Miltenyi MACS® Microbeads

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.

The unlabeled cells pass through while the magnetically labeled cells are retained within the column. The flow-through can be collected as the unlabeled cell fraction. After a short washing step, the column is removed from the separator, and the magnetically labeled cells are eluted from the column. Thus, with MACS MicroBead Technology both labeled and unlabeled cells can easily be isolated with high purity and recovery.

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

To remove a certain cell type from a mixture of cells, the unwanted cell type is magnetically labeled. During separation, the unlabeled target cells are collected in the flow-through fraction. The unwanted cell type is retained within the column. Optionally, the retained cells can be eluted after removal of the column from the separator.

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.