GB/Z 43592.2-2025Nanotechnologies - Magnetic nanomaterials - Part 2: Specification of characteristics and measurement methods for nanostructured magnetic beads for nucleic acid extraction (English PDF)

Foreword

This document is a standard or guiding technical document.

This document complies with the provisions of GB/T 1.1-2020 "Standardization Work Guidelines Part 1: Structure and Drafting Rules of Standardization Documents". Drafting.

This document is Part 2 of GB /Z 43592 "Nanotechnology - Magnetic Nanomaterials". GB /Z 43592 has already published the following parts.

---Part 1: Properties and Measurement Specifications of Magnetic Nanoparticle Suspensions;

---Part 2: Characteristics and Measurement Specifications of Magnetic Beads for Nucleic Acid Extraction This document is equivalent to ISO /T S19807-2.2021 "Nanotechnology - Magnetic Nanomaterials - Part 2: Magnetic Beads for Nucleic Acid Extraction".

The document type of "Characteristics and Measurement Specifications" has been changed from an ISO technical specification to a national standardization guidance technical document of my country.

The following minimal editorial changes have been made to this document.

---For ease of use, a note has been added to Table 2, and note 2 has been added to 5.2.3.

Introduction

Magnetic beads are a type of material formed by a large number of magnetic nanoparticles fixed inside a non-magnetic matrix (usually silica or organic polymers).

These are microspheres with a particle size distribution ranging from tens of nanometers to hundreds of micrometers (see Appendix A). Magnetic beads are typically supplied in suspension form, and the dispersion medium can... Purified water, ethanol, isopropanol, and sodium azide solution are selected. Based on its unique magnetic properties and maneuverability in a magnetic field, suspension... Liquid-form magnetic nanobeads have become one of the most widely used nanomaterials in the fields of biology and chemistry.

When the size of magnetic particles is reduced to a sufficiently small size, a single magnetic domain structure is formed, exhibiting a large macroscopic spin.

For particles with smaller diameters (such as iron oxide less than 30 nm), thermal energy can cause the magnetization direction of the particles to rotate frequently. If an object When the timescale of magnetization direction rotation is smaller than the timescale of measurement, the phenomenon can be described as "superparamagnetism," and the object is said to possess superparamagnetism.

Sex. In a non-interacting aggregate composed of a large number of small particles possessing this property, in the absence of an external magnetic field, due to thermally induced... The (magnetic moment) will shift, resulting in a state where the average magnetization is zero. However, under the influence of an external magnetic field, aggregates of magnetic particles will acquire a strong... The net magnetization intensity. This is because the magnetic field overcomes the thermal motion of the particles, causing the macroscopic magnetic moments of the magnetic particles in the aggregate to tend towards parallel alignment.

When magnetic particles with this characteristic constitute a large proportion of a magnetic bead, it is called a "superparamagnetic bead." However, it is important to note that... Yes, these magnetic beads themselves may not be "superparamagnetic" and are collectively referred to as "magnetic beads" in this document.

Magnetic beads have been applied in many fields, especially in biosensing applications (such as in vitro diagnostics), targeted drug delivery, magnetic resonance imaging, and biotechnology.

In the fields of isolation and genetic engineering, for example, magnetic beads with specific surface modifications can be used to efficiently lyse blood, saliva, urine, leaves, or viruses.

Nucleic acids (carrying genetic information) are isolated and extracted from organisms.

Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) carry the key genetic information that organisms use to build or maintain their biological structures.

Information. Accurate DNA identification can provide valuable health information. In recent years, scientists have not only discovered extracellular DNA in human blood, but also... Cell-free DNA (cfDNA) and circulating tumor DNA (ctDNA) were also discovered. Currently, ctDNA extraction has become a method for identifying or tracking cancer.

Liquid biopsy is one of the most widely used methods for tracking cancer progression. Typically, the concentration of cfDNA in the blood is extremely low, ranging from 5 ng/mL.

30 ng/mL. However, the ctDNA content is only 1% or less of the total cfDNA. Therefore, establishing a reliable method for ctDNA extraction is crucial.

The method is crucial. A proper description of the physicochemical properties of magnetic beads used for DNA extraction is essential for the developers of extraction kits and their application.

This is extremely valuable for users of DNA analysis.

The binding of nucleic acids to magnetic beads depends on one or more of the following. electrostatic interactions, hydrophobic interactions, hydrogen bonds, or specific binding. Once the cell... When DNA or RNA from tissue lysates is released into solution, nucleic acids can bind to surface-modified magnetic beads, forming a "nucleic acid-magnetic" combination. "Bead complex". Then, under a suitable combination of magnetic field and magnetic field gradient, this complex can be separated from the solution. This is achieved by washing... After removing residual impurities, the nucleic acid is desalted and purified before eluting from the magnetic beads to obtain the desired high-purity nucleic acid. During nucleic acid extraction, the process should not be interrupted.

Magnetic beads of the same morphology and their dispersion media have different physicochemical properties (such as specific surface area, magnetic bead concentration, etc.). These physicochemical properties vary to different degrees.

The degree of influence on the performance of magnetic beads in extracting nucleic acids.

Like other nanostructured materials, the production process and material specifications of magnetic beads are highly complex. The synthesis conditions during production and functionalization are crucial.

Even minute changes can cause significant differences in the performance and bonding ability of magnetic beads. Therefore, consistent characteristics are required for magnetic bead products.

However, the characteristics offered by different manufacturers in the market vary, and most manufacturers do not provide methods for measuring these characteristics.

Therefore, users or regulators find it difficult to compare different products or verify their characteristics, thus increasing the difficulty of subsequent application development. To ensure nucleic acid extraction... To improve product quality and enhance user confidence, a universally accepted specification for the characteristics and measurement of magnetic beads is required.

GB /Z 43592 "Nanotechnology - Magnetic Nanomaterials" aims to establish different application scenarios for magnetic nanomaterials in the biomedical field.

The characteristics and measurement methods are proposed to consist of two parts.

---Part 1: Properties and Measurement Specifications of Magnetic Nanoparticle Suspensions. The purpose is to clarify the properties and measurement of magnetic nanoparticle suspensions.

This method serves as the basis for the GB /Z 43592 series of standards.

---Part 2: Characteristics and Measurement Specifications of Magnetic Beads for Nucleic Acid Extraction. The aim is to provide information on the application of magnetic nanomaterials in nucleic acid extraction.

Characteristics and measurement specifications.

1 Scope

This document specifies the characteristics of suspensions and powdered magnetic beads for nucleic acid extraction, including key properties and additional features for nucleic acid extraction.

The characteristics are described, and applicable measurement methods are also described.

This document relates to magnetic beads containing a large number of magnetic nanoparticles (with superparamagnetism).

This document does not cover health, safety, or environmental aspects related to magnetic beads.

2 Normative references

The contents of the following documents, through normative references within the text, constitute essential provisions of this document. Dated citations are not included.

For references to documents, only the version corresponding to that date applies to this document; for undated references, the latest version (including all amendments) applies. This document.

ISO /T S80004-1 Nanotechnology Vocabulary Part 1: Core terms

Note: GB/T 30544.1-2014 Nanotechnology Terminology Part 1: Core Terminology (ISO /T S80004-1.2010, IDT)

ISO /T S80004-6 Nanotechnology Terminology Part 6: Characterization of Nanomaterials

Note: GB/T 30544.6-2016 Nanotechnology Terminology Part 6: Characterization of Nanomaterials (ISO /T S80004-6.2013, MOD)

3 Terms and Definitions

The terms and definitions defined in ISO /T S80004-1 and ISO /T S80004-6, as well as the following terms and definitions, apply to this document.

The URLs for the terminology databases maintained by ISO and IEC for standardization are as follows.