ORIGINAL CONTRIBUTION Design and fabrication of novel core-shell nanoparticles for theranostic applications Seyed Mohammad Reza Dadfar 1 & Saeed Pourmahdian 1 & Mohammad Mehdi Tehranchi 2,3 & Seyed Mohammadali Dadfar 4 Received: 21 June 2020 /Revised: 25 July 2020 /Accepted: 7 August 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020 Abstract Superparamagnetic iron oxide nanoparticles (SPIONs) were prepared by co-precipitation method, functionalized respectively with tetraethyl orthosilicate (TEOS) and 3-(trimethoxysilyl)propyl methacrylate (TMSPM), and monodispersed by filtration and centrifugation. The vinyl-functionalized monodispersed SPIONs were then coated with a shell of the novel dual-responsive hydrogel having semi-interpenetrating polymer network (semi-IPN) structure. The formulation of this hydrogel, which was designed and synthesized in the previous study, was based on sodium alginate (Alg-Na) polymer and temperature-sensitive N- isopropylacrylamide (NIPAA) and pH-sensitive N-ethylmaleamic acid (NEMA) monomers. Sodium alginate acting as a pore- forming agent has a key role in the generation of semi-IPN structure and significantly decreases the time to reach the equilibrium swelling. Totally, two series of core-shell nanoparticles (CSNs) with the same magnetic core and different shell thicknesses were fabricated and exposed to different tests including transmission electron microscopy (TEM), dynamic light scattering (DLS), magnetic property evaluations, and magnetic resonance imaging (MRI) measurements. The obtained results of these tests revealed that these CSNs have the potential to be used as new theranostic platforms for simultaneous cancer diagnosis and therapy. Keywords Core-shell nanoparticles . Iron oxide nanoparticles . Magnetic properties . MRI . Responsive hydrogel . Theranostic Introduction Cancer is one of the major causes of morbidity and mortality worldwide. According to the last release of the Global Cancer Observatory (GCO) database in September 2018, it was estimated more than 18,000,000 new cases of cancer and more than 9,500,000 deaths from cancer in 2018 for both sexes and all ages. Fortunately, recent advances in various science and technology domains, especially nanoscience and nanotechnology, have provided innovative and more effective methods for early diagnosis, imaging, and therapy of this dan- gerous and deadly disease [1–4]. For an effective cancer treatment, advanced diagnostic and therapeutic procedures with minimal side effects should be used. An emerging trend in this direction is the use of theranostic agents and approaches representing materials and techniques which provide the modalities of diagnosis and therapy at the same time condensed into one package. Theranostic settings by offering various benefits like eliminat- ing multi-step procedures, preventing delay in treatment, re- ducing lethal effects to normal tissues, and overcoming unde- sirable differences in selectivity and biodistribution between diagnostic and therapeutic agents are opening new avenues towards more effective cancer treatment [5–7]. Superparamagnetic iron oxide nanoparticles (SPIONs) have attracted much attention in biomedical fields [7–10] such as controlled delivery of drugs, proteins and nucleic acids [8, 11], hyperthermia [12, 13], magnetic resonance imaging (MRI) [13–15], magnetic particle imaging (MPI) [16], bio- molecules separation [17], and tissue engineering [18]. Also, * Seyed Mohammad Reza Dadfar smrdadfar@gmail.com; smrezadadfar@aut.ac.ir 1 Department of Polymer Engineering and Color Technology, Amirkabir University of Technology, Tehran, Iran 2 Department of Physics, Shahid Beheshti University, Tehran, Iran 3 Laser & Plasma Research Institute, Shahid Beheshti University, Tehran, Iran 4 Institute for Experimental Molecular Imaging, Faculty of Medicine, RWTH Aachen University, Aachen, Germany https://doi.org/10.1007/s00396-020-04731-3 / Published online: 20 August 2020 Colloid and Polymer Science (2020) 298:1433–1442