Magnetic particles with a closed ultrathin silica layer, method for the production thereof and their use

• US 10,385,331 B2
• Filed: 02/16/2017
• Issued: 08/20/2019
• Est. Priority Date: 06/23/2005
• Status: Active Grant

• Current Assignee: Siemens Healthcare Diagnostics GmbH (Siemens AG)
• Original Assignee: Siemens Healthcare Diagnostics GmbH (Siemens AG)
• Inventors: Hennig, Guido, Hildenbrand, Karlheinz
• Primary Examiner(s): Forman, Betty J
• Application Number:
  US15/434,355
• Publication Number:
  US 20170159043A1
• Time in Patent Office: 915 Days
• CPC Class Codes: C12N 15/1013 by using magnetic beads
• CPC Class Codes: C12Q 1/6806 Preparing nucleic acids for analysis, e.g. for polymerase chain reaction [PCR] assay C12Q1/6804 takes precedence
• CPC Class Codes: H01F 1/01 of inorganic materials H01F1/44 takes precedence
• CPC Class Codes: H01F 1/112 with a skin H01F1/113 takes precedence
• CPC Class Codes: H01F 1/36 in the form of particles H01F1/346, H01F1/348 and H01F1/38 take precedence
• CPC Class Codes: H01F 41/005 Impregnating or encapsulating insulating of windings H01F41/12

Abstract

A method for producing silicate-containing magnetic particles having a closed and tight silicate layer and high purity. In addition, the novel method prevents an uncontrolled formation of aggregates and clusters of silicates on the magnetite surface, thereby having a positive influence on the properties and biological applications. The method enables depletion of nanoparticulate solid substance particles on the basis of a fractionated centrifugation. The silicate-coated magnetic particles exhibit optimized magnetization and suspension behavior as well as advantageous run-off behavior from plastic surfaces. These highly pure magnetic particles coated with silicon dioxide are preferably used for isolating nucleic acids from cell and tissue samples, whereby the separating out from a sample matrix ensues by means of magnetic fields. The particles are particularly well suited for the automatic purification of nucleic acids, mostly from biological body samples for the purpose of analyzing them with different amplification methods.

Claims

1. A method for purification of nucleic acids from a biological body sample, comprising:

dissolving the biological body sample containing a nucleic acid into a sample solution;

adding silica-coated magnetic particles to the sample solution, the silica-coated magnetic particles comprising a magnetite core and a uniformly thick distribution of a homogenous single to multiple molecular closed and tight silicate layer on the magnetite core, wherein the silicate layer is formed by depositing an initial silicate layer on the magnetite core and continuously diluting the initially-coated magnetite core using cross flow microfiltration at constant volume to reduce a pH value to a neutral pH value, the silicate layer has a thickness of 0.2 nm to 5 nm, and the silica-coated magnetic particles have grain size distribution between 0.1 μ

m and 1 μ

m;

incubating the sample solution at a temperature at which the nucleic acid bonds to the silica-coated magnetic particles;

removing constituents not bonded to the silica-coated magnetic particles with the application of a magnetic field to the sample solution;

removing unspecifically bonded molecules from the nucleic acid with the application and removal of a washing buffer;

separating nucleic acid from the silica-coated magnetic particles with the addition of an elution buffer; and

separating eluate with nucleic acid with the application of a magnetic field.

2. The method of claim 1, wherein the nucleic acids are RNA or DNA.

3. The method of claim 2, wherein the nucleic acids are RNA of HCV or HIV.

4. The method of claim 3, wherein the RNA or DNA is from fixed body samples.