Enhanced Diffusion-based Loading of Drugs on Mesoporous Silica from Supercritical Carbon dioxide
The use of mesoporous nanoparticles (MSPs) as carriers for drug delivery systems has gained importance, as they are now recognized as GRAS (Generally Recognized as Safe) for human intake. MSPs have a porous structure varying from 2-50 nm. These pores provide a high surface area for adsorption of drug, yielding high loadings due to their high surface area to volume ratios. However diffusional resistance of the solid drug to the pore surface often poses a problem.
Recently DiSupLo (Diffusion Supported Loading) method using ethanol vapors was reported for fast, uniform and controlled drug loading on MSPs. However, at the end of the process ethanol requires removal from the solid mixture of the drug and MSPs through drying, which may clog the pores hindering release of the loaded drug from the pores. Moreover, ethanol may not be a suitable solvent for the drug. On the contrary, Supercritical carbon dioxide (scCO2) is known to solubilize a wide variety of drugs. It is GRAS and a green substitute to the traditional organic solvents. Moreover, removal of scCO2 at the end of the operation simply requires depressurization of the vessel.
The present work will explore a new method: “Supercritically Enhanced Diffusion-based Loading” on
MSPs by replacing ethanol with scCO2 for carrying the drug to MSP as the two would be uniformly homogenized as a solid mixture. There would be several advantages of the process, as diffusional resistance of the drug transfer to the bed heights of the porous MSPs would be minimized enabling uniform, fast, and efficient loading, thereby less amount of drug would be needed for making the drug formulation with MSPs of the desired loading having uniform concentration.