Mesoporous Silica-Based Drug Delivery Systems Obtained from Sodium Silicate as an Economical Synthesis

In this paper, the synthesis of a mesoporous silica obtained using sodium silicate (MS-silicate) as a basic reagent and economic synthesis is proposed. The characterization of the material with different techniques and the modification of its surface with amino and thiol groups is proposed to use these silicas as possible excipients for drugs using folic acid as a sample molecule. The results show that MS-silicate has a high surface area (924 m \(^2\) g \(^\text {-1}\) ) with two pore distributions at 3.65 nm and 6.55 nm with 26.6% microporosity with an isoelectric point (IEP) at pH=2. By modifying the surface with amino and thiol groups, the surface area is reduced by about 80% and the volume of microporosity is maintained at 20% for the NH \(_2\) group and 13.6% for the thiol group. The charge on the surface is modified to positive charge for the amino group with IEP at pH=9 and negative charge with IEP at pH<1 for the thiol group. The structural modification in silica changes the adsorption capacity of folic acid (drug model) with the behavior MS-silicate>MS-silicate-NH \(_2>\) MS-silicate-SH. While the desorption profiles depend on the pH and the attraction or repulsion interactions generated between the drug and the generated surface charge. According to the Korsmeyer-Peppas model; the diffusion coefficient (n) for the three silicas shows anomalous type release mechanisms except for the MS-silicate-SH.