TABLE II.

Physical and magnetic characteristics of SIPPs and SPIONs.

	Variable	Units	SIPP#1	SIPP#2	SIPP#3	SPIONsa
R	Fe:Pt ratio	—	1.44	2.35	3.67	—
D	Diameter of particle	nm	9.28	9.98	10.03	50b
σ	Standard deviation in diameter	nm	1.94	2.90	3.43	—
ρ	Density	g/cm3	5.2	5.2	5.2	2.5c
M	Mass of iron per particle	pg	1.5 × 10− 6	2.2 × 10− 6	2.6 × 10− 6	1.6 × 10−5
CFe	Fe concentration of solution	g/mL	1.2 × 10− 3	1.9 × 10− 3	2.8 × 10− 2	2.7 × 10−4c
Cp	Particle concentration	Particles/mL	8 × 1014	9 × 1014	1 × 1016	2 × 1014c
Tb	Blocking temperature	Kelvin	170	210	195	155c
K	Effective anisotropy energy	J/m3	1.4 × 105	1.4 × 105	1.3 × 105	1.2 × 105c,d
µM	Mass magnetization	A m2/kg Fe	61.7	69.2	71.8	82.0c
µV	Volume magnetization	A/m	7.4 × 105	7.4 × 105	6.8 × 105	2.0 × 105

^aMACS® iron oxide particles from Miltenyi Biotec.

^bHydrodynamic diameter according to manufacturer.

^cTaylor et al. (Ref. 9).

^dCalculated using a magnetic core diameter of 10 nm.