Chapter 2 Surface Chemistry and Properties of Magnetic Nanoparticles Anshida Mayeen, Anju K. Sajan, and Nandakumar Kalarikkal 1 Introduction Magnetic nanoparticles are those materials whose particle size distribution was in nanodimensions and it can be manipulated by magnetic fields. Generally, magnetic nanoparticles are inorganic zero-dimensional materials with metal-based configu- ration. They may be either pure magnetic metals like nickel (Ni), cobalt (Co), iron (Fe), etc., or composed of magnetic bimetallic alloy like materials, or it is composed of magnetic oxides like spinel ferrites, inverse spinel ferrites, etc. Magnetic nanoparticles can be easily tuned by alternating current magnetic field and can be tailored for various applications [1–4]. Magnetic nanoparticles in nanometer regime have the ability to exhibit drastic intrinsic and extrinsic properties such as high saturation magnetization, less toxicity and high degree of biocompatibility. In this contest, magnetic nanoparticles possess wide range of applications in diversified fields such as industrial, environmental, analytical and biomedical [5]. Magnetic nanoparticles in the nanoscale possess drastic property change when compared to the bulk materials, and these behaviors can be attributed to the interplay of quantum, finite-size interactions with surface and interface. In partic- ular, magnetic nanoparticles serve as powerful building blocks that have led to many nanotechnology applications in fields such as ultrahigh-density magnetic recording, biomedicine (e.g., guided drug delivery, and cancer treatment through A. Mayeen  N. Kalarikkal School of Pure and Applied Physics, Mahatma Gandhi University, Kottayam, Kerala 686560, India A. Mayeen (&) Department of Physics, Thangal Kunju Musaliar College of Engineering, Kollam 691005, India A. K. Sajan  N. Kalarikkal International and Inter University Centre for Nanoscience and Nanotechnology, Mahatma Gandhi University, Kottayam, Kerala 686560, India © Springer Nature Singapore Pte Ltd. 2021 K. S. Joshy et al. (eds.), Magnetic Nanoparticles, Gels Horizons: From Science to Smart Materials, https://doi.org/10.1007/978-981-16-1260-2_2 31