SYNTHESIS AND APPLICATIONS OF Fe3O4/SiO2 CORE-SHELL MATERIALS

Abstract

Multifunctional nanoparticles based on magnetite/silica core-shell, consisting of iron oxides coated with silica matrix doped with fluorescent components such as organic dyes (fluorescein isothiocyanate - FITC, Rhodamine 6G) or quantum dots, have drawn remarkable attention in the last years. Due to the bi-functionality of these types of nanoparticles (simultaneously having magnetic and fluorescent properties), they are successfully used in highly efficient human stem cell labeling, magnetic carrier for photodynamic therapy, drug delivery, hyperthermia and other biomedical applications. Another application of core-shell-based nanoparticles, in which the silica is functionalized with aminosilanes, is for immobilization and separation of various biological entities such as proteins, antibodies, enzymes etc. as well as in environmental applications, as adsorbents for heavy metal ions. In vitro tests on human cancerous cells, such as A549 (human lung carcinoma), breast, human cervical cancer, THP-1 (human acute monocytic leukaemia) etc. , were conducted to assess the potential cytotoxic effects that may occur upon contact of nanoparticles with cancerous tissue. Results show that core-shell nanoparticles doped with cytostatics (cisplatin, doxorubicin, etc.), are easily adsorbed by affected tissue and in some cases lead to an inhibition of cell proliferation and induce cell death by apoptosis. The goal of this review is to summarize the advances in the field of core-shell materials, particularly those based on magnetite/silica with applicability in medicine and environmental protection. This paper briefly describes synthesis methods of silica-coated magnetite nanoparticles (Stöber method and microemulsion), the method of encapsulating functional groups based on aminosilanes in silica shell, as well as applications in medicine of these types of simple or modified nanoparticles for cancer therapy, MRI, biomarker immobilization, drug delivery, biocatalysis etc., and in environmental applications (removal of heavy metal ions and catalysis).

Antimicrobial and Physicochemical Properties of Artificial Saliva Formulations Supplemented with Core-Shell Magnetic Nanoparticles

“…The synthesis and morphology of core-shell magnetic nanoparticles are shown in Figure 8. After that, in both procedures, the nanoparticles were washed three times with water and ethanol and allowed to dry in an oven at 50 • C overnight [53].…”

Structure Analysis of Fe3O4@SiO2 Core Shells Prepared from Amorphous and Crystalline SiO2 Particles

“…Magnetite (Fe3O4), besides maghemite (γ-Fe2O3) and hematite (α-Fe2O3), is an iron oxide that possesses a strong magnetic property. Fe3O4 is commonly known as black iron oxide, magnetic iron ore, loadstone, ferrous ferrite, or a Hercules stone that shows the strongest magnetic characteristic [15]- [17].…”

“…Based on the previous reports, various methods have been employed such as hydrolysis, microemulsions, and co-precipitation. Meanwhile, the Fe3O4/SiO2 nanocomposites have been fabricated via coprecipitation method [1], [15], [23], [24]. In this work, we exploited a simple coprecipitation method at room temperature which easier to control the particle size of the samples.…”

Single Step Synthesis of Glutamic/tartaric Acid-stabilised Fe3O4 Nanoparticles for Targeted Delivery Systems

“…Among the various magnetic nanoparticles (MNPs) used as nanocarriers for delivery of chemotherapeutic agents, Fe3O4 nanoparticles have attracted special attention because they provide opportunities for bioapplications due to their superparamagnetism [1][2][3]. Nevertheless, there are some major drawbacks that limits their practical applications: (i) bare Fe3O4 nanoparticles are highly susceptible to acidic and oxidative conditions and (ii) the existence of strong van der Waals and magnetic attractions between particles, which might cause the MNPs dispersion to be very unstable and all particles to be prone to aggregation, therefore coating an outer protective layer is very important to maintain the stability of the magnetic component [4][5]. An effective strategy to achieve this is by encapsulating Fe3O4 nanoparticles in an inorganic shell (C [6], SiO2 [1,5,7], ZnO [8] etc.)…”

“…Nevertheless, there are some major drawbacks that limits their practical applications: (i) bare Fe3O4 nanoparticles are highly susceptible to acidic and oxidative conditions and (ii) the existence of strong van der Waals and magnetic attractions between particles, which might cause the MNPs dispersion to be very unstable and all particles to be prone to aggregation, therefore coating an outer protective layer is very important to maintain the stability of the magnetic component [4][5]. An effective strategy to achieve this is by encapsulating Fe3O4 nanoparticles in an inorganic shell (C [6], SiO2 [1,5,7], ZnO [8] etc.) to form magnetic nanocomposites, which can extend their technical application as a result of unique characteristics of the shell (high stability under extreme conditions and naturally porous structure) and their ability to provide a platform for chelating groups [9].…”