MACS MicroBeads are 50-nm
superparamagnetic particles that are conjugated to highly specific antibodies
against a particular antigen on the cell surface. Due to the small size, they
do not activate cells and they will not saturate cell surface epitopes. Unlike
larger beads, MACS MicroBeads do not have to be removed for any downstream
application. MicroBeads are non-toxic and biodegradable. They have been tested
according to the International Standard (ISO 10993) and USP guidelines for
biocompatibility.
Only
MACS MicroBeads are always in suspension (colloidal) – allowing fast binding
kinetics and short labeling procedures. Unlike non-colloidal solutions or very
large beads, you will never have to deal with clumping artifacts and you can
count on superb quality and lot-to-lot consistency.
MACS Columns contain a matrix
composed of ferromagnetic spheres covered with a cell-friendly coating. When
placed on a magnetic separator, the spheres amplify the magnetic field by
10,000-fold, thus inducing a high gradient within the column. This is crucial
for isolation of cells that are only minimally labeled, leaving enough epitopes
free for concurrent antibody staining.
The
space between the spheres is several times larger than primary and most
cultured cells. This allows the cells to freely flow through the column.
Magnetically labeled cells are held in suspension within the column and do not
actually 'bind' the column matrix. This suspension minimizes stress on the
cells and allows for efficient sterile washing by avoiding cell aggregation.
MACS Separators are available in
different formats to accommodate different column options.
The combination of MACS MicroBeads, columns, and the magnetic separator provide the perfect tool set for unmatched cell separation results.
Just three easy steps
It
takes only a few simple steps to get pure cell populations Cells in a
single-cell suspension are magnetically labeled with MACS MicroBeads. The
sample is applied to a MACS Column placed in a MACS Separator.
Direct magnetic labeling
Direct
labeling with MACS® MicroBeads is the fastest way of magnetic labeling. MACS
MicroBeads specifically bind to antigens on the cell surface. Only one
incubation step is required. Direct magnetic labeling requires a minimal number
of washing steps and therefore minimizes cell loss.
Highly
specific cell separation reagents for direct labeling of numerous cell types
with MACS MicroBeads are available for human, mouse, rat, and non-human primate
cells.
Indirect magnetic labeling
Indirect
magnetic labeling is based on a two-step procedure. In a first step, the cells
are labeled with a primary antibody directed against a cell surface marker.
In
a second step, the cells are magnetically labeled with MACS MicroBeads, which
either bind to the primary antibody or to a molecule that is conjugated to the
primary antibody.
The
primary antibody can either be unconjugated, biotinylated, or
fluorochrome-conjugated. Accordingly, magnetic labeling is achieved with
Anti-Immunoglobulin MicroBeads, Anti-Biotin MicroBeads, or Anti-Fluorochrome
MicroBeads.
Indirect
labeling can also be performed by using a cocktail of primary antibodies to
concurrently label a number of unwanted cell types, for example, for the
untouched isolation of target cells.
Positive selection: The fastest way to pure target cells
Positive
selection means that a particular target cell type is magnetically labeled.
During separation, the magnetically labeled cells are retained within the
column.
Unlabeled cells flow through. After a washing step, the column is removed from the magnetic field of the separator, and the target cells are eluted from the column. Positive selection can be performed by direct or indirect magnetic labeling. Specific MACS MicroBeads are available for the positive selection of numerous cell types.
Depletion: Removal of an unwanted cell type
Untouched isolation: Isolation of cells in an unlabeled form
To
isolate a particular target cell type in an unlabeled, i.e., untouched form,
non-target cells are magnetically labeled and depleted. During separation, the
unlabeled target cell type is collected in the flow-through fraction. The
mixture of magnetically labeled non-target cells is retained within the
column.Optionally, the magnetically labeled cells can be eluted after removal
of the column from the magnetic field of the separator.
MACS Cell Isolation Kits for untouched isolation contain a cocktail of titrated
antibodies and MACS MicroBeads for indirect magnetic labeling. They are the
preferred choice if binding of antibodies to the target cells is not desired.