Studying the Effect of Functional Group and Size of Silica Nanoparticles Loaded with Quercetin on their in vitro Characteristics

Silica nanoparticles (SNs) possess unique properties making them ideal carriers for many agents. Both the size and the surface chemistry are important features that impact the in vitro characteristics of their loaded agents. In this study, different surface functionalization of SNs with a particle size of 200 nm (propyl thiol, propyl carboxylic acid, and propyl amine) and two different sizes of propyl amine SNs (200 and less than 100 nm) were investigated. The nanoparticles (NPs) parameters were characterized using Dynamic Light Scattering (DLS) and their Encapsulation Efficiency (EE) and Loading Capacity (LC) with quercetin were measured using UV Spectrophotometer. Quercetin cumulative release was studied in phosphate buffer saline (PBS) (pH 7.4, 37°C) and its in vitro cytotoxicity toward HeLa cells was evaluated using an MTT assay. Our results showed that the mean particle size of all samples increased after drug loading and the polydispersity (PD) values were all within the acceptable range (0.2-0.5). All SNs exhibited negative values of zeta potential with the highest value for propyl-carboxylated NPs. The EE and LC percentages of quercetin in SNs depend on the type of surface functional group where the aminated SNs showed higher percentages compared to the other groups. A direct relation was observed between the drug release rate and the cytotoxicity where the highest and smallest values were exhibited by thiolated and aminated SNs, respectively. Surface modifications have thus a more pronounced effect on the in vitro properties of our studied SNs compared to the size.