Green Synthesis-Based Magnetic Diatoms For Biological Applications

Here, we report the green synthesis of silica-based materials for the treatment of biological samples such as bacteria enrichment and exosome isolation. The synthesized materials were nanosized, recyclable, and magnetically separable using an eco-friendly hydrothermal synthesis approach. Fe3O4 formation on the surface of biosilica porous diatomite via precipitation was used to create a magnetic diatom (mag-DE) through a bottom-up approach, which was low cost, robust, nontoxic, and eco-friendly. Following the addition of L-arginine-containing amino groups, the mag-DE showed broad absorbance in the visible light spectrum (UV-vis), and the amine functional groups of 3-aminopropyl triethoxysilane on the DE via the amidine bond were confirmed using Fourier transform infrared analysis. Further studies were conducted by conjugating the mag-DE with concanavalin A (ConA), a known micro-antimicrobial agent for bacterial enrichment, as well as with a specific antibody for exosome isolation. The large-volume samples obtained were easy to use, and the materials could enrich a minimum of 50 colony-forming units (CFUs) of Salmonella and also showed a promising ability to capture another bacterial species. In addition, the modified synthetic mag-DE could be used for exosome isolation using affinity purification. Functionalized mag-DE could be magnetically isolated in a rapid and more efficient manner than using the conventional method, which can be altered for exosome isolation in research and clinical applications. This study presents the unique physical and chemical properties of green synthesized mag-DE, whose surface can be easily modified. Thus, it creates a novel potential strategy for several desirable applications for various types of biological samples.