects is mainly focused on mosquitoes that transmit diseases to humans, with satisfactory results regarding mortality estimates. Entomopathogenic fungi can be employed in the synthesis of silver nanoparticles for potential use in insect control, but there is a need to expand studies on toxicity so to enable their use also in insect control in agriculture.

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Introdução: Nos últimos anos ocorreu o aumento de casos relacionados com a infecção por Candida spp. e Staphylococcus spp., bem como o aparecimento de cepas resistentes a antibióticos convencionais. A biossíntese de nanopartículas consiste na redução de um íon metálico por compostos de origem natural como metabólitos secundários de plantas e organismos, sendo a forma mais indicada por apresentar menor toxicidade quando comparada à síntese química. Desta forma, a síntese biológica constitui uma alternativa para a obtenção de novos agentes ativos para o tratamento de infecções microbianas. Objetivos: Sintetizar nanopartículas de prata a partir do extrato aquoso de Mikania glomerata Sprengel e avaliar possível atividade microbicida e citotóxica. Material e Métodos: Para a síntese das nanopartículas de prata (AgNPs) foi utilizado um extrato aquoso das folhas de M. glomerata e uma solução de nitrato de prata. As AgNPs sintetizadas foram avaliadas por espectrofotômetro UV-vis e espectrometria de absorção atômica com chama. Além disso, a atividade antimicrobiana foi avaliada contra cepas de Candida albicans e Staphylococcus aureus e atividade citotóxica contra linhagens celulares HeLa e Vero. Resultados: As AgNPs são mais eficientes no combate à linhagem de Candida albicans e Staphylococcus aureus quando comparadas ao extrato puro administrado. Até a concentração de 100 mg/mL do extrato puro não foi observado efeito inibitório em ambos os micro-organismos. Entretanto quando em contato com as AgNPs, a concentração inibitória foi de 0,006 mg/mL e 0,1 mg/mL para S. aureus e C. albicans, respectivamente. O efeito citotóxico nas células se comportou de maneira dose-dependente, apresentando maior potencial citotóxico contra a linhagem celular cancerosa HeLa. Conclusão: As AgNPs sintetizadas apresentaram potencial antimicrobiano contra C. albicans e S. aureus, além de baixa atividade contra células normais, indicando sua confiabilidade para aplicação das AgNPs como forma alternativa de tratamento. Estes resultados são promissores e contribuem para pesquisa relacionada à produção de medicamentos utilizando extrato de plantas e metais.

Introduction: In recent years there has been an increase in cases related to infection by Candidaspp. and Staphylococcus spp., as well as the appearance of strains resistant to conventional antibiotics. Nanoparticle biosynthesis consists of the reduction of a metal ion by compounds of natural origin as secondary metabolites of plants and organisms, being the most indicated form because it presents less toxicity when compared to the chemical synthesis. In this way, the biological synthesis is an alternative to obtain new active agents for the treatment of microbial infections. Objective: Synthesize silver nanoparticles from the aqueous extract of Mikania glomerata Sprengel and evaluate possible microbicidal and cytotoxic activity. Material and Methods: For the synthesis of the silver nanoparticles (AgNPs) an aqueous extract of the leaves of Mikania glomerata plus a solution of silver nitrate was used. AgNPs synthesized was evaluated by UV-vis spectrophotometer and FAAS. Furthermore, antimicrobial activity was evaluated against strains of Candida albicans and Staphylococcus aureus and cytotoxicity activity against HeLa and Vero cell lines. Results: AgNPs are shown to be more efficient in combating Candida albicans and Staphylococcus aureusstrains when compared to the pure administered extract. Up to the concentration of 100 mg/mL of the pure aqueous extract no inhibitory effect was observed on both microorganisms. However when the strains were in contact with AgNPs, the inhibitory concentration was 0.006 mg/mL and 0.1 mg/mL for S. aureus and C. albicans, respectively. The cytotoxic effect on the cells behaves in a dose-dependent manner, presenting greater cytotoxic potential against the HeLa cancer cell line. Conclusion: Thus, these results are promising and contribute to research related to the production of drugs using plant extract and metals. The AgNPs synthesized presented the antimicrobial potential against C. albicans and S. aureus, in addition to low activity against normal cells, indicating their reliability for application of AgNPs as an alternative form of treatment.

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Multidrug-resistant bacteria (MDRB) are extremely dangerous and bring a serious threat to health care systems as they can survive an attack from almost any drug. The bacteria's adaptive way of living with the use of antimicrobials and antibiotics caused them to modify and prevail in hostile conditions by creating resistance to known antibiotics or their combinations. The emergence of nanomaterials as new antimicrobials introduces a new paradigm for antibiotic use in various fields. For example, silver nanoparticles (AgNPs) are the oldest nanomaterial used for bactericide and bacteriostatic purposes. However, for just a few decades these have been produced in a biogenic or bio-based fashion. This review brings the latest reports on biogenic AgNPs in the combat against MDRB. Some antimicrobial mechanisms and possible silver resistance traits acquired by bacteria are also presented. Hopefully, novel AgNPs-containing products might be designed against MDR bacterial infections.