Characterization and Suspension of MgONPs

The MgONPs were purchased from Sigma-Aldrich. These particles were distributed in deionized water and poured into a matrix potting medium (Pindstrup Mosebrug A/S, Shanghai, China) to conduct the plant experiment. The practical size of the particles was characterized using TEM (JEM-2100, JEOL, Tokyo, Japan) and SEM (S-570, Hitachi, Tokyo, Japan), and the particles were characterized in detail as described in our previous study [13 (link)]. The nitrogen adsorption–desorption isotherms of the MgONPs were evaluated using a Micromeritics Analyzer (ASAP 2010, Norcross, GA, USA) with nitrogen. The zeta potential of the MgONP in the matrix extraction was evaluated using a Malvern Zetasizer Nano Series (Malvern, UK). The matrix was suspended in deionized water to filtrate until the large particle residue was removed to obtain the matrix extraction. The MgONPs were suspended in deionized water to obtain the final suspension concentration of 250, 150 and 50 μg/mL and sonicated for 30 min for experimental use.