Determination of the optical interference of iron oxide nanoparticles in fluorometric cytotoxicity assays.

Nanomaterials are known to exhibit unique interactions with light. Iron oxide nanoparticles (IONPs), composed of magnetite (black iron oxide) specifically, are known to be highly absorptive throughout the visible portion of the spectrum. We sought to investigate and overcome optical interference of IONPs in colorimetric, fluorometric and luminescence assays by introducing additional controls and determining the concentration-dependent contribution to optical artifacts which could confound, skew, or invalidate results. We tested the in vitro cytotoxicity of ∼8 nm spherical magnetite nanoparticles capped with alginate on a human lung carcinoma (A549) cell line for different exposure periods and at various concentrations. We observed significant interference with both the MTT reagent and the absorption at 590 nm, a concentration-dependent reduction in the luminescence, fluorescence at ∼490 nm (viability marker), and fluorescence at 530 nm (cytotoxicity marker). After introducing an additional correction, we obtained more accurate results, including a clear decrease in viability at 12-h post-treatment, with apparent near complete recovery after 24-h in addition to a dose-independent, time-dependent alteration in the cell proliferation rate. A small increase in cytotoxicity was noted at the 24-h timepoint at the two highest concentrations. According to our results, the MTT reagents appear to interact substantially with IONPs at concentrations above 0.1 mg/mL, therefore, this assay is not recommended for IONP cytotoxicity assessment at higher concentrations.

Future of Mesoporous Silica Nanoparticles in Nanomedicine: Protocol for Reproducible Synthesis, Characterization, Lipid Coating, and Loading of Therapeutics (Chemotherapeutic, Proteins, siRNA and mRNA).

Owing to their uniform and tunable particle size, pore size, and shape, along with their modular surface chemistry and biocompatibility, mesoporous silica nanoparticles (MSNs) have found extensive applications as nanocarriers to deliver therapeutic, diagnostic and combined "theranostic" cargos to cells and tissues. Although thoroughly investigated, MSN have garnered FDA approval for only one MSN system via oral administration. One possible reason is that there is no recognized, reproducible, and widely adopted MSN synthetic protocol, meaning not all MSNs are created equal in the laboratory nor in the eyes of the FDA. This manuscript provides the sol-gel and MSN research communities a reproducible, fully characterized synthetic protocol to synthesize MSNs and corresponding lipid-coated MSN delivery vehicles with predetermined particle size, pore size, and drug loading and release characteristics. By carefully articulating the step-by-step synthetic procedures and highlighting critical points and troubleshooting, augmented with videos and schematics, this Article will help researchers entering this rapidly expanding field to yield reliable results.

Templated synthesis enhances the cobalt adsorption capacity of a porous organic polymer.

Divalent transition metals such as Co(II) are important targets for removal from water sources, due to their potential toxicity as well as their high value. In this study, we found that a series of porous organic polymers based on amide-linked tetraphenylmethane units are effective Co(II) ion adsorbents in aqueous solution. To increase the density of Co(II) binding sites, we then developed a templated synthesis in which the branched, rigid monomers are pre-assembled around Co(II) ions prior to polymerization. After polymer formation, the Co(II) template ions are removed to yield a material rich in Co(II) binding sites. Ion adsorption isotherms show that the Co(II)-templated material has an ion adsorption capacity significantly greater than those of the non-templated materials, highlighting the utility of a templated synthetic route. SEM and TEM images show the morphology of the templated polymer to be dramatically different from the non-templated polymers and to be similar in size and shape to the Co(II)-monomer precursors, emphasizing the role of the template ions in directing the formation of the resulting polymer. This guest-templated approach requires no functionalization of the generic monomer and represents a promising synthetic route to high-capacity ion adsorbents for water purification and aqueous separations.