Abstract
Tetrapleura tetraptera (Schumach. & Thonn) Taub. (Fabaceae) is a well-known medicinal plant with various therapeutic uses, stemming from the rich phytochemical content of its fruit, leaves and stem. Magnetic solid phase extraction (MSPE) has been widely utilised for the extraction and subsequent analysis of phytochemicals in natural products. Iron oxide nanoparticles (IONPs) are often used in MSPE and can be further functionalised to improve extraction efficiency and selectivity. While multi-step batch procedures for the synthesis of these sorbents have been established, the use of flow methods has not been fully explored, mainly due to the prohibitive costs of flow equipment.
Herein, we introduce a low-cost 3D-printed modular flow system for the automated synthesis of phenyl-functionalised silica-coated iron oxide nanoparticles. This system consists of 3D-printed polypropylene (PP) reactors with varying geometries connected in series to synthesise bare IONPs, silica-coated IONPs, or phenyl-functionalised silica-coated IONPs using laminar flow regimes. The simplicity, affordability, robustness, and customisability of the system were demonstrated. The synthesised IONPs were characterised using Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM), zeta potential, powder X-ray diffraction (XRD), thermogravimetric analysis (TGA) and vibrating sample magnetometry (VSM). The continuous flow system resulted in fast reactions under ambient conditions, with a production rate of approximately 5 mg/min. The produced IONPs were small (approximately 10 nm), resulting in a larger surface-to-volume ratio. Furthermore, the synthesised IONPs retained large enough saturation magnetisation values, which, together with larger surface-to-volume ratios, are ideal for MSPE.
A comparative study of batch and flow synthesised IONPs for the MSPE of phytochemical constituents in extracts from the fruit, leaves, and stems of Tetrapleura tetraptera (Schumach. & Thonn) Taub. (Fabaceae) was conducted. A traditional batch synthesis method...