EFFECT OF SILICA COATING IN ACRYLIC ARTIFICIAL TEETH ON SURFACE ROUGHNESS, CONTACT ANGLE, AND GROWTH OF STREPTOCOCCUS MUTANS

ABSTRACTBackground: Acrylic resin artificial teeth is easily to have bacterial adhesion. It is necessary to perform a treatment on that surface, in order to reduce bacterial adhesion. This study aimed to reveal the effect of silica coating in acrylic resin artificial teeth on surface roughness, contact angle measurement, and the growth of Streptococcus mutans.Method: The study was conducted on two groups (n=16) of disk-shaped acrylic resin artificial teeth with a diameter of 10 mm and thickness of 2 mm. A 2% silica coating material was obtained by diluting 2 g silica nanoparticles on 100 ml of ethanol. Surface roughness, contact angle measurement, and the growth of Streptococcus mutans was measured using surface roughness measuring instrument, camera digital, and colony counter. The data obtained were then analyzed using T-test (p<0.05).Result: The results showed that the surface roughness and contact angle measurement in group I (0.29±0.08 μm); (79,49º ± 10,88º) was higher than group II (0.17±0.05 μm); (34,77º±0,05º). The growth of Streptococcus mutans in group I was also higher (32.28±3.75 CFU/ml) than group II (24.83±3.47 CFU/ml). Conclusion: The study concluded that there is an effect of silica coating on surface roughness, contact angle measurement, and the growth of Streptococcus mutans in acrylic resin artificial teeth.

Chemical synthesis of nanopowder Nd2Fe14BаSiO2 of the nucleus-shell type

Nanoparticles of the alloy with the composition Nd-Fe-B were formed by the chemical method of co-precipitation reduction using a reducing agent sodium borohydride. The nanoparticle size was 35–95 nm. The silica coating was applied after stabilizing the nanoparticles with APTMS. The core of Nd-Fe-B alloy nanoparticles covered with a SiO2 shell, Nd2Fe14BаSiO2, the particle size was 35–125 nm with a shell width of 8–15 nm.

Silica Coating of Ferromagnetic Iron Oxide Magnetic Nanoparticles Significantly Enhances Their Hyperthermia Performances for Efficiently Inducing Cancer Cells Death In Vitro

Increasing the biocompatibility, cellular uptake, and magnetic heating performance of ferromagnetic iron-oxide magnetic nanoparticles (F-MNPs) is clearly required to efficiently induce apoptosis of cancer cells by magnetic hyperthermia (MH). Thus, F-MNPs were coated with silica layers of different thicknesses via a reverse microemulsion method, and their morphological, structural, and magnetic properties were evaluated by multiple techniques. The presence of a SiO2 layer significantly increased the colloidal stability of F-MNPs, which also enhanced their heating performance in water with almost 1000 W/gFe as compared to bare F-MNPs. The silica-coated F-MNPs exhibited biocompatibility of up to 250 μg/cm2 as assessed by Alamar Blues and Neutral Red assays on two cancer cell lines and one normal cell line. The cancer cells were found to internalize a higher quantity of silica-coated F-MNPs, in large endosomes, dispersed in the cytoplasm or inside lysosomes, and hence were more sensitive to in vitro MH treatment compared to the normal ones. Cellular death of more than 50% of the malignant cells was reached starting at a dose of 31.25 μg/cm2 and an amplitude of alternating magnetic field of 30 kA/m at 355 kHz.

Improvement of monodispersity and shape symmetry of silica shell for PbS quantum dots by introducing surface silanization and adjusting reverse micelle size

Increasing the thickness of the quantum dot silica coating layer reduces monodispersity and shape symmetry. This paper reports three effective ways to solve this problem and achieve a large silica-coated QDs, i.e., proper silanization on the QD surface, control of reverse micelle size by adjusting the amount of QD solvent, and two-step formation of silica shell. Proper substitution of ligands on the QD surface in the early stages of silica shell formation was important for uniform coating reaction. An amount of toluene as QD solvent determined the size of reverse micelles during the silica shell formation. There was an optimum combination of inverse micelle size and silica shell size to obtain silica-coated QDs with good monodispersity and high shape symmetry. We succeeded in growing the thick silica shell with expanding reverse micelle size by additionally supplying toluene with the raw material using the optimum silica-coated QDs as growth nucleus

Ultra-Fine Control of Silica Shell Thickness on Silver Nanoparticle-Assembled Structures

To study the distance-dependent electromagnetic field effects related to the enhancement and quenching mechanism of surface-enhanced Raman scattering (SERS) or fluorescence, it is essential to precisely control the distance from the surface of the metal nanoparticle (NP) to the target molecule by using a dielectric layer (e.g., SiO2, TiO2, and Al2O3). However, precisely controlling the thickness of this dielectric layer is challenging. Herein, we present a facile approach to control the thickness of the silica shell on silver nanoparticle-assembled silica nanocomposites, SiO2@Ag NPs, by controlling the number of reacting SiO2@Ag NPs and the silica precursor. Uniform silica shells with thicknesses in the range 5–40 nm were successfully fabricated. The proposed method for creating a homogeneous, precise, and fine silica coating on nanocomposites can potentially contribute to a comprehensive understanding of the distance-dependent electromagnetic field effects and optical properties of metal NPs.