Magnetic Nanoparticles

Magnetic nanoparticles are iron derivative spherical nanocrystals of 10—20 nm size with a Fe²⁺ and Fe³⁺ core surrounded by dextran or PEG molecules. Due to magnetic properties these particles can be employed to label biomolecules in bioassays, as well as magnetic resonance imaging (MRI) and image contrast for the diagnosis of tumor and other diseases [70,71]. Magnetic nanoparticles can be applied in magnetic-assisted drug delivery, targeting, hyperthermia treatment of tumors, and magnetic transfection of cells [72].

Gold Nanoparticles

Gold nanoparticles can be considered as a type of metallic nanoparticle; others are made of Ni, Pt, and TiO2 nanoparticles. Gold nanoparticles (AuNPs), also known as colloidal gold, constitute a suspension of submicrometer-sized gold metal particle in a fluid and can be obtained with diameters between 3 and 200 nm [73]. Gold nanoparticles (<50 nm) can be prepared with different geometries, such as nanospheres, nanoshells, nanorods, or nanocages. These particles show localized surface plasmon resonant properties, i.e., under irradiation they absorb light and emit photons with the same frequency in all directions. Gold nanoparticles possess extraordinary optical and electronic properties with high stability and biocompatibility, which render these particles excellent label as biosensors for imaging and diagnostic purposes [73,74]. AuNPs are fabricated along with the organic polymers (liposome) to form hybrid systems. This construct can integrate diagnostic and therapeutic agents for effective delivery accompanied by real-time monitoring of treatment response and tumor growth [75].