System and method for determining size and size distribution of magnetic nanoparticles using VSM magnetization data

摘要

A method and apparatus for performing accurate measurements of the magnetic properties of magnetic nanoparticles (MNPs) in both liquid media and biological matrices for providing information on their size, size distribution and concentration in these media and matrices and, resulting in parameters that influence their functionality and effectiveness.

主权项

1. A method of analyzing a tumor in a subject, the method comprising:
sequentially introducing a plurality of solutions, each containing a predetermined range of sizes of magnetic nanoparticles (MNPs), respectively, into the tumor; capturing an MRI image of the tumor after the introduction of each solution; comparing the plurality of captured MRI images to a plurality of stored images, each stored image having corresponding MNP size and size distribution information as determined by a computer-implemented method of determining a size and size distribution of superparamagnetic nanoparticle cores in a sample comprising:
performing a magnetic measurement analysis of the sample and generating magnetization data therefrom;determining an asymptotic portion of high field data from the magnetization data for each of four branches (A,B,C,D) as MH vs. 1/H where MH is the measured magnetization in a magnetic field of intensity H approaching its saturation value;performing a linear regression analysis of the data in each branch and generating a first correlation curve of the form MH=α/H+β;calculating both a number average particle volume, {tilde over (V)}n, and a saturation magnetization, Msat, of the sample, as a function of the first correlation curve;combining low field, linear data of MH for branches A and C, and branches B and D, and obtaining two plots of MH vs. H for values of H within a range from −50 Oe to +50 Oe;performing a linear regression analysis of the data in each branch combination and generating a second correlation curve of the form MH=γH+δ;calculating a volume average particle volume {tilde over (V)}v as a function of the saturation magnetization value Msat obtained from the high field measurements, and using the value of the slope γ for the ratio of MH/H;calculating a volume average spherical equivalent magnetic particle diameter {hacek over (D)}v and a number average spherical equivalent magnetic particle diameter {hacek over (D)}n as a function of {tilde over (V)}v and {tilde over (V)}n; andcalculating a dispersity value, d, of the sample, as a function of the diameter values {hacek over (D)}v and {hacek over (D)}n; and analyzing the tumor as a function of the comparison of the plurality of captured MRI images to the plurality of stored images.