Nanocellulose (NC) is a promising material for drug delivery due to its high surface area-to-volume ratio, biocompatibility, biodegradability, and versatility in various formats (nanoparticles, hydrogels, microspheres, membranes, and films). In this study, nanocellulose films were derived from “Bolaina blanca” (Guazuma crinita) and combined with nanoporous silicon microparticles (nPSi) in concentrations ranging from 0.1% to 1.0% (w/v), using polyvinyl alcohol (PVA) as a binding agent to create NC/nPSi composite films for drug delivery systems. The physicochemical properties of the samples were characterized using UV-Vis spectroscopy, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy–attenuated total reflectance (FTIR–ATR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The mechanical properties and drug release capabilities were also evaluated using methylene blue (MB) as an antibacterial drug model. Antibacterial assays were conducted against S. aureus and E. coli bacteria. The results show that NC/nPSi composites with 1% nPSi increased the T_50% by 10 °C and enhanced mechanical properties, such as a 70% increase in the elastic modulus and a 372% increase in elongation, compared to NC films. Additionally, MB released from NC/nPSi composites effectively inhibited the growth of both bacteria. It was also observed that the diffusion coefficients were inversely proportional to the % nPSi. These findings suggest that this novel NC/nPSi-based material can serve as an effective controlled drug release system.

The development of pH-sensitive microcapsules based on natural antioxidants from Peruvian purple corn (Zea mays L.) cob was successfully achieved using various wall materials, including maltodextrin, gum arabic, and soy protein isolate, via spray drying. The proportions of wall materials were optimized using a mixed simplex-centroid design, resulting in a microencapsulation efficiency of 95-98 %. The total polyphenol content was 2-3 mg of gallic acid equivalents per g of microcapsules, while the anthocyanin content was 2-3 mg/g of microcapsules. The physicochemical properties of the resulting microencapsulated anthocyanin-rich powders (MAP) were evaluated at different intervals (0 and 48 h) and pH levels (4, 7, and 10). The microcapsules exhibited remarkable color stability (∆E* < 1) at pH 4 and 7 over 48 h, with minimal variations in the a* values across pH levels, demonstrating their capacity to retain the characteristic red hue of anthocyanin over time and across varying pH conditions. A structural X-ray diffraction (XRD) analysis showed a semicrystalline structure in all formulations. Fourier-transform infrared (FTIR) analysis revealed that the anthocyanin extract interacted with the wall materials through hydrogen bonding and hydrophobic interactions. The morphological analysis by scanning electron microscopy (SEM) showed that microcapsules with equal proportions of encapsulating agents exhibited fewer surface irregularities than those made with single-wall materials. These results underscore the stability of microcapsules, highlighting their potential as natural antioxidants for applications in the food industry and intelligent packaging.

ZnO nanorods (NRs) films, nitrogen-doped (ZnO:N), and ZnO doped with nitrogen and decorated with silver nanostructures (ZnO:N-Ag) NRs films were vertically supported on undoped and N doped ZnO seed layers by a wet chemical method. The obtained films were characterized structurally by X-ray diffraction. Morphological and elemental analysis was performed by scanning electron microscopy, including an energy dispersive X-ray spectroscopy facility and their optical properties by Ultraviolet-Visible Spectroscopy. Analysis performed in the NRs films showed that the nitrogen content in the seed layer strongly affected their structure and morphology. The mean diameter of ZnO NRs ranged from 70 to 190 nm. As the nitrogen content in the seed layer increased, the mean diameter of ZnO:N NRs increased from 132 to 250 nm and the diameter dispersion decreased. This diameter increase occurs simultaneously with the incorporation of nitrogen into the ZnO crystal lattice and the increase in the volume of the unit cell, calculated using the X-ray diffraction patterns and confirmed by a slight shift in the XRD angle. The diffractograms indicated that the NRs have a hexagonal wurtzite structure, with preferential growth direction along the c axis. The SEM images confirmed the presence of metallic silver in the form of nanoparticles dispersed on the NRs films. Finally, the degradation of methyl orange (MO) in an aqueous solution was studied by UV-vis irradiation of NRs films contained in the bulk of aqueous MO solutions. We found a significant enhancement of the photocatalytic degradation efficiency, with ZnO:N-Ag NRs film being more efficient than ZnO:N NRs film, and the latter better than the ZnO NRs film.

This paper focuses on the synthesis of cobalt ferrite nanoparticles by the sol–gel method and their photocatalytic activity to eliminate bacteria in aqueous media at two different scales: in a laboratory reactor and a solar pilot plant. Cobalt ferrite nanoparticles were prepared using Co(II) and Fe(II) salts as precursors and cetyltrimethyl ammonium bromide as a surfactant. The obtained nanoparticles were characterized by X-ray diffraction, scanning and transmission electron microscopy. Escherichia coli (E. coli) strain ATCC 22922 was used as model bacteria for contact biocidal analysis carried out by disk diffusion method and photocatalysis under an ultraviolet A (UV-A) lamp for laboratory analysis and solar radiation (radiation below 350 W/m² in a typical cloudy day) for the pilot plant analysis. The results showed that cobalt ferrite nanoparticles have an average diameter of (36 ± 20) nm and the X-ray diffraction pattern shows a cubic spinel structure. Using the disk diffusion technique, it was obtained inhibition zones of (17 ± 2) mm diameter. Results confirm the photocatalytic elimination of E. coli in water samples with remaining bacteria below 1% of the initial concentration during the experiment time (30 min for laboratory tests and 1.5 h for pilot plant tests).

Background and Objective: A previous study investigated the in vitro release of methylene blue (MB), a widely used cationic dye in biomedical applications, from nanocellulose/nanoporous silicon (NC/nPSi) composites under conditions simulating body fluids. The results showed that MB release rates varied significantly with the nPSi concentration in the composite, highlighting its potential for controlled drug delivery. To further analyze the relationship between diffusion dynamics and the MB concentration, this study developed a finite element (FE) method to solve Fick’s equations governing the drug delivery system. Methods: Release profiles of MB from NC/nPSi composites with varying nPSi concentrations (0%, 0.1%, 0.5%, and 1.0%) were experimentally measured in triplicate using phosphate-buffered saline (PBS) at 37 °C, pH 7.4, and 100 rpm. Mathematical models incorporating linear and quadratic dependencies of the diffusion coefficient on the MB concentration were developed and tested using the FE method. Model parameters were refined by minimizing the error between simulated and experimental MB release profiles. Results: The proposed FE method closely matched experimental data, validating its accuracy and robustness in simulating the diffusion and release processes. Conclusions: This study emphasizes the significant impact of the nPSi concentration on enhancing release control and highlights the importance of material composition in designing drug delivery systems. The findings suggest that the FE method can be effectively applied to model other complex systems, paving the way for advancements in precision drug delivery and broader biomedical applications.