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MACS vs. FACS vs. BACS: What to Consider When Sorting Cell Populations

October 2020

scientists separating cells in a research lab

MACS, FACS, and BACS are cell sorting techniques with individualized processes to isolation. Each method has advantages and disadvantages. Depending on the goal, it may be more beneficial to choose one or the other.


Magnetic-activated cell sorting, or MACS, is a cell separation technology which separates cells using magnets to target them. MACS is a popular form of cell isolation known to be reliable with a sustainable processing time.

How Does MACS work?

The process of cell isolation by magnetic sorting depends on the surface antigens of the cells. The cells are separated by magnetic particles through an antibody interaction with surface markers of the targeted cells. Those cells are then isolated for a separate sample.

Let’s break it down:

  • Magnetic beads coated with antibodies or enzymes associated with surface markers of the targeted cells are added to the sample
  • Magnetic beads label the cells with recognizable surface markers
  • The targeted cells attach to the magnetic beads and are magnetized to the column walls while non-targeted cells flow through the sample column
  • Cells isolate between targeted and non-targeted

Cells sorted by magnetic activated can take on a positive or negative cell selection approach. This solely depends on whether the targeted cells stay attached to the walls of the column or pass through.

Advantages and Disadvantages

The main benefit of MACS is its speed. Magnetic-activated cell sorting is 4-6 times faster than FACS. This allows researchers to run a higher quantity of samples in a shorter time.

On the other hand, MACS has hidden costs associated with the storage and upkeep of necessary devices. The columns and beads require money to take care of, and time to learn.

MACS can also be extremely harsh on fragile cells. The magnetic nature of the process can cause damage to the target cell membrane. When working with cells of a higher rarity, MACS can make it difficult to safely extract a high percentage of the desired substance. 


Fluorescence-activated cell sorting, also known as FACS, is a type of flow cytometry using fluorescent labeling to target and isolate groups of cells. After being run through a cytometer, they are sorted based on their physical characteristics (size, granularity, etc). Common practices of FACS include hematopoiesis, oncology, and stem cell research.

How Does FACS Work?

FACS is cell separation based on the cell surface markers and sorts the biological mixture in two or more containers based on light scattering. Proteins and carbohydrates give each cell unique surface phenotypes. The cells are given specific antibodies which are associated with the cell surface antigens. Cells are then targeted by those antigens.

Let’s break it down:

  • Antibodies match with antigens on the surface of targeted cell
  • Targeted cell is labeled with fluorescent marker and mixed into the cell sample
  • One at a time, cells flow through a point of analysis where they are hit by a laser beam
  • Cells are then emptied into containers based on their fluorescence or specific light labeling/scattering pattern

Cells are separated by their fluorescent properties or by scattered light – either by cell size or a scatter that indicates granularity. Check out our article on FACS vs. flow cytometry to get a better understanding of how they differ.

Advantages and Disadvantages

FACS is much more versatile than MACS. The ability to separate cells based on their surface markers as well as size and granularity allow for more in-depth isolations. This trait has made FACS a standard in many research labs, but that doesn’t mean there are no limitations.

Flow cytometers, which are machines required to perform FACS, are very costly. Additionally, proper training for operating the equipment can be time consuming. Although sample sizes can be large, the amount of time it takes to run a single sample falls around 2-3 hours. The high quantity also increases the likelihood of contamination in the sample. When such a high volume of cells is flowing through the laser, it’s easy for cells to get sorted incorrectly or misidentified.


BACS or buoyancy-activated cell sorting is the process of isolating cells based on microbubbles binding to antibodies. Buoyancy-activated microbubbles are composed of gas at the core and shelled by polymers, lipids, and proteins.

How Does BACS Work?

BACS can be used for a wide variety of biological research, but how does BACS work? Let’s break it down:

  • Microbubbles are mixed with cell samples, allowing them to identify and bind to targeted cells and separate from non-targeted cells
  • Once targeted cells have been secured, microbubbles float to the top. The targeted cells are carried through leaving behind the non-targeted cells
  • The targeted cells are collected from top of the sample to be isolated or removed from the enriched sample left behind

Comparing MACS and FACS to BACS Microbubble Technology

Akadeum’s buoyancy-activated cell sorting is a quick alternative to more traditional cell sorting technology. It has proven ability to reduce cell sorting time and is easy to use. BACS microbubble technology takes an average of 10-30 minutes for cell selection. FACS and MACS equipment can run a high price, but with Akadeum’s BACS, no additional equipment is needed.

Check out Akadeum’s Microbubble Technology today  

If you are searching for a way to improve the quality and viability of sorted cells while dramatically saving time and reducing costs, look no further than Akadeum’s buoyancy-activated microbubble technology.

Contact us with questions, and try our products today.

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