Abstract
Diatoms have the peculiarity to synthesize amorphous silica around the cell wall. Frustules (empty silica shells) have the advantages of being biocompatible, biodegradable, nontoxic and rich with hydroxyl groups on the surface. Frustules have been used in diverse fields, but recently their application in the biomedical field has been investigated. Drug delivery systems (DDS) have been studied to improve the therapeutic effect of different drugs, especially hydrophobic drugs. Different encapsulation methodologies have been used to load the drug in a carrier such as drop-wise methodology or solvent evaporation. However, a reproducible methodology that reduces handling error must be explored. Herein, a novel technique ESCARGOT (Embedded SCAffold RemovinG Open Technology) was used to fabricate the microfluidic device and exploited as a novel tool to encapsulate hydrophobic drugs into the in-house developed biogenic silica from Cyclotella sp. Isorhamnetin was used as a model drug with hydrophobic in nature. Three different concentrations were studied: 20, 60 and 100 μg/mL, and three different resident times in the device (0.4, 1 and 2 min). The highest encapsulation efficiency (EE%) and loading capacity (LC%) were 17.92% and 1.63% respectively. According to the statistical analysis, the optimum conditions to obtain a maximum EE% were 2 min and 20 μg/mL. The isorhamnetin release behavior was observed with a burst release in the first hour with 48.26%, while the total amount of drug was delivered in 3 h. The feasibility of frustules as carriers and the microfluidic device as a mixer was successfully accessed. This methodology could be used as a standardization technique to obtain reproducible results.