Designing chemiluminescence (CLIA) kits requires consideration of different aspects, including raw materials for reagent development and method selection, as well as the choice of assay. The material supplier is a key factor in the successful design and development of the assay.

An ideal supplier should be able to provide not only the required raw materials at a reliable cost, but also the required batches to scale up the reagents. In addition, the supplier should offer different batches to assess lot-to-lot variability to check the impact on the assay to be developed.

1. Strategy for magnetic bead selection

Magnetic beads are available in different sizes, ranging from nanometers to a few microns. Smaller magnetic beads may require more time to separate using a magnetic separator. The separation time of magnetic beads depends heavily on the amount of magnetic pigment. Higher pigment percentages will lead to faster magnetic bead separation. A balance between the magnetic pigment and the size of the beads should be achieved to maintain the correct density of the beads.

Designing a CLIA assay requires consideration of different aspects, including the raw materials for reagent development and method selection, as well as the choice of assay method. The material supplier is a key factor in the successful design and development of the assay.

2. Chemically modified magnetic beads for CLIA

A simple but less stable strategy for surface conjugation of magnetic beads can be achieved by direct passive adsorption of antigens or antibodies onto the surface of "normal" magnetic beads. Alternatively, if covalent attachment of antigens or antibodies is important for the assay, then modifying the surface chemistry of the magnetic beads is a good option. Activation groups take advantage of the large surface area of the magnetic beads to provide rich anchor points for your antibody or antigen to be covalently attached to the beads.

Some examples of pre-activated chemicals that can be used are the popular Tosyl moieties or epoxy resins. There are other groups that need to be activated such as carboxyl groups (-COOH), amines (-NH2) and hydroxyl groups (-OH). This practice is also known as chemical functionalization of magnetic beads.

3. Bio-modified magnetic beads for CLIA

Biomodified magnetic beads (also known as surface biofunctionalization) are also a common strategy for CLIA development.

There are several types of bio-modified magnetic beads. The antibody or antigen of choice can be modified with biotin linkers that bind to magnetic beads modified with streptavidin. Protein A binds to the Fc region of most immunoglobulins, making it an attractive choice for immobilizing antibodies on magnetic beads.

Similarly, protein G binds to the Fc or Fab regions of a range of immunoglobulins and can be used to immobilize antibodies. Sometimes Protein A and G are used together to increase the potential antibody binding profile. It is also possible to attach specific proteins, but this needs to be optimized.

When selecting biologically modified magnetic beads for use in CLIA assays, it is important to check the compatibility of these beads with the sample type to prevent non-specific interactions between components of the sample and the biological surface of the beads.