Microfluidic Synthesis of Iron Oxide Nanoparticles

Abstract

Research efforts into the production and application of iron oxide nanoparticles (IONPs) in recent decades have shown IONPs to be promising for a range of biomedical applications. Many synthesis techniques have been developed to produce high-quality IONPs that are safe for in vivo environments while also being able to perform useful biological functions. Among them, coprecipitation is the most commonly used method but has several limitations such as polydisperse IONPs, long synthesis times, and batch-to-batch variations. Recent efforts at addressing these limitations have led to the development of microfluidic devices that can make IONPs of much-improved quality. Here, we review recent advances in the development of microfluidic devices for the synthesis of IONPs by coprecipitation. We discuss the main architectures used in microfluidic device design and highlight the most prominent manufacturing methods and materials used to construct these microfluidic devices. Finally, we discuss the benefits that microfluidics can offer to the coprecipitation synthesis process including the ability to better control various synthesis parameters and produce IONPs with high production rates.

Fabrication and Applications of Microfluidic Devices: A Review

“…They are cheap, widely accessible, easy to a machine; and can withstand high heat loads, high pressure, and toxic chemicals (except strong acids). Besides, their resistance to robust handling is convenient for cleaning operations [ 25 , 26 , 27 ]. The most popular metals for microfluidic devices are aluminum, copper, and iron, but they are most commonly found in alloys with other metals in order to fine-tune their chemical resistances [ 27 ].…”

“…Besides, their resistance to robust handling is convenient for cleaning operations [ 25 , 26 , 27 ]. The most popular metals for microfluidic devices are aluminum, copper, and iron, but they are most commonly found in alloys with other metals in order to fine-tune their chemical resistances [ 27 ]. Microfluidic devices made of metals have been demonstrated useful in nanomaterial synthesis, as size-tunable methacrylic nanoparticles were obtained in a stainless steel multi-lamination micromixer [ 26 ].…”

“…An example of materials appealing for nanomedicine is represented by iron oxide nanoparticles, which can be used as diagnostic and therapeutic agents against human disease. These non-toxic and biodegradable particles can act as contrast agents in magnetic resonance imaging or fluorescence imaging, drug carriers for small-molecule delivery, transfection vectors for gene therapy, and enhancers for magnetic hyperthermia [ 27 ]. Moreover, superparamagnetic iron particles can be employed in the on-demand release of active ingredients by magnetic positioning and exposure to an external stimulus, e.g., radiofrequency, heat, or in combination with responsive polymers for magnetic drug targeting [ 114 ].…”

Nanomaterials Synthesis through Microfluidic Methods: An Updated Overview

“…Moreover, the need for large spaces, expensive equipment, and high-power consumption translates into high costs [ 7 , 71 , 72 , 74 ]. Other industrial scale-up issues include alternation of synthesis conditions and insufficient control of the mixing process during the preparation of nanoparticles [ 75 ], complex stepwise operations, waste of resources, poor reproducibility, safety concerns [ 42 ], highly specialized and difficult to manufacture equipment, and long synthesis times [ 76 ]. In addition to the disadvantages associated with the synthesis process, the obtained products may also suffer from uncontrolled particle growth (narrow size distribution shifted to large particle dimensions [ 77 ]), potential contamination [ 7 ], non-proper surface structures [ 72 ], and poor size distribution (high polydispersity index values) [ 42 ], which further affect the functionalities of the materials.…”

“…Other MNPs that have gained research attention are iron oxide nanoparticles (IONPs) [ 119 ]. These materials have promising properties required in nanomedical applications, making their microfluidic production a natural step towards enhancing IONPs quality [ 76 ].…”