Experiment #5 - Conjugate Blocking

Make sure to check out experiment #4 - optimize antibody incubation time before completing this step.

Provided with this kit is an NCX Blocking Buffer with a formulation of 4 mM sodium borate 1% BSA at pH 8.2 (pH 8.2 allows for optimum binding of BSA to antibodies). Blocking a conjugate can often decrease non-specific binding via the addition of non-specific proteins such as bovine serum albumin (BSA) or casein protein.

Fortis Life Science standard protocols include a 1 hour blocking step with the supplied blocking buffer. Blocking is typically performed immediately following the quench step but can be done at any time post-conjugation.

Human heart with blocked arteries. 3d illustration

Blocking Protocol

  1. Aliquot 0.5 mL of the optimal conjugate from Experiment #4.
  2. Spin conjugate at 2k RCF for 5 minutes.
  3. Remove ~450 µL of supernatant and resuspend with ~450 µL NCX Blocking Buffer (4 mM sodium tetraborate, 1% BSA, 0.05% sodium azide, pH 8.2)
  4. Incubate/mix for 1 hour.
  5. Spin conjugate at 2k RCF for 5 minutes
  6. Remove supernatant
  7. Re-suspend in the NCX Conjugate Diluent (0.5× PBS, 0.5% BSA, 0.5% casein, 1% Tween 20, 0.05 % azide pH 8)

Compare performance of blocked conjugate to unblocked conjugate. If the blocking step improves performance, it is recommended to investigate the following blocking times: 30 minutes, 1 hour, 2 hour, and overnight. If the blocking step did not demonstrate an improvement in conjugate performance or stability, we recommend that you do not include a blocking step.