Objective: An eucalyptus essential oil-based nanoemulsion was produced and evaluated for its antimicrobial properties against Streptococcus mutans and its cytotoxicity in the surface mucous cells of rabbits. Methods: The essential oil-based nanoemulsion was synthesized with two species of eucalyptus—Eucalyptus citriodora and Eucalyptus globulus—followed by physicochemical characterization and the determination of antimicrobial activity and cell viability. Subsequently, the mouthwash formulations (fluoride and fluoride-free) were functionalized with the nanoemulsion, and their in vitro antimicrobial actions were evaluated against S. mutans. Results: The nanoemulsion presented an average particle size of around 100 nm, a polydispersity index close to 0.3, a zeta potential between −19 and −30 mV, a pH close to 7, a spherical shape, and a cell viability above 50%. The antimicrobial activity analysis showed that the nanoemulsion was effective in the control of S. mutans. The mouthwashes functionalized with the nanoemulsion also presented bacteriostatic and bactericidal properties. Conclusions: The bio-based material produced with eucalyptus essential oil presented adequate physicochemical characteristics, with the potential to be used as an innovative material in preventive dentistry, contributing to the maintenance of oral and systemic health.

The increasing demand for sustainable alternatives to non-biodegradable plastic packaging is driving the development of active packaging based on biopolymers such as methylcellulose. In this study, innovative methylcellulose nanocomposite films incorporating zein nanoparticles loaded with propolis and curcumin were developed for active packaging applications. The zein nanoparticles revealed excellent physicochemical properties, with a zeta potential above 30 mV, suggesting adequate stability. Transmission electron microscopy confirmed nanoparticles containing curcumin and propolis with uniform sizes ranging from approximately 130 to 140 nm with low polydispersity. Release studies revealed that approximately 25% of the curcumin and 35% of the propolis were released from the nanoparticles within 24 h. The release mechanism was best described by the Korsmeyer–Peppas model, suggesting a sustained release profile. The nanoparticles reduced the hydrophobicity and rigidity of the films, as evidenced by a lower elastic modulus and higher percentage elongation, thereby suggesting greater flexibility. Fourier Transform Infrared Spectroscopy (FTIR) analysis revealed the incorporation of bioactive compounds in the polymer matrix. Differential scanning calorimetry (DSC) revealed the thermal parameters of the synthesized films. Furthermore, the films exhibited antibacterial and antioxidant activities, making them highly suitable for use as biodegradable active packaging.

Introduction: Oral infections pose significant public health challenges, often exacerbating other comorbidities and increasing systemic health risks. Traditional treatments often fail to eliminate persistent micro-organisms and contribute to the rise of antimicrobial resistance. Nanoparticulate systems offer a promising solution by delivering active agents directly to targeted sites, providing more effective and localized treatment options. Objective: This study aimed to synthesize and characterize methylcellulose nanoparticles containing methylene blue at different concentrations using the nanoprecipitation method. We also evaluated their biocompatibility and antimicrobial activity against key micro-organisms commonly found in oral infections. Methods: The study involved physicochemical and morphological characterizations, including encapsulation efficiency, particle size, polydispersity index, zeta potential, and transmission electron microscopy (TEM). Additionally, controlled release profiles, antimicrobial efficacy against major oral pathogens, and biocompatibility in vitro assessments were performed. Results: The results revealed encapsulation efficiency between 99.1 and 98.8%, with particle sizes ranging from 186 to 274 nm and a zeta potential of 1.7 to 2.9 mV achieved at lower concentrations of methylene blue and methylcellulose. The nanoparticles demonstrated sustained drug release of 85% for the smaller particles and 45% for the larger particles for more than 10 h. The nanoparticles exhibited superior antimicrobial activity compared to pure methylene blue. Cell viability studies indicated that the nanoparticles were biocompatible with approximately 40% cell viability at lower concentrations of the nanoparticles. Conclusions: These findings suggest that methylene blue nanoparticles could serve as a promising adjunct in dental treatments. They offer targeted antimicrobial action while potentially reducing the development of antimicrobial resistance.

Objective: This study aimed to evaluate the in vitro efficacy of silver nanoparticles (AgNPs) synthesized by bioreduction using lemongrass (Cymbopogon citratus) essential oil against multidrug-resistant (MDR) bacteria isolated from an Intensive Care Unit (ICU). Methods: The essential oil was extracted and characterized by gas chromatography–mass spectrometry (GC-MS). Antioxidant activity was assessed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay, the 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assay, and total phenolic content. AgNPs (3 mM and 6 mM silver nitrate) were characterized by UV-Vis spectroscopy, dynamic light scattering (DLS), zeta potential, transmission electron microscopy (TEM), and Fourier-transform infrared (FTIR) spectroscopy. Bacterial isolates were obtained from ICU surfaces and personal protective equipment (PPE). Results: The essential oil presented citral A, citral B, and β-myrcene as major components (97.5% of identified compounds). AgNPs at 3 mM showed smaller size (87 nm), lower Polydispersity Index (0.14), and higher colloidal stability (−23 mV). The 6 mM formulation (147 nm; PDI 0.91; −10 mV) was more effective against a strain of Enterococcus spp. resistant to all antibiotics tested. FTIR analysis indicated the presence of O–H, C=O, and C–O groups involved in nanoparticle stabilization. Discussion: The higher antimicrobial efficacy of the 6 mM formulation was attributed to the greater availability of active AgNPs. Conclusions: The green synthesis of AgNPs using C. citratus essential oil proved effective against MDR bacteria and represents a sustainable and promising alternative for microbiological control in healthcare environments.