Properties of amorphous silica nanoparticles colloid drug delivery system synthesized using the micelle formation method

This study describes the formation and properties of a silica nanocolloid drug delivery system synthesized using micelle formation method. Previously, we have reported feasibility of using the same approach to entrap colorless water soluble drug (isoniazid). However, the entrapment of the drug inside nanoparticles (NPs) could not be observed due to its colorless nature. In this study, poor water soluble Rifampicin (RIF) was used as a drug model. Orange color of RIF enables observation and measurement using UV–Vis spectrophotometer. Several parameters were systematically studied: reaction temperature (25–70 °C) produced 28–97 nm, amount of surfactant (4–9 g) produced 44–66 nm, butanol volume (6–18 ml) produced 50–157 nm, and drug concentration. Particle size could be tuned from 28 to 157 nm by varying synthesis parameters. NP size was highly influenced by reaction temperature and butanol. Silica nanocolloid-entrapped RIF (50 and 70 nm SiRif) were synthesized and further analyzed for biological application. The stability of SiRif in biological media, such as in 0.1, 0.5, and 1.0 M NaCl solution and 5, 10, and 25 % mouse serum, was examined. RIF was successfully entrapped inside silica nanocolloids. Moreover, 50 and 70 nm SiRif exhibited almost similar stability in NaCl and mouse serum. The drug release profiles in 0.1 and 1.0 mM phosphate buffer solutions and different pH at 37 °C were examined for several days. Results indicate that 70 nm SiRif had higher drug loading and slower release profile than 50 nm SiRif. 70 nm SiRif was optimally released at pH 6.8.