20.500.12556/DKUM-95858 Modular flow synthesis of citric acid-coated superparamagnetic iron oxide nanoparticles preliminary results Superparamagnetic iron oxide nanoparticles (SPIONs) with sizes below 10 nm are biocompatible and non-toxic, making them promising for biomedical applications. To prevent their agglomeration and enhance their functionality, the nanoparticles were coated with citric acid (CA), which modifies the surface charge, improves dispersion stability, and facilitates biomedical use. In this work, a modular flow-through microreactor system was employed to synthesize and coat the nanoparticles in a single, continuous two-step process. The system enables precise control over temperature and mixing, ensuring uniform reaction conditions and minimizing hot spots. The synthesized Fe3O4 nanoparticles exhibited an average crystallite size of ~5 nm (XRD) and particle sizes of 4–6 nm (TEM). FTIR analysis confirmed the successful surface functionalization with CA, while TGA indicated a coating mass fraction of approximately 4–20 wt%, increasing with higher CA concentration. Zeta potential measurements revealed strong colloidal stability, with values around −35 mV at pH 6.5. Among the tested CA concentrations, the sample with a molar ratio of Fe3O4:CA = 1:0.25 exhibited the most favorable properties, including narrow size distribution and improved dispersion stability. These findings demonstrate that the continuous modular flow approach enables the reproducible synthesis of highly stable, sub-10 nm CA-coated SPIONs, offering promising potential for biomedical applications, particularly as magnetic resonance imaging (MRI) contrast agents. superparamagnetic iron oxide nanoparticles citric acid modular flow microreactor system continuous synthesis zeta potential measurements nanodelci meritve zeta potenciala mikrorektorski sistem true false true MDPI Angleški jezik Slovenski jezik https://www.mdpi.com/journal/micromachines © 2025 by the authors Članek v reviji 2025-11-03 08:53:29 2025-11-03 08:53:29 2025-11-04 03:34:50 0000-00-00 00:00:00 2025 0 0 13 str. iss. 11, [article no.] 1228 Vol. 16 Oct. 2025 0000-00-00 Zaloznikova Objavljeno NiDoloceno 2025-10-13 2025-10-28 2025-10-29 620.3 255572227 10.3390/mi16111228 2072-666X micromachines-16-01228.pdf micromachines-16-01228.pdf 1 4842978EFB279A9E67161EA0A754F53B b99c0a1dbbd6fa05d732bfb2dc2755c3f9adc1401bf96cc62e3a200378350c5b a24415c9-b88a-11f0-b13b-00155d000105 https://dk.um.si/Dokument.php?lang=slv&id=200321 Fakulteta za kemijo in kemijsko tehnologijo 0 0 0