Editing Silica Nanoparticles (section)

=== Protocol 3<br>  ===

from Synthesis of cationic mesoporous silica nanoparticles as a carrier for the delivery of nucleic acids (Iranian)<br> 

Synthesis and surface modification of MSNPs was<br>carried out through three major steps. At the first step,<br>silica nanoparticles were synthesized by template<br>removing method in which CTAB, templating surfactant,<br>was mixed with TEOS, the silica precursor, in a basic<br>aqueous solution (pH 11). 100 mg of CTAB was added to<br>the solution of 48 mL deionized water and 350 μL of<br>sodium hydroxide (2M) and heated to 80°C. Stirrer’s<br>rotational rate was a variable in this study (Table 1).<br>When the temperature stabilized, TEOS was added drop<br>wise. The TEOS concentration was the other variable<br>(Table 1). After 2 h, the solution was centrifuged and the<br>particles were refluxed in a solution of 30 mL of ethanol<br>and 3 mL hydrochloric acid (12 M). After 6 h, the<br> 

mixture was centrifuged and the precipitate was washed<br>with water and ethanol, 3 times each. The surfactants<br>were completely removed by calcination at 600 °C for 6<br>h.<br>The second step of the fabrication was expanding the<br>pores of MSNPs through the calcination method in the<br>presence of complex salts [7]. In this step, MSNP-2 with<br>an average size of 100 nm were dispersed with ultrasonic<br>in a solution containing NaCl, LiCl and KNO3. The<br>mixture was dried at 70 °C, and then calcinated at 350,<br>400, or 450 °C for 2 h.<br>The final step in the fabrication was the surface<br>functionalization. During this step the MSNPs (MSNP-2-<br>1 to MSNP-2-4) were functionalized with N-(2-<br>aminoethyl)-3-aminopropyltrimethoxy-silane<br>(EDS),<br>which causes a relatively positive charge on the MSNPs<br>surface.<br> 

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