Fe3o4 particles

DMADDM was synthesized and verified according to a method described previously. The MNPs used consisted of ferrimagnetic magnetite (Fe₃O₄) particles 50–100 nm in size (Sigma-Aldrich, St. Louis, MO, USA) [55 (link),56 (link)]. DMADDM and MNPs were mixed with EndoREZ (Ultradent, South Jordan, UT, USA) together or singly. The specimens were prepared according to a previous study [14 (link)].
These four groups were investigated:
(1) Unmodified EndoREZ (designated “Control”)
(2) EndoREZ + 1% MNPs (designated as “1% MNP”)
(3) EndoREZ + 2% MNPs (designated as “2% MNP”)
(4) EndoREZ + 2.5% DMADDM (designated as “2.5% DMADDM”)
(5) EndoREZ + 2.5% DMADDM + 1% MNPs (designated as “2.5% DMADDM + 1% MNP”)
(6) EndoREZ + 2.5% DMADDM + 2% MNPs (designated as “2.5% DMADDM + 1% MNP”)
The sealers were placed in cylindrical plastic molds (5 mm in diameter and 2.5 mm in height) for cytotoxicity and solubility tests. Resin flakes were made using a 48-well plate cover as a mold to test the antibacterial effect; 20 mg of each sealer was placed on the flakes as flatly as possible. All the samples were transferred into new 24-well plates in a humid environment at 37 °C for 7 days and sterilized using an ethylene oxide sterilizer.

Titanium dioxide particles were obtained from the AEROXIDE^® TiO₂ P 25 (Evonik, Essen, Germany). The Fe₃O₄ particles used as a core for the nanostructures and as reference samples were purchased from Sigma Aldrich (637106) and were used as received. The nanomagnetite structure size was 50–100 nm (purity 97%, according to information provided by the supplier). Titanium (IV) butoxide (TBT) and hexadecyl (trimethyl)azanium bromide (CTAB) were purchased from Sigma Aldrich (MERCK, Darmstadt, Germany). Ethanol, propanol and 30% hydrochloric acid ammonia solution were bought from Chempur (Piekary Slaskie, Poland).

Commercially available carboxylic (-COOH) functionalized MWCNTs were purchased from DK Nano Technology Co. (Beijing, China). According to the manufacturer, the purity was more than 99% by mass, the average diameter and length of MWCNTs-COOH were approximately 10–20 nm and 10–30 µm, and the COOH content was approximately 2% (w/w). A ten percent (w/v) MWCNTs-COOH stock water suspension was used for the experiments. Nano-sized Fe₃O₄ particles (50–100 nm) were purchased from Sigma-Aldrich (637106; St. Louis, MO, USA).