Please recommend a suitable HRP substrate for high-sensitivity ELISA. Which is more linear in color and luminescence?

Chemiluminescent HRP substrates generally offer a wider linear range and higher sensitivity than TMB colorimetric substrates, making them more suitable for low-abundance targets and serum samples with a broad concentration range. However, they require a microplate reader equipped with a luminescence detection module, and the luminescent signal varies greatly over time, so the interval between sample addition and reading must be kept consistent. TMB colorimetric detection is simple to perform and has a relatively narrow linear range, making it suitable for medium- to high-abundance targets and situations with limited budgets. If your target concentration is very low, it is recommended to use luminescence; if the issue is only high background while the sample signal is not weak, you can optimize your existing TMB system rather than switching platforms.

A high TMB background may not necessarily be a problem with the substrate itself. First, create blank wells, wells without detection antibodies, and wells with only substrate added. Determine whether the background comes from the coating/sealing/washing plate or the substrate. Serum samples often have interference from endogenous peroxidase or heterophilic antibodies. You can try adding normal serum to the blocking solution, 0.05% Tween-20 to the washing solution, and extending the blocking after coating. If it is confirmed that the substrate background is high, switching to ultra sensitive TMB or reducing the substrate incubation time can improve it. It is recommended to optimize the system before deciding whether to use chemiluminescence for high-sensitivity ELISA.

Chemiluminescent substrates usually need to be mixed from Solution A and Solution B immediately before use, and should be brought to room temperature beforehand; after adding the substrate, avoid strong light and read within a fixed time window. If using TMB, control the incubation temperature and time, and read the plate as soon as possible after stopping with stop solution to improve background and linearity. Serum samples can be centrifuged before loading to remove lipids and reduce interference. For small-batch trials, prepare two standard curves (colorimetric and luminescent) with the same antibody set, and compare the signal-to-noise ratio and limit of detection. Within budget, domestic luminescent solutions can also be purchased for preliminary experiments, and after confirming equipment compatibility, proceed with bulk procurement.

Within a budget of 500 yuan per box, small packages of domestically produced ultra sensitive ECL substrates or HRP luminescent solutions can cover 200 wells. When purchasing, find a stable batch supplier and request three batches of samples for parallel plate comparison, with a focus on blank hole RLU, standard curve slope, and inter batch variation. The chromogenic substrate can be selected from slow kinetics TMB or membrane grade TMB, with a lower background. Don't just look at the unit price, calculate the cost based on the actual usage of 200 holes; Some 100mL luminescent liquids can make several boards. It is recommended to choose a brand that has technical support, provides COA, and stable agent channels.