Macrofluidic Coaxial Flow Platforms to Produce Tunable Magnetite Nanoparticles: A Study of the Effect of Reaction Conditions and Biomineralisation Protein Mms6

Abstract

Magnetite nanoparticles’ applicability is growing extensively. However, simple, environmentally-friendly, tunable synthesis of monodispersed iron-oxide nanoparticles is challenging. Continuous flow microfluidic synthesis is promising; however, the microscale results in small yields and clogging. Here we present two simple macrofluidics devices (cast and machined) for precision magnetite nanoparticle synthesis utilizing formation at the interface by diffusion between two laminar flows, removing aforementioned issues. Ferric to total iron was varied between 0.2 (20:80 Fe3+:Fe2+) and 0.7 (70:30 Fe3+:Fe2+). X-ray diffraction shows magnetite in fractions from 0.2–0.6, with iron-oxide impurities in 0.7, 0.2 and 0.3 samples and magnetic susceptibility increases with increasing ferric content to 0.6, in agreement with each other and batch synthesis. Remarkably, size is tuned (between 20.5 nm to 6.5 nm) simply by increasing ferric ions ratio. Previous research shows biomineralisation protein Mms6 directs magnetite synthesis and controls size, but until now has not been attempted in flow. Here we report Mms6 increases magnetism, but no difference in particle size is seen, showing flow reduced the influence of Mms6. The study demonstrates a versatile yet simple platform for the synthesis of a vast range of tunable nanoparticles and ideal to study reaction intermediates and additive effects throughout synthesis.

Ethylenediamine series as additives to control the morphology of magnetite nanoparticles

“…Within the green chemistry remit (ambient conditions), some control can be offered by changing reaction conditions, such as micro 22 and milli-fluidics flow synthesis 23 or pHregulated synthesis, 24 however, these methods are not currently scalable to large-scale production and offer less control over particle shape.…”

Magnetosomes and Magnetosome Mimics: Preparation, Cancer Cell Uptake and Functionalization for Future Cancer Therapies

“…This is because addition of the iron solution to the base in the reverse reaction will always mean a lower concentration of available iron when the MNP forms [ 36 ]. While in the control reaction, there is more available iron and it is supplied for longer, as the ferrous species slowly converts to grow larger particles than is seen for precipitations using a precursor solution with a higher ferric ratio [ 37 ]. The resulting MNP were then coated with either oleic acid (OA@cMNP) or silica (Si@cMNP/Si@rMNP) ( Figure 2 d–f, respectively) to mimic the magnetosomes with the aim of leading to improved biocompatibility and to provide a suitable surface for further functionalization.…”

Microfluidic Synthesis of Iron Oxide Nanoparticles

“…Alternatively, parameters such as polymer concentration, temperature, [ 29 ] and ratio of iron solution to base solution may be altered and automatically controlled in microfluidic-device-aided coprecipitation synthesis [ 75 ]. Increasing the amount of the polymer during coprecipitation synthesis yields smaller IONPs due to the faster rate of particle encapsulation that occurs with more polymer present.…”