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This work aims to produce hybrid materials with potential applications in dye photodegradation. Therefore, hybrid films were obtained by incorporating cobalt (II, III) oxide (Co 3 O 4 ) or cobalt ferrite (CoFe 2 O 4 ) nanoparticles (NPs) with 18 ± 1.6 nm and 26 ± 1.3 nm, respectively, into a poly 3-hydroxybutyrate (P3HB) polymeric matrix. The Co 3 O 4 @P3HB and CoFe 2 O 4 @P3HB hybrid films were fabricated by solvent casting in a ratio of 85 mg to 15 mg (P3HB-NPs). Different spectroscopic and microscopy techniques characterized the Co 3 O 4 and CoFe 2 O 4 NPs and the P3HB, Co 3 O 4 @P3HB and CoFe 2 O 4 @P3HB films. The optical band gap for Co 3 O 4 and CoFe 2 O 4 NPs was estimated from their diffuse reflectance spectra (DRS) around 2.5 eV. X-ray diffraction (XRD) of the hybrid films revealed that the nanometric sizes of the Co 3 O 4 and CoFe 2 O 4 nanoparticles incorporated into the P3HB are preserved. The magnetic hysteresis curve of CoFe 2 O 4 nanoparticles and CoFe 2 O 4 @P3HB film showed a ferromagnetic behaviour at 300 K. Transmission electron microscopy (TEM) confirmed the formation of nanocrystals, and scanning electron microscopy (SEM) provided evidence for the successful incorporation of the NPs into the P3HB matrix. The surface roughness and hydrophilicity of the hybrid films are increased compared to the P3HB film. The impact of the nanoparticles and the hybrid films on the photodegradation of methyl orange (MO) in its acidic form was studied. The photodegradation tests were carried out by direct sunlight exposure. The CoFe 2 O 4 @P3HB hybrid film achieved 85% photodegradation efficiency of a methyl orange solution of 20 ppm after 15 minutes of exposure to sunlight. After 30 minutes of exposure to sunlight, the nanoparticles and the hybrid films reached about 90% of the MO degradation. The results suggest that combining nanoparticles with the polymer significantly enhances photodegradation compared to isolated nanoparticles.

An easy mechanochemical and eco-friendly method was employed to obtain nanocrystals with an average size of about 9 nm of zinc ferrite (ZnFe 2 O 4 ) and copper ferrite (CuFe 2 O 4 ). Their corresponding X-ray diffraction (XRD) patterns reveal a cubic crystal structure for ZnFe 2 O 4 , whereas in CuFe 2 O 4 the tetragonal and cubic crystal phases coexist, the latter being the majority phase. The transmission electron microscopy (TEM) images of these nano ferrites corroborate the formation of nanocrystals with dimensions consistent with those obtained from the XRD patterns. Furthermore, their corresponding Raman spectra confirm the structure and composition of nano ferrites. In addition, both nano ferrites show an electron paramagnetic resonance (EPR) spectrum with a wide band with g ~ 2.0, characteristic of ferromagnetic oxides. Besides, the antibacterial effect of ZnFe 2 O 4 and CuFe 2 O 4 nanocrystals against two opportunistic pathogens, Staphylococcus epidermidis (ATCC 14,990) and Pseudomonas aeruginosa (ATCC 43,636), was tested. The minimum bactericidal concentration (MBC) results showed that ZnFe 2 O 4 was more effective against S. epidermidis , while CuFe 2 O 4 was for P. aeruginosa . On the other hand, when 27 mg/mL of nano ferrites were dispersed in the agar plates, the growth of S . epidermidis was 100% inhibited, whereas ZnFe 2 O 4 and CuFe 2 O 4 inhibited 67% and 78% of P. aeruginosa growth, respectively.

[This corrects the article DOI: 10.1371/journal.pone.0312611.].

Magnesium aluminate spinel nanoparticles (MgAl2O4-S-NPs) represent a promising class of nanoceramics with potential biomedical applications due to their physicochemical stability and antimicrobial properties. This study aimed to determine the structural characteristics, composition, and biological performance of MgAl2O4 spinel nanoparticles that were synthesized via a mechanochemical method. Structural and compositional characterization was performed using X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM). Antibacterial activity was evaluated against Helicobacter pylori and Enterococcus faecalis using bacterial viability assays. Structural and morphological analyses confirmed the successful formation of single-phase cubic MgAl2O4 with a polyhedral morphology and nanoscale size distribution. Bacterial viability was quantified through optical density measurements following exposure to MgAl2O4-S-NPs at different concentrations. The nanoparticles exhibited both bacteriostatic and bactericidal effects, with activity being demonstrated against the tested bacterial strains. Mechanochemically synthesized MgAl2O4-S-NPs are promising candidates for biomedical applications, including dental materials, antimicrobial coatings, and infection-control strategies. Overall, the findings highlight the potential of MgAl2O4-S-NPs as effective antimicrobial agents that can be produced through an environmentally friendly synthesis route.

Hybrid films for applications in organic electronics from NiFe2O4 nanoparticles (NPs) in poly(3,4 ethylene dioxythiophene), poly(4-styrenesulfonate) (PEDOT:PSS), and poly(methyl methacrylate) (PMMA) were fabricated by the spin-coating technique. The films were characterized by infrared spectroscopy, atomic force microscopy, scanning electron microscopy, and energy-dispersive spectroscopy to subsequently determine their optical parameters. The electronic transport of the hybrid films was determined in bulk heterojunction devices. The presence of NiFe2O4 NPs reinforces mechanical properties and increases transmittance in the hybrid films; the PEDOT:PSS-NiFe2O4 NPs film is the one that has a maximum stress of 28 MPa and a Knoop hardness of 0.103, while the PMMA-NiFe2O4 NPs film has the highest transmittance of (87%). The Tauc band gap is in the range of 3.78–3.9 eV, and the Urbach energy is in the range of 0.24–0.33 eV. Regarding electrical behavior, the main effect is exerted by the matrix, although the current carried is of the same order of magnitude for the two devices: glass/ITO/polymer-NiFe2O4 NPs/Ag. NiFe2O4 NPs enhance the mechanical, optical, and electrical behavior of the hybrid films and can be used as semi-transparent anodes and as active layers.

This study presents an in vitro analysis of the bactericidal and cytotoxic properties of hybrid films containing nickel oxide (NiO) and nickel ferrite (NiFe2O4) nanoparticles embedded in polypropylene (PP). The solvent casting method was used to synthesize films of PP, PP@NiO, and PP@NiFe2O4, which were characterized by different spectroscopic and microscopic techniques. The X-ray diffraction (XRD) patterns confirmed that the small crystallite sizes of NiO and NiFe2O4 NPs were maintained even after they were incorporated into the PP matrix. From the Raman scattering spectroscopy data, it was evident that there was a significant interaction between the NPs and the PP matrix. Additionally, the Scanning Electron Microscopy (SEM) analysis revealed a homogeneous dispersion of NiO and NiFe2O4 NPs throughout the PP matrix. The incorporation of the NPs was observed to alter the surface roughness of the films; this behavior was studied by atomic force microscopy (AFM). The antibacterial properties of all films were evaluated against Pseudomonas aeruginosa (ATCC®: 43636™) and Staphylococcus aureus (ATCC®: 23235™), two opportunistic and nosocomial pathogens. The PP@NiO and PP@ NiFe2O4 films showed over 90% bacterial growth inhibition for both strains. Additionally, the effects of the films on human skin cells, such as epidermal keratinocytes and dermal fibroblasts, were evaluated for cytotoxicity. The PP, PP@NiO, and PP@NiFe2O4 films were nontoxic to human keratinocytes. Furthermore, compared to the PP film, improved biocompatibility of the PP@NiFe2O4 film with human fibroblasts was observed. The methodology utilized in this study allows for the production of hybrid films that can inhibit the growth of Gram-positive bacteria, such as S. aureus, and Gram-negative bacteria, such as P. aeruginosa. These films have potential as coating materials to prevent bacterial proliferation on surfaces.

This work focuses on the obtaining and the bactericidal properties study, in vitro, of hybrid films as potential coating materials to inhibit bacteria proliferation. In consequence, hybrid films from nickel oxide (NiO) and nickel ferrite (NiFe 2 O 4 ) nanoparticles (NPs) embedded in poly-3-hydroxybutyrate (P3HB) were obtained by the solvent casting method. P3HB@NiO and P3HB@NiFe 2 O 4 hybrid films and P3HB film were characterized by X-ray diffraction (XRD), Raman scattering, and scanning electron microscopy (SEM). The XRD of the hybrid films showed that NiO and NiFe 2 O 4 NPs incorporated in the P3HB conserved their nanometric size, and by Energy-dispersive X-ray spectroscopy (EDS) were observed that NPs are homogeneously distributed in the films. The bactericidal effect of the obtained films was evaluated in vitro from the broth surface method against two opportunistic and nosocomial pathogens, Staphylococcus aureus and Pseudomonas aeruginosa . The results showed that P3HB film, P3HB@NiO, and P3HB@NiFe 2 O 4 hybrid films reduced 90%, 98%, and 97% of the growth of S. aureus , respectively. For P. aeruginosa, their growth was reduced by 90%, 94%, and 96%, respectively. In addition, the cytotoxic effect of NiO and NiFe 2 O 4 NPs, as well as P3HB film, and P3HB@NiO, and P3HB@NiFe 2 O 4 hybrid films was evaluated using human skin cells; keratinocytes and fibroblast, being the NPs less cytotoxic than films. Although P3HB is known as a biocompatible polymer, here is demonstrated that in our work conditions, their films have bactericidal properties and are cytotoxic to keratinocytes and fibroblasts, the first barrier of the human skin. However, the P3HB@NiO and P3HB@NiFe 2 O 4 hybrid films synergize the bactericidal effect between the P3HB and the NPs. On the other hand, the NPs decrease the P3HB cytotoxicity to keratinocytes. The methodology used in this work is particularly suitable for producing hybrid films with antibacterial activity against Gram-positive and Gram-negative bacterial strains.

This work aims to produce hybrid materials with potential applications in dye photodegradation. Therefore, hybrid films were obtained by incorporating cobalt (II, III) oxide (Co.sub.3 O.sub.4) or cobalt ferrite (CoFe.sub.2 O.sub.4) nanoparticles (NPs) with 18 ± 1.6 nm and 26 ± 1.3 nm, respectively, into a poly 3-hydroxybutyrate (P3HB) polymeric matrix. The Co.sub.3 O.sub.4 @P3HB and CoFe.sub.2 O.sub.4 @P3HB hybrid films were fabricated by solvent casting in a ratio of 85 mg to 15 mg (P3HB-NPs). Different spectroscopic and microscopy techniques characterized the Co.sub.3 O.sub.4 and CoFe.sub.2 O.sub.4 NPs and the P3HB, Co.sub.3 O.sub.4 @P3HB and CoFe.sub.2 O.sub.4 @P3HB films. The optical band gap for Co.sub.3 O.sub.4 and CoFe.sub.2 O.sub.4 NPs was estimated from their diffuse reflectance spectra (DRS) around 2.5 eV. X-ray diffraction (XRD) of the hybrid films revealed that the nanometric sizes of the Co.sub.3 O.sub.4 and CoFe.sub.2 O.sub.4 nanoparticles incorporated into the P3HB are preserved. The magnetic hysteresis curve of CoFe.sub.2 O.sub.4 nanoparticles and CoFe.sub.2 O.sub.4 @P3HB film showed a ferromagnetic behaviour at 300 K. Transmission electron microscopy (TEM) confirmed the formation of nanocrystals, and scanning electron microscopy (SEM) provided evidence for the successful incorporation of the NPs into the P3HB matrix. The surface roughness and hydrophilicity of the hybrid films are increased compared to the P3HB film. The impact of the nanoparticles and the hybrid films on the photodegradation of methyl orange (MO) in its acidic form was studied. The photodegradation tests were carried out by direct sunlight exposure. The CoFe.sub.2 O.sub.4 @P3HB hybrid film achieved 85% photodegradation efficiency of a methyl orange solution of 20 ppm after 15 minutes of exposure to sunlight. After 30 minutes of exposure to sunlight, the nanoparticles and the hybrid films reached about 90% of the MO degradation. The results suggest that combining nanoparticles with the polymer significantly enhances photodegradation compared to isolated nanoparticles.

Adsorption of Pb(II) from aqueous solution using MFe2O4 nanoferrites (M = Co, Ni, and Zn) was studied. Nanoferrite samples were prepared via the mechanochemical method and were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), micro-Raman, and vibrating sample magnetometry (VSM). XRD analysis confirms the formation of pure single phases of cubic ferrites with average crystallite sizes of 23.8, 19.4, and 19.2 nm for CoFe2O4, NiFe2O4, and ZnFe2O4, respectively. Only NiFe2O4 and ZnFe2O4 samples show superparamagnetic behavior at room temperature, whereas CoFe2O4 is ferromagnetic. Kinetics and isotherm adsorption studies for adsorption of Pb(II) were carried out. A pseudo-second-order kinetic describes the sorption behavior. The experimental data of the isotherms were well fitted to the Langmuir isotherm model. The maximum adsorption capacity of Pb(II) on the nanoferrites was found to be 20.58, 17.76, and 9.34 mg·g−1 for M = Co, Ni, and Zn, respectively.