Fernanda Ferraz Camilo

Neisseria gonorrhoeae is the causative agent of gonorrhea, one of the most common sexually transmitted infections globally. Due to its increasing resistance to available antibiotics, it has been classified by the World Health Organization as a high-priority pathogen for the development of new antimicrobial strategies. In this context, natural products represent a valuable source of structurally diverse bioactive compounds and continue to serve as an inspiration for antibacterial discovery. However, their clinical application is often limited by poor solubility and low bioavailability. The incorporation of nanomaterials such as silver nanoparticles (AgNPs) has emerged as a promising strategy to overcome these limitations and improve the biological performance of natural product-based systems. In this study, combinations of gibbilimbol B analogues with AgNPs were prepared and evaluated for their in vitro bactericidal activity against N. gonorrhoeae. The individual compounds exhibited moderate bactericidal activity and low cytotoxicity toward mammalian cells, whereas combinations with AgNPs enhanced antibacterial efficacy. At the tested concentrations, the combination of AgNPs with analogue 4 showed a bactericidal effect significantly greater than the combined effect expected from the individual components, supporting a synergistic interaction under this specific experimental condition. Furthermore, the individual compounds, AgNPs, and selected AgNP–gibbilimbol analogue combinations retained bactericidal activity against antimicrobial-resistant gonococcal isolates from the CDC/FDA collection. This is the first study to combine gibbilimbol analogues with AgNPs and evaluate the bactericidal activity of these mixtures, highlighting the potential of such combinations as a novel antibacterial strategy against drug-resistant N. gonorrhoeae.

Sour rot caused by Geotrichum citri-aurantii is one of the most destructive postharvest diseases affecting citrus fruits, mainly the ‘Lima’ variety, leading to severe economic losses. Beyond its economic impact, the management of postharvest diseases is linked to global efforts to reduce food losses and decrease reliance on synthetic agrochemicals, aligning with the Sustainable Development Goals related to responsible production. In this context, active coating-based strategies have emerged as promising alternatives to conventional fungicides. In this study, in vitro and in vivo experiments were conducted to evaluate the antifungal capabilities of an emulsion produced by mixing a chitosan solution with the major constituents of oregano ( Origanum vulgare) essential oil - carvacrol, thymol, and p-cymene . We also treated postharvest oranges with this emulsion to evaluate. The physicochemical quality and defense enzyme activity. The formulated emulsion exhibited a broad oil droplet size distribution in the micrometric range and a good film-forming capacity. In vitro experiments demonstrated complete inhibition of colony formation at 0.25 µL mL⁻¹ and inhibition of mycelial growth at 3.00 µL mL⁻¹, whereas lower antifungal efficacy was observed in the vapor phase. When applied to orange fruit, the emulsion at 7.5 µL mL⁻¹ reduced disease severity. The treatment also maintained higher firmness values and more stable pH and color attributes at the evaluated sampling times. Changes in the activity of enzymes were also observed at specific sampling times following treatment. Overall, the results indicate that the emulsion is a promising alternative for controlling sour rot while preserving the postharvest quality of citrus fruits.

Soft photonic materials capable of maintaining optical functionality under large mechanical deformation are highly desirable for wearable photonics, flexible sensors, optical and mechanically adaptive photonic systems. Here, we report highly stretchable luminescent elastomers based on the thermoplastic copolymer PEBAX 2533 incorporating a europium β‐diketonate complex. The transparent films combine intense europium emission with exceptional mechanical flexibility, displaying elongation at break exceeding 1200%, while maintaining high optical transparency in the visible range. The elastomers exhibit intense red luminescence with absolute quantum yields of 0.61. Under mechanical deformation, the ⁵ D ₀ → ⁷ F ₀ transition shows a strain‐dependent spectral shift and intensity modulation, enabling optical strain readout with sensitivities of –1.6 ± 0.2 cm ⁻¹ ·ε ⁻¹ and −0.44 ± 0.04 ε ⁻¹ , respectively. The luminescence spectra also display a thermal dependence, characterized by a blue shift and intensity decrease of the Eu ³⁺ emission with a temperature sensitivity of 0.08 ± 0.01 cm ⁻¹ ·°C ⁻¹ over the investigated temperature range. The coexistence of large deformability, high transparency, efficient Eu ³⁺ emission, and two independently calibrated optical responses establishes Eu‐doped elastomers as a versatile soft photonic platform for multimodal optical transduction, highlighting their potential for flexible sensing technologies in which mechanical and thermal perturbations are optically encoded within the same material platform.

Silver nanoparticles (AgNPs) have attracted considerable attention due to their outstanding catalytic and antimicrobial properties. Nevertheless, most aqueous syntheses yield colloids with low metal concentrations and limited long-term stability, restricting their practical use. To address these challenges, highly concentrated and stable AgNP dispersions were prepared, reaching concentrations of up to 100 mM, by chemical reduction of AgBF4 with tetrabutylammonium borohydride in the presence of polyvinylpyrrolidone (PVP) as a stabilizer. The dispersions contained predominantly spherical nanoparticles with narrow size distributions and remained stable for at least 1 month. For improved reusability, the AgNPs were incorporated into regenerated cellulose films produced in 1-butyl-3-methylimidazolium chloride. Owing to its abundance, renewability, and biocompatibility, cellulose provides a sustainable and environmentally friendly platform for supporting metal nanoparticles, offering easy handling and potential for reuse. The resulting AgNP-cellulose composites contained up to 5 wt % of silver and preserved the cellulose type II structure. Structural, thermal, and morphological analyses confirmed the homogeneous distribution of PVP-stabilized AgNPs within the matrix. The hybrid films exhibited high catalytic activity toward 4-nitrophenol reduction and could be reused for at least five consecutive cycles with minimal loss of performance. In addition, antibacterial assays against Escherichia coli (ATCC 8739) and Staphylococcus aureus (ATCC 25923) showed antibacterial activity, with a statistically supported and concentration-dependent response that was more pronounced for the Gram-positive strain. This work demonstrates a straightforward strategy to combine concentrated AgNP dispersions and cellulose supports, yielding recyclable catalytic and antimicrobial materials.

Ordered mesoporous silica materials have attracted considerable attention due to their unique structural, textural, and morphological properties, alongside their versatile applications in catalysis, adsorption, and drug delivery systems. This study explores the influence of ionic liquids (ILs) on the synthesis of SBA-15 and SBA-15/CeO₂ nanocomposites. DMIBr (1-dodecyl-3-methylimidazolium bromide) and DMIBF₄(1-dodecyl-3-methylimidazolium tetrafluoroborate) were the analyzed ILs. The objective was to evaluate how these ILs modulate the structural, textural, and morphological properties of the resulting nanocomposites. SAXS analysis confirmed the formation of well-ordered mesoporous structures with hexagonal arrangements, corroborating with physisorption data and TEM images. XRD measurements confirmed the presence of CeO₂ nanoparticles within the nanocomposites, exhibiting a fluorite-type cubic crystal structure, supported by Raman spectroscopy, which identified characteristic peaks corresponding to Ce–O vibrational modes. XPS analysis provided detailed insights into the surface chemistry, revealing the presence of Ce³⁺ and Ce⁴⁺ ions, oxygen species, and their interaction with the silica matrix. The Ce³⁺ ions, associated with oxygen vacancies in the CeO₂ lattice, were identified as key active sites for adsorption and catalysis. SEM images displayed distinct morphologies of the nanocomposites, attributed to the specific used IL. These results underscore the pivotal role of ILs in tailoring the properties of SBA-15/CeO₂ nanocomposites, offering valuable knowledge for their potential applications in diverse fields.

This study investigates the adsorption and reduction of NO₂ on biochar (BCC) and silver-modified biochar (Ag-BCC) in a continuous flow. Ag-BCC showed a higher NO₂ adsorption capacity (11.78 mg/g) than BCC (11.04 mg/g) at 200 °C, despite its lower surface area (345 vs. 402 m²/g). While neither material decomposed NO₂ at 22 °C, Ag-BCC achieved a NO/NO₂ ratio of 20% (vs. 9% for BCC) at 200 °C, highlighting the catalytic role of silver in NO₂ conversion. Breakthrough curve modeling identified the Dose–Response model as optimal, accurately describing adsorption kinetics at all temperatures (22–200 °C). Adsorption rate constants decreased with increasing temperature, confirming exothermicity. Overall, the results highlight the enhanced performance of Ag-BCC for NO₂ capture and conversion, underlining the potential of surface-modified biochars in the sustainable mitigation of air pollution.

Bimetallic nanoparticles (BNPs) have attracted much attention recently due to their improved properties compared to monometallic ones. Gold and silver nanoparticles (AuAgNPs) are among the most studied BNPs. Using these particles as powder or dispersion has drawbacks such as ease of aggregation and difficulty separating and recovering from the reaction medium. Therefore, immobilizing these nanoparticles in polymeric matrices, such as cellulose, is appealing. In this context, the present work focused on preparing unmodified cellulose membranes containing AuAgNPs for use as heterogeneous catalysts in reducing the pollutant 4-nitrophenol. Incorporating these nanoparticles into cellulose membranes represents a significant advancement in heterogeneous catalysis. In addition to being eco-friendly, cellulose membranes offer ease of handling and the potential for reusability, which are crucial factors in catalysis. The nanoparticles were prepared in an aqueous medium from the seeded growth of a silver shell around AuNP seeds. Images recorded by transmission electron microscopy showed that the particles have diameters smaller than 100 nm and are core-shell type. The cellulose membrane was prepared by dissolving microcrystalline cellulose in an ionic liquid, followed by a regeneration process using water. Next, the bimetallic nanoparticles were incorporated into the cellulose membrane. The analyses revealed that the membranes contain bimetallic nanoparticles homogeneously distributed in the matrix, and the inductively coupled plasma-optical emission spectroscopy (ICP-OES) showed that the membrane has 0.339 wt % in silver and 0.069% in gold. The membranes produced were efficient heterogeneous catalysts in reducing 4-nitrophenol, used for at least four cycles without loss of efficiency. This material can be easily isolated from the reaction medium, avoiding centrifugation or filtration processes for reuse. This study represents the first use of AuAgNPs supported on nonmodified cellulose membranes as heterogeneous catalysts, marking an advancement in catalysis and material science.

This study focuses on comparing the efficiency of commercially available TiO₂ (P25) with synthesized TiO₂ nanoparticles (TiO₂NP) impregnated in nonmodified cellulose membranes, specifically targeting the degradation of Indigo Carmine (IC) dye. We developed a novel method to enhance the interaction between cellulose and TiO₂, thereby improving efficiency and reusability. This involves dissolving microcrystalline cellulose in 1-butyl-3-methylimidazolium chloride (BMImCl) and dispersing the TiO₂ samples within this solution. The resulting cellulose membrane embedded with TiO₂ nanoparticles (TiO₂NP) exhibited a higher adsorption capacity and greater photocatalytic efficiency against IC compared to that of P25. This improvement is attributed to the larger surface area and increased reactivity of the synthesized TiO₂NPs. Furthermore, the CEL_TiO₂NP membranes demonstrated excellent stability and reusability, maintaining their catalytic efficiency over multiple cycles. This study presents new opportunities for developing efficient, reusable photocatalytic materials for environmental remediation using eco-friendly cellulose.