Iron Oxide–Silica Core–Shell Nanoparticles Functionalized with Essential Oils for Antimicrobial Therapies

Abstract

Recent years have witnessed a tremendous interest in the use of essential oils in biomedical applications due to their intrinsic antimicrobial, antioxidant, and anticancer properties. However, their low aqueous solubility and high volatility compromise their maximum potential, thus requiring the development of efficient supports for their delivery. Hence, this manuscript focuses on developing nanostructured systems based on Fe3O4@SiO2 core–shell nanoparticles and three different types of essential oils, i.e., thyme, rosemary, and basil, to overcome these limitations. Specifically, this work represents a comparative study between co-precipitation and microwave-assisted hydrothermal methods for the synthesis of Fe3O4@SiO2 core–shell nanoparticles. All magnetic samples were characterized by X-ray diffraction (XRD), gas chromatography-mass spectrometry (GC-MS), Fourier-transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), zeta potential, scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetry and differential scanning calorimetry (TG-DSC), and vibrating sample magnetometry (VSM) to study the impact of the synthesis method on the nanoparticle formation and properties, in terms of crystallinity, purity, size, morphology, stability, and magnetization. Moreover, the antimicrobial properties of the synthesized nanocomposites were assessed through in vitro tests on Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Candida albicans. In this manner, this study demonstrated the efficiency of the core–shell nanostructured systems as potential applications in antimicrobial therapies.

Dextran-Coated Iron Oxide Nanoparticles Loaded with Curcumin for Antimicrobial Therapies

“…The predominant effect is exothermic, which appears as a broad, combined effect, with the maximum at ~200 °C. The DSC exothermic peak at ~515 °C is attributed to the specific phase transition from maghemite to hematite, which commonly occurs after 500 °C [ 29 , 36 ].…”

“…The microwave-assisted hydrothermal method is a widely used technique for the synthesis of numerous nanoparticles, such as hydroxyapatite [ 37 , 38 , 39 ], zinc oxide [ 40 , 41 , 42 ], and copper oxide [ 43 , 44 ], as it allows for the control of the nanoparticle morphology, size, and porosity. While recent years have witnessed an increased interest in applying this method in developing iron oxide nanoparticles [ 29 , 45 , 46 , 47 ], its utilization is still limited, with most studies focusing on more readily available methods (i.e., coprecipitation). As it was indicated by the XRD and SAED results, the microwave-assisted hydrothermal method ensured the synthesis of highly crystalline iron oxide nanoparticles consisting of one or two mineral phases.…”

“…The synthesis of the drug-delivery systems involved three distinct steps. Initially, the iron oxide nanoparticles were obtained through the microwave-assisted hydrothermal method, similar to one of our previous studies [ 29 ]. Briefly, FeSO 4 ·7H 2 O and FeCl 3 ·6H 2 O were dissolved in ultrapure water (1:2 molar ratio), and the solution was dripped into an alkaline solution of NH 4 OH using a peristaltic pump.…”

An In Vitro and In Vivo Study of the Efficacy and Toxicity of Plant-Extract-Derived Silver Nanoparticles

“…The structure of the silver nanoparticles was quite distinct when synthesized using turmeric extracts. Core–shell-type spherical nanoparticles with an almost uniform distribution were observed by Chircov et al in their study of iron oxide and were reported with the help of SAED patterns as well [ 39 ]. It was also observed that when these NPs are used for healing purposes (scratch test), this led to better healing properties than others.…”

PEG-Functionalized Magnetite Nanoparticles for Modulation of Microbial Biofilms on Voice Prosthesis

“…The sample continues to slowly lose mass, 1.08%, up to 900 °C, while the residual mass is noted to be 94.88%. The exothermic peak registered at a temperature of 572.5 °C corresponds to the physical transformation of maghemite into hematite [ 53 ].…”