Magnetic Nanoparticle Synthesis: From Lab to Production

Magnetic nanoparticles (MNPs) are a crucial component in various scientific and industrial applications, including biomedical imaging, targeted drug delivery, catalysis, and environmental remediation. The precise control of magnetic nanoparticle properties such as size, shape, magnetic behavior, and surface functionality is essential to meet the specific requirements of these applications. Ultrasonic synthesis, facilitated by Hielscher probe-type sonicators, offers a versatile and scalable method to produce high-quality magnetic nanoparticles.

Sonication in Nanoparticle Synthesis

Ultrasonication employs high-intensity ultrasound waves to generate localized high-energy zones in a liquid medium through acoustic cavitation. This phenomenon produces intense shear forces, high pressures, and elevated temperatures, creating an environment conducive to the controlled nucleation and growth of nanoparticles. The advantages of ultrasonication include uniform mixing, enhanced mass transfer, the ability to influence reaction kinetics and to functionalize particles, making it particularly effective for synthesizing uniform magnetic nanoparticles.

Magnetic Nanoparticles Synthesis: From Lab to Large-Scale Production

Laboratory-Scale Magnetic Nanoparticles Synthesis

In laboratory settings, Hielscher probe-type sonicators are commonly used to synthesize magnetic nanoparticles via co-precipitation, thermal decomposition, or solvothermal methods. By controlling ultrasonic parameters such as amplitude, sonication duration, pulse mode, and temperature researchers can achieve uniform particle sizes and narrow size distributions.
For example, the co-precipitation method benefits significantly from ultrasonic cavitation, which enhances the mixing of ferrous and ferric precursors with alkaline solutions, resulting in homogeneously nucleated magnetite (Fe₃O₄) nanoparticles. Additionally, ultrasonication reduces reaction time and improves the magnetic and structural properties of the nanoparticles.
Read more about ultrasonic magnetite synthesis!

Pilot and Industrial-Scale Production

The scalability of Hielscher sonicators is a critical advantage when transitioning from lab-scale research to industrial-scale production. In pilot-scale systems, larger ultrasonic probes (sonotrodes) and flow-through reactors enable the continuous production of magnetic nanoparticles with consistent quality. The ability to operate under high-pressure conditions and control process parameters ensures reproducibility and scalability.
For industrial production, Hielscher ultrasonic reactors can process large volumes of precursor solutions, maintaining the desired particle characteristics. This scalability is essential for applications requiring bulk quantities of magnetic nanoparticles, such as in magnetic separation technologies or drug delivery systems.

Case Study: Ultrasonic Magnetic Nanoparticle Synthesis

Ilosvai et al. (2020) combined sonochemistry with combustion to synthesize magnetic nanoparticles using iron(II)-acetate and iron(III)-citrate precursors dispersed in polyethylene glycol (PEG 400) with ultrasonic homogenization. These nanoparticles were tested for DNA separation, using plasmid DNA from E. coli. Characterization techniques revealed well-dispersed nanoparticles with a hydroxyl-functionalized surface, identified by FTIR, and magnetic phases of magnetite, maghemite, and hematite, confirmed by XRD. The nanoparticles showed good dispersibility in water, as indicated by electrokinetic potential measurements, making them suitable for bioseparation applications.

Protocol of Ultrasonic Magnetic Nanoparticle Synthesis

Magnetic nanoparticles were synthesized using a sonochemical combustion method with two different precursors: iron(II) acetate (sample A1) and iron(III) citrate (sample D1). Both samples followed the same procedure, differing only in the precursor used. For sample A1, 2 g of iron(II) acetate was dispersed in 20 g of polyethylene glycol (PEG 400), while for sample D1, 3.47 g of iron(III) citrate was used. Dispersion was achieved using the Hielscher high-efficiency sonicator UIP1000hdT (see picture left).
After sonochemical treatment, the PEG was combusted with a Bunsen burner to produce magnetic iron oxide nanoparticles.
 

Results

The resulting nanoparticles were characterized using XRD, TEM, DLS, and FTIR methods. The synthesis successfully combined sonochemical and combustion techniques, yielding magnetic nanoparticles. Notably, sample A1 proved suitable for DNA purification and offered a more cost-effective alternative to existing commercial options.
 

TEM of ultrasonically synthesized magnetic nanoparticles: Left: iron(II) acetate (sample A1); right: iron(III) citrate (sample D1).
Study and image: ©Ilosvai et al. 2020.

Hielscher Sonicators: Technological Advantage in Nanoparticle Synthesis

Hielscher Ultrasonics is the leader in ultrasonic processing technology, offering probe-type sonicators with up to 16,000 watts per sonicator designed for applications ranging from laboratory-scale experiments to industrial production. These devices provide high-intensity ultrasonic power, precise amplitude control, and temperature monitoring, making them ideal for sensitive processes such as magnetic nanoparticle synthesis.

Key features of Hielscher sonicators include:

• Precisely Adjustable Amplitude: Enables fine-tuning of cavitation intensity for optimal nanoparticle synthesis.
• Scalability: Modular designs allow seamless transition from small-scale R&D to large-scale production.
• Integrated Temperature Control: Prevents overheating and ensures stable reaction conditions.
• Durability and Versatility: Suitable for various solvents and precursor systems, including aqueous and organic phases.

Design, Manufacturing and Consulting – Quality Made in Germany

Hielscher ultrasonicators are well-known for their highest quality and design standards. Robustness and easy operation allow the smooth integration of our ultrasonicators into industrial facilities. Rough conditions and demanding environments are easily handled by Hielscher ultrasonicators.

Hielscher Ultrasonics is an ISO certified company and put special emphasis on high-performance ultrasonicators featuring state-of-the-art technology and user-friendliness. Of course, Hielscher ultrasonicators are CE compliant and meet the requirements of UL, CSA and RoHs.

The table below gives you an indication of the approximate processing capacity of our ultrasonicators: