Sio2 nps

SiO₂ NPs were obtained from NaBond Technologies Co., Ltd. (Shenzhen, China). The synthesis and characterization of NPs were described in detail in our previous paper [24 (link)]. Briefly, amorphous SiO₂ NPs were synthesized by the reactive laser ablation method and homogenized in Milli-Q water, ultrasonicated, and sterilized by autoclaving at 121 °C for 15 to 20 min. The NPs are spherical in shape and have a mean size of less than 10 nm. The NPs characteristics were analyzed using transmission electron microscopy (TEM) (FEI, Hillsboro, OR, USA), energy-dispersive X-ray spectroscopy (EDX) (Oxford Instruments, Abingdon, UK), and zeta potential analyses. The SiO₂ NPs were dispersed in distilled water at a concentration of 250 μg/mL. Three small drops (10 µL) of this diluted mixture were added consecutively on top of a pure carbon film copper grid (Ted Pella, Inc., Redding, CA, USA). Each time, the excess was carefully removed using filter paper. The sample was analyzed in bright field mode using a Tecnai F20 G² TWIN crio- TEM from (FEI, Hillsboro, OR, USA) at an acceleration voltage of 200 kV. The zeta potential of SiO₂ NPs (62.5 μg/mL) in ultrapure Milli-Q water was assessed using a Malvern Nano-ZS instrument (Malvern Instruments, Malvern, Worcestershire, UK). The measurements were performed in triplicate at 25 °C using the refractive index of 1.46.

SiO₂NPs were purchased from Naqaa Nanotechnology Co., Cairo, Egypt, and were synthesized and prepared following Stöber’s method [25 (link)]. Appropriate quantities of ethanol, tetraethoxyorthosilicate, and distilled water were continuously stirred for 30 min. To this solution the required amount of ammonia was added to adjust the pH to 9. Then, the reaction mixture was continuously stirred for 48 h at room temperature. A white-colored precipitate solution was obtained. Then, this solution was ultra-centrifuged at 8000 rpm for 15 min. After centrifugation, drying was carried out, resulting in pure white SiO₂NPs [18 (link)].
The morphology and particle size of SiO₂NPs was determined at 120 KV by transmission electron microscopy (TEM) (JEM-1400, TEM, JEOL Ltd., Tokyo, Japan). Surface characterization of the synthesized SiO₂NPs was accomplished using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) (JSM-5300, JEOL Ltd., Tokyo, Japan). TEM, SEM, and EDX procedures were performed at the Electronic Microscope Unit (Faculty of Science, Alexandria University, Egypt). The zeta potentials of SiO₂NPs in solution were evaluated using a Zetasizer Nano Series apparatus (Model 1801102S, Malvern Instruments, UK) at the Central Laboratory, Faculty of Pharmacy, Alexandria University, Alexandria, Egypt.