Abstract: The present invention provides methods and apparatuses for detecting, measuring, or locating cells or substances present in even very low concentrations in vivo in subjects, using targeted magnetic nanoparticles and special magnetic systems. The magnetic systems can comprise magnetizing subsystems and sensors subsystems, including as examples SQUID sensors and atomic magnetometers. The magnetic systems can detect, measure, or location particles bound by antibodies to cells or substances of predetermined types. Example magnetic systems are capable of detecting sub-nanogram amounts of these nanoparticles.

Abstract: A method for measuring the average viscosity of a test fluid uses calibrated magnetic nanoparticles, with certain chosen hydrodynamic diameters and actual lateral dimensions (e.g. diameters), that are mixed into a small volume of the test fluid and a single magnetic relaxation curve measurement to provide data for viscosity determination. The distribution of hydrodynamic particle sizes of an ensemble of magnetic nanoparticles that are magnetically blocked at room temperature can be determined. Modifications of the method can be used to determine the distribution of viscosities in a complex fluid at the sub-microscopic level providing a novel type of viscosity measurement.

Abstract: An apparatus and method for performing biopsies in-vivo using magnetically labeled nanoparticles is disclosed. One embodiment of the apparatus is called a magnetic needle. When used in a biopsy, one embodiment of the present invention collects diseased cells in-vivo which have been tagged with magnetic nanoparticles coated with receptors for specific diseased cells.

Abstract: The present invention can provide a method of determining the presence, location, quantity, or a combination thereof, of a biological substance, comprising: (a) exposing a sample to a plurality of targeted nanoparticles, where each targeted nanoparticle comprises a paramagnetic nanoparticle conjugated with one or more targeting agents that preferentially bind with the biological substance, under conditions that facilitate binding of the targeting agent to at least one of the one or more biological substances; (b) subjecting the sample to a magnetic field of sufficient strength to induce magnetization of the nanoparticles; (c) measuring a magnetic field of the sample after decreasing the magnetic field applied in step b below a threshold; (d) determining the presence, location, quantity, or a combination thereof, of the one or more biologic substances from the magnetic field measured in step (c).