Green Synthesis-Based Magnetic Diatoms for Biological Applications

Abstract

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. Fe 3 O 4 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.

Diatoms with Invaluable Applications in Nanotechnology, Biotechnology, and Biomedicine: Recent Advances

“…Isolation of toxic and pathogenic bacteria using functionalized magnetic diatoms. Con A, concanavalin A. Reproduced with permission from ref . Copyright 2021 American Chemical Society.…”

“…108 Additionally, the organic extracts of Chaetoceros pseudocurvisetus and Skeletonema costatum exhibited antituberculosis effects with no toxicity on normal human cell lines. 112 Impressively, Shin et al 113 have shown the biological and clinical capabilities of green-synthesized magnetic (Fe 3 O 4 ) diatoms functionalized by APTES. They were deployed for bacterial enrichment and isolation of Salmonella sp., after conjugated with concanavalin A (as micro-antimicrobial agent) and also for the exosome isolation while conjugated with precise antibody; the magnetic particles were precipitated on the surface of diatomite biosilica (Figure 15).…”

“…They were deployed for bacterial enrichment and isolation of Salmonella sp., after conjugated with concanavalin A (as micro-antimicrobial agent) and also for the exosome isolation while conjugated with precise antibody; the magnetic particles were precipitated on the surface of diatomite biosilica (Figure 15). 113 2.7. Biofuel Production.…”

Chimeric nanocomposites for the rapid and simple isolation of urinary extracellular vesicles

“…LF was immobilized on the thiol‐modified surfaces of the MNPs by attaching it with the heterobifunctional crosslinker GMBS (Dao et al., 2021 ). Hydroxyl groups on the surface of the MNPs were converted to thiol groups by using a silanization solution of 4% (v/v) 3‐MPS overnight at room temperature, followed by washing with ethanol and incubation with 1 mM GMBS solution at room temperature for 1 h. LF was attached to the GMBS‐immobilized surface at room temperature for 1 h. The modified MNPs were immediately used or stored at 4°C.…”

Hedgehog-inspired immunomagnetic beads for high-efficient capture and release of exosomes

“…Generally, antibodies are modified onto the surface of spherical magnetic beads to target the exosome antigens and achieve high-specificity of exosome capture. Although it has made remarkable progress, one should notice that biological fluids often contain a large number of non-target substances, such as cell debris, protein precipitates, large-size extracellular vesicles, etc., 19 and these substances would adsorb on the surface of the traditional spherical immunomagnetic beads non-specifically to decrease the purity of the obtained specimens, even if the antifouling components (e.g., PEG) 20 have been employed to repel possible nonspecific adsorption.…”