Synthesis, Characterization, and Evaluation of the Antimicrobial Effects and Cytotoxicity of a Novel Nanocomposite Based on Polyamide 6 and Trimetaphosphate Nanoparticles Decorated with Silver Nanoparticles Leonardo Antônio de Morais, Francisco Nunes de Souza Neto, Thayse Yumi Hosida, Danilo Martins dos Santos, Bianca Carvalho de Almeida, et al. Antibiotics, 2024 This study aimed to develop a polymeric matrix of polyamide-6 (P6) impregnated with trimetaphosphate (TMP) nanoparticles and silver nanoparticles (AgNPs), and to evaluate its antimicrobial activity, surface free energy, TMP and Ag+ release, and cytotoxicity for use as a support in dental tissue. The data were subjected to statistical analysis (p < 0.05). P6 can be incorporated into TMP without altering its properties. In the first three hours, Ag+ was released for all groups decorated with AgNPs, and for TMP, the release only occurred for the P6-TMP-5% and P6-TMP-10% groups. In the inhibition zones, the AgNPs showed activity against both microorganisms. The P6-TMP-2.5%-Ag and P6-TMP-5%-Ag groups with AgNPs showed a greater reduction in CFU for S. mutans. For C. albicans, all groups showed a reduction in CFU. The P6-TMP groups showed higher cell viability, regardless of time (p < 0.05). The developed P6 polymeric matrix impregnated with TMP and AgNPs demonstrated promising antimicrobial properties against the tested microorganisms, making it a potential material for applications in scaffolds in dental tissues.
Beneficial Bacteria Associated With Silica Nanoparticles for Growth Promotion of Paspalum notatum Amanda Carolina Prado de Moraes, Kathryn Louise Kingsley, Lucas da Silva Ribeiro, Bianca Baccili Zanotto Vigna, Emerson Rodrigues de Camargo, et al. Applied and Environmental Soil Science, 2024 Plant growth–promoting bacteria (PGPB) can play an essential role as biofertilizers to increase pasture efficiency and reduce the application of agrochemicals. Plant growth can be potentialized when these bacteria are combined with silica nanoparticles (SiNPs). The present study aimed to evaluate the effect of PGPB associated with SiNPs on the growth of bahiagrass (Paspalum notatum) seedlings. The PGPB were isolated from rhizospheric soils and leaves of Paspalum spp. grown in the tropical high‐altitude region of Brazil and selected by their ability to fix nitrogen, solubilize phosphate, and synthesize indoleacetic acid (IAA). They were identified as Alcaligenes faecalis, Enterobacter asburiae, and Serratia marcescens by 16S rDNA sequencing. Spherical SiNPs (85 nm in diameter) were synthesized by the hydrolysis of the silicon precursor tetraethyl orthosilicate (TEOS), characterized by infrared spectroscopy and scanning electron microscopy (SEM) and applied at 5% (0.05 mg·mL−1) and 10% (0.1 mg·mL−1) concentrations. Disinfected P. notatum seeds were treated with PGPB, SiNPs, and PGPB + SiNPs and cultivated in magenta boxes containing peat, sand, and perlite. The seedlings were evaluated for their germination percentage, root length, shoot length, root dry weight, and shoot dry weight. Disinfected seeds subjected to the same treatments were also grown in Petri dishes containing 0.7% agarose. The roots of the seedlings in Petri dishes were stained with diaminobenzidine tetrahydrochloride (DAB) and visualized using a light microscope to confirm bacterial colonization. The three strains without SiNPs promoted the growth of P. notatum seedlings. S. marcescens treatment presented the greatest shoot length, and both concentrations of nanosilica with PGPB improved or maintained root lengths. Treatments of S. marcescens and E. asburiae with 10% SiNPs showed 100% seed germination. Seedlings inoculated with 10% SiNPs with S. marcescens and E. asburiae alone showed the highest shoot dry weight, and all treatments increased root dry weight compared to the control. The 10% SiNPs’ concentration inoculated with S. marcescens and A. faecalis positively affected P. notatum seedlings’ growth. This study suggests that nanosilica can be applied with PGPB to improve the development of bahiagrass and reduce the need for applications of agrochemicals.
Facile Synthesis of PVP-Coated Silver Nanoparticles and Evaluation of Their Physicochemical, Antimicrobial and Toxic Activity Francisco N. Souza Neto, Leonardo A. Morais, Luiz F. Gorup, Lucas S. Ribeiro, Tassia J. Martins, et al. Colloids and Interfaces, 2023 This study focuses on the synthesis of silver nanoparticles (AgNPs) at different high concentrations and investigates their physicochemical properties, antimicrobial activity, and cytotoxicity. AgNPs were synthesized using the alcohol reduction process, involving the reduction of AgNO3 and its subsequent stabilization via PVP at 80 °C for 4 h. The AgNO3/PVP molar ratio and the average molecular weight were modified in this study. Characterization analyses revealed that the synthesized AgNPs exhibited characteristic surface plasmon resonance absorption peaks at approximately 415 nm, as observed in the UV–Vis spectrum. The results presented in X-ray diffractograms confirmed the face-centered cubic structure of metallic Ag in the nanoparticles. The nanoparticles demonstrated uniform size and shape, with controllable dimensions ranging from 3 to 800 nm. Regarding antimicrobial activity, the MIC solutions exhibited higher potency against the planktonic cells of Candida albicans. The determination of inhibition halos indicated that the silver nanoparticles had an impact on the microorganisms Streptococcus mutans, Candida albicans, and Actinomyces israelii. Furthermore, lower-concentration compositions showed reduced cytotoxic effects compared to higher-concentration particles. Based on the findings, it was concluded that the AgNO3/PVP molar ratio plays a crucial role in the production of AgNPs. These synthesized nanoparticles exhibit desirable physicochemical properties and demonstrate potential antimicrobial activity and controlled cytotoxicity.
Nanocatalysts for fuel cells Elisangela Pacheco da Silva, Vanessa Hafemann Fragal, Rafael Silva, Alexandre Henrique Pinto, Thiago Sequinel, et al. Nanotechnology in the Automotive Industry, 2022
Conductive nanopaints: A remarkable coating Maria Nayane de Queiroz, Antônia Millena de Oliveira Lima, Manuel Edgardo Gomez Winkler, Vanessa Hafemann Fragal, Adley Forti Rubira, et al. Nanotechnology in the Automotive Industry, 2022
Polymeric nanocomposites for automotive application Francisco Nunes de Souza Neto, Gabriella Ribeiro Ferreira, Thiago Sequinel, Glenda Biasotto, Sandra Andrea Cruz, et al. Smart Polymer Nanocomposites Design Synthesis Functionalization Properties and Applications, 2022
