METHOD FOR DETERMINING THE ENERGY OF INDIVIDUAL MAGNETIC PARTICLES ACQUIRED BY THEM IN A LOW-FREQUENCY ALTERNATING MAGNETIC FIELD Russian patent published in 2021 - IPC G01N21/64 A61B5/00 

FIELD: biophysics.

SUBSTANCE: invention can be used to determine the energy of individual magnetic particles acquired by them in a low-frequency alternating magnetic field, in biomedicine it can be applied for accurate modeling of experiments based on magnetomechanical phenomena, such as activation of membrane receptors, targeted delivery of drugs and their controlled release, inactivation of biologically active molecules, etc. For this, various zones on the surface of one substrate or the entire surface of one of the sides of the substrate are treated with an aqueous solution of a single-stranded nucleotide containing an anchor group at the end of the chain, with the formation of a covalent bond between the anchor group and the surface of the substrate. Each part of the zones or all of the other substrate contains a nucleotide only with its own fixed number of nucleotide units in the chain. The substrate is treated with an organic compound capable of forming a covalent bond with the substrate surface in places where a covalent bond between the substrate and the nucleotide has not been formed, followed by washing the substrate (s) with an aqueous solution and drying the substrate (s), treating the substrate (s) with an aqueous solution of another single-stranded nucleotide complementary to previously used nucleotides, with a known binding energy between complementary regions of different lengths, containing a covalently bound magnetic nanoparticle and a covalently bound fluorescent dye and having a fixed number of nucleotide units in the chain, which is not less than the number of nucleotide units in the chain at the longest previously used nucleotide. The substrate (s) is re-rinsed with an aqueous solution, then redried. The fluorescence intensity of the immobilized dye on the dry substrate(s) is then measured. The substrate(s), placed in an aqueous solution, are treated with a low-frequency alternating magnetic field at arbitrarily selected values of only one variable parameter, including the duration of exposure to the magnetic field or the amplitude of the magnetic field, and constant values of two other parameters selected from the group including the duration of magnetic field exposure duration, magnetic field amplitude and magnetic field frequency. The substrate (s) is then washed with an aqueous solution for the third time, dried for the third time, the fluorescence intensity of the immobilized dye remaining on the substrate (s) is re-measured. Fluorescence intensity of the dye on the substrate (s) is compared before and after the treatment of the substrate (s) with a magnetic field and washing, the fraction of the nucleotide removed from the surface of the substrate(s), containing the dye and magnetic nanoparticle covalently bound to it, is determined, and on its basis the decision is made whether, with the value of the variable parameter used in the experiment, the destruction of complementary bonds between different nucleotides occurred, then to be performed is a construction of a calibration curve for the dependence of the value of this energy per mole of complementary bonds of different nucleotides on the experimentally determined value of the variable parameter. It is used to determine the energy acquired by the magnetic particles, with an arbitrary value of the variable parameter and recalculating the result obtained for the energy acquired by an individual magnetic particle.

EFFECT: method provides an experimental determination of the energy of individual magnetic particles acquired by them in a low-frequency alternating magnetic field.

1 cl, 4 tbl, 6 ex, 6 dwg