Modified supercritical antisolvent method with enhanced mass transfer to fabricate drug nanoparticles.

The main aim of this study was to modify the supercritical antisolvent precipitation method to enhance the mass transfer in order to prepare smaller nanoparticles of drugs. The supercritical antisolvent apparatus was customized by introducing a titanium horn in the precipitation chamber for generation of the ultrasonic field for enhanced mass transfer and the method was called supercritical antisolvent with enhanced mass transfer (SAS-EM). The effects of flow rate, ultrasonic amplitude, drug concentration and flow time on the particle size were investigated. The results showed that increasing the flow rate, incrementing the ultrasonic power up to an optimum point, decreasing the drug concentration and reducing the flow time helped to achieve smaller quercetin particles in the range of 120-450 nm. It is also shown that there is a tradeoff between the particle size and the yield; therefore the process parameters can be selected based on the particle size requirement. DSC studies suggested that the crystallinity of SAS-EM prepared quercetin nanoparticles decreased as compared to original quercetin powder. The dissolution of SAS-EM prepared nanoparticles increased significantly in comparison with the original quercetin powder. However, there was no significant difference in the dissolution of various quercetin nanoparticles samples prepared by the SAS-EM process. The best dissolution percent achieved was 75% for the smallest size sample prepared at the flow rate of 5 ml/min, power supply of 200 W, drug concentration of 10mg/ml, and flow time of 4 min.