415Magnetic Nanosensors
(a glucose polymer) coating of approximately 10 nm thickness is about
25–30 nm (Perez et al. 2004). This is equivalent to a 750–1200 kDa globular
protein (protein that consists of long chains of amino acids folded up into
complex shapes). 1 kDa = the weight of 1000 hydrogen atoms = 1.66 × 10
−21
g.
Are these nanoparticles superparamagnetic? Yes.
What is superparamagnetism? Superparamagnetism occurs when a mate-
rial is composed of very small crystallites (1–10 nm) (Gossuin et al. 2009).
In this case, even though the temperature is below the Curie or Neel tem-
perature (the temperature above which a ferromagnetic substance loses
its ferromagnetism and becomes paramagnetic) and the thermal energy
is not sufcient ...