Microbeads
Encyclopedia
Microbeads are uniform polymer particles, typically 0.5 to 500 micrometres in diameter. Bio-reactive molecules can be adsorbed or coupled to their surface, and used to separate biological materials such as cell
s, protein
s, or nucleic acid
s.
Microbeads are used for isolation and handling of specific material or molecules, as well as for analyzing sensitive molecules, or those that are in low abundance, e.g. in miniaturized and automated settings.
beads of the same spherical sizes at the University of Trondheim, Norway
in 1976. He then created superparamagnetic microbeads (Dynabeads
). These beads exhibit magnetic properties when placed in a magnetic field, with no residual magnetism
when removed from the magnetic field, thereby leading to the development of magnetic separation technology.
Microbeads enable fast liquid-phase kinetics, and displays a large surface area per volume. Microbeads can execute rapid separation throughout the application protocol by applying a magnet
. Other processes such as centrifugation
, filtration
, columns or precipitation
, are not needed.
material was crafted to produce monosized spherical beads. Uniformity of size, shape and surface area provides optimal accessibility and reaction kinetics
, for rapid and efficient binding.
; a biomolecule
such as antibody
, streptavidin
, protein
, antigen
, DNA
/RNA
or other molecule. There are three steps involved in the magnetic separation process:
Microbeads are used for cell isolation and cell expansion. Proteins and protein complexes can be separated, e.g in immunoprecipitation
protocols. Molecular studies and diagnostics also benefit from microbeads (e.g immunoassay
IVD and nucleic acid
IVD). When microbeads are coupled with streptavidin
, they offer a very efficient way to isolate any biotinylated molecule. This is frequently used in DNA
/RNA
binding protein studies, sequencing
, and to prepare single stranded templates. Gene expression
analysis also benefits from microbeads, such as isolating mRNA for transcriptional analysis.
There are many uses for microbeads, mostly for biotechnology
and biomedical research
. Microbeads and magnetic separation technology have enabled a range of innovative methods to benefit research on disease prevention, medicine, and other fields to improve the human condition.
Cell (biology)
The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life that is classified as a living thing, and is often called the building block of life. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos....
s, protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
s, or nucleic acid
Nucleic acid
Nucleic acids are biological molecules essential for life, and include DNA and RNA . Together with proteins, nucleic acids make up the most important macromolecules; each is found in abundance in all living things, where they function in encoding, transmitting and expressing genetic information...
s.
Microbeads are used for isolation and handling of specific material or molecules, as well as for analyzing sensitive molecules, or those that are in low abundance, e.g. in miniaturized and automated settings.
Background
Microbeads were created when the late Dr. John Ugelstad managed to form polystyrenePolystyrene
Polystyrene ) also known as Thermocole, abbreviated following ISO Standard PS, is an aromatic polymer made from the monomer styrene, a liquid hydrocarbon that is manufactured from petroleum by the chemical industry...
beads of the same spherical sizes at the University of Trondheim, Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
in 1976. He then created superparamagnetic microbeads (Dynabeads
Dynabeads
Dynabeads are superparamagnetic, monosized and spherical polymer particles with a consistent, defined surface for the adsorption or coupling of various bioreactive molecules or cells....
). These beads exhibit magnetic properties when placed in a magnetic field, with no residual magnetism
Magnetism
Magnetism is a property of materials that respond at an atomic or subatomic level to an applied magnetic field. Ferromagnetism is the strongest and most familiar type of magnetism. It is responsible for the behavior of permanent magnets, which produce their own persistent magnetic fields, as well...
when removed from the magnetic field, thereby leading to the development of magnetic separation technology.
Microbeads enable fast liquid-phase kinetics, and displays a large surface area per volume. Microbeads can execute rapid separation throughout the application protocol by applying a magnet
Magnet
A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials, such as iron, and attracts or repels other magnets.A permanent magnet is an object...
. Other processes such as centrifugation
Centrifugation
Centrifugation is a process that involves the use of the centrifugal force for the sedimentation of mixtures with a centrifuge, used in industry and in laboratory settings. More-dense components of the mixture migrate away from the axis of the centrifuge, while less-dense components of the mixture...
, filtration
Filtration
Filtration is commonly the mechanical or physical operation which is used for the separation of solids from fluids by interposing a medium through which only the fluid can pass...
, columns or precipitation
Precipitation (chemistry)
Precipitation is the formation of a solid in a solution or inside anothersolid during a chemical reaction or by diffusion in a solid. When the reaction occurs in a liquid, the solid formed is called the precipitate, or when compacted by a centrifuge, a pellet. The liquid remaining above the solid...
, are not needed.
Uniformity
John Ugelstad was able to develop a method to create uniformly sized microbeads. PolystyrenePolystyrene
Polystyrene ) also known as Thermocole, abbreviated following ISO Standard PS, is an aromatic polymer made from the monomer styrene, a liquid hydrocarbon that is manufactured from petroleum by the chemical industry...
material was crafted to produce monosized spherical beads. Uniformity of size, shape and surface area provides optimal accessibility and reaction kinetics
Chemical kinetics
Chemical kinetics, also known as reaction kinetics, is the study of rates of chemical processes. Chemical kinetics includes investigations of how different experimental conditions can influence the speed of a chemical reaction and yield information about the reaction's mechanism and transition...
, for rapid and efficient binding.
Applications
Microbeads serve as the main tool for bio-magnetic separations. A range of patented processes and applications have been developed based on the use of microbeads in academic and industrial research. Microbeads are pre-coupled with a ligandLigand (biochemistry)
In biochemistry and pharmacology, a ligand is a substance that forms a complex with a biomolecule to serve a biological purpose. In a narrower sense, it is a signal triggering molecule, binding to a site on a target protein.The binding occurs by intermolecular forces, such as ionic bonds, hydrogen...
; a biomolecule
Biomolecule
A biomolecule is any molecule that is produced by a living organism, including large polymeric molecules such as proteins, polysaccharides, lipids, and nucleic acids as well as small molecules such as primary metabolites, secondary metabolites, and natural products...
such as antibody
Antibody
An antibody, also known as an immunoglobulin, is a large Y-shaped protein used by the immune system to identify and neutralize foreign objects such as bacteria and viruses. The antibody recognizes a unique part of the foreign target, termed an antigen...
, streptavidin
Streptavidin
Streptavidin is a 60000 dalton protein purified from the bacterium Streptomyces avidinii. Streptavidin homo-tetramers have an extraordinarily high affinity for biotin . With a dissociation constant on the order of ≈10-14 mol/L, the binding of biotin to streptavidin is one of the strongest...
, protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
, antigen
Antigen
An antigen is a foreign molecule that, when introduced into the body, triggers the production of an antibody by the immune system. The immune system will then kill or neutralize the antigen that is recognized as a foreign and potentially harmful invader. These invaders can be molecules such as...
, DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
/RNA
RNA
Ribonucleic acid , or RNA, is one of the three major macromolecules that are essential for all known forms of life....
or other molecule. There are three steps involved in the magnetic separation process:
- Bind - Microbeads bind to the desired target, relative to the specific affinity of the ligandLigandIn coordination chemistry, a ligand is an ion or molecule that binds to a central metal atom to form a coordination complex. The bonding between metal and ligand generally involves formal donation of one or more of the ligand's electron pairs. The nature of metal-ligand bonding can range from...
on the surface of the beads. - Wash - Microbeads will move to the side of the tube in response to a magnetic field, along with the bound material. This happens quickly and efficiently because of the magnetic field and the micro-sized particles. The un-bound and un-wanted material that is left behind in the sample is removed by pipetting/aspiration. The bead-bound material is washed using the appropriate buffers, by applying the magnet.
- Elute - Once the bead-bound target is isolated and washed, it can be released in the appropriate solution and desired volume. It can then be used for any downstream application directly, or the microbeads can be released and removed.
Microbeads are used for cell isolation and cell expansion. Proteins and protein complexes can be separated, e.g in immunoprecipitation
Immunoprecipitation
Immunoprecipitation is the technique of precipitating a protein antigen out of solution using an antibody that specifically binds to that particular protein. This process can be used to isolate and concentrate a particular protein from a sample containing many thousands of different proteins...
protocols. Molecular studies and diagnostics also benefit from microbeads (e.g immunoassay
Immunoassay
An immunoassay is a biochemical test that measures the presence or concentration of a substance in solutions that frequently contain a complex mixture of substances. Analytes in biological liquids such as serum or urine are frequently assayed using immunoassay methods...
IVD and nucleic acid
Nucleic acid
Nucleic acids are biological molecules essential for life, and include DNA and RNA . Together with proteins, nucleic acids make up the most important macromolecules; each is found in abundance in all living things, where they function in encoding, transmitting and expressing genetic information...
IVD). When microbeads are coupled with streptavidin
Streptavidin
Streptavidin is a 60000 dalton protein purified from the bacterium Streptomyces avidinii. Streptavidin homo-tetramers have an extraordinarily high affinity for biotin . With a dissociation constant on the order of ≈10-14 mol/L, the binding of biotin to streptavidin is one of the strongest...
, they offer a very efficient way to isolate any biotinylated molecule. This is frequently used in DNA
DNA
Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms . The DNA segments that carry this genetic information are called genes, but other DNA sequences have structural purposes, or are involved in...
/RNA
RNA
Ribonucleic acid , or RNA, is one of the three major macromolecules that are essential for all known forms of life....
binding protein studies, sequencing
DNA sequencing
DNA sequencing includes several methods and technologies that are used for determining the order of the nucleotide bases—adenine, guanine, cytosine, and thymine—in a molecule of DNA....
, and to prepare single stranded templates. Gene expression
Gene expression
Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product. These products are often proteins, but in non-protein coding genes such as ribosomal RNA , transfer RNA or small nuclear RNA genes, the product is a functional RNA...
analysis also benefits from microbeads, such as isolating mRNA for transcriptional analysis.
There are many uses for microbeads, mostly for biotechnology
Biotechnology
Biotechnology is a field of applied biology that involves the use of living organisms and bioprocesses in engineering, technology, medicine and other fields requiring bioproducts. Biotechnology also utilizes these products for manufacturing purpose...
and biomedical research
Biomedical research
Biomedical research , in general simply known as medical research, is the basic research, applied research, or translational research conducted to aid and support the body of knowledge in the field of medicine...
. Microbeads and magnetic separation technology have enabled a range of innovative methods to benefit research on disease prevention, medicine, and other fields to improve the human condition.