Publication | Closed Access
Quantification of Magnetic Nanoparticles by Magnetorelaxometry and Comparison to Histology After Magnetic Drug Targeting
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2006
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Magnetic nanoparticles serve as contrast agents and drug carriers, enabling Magnetic Drug Targeting (MDT) for precise tumor delivery, and their distribution—especially within tumors—must be mapped, for which histology offers microscopic quantification. The study aimed to quantify ferrofluid delivered by MDT using magnetorelaxometry. We measured mm³ VX2 carcinoma tissue samples by magnetic relaxation, quantified iron against a reference ferrofluid, and reconstructed the intratumoral particle distribution. Integral magnetorelaxometry and microscopic histology complement each other effectively in mapping particle distribution.
Magnetic nanoparticles can be used in medicine in vivo as contrast agents and as a drug carrier system for chemotherapeutics. Thus local cancer therapy is performed with Magnetic Drug Targeting (MDT) and allows a specific delivery of therapeutic agents to desired targets, i.e., tumors, by using a chemotherapeutic substance bound to magnetic nanoparticles and focused with an external magnetic field to the tumor after intraarterial application. Important for this therapeutic principle is the distribution of the particles in the whole organism and especially in the tumor. Therefore we used magnetorelaxometry to quantify ferrofluids delivered after MDT. Tissue samples of some mm 3 volume of a VX2 squamous cell carcinoma were measured by magnetic relaxation and the amount of iron was determined using the original ferrofluid suspension as a reference. From this the distribution of the magnetic particles within the slice of tumor was reconstructed. Histological cross-sections of the respective tumor offer the opportunity to map quantitatively the particle distribution and the vascularisation in the targeted tumor on a microscopic scale. Our data show that the integral method magnetorelaxometry and microscopic histological methods can complete each other efficiently.