How can the high background of mouse TNF-α ELISA for brain tissue homogenates be resolved?

The composition of the lysis buffer is critical. Avoid using RIPA containing strong detergents such as SDS, NP-40, or sodium deoxycholate, as these can disrupt antigen-antibody binding, resulting in high background or false positives. Instead, use PBS or a hypotonic buffer containing 0.1% Triton X-100, supplemented with protease inhibitor cocktail and PMSF. Lyse on ice, then centrifuge at 4°C and collect the supernatant. Inhibitors generally do not interfere with ELISA, but note that PMSF has a short half-life and should be added fresh immediately before use.

High background in brain tissue is mostly due to matrix effects. Do not measure the original sample directly at first; use the kit sample diluent to prepare three dilution levels of 1:2, 1:5, and 1:10 and back-calculate. If the back-calculated concentration increases with the dilution factor, it indicates matrix inhibition or false signal; if the back-calculated concentration decreases, it may be background interference. Hippocampal samples have high protein content, so it is recommended to start testing at at least 1:5. If the sample volume is limited, first take 3 uL for a dilution pilot test; there is no need to use more than ten microliters at once.

For low sample volumes, you can look for high-sensitivity or low-sample-volume versions of kits, which typically allow 1:1 or 1:2 dilution to reduce sample consumption. A dozen or so microliters is enough for one replicate well, but it is recommended to reserve at least enough for upper and lower sample replicates, so prioritize kits with a standard curve sensitivity of 1-2 pg/mL. In terms of brands, you can look into Xinbosheng, Lianke, Thermo high-sensitivity series, etc., but be sure to confirm whether they have been validated for brain tissue homogenate, and do not rely solely on serum data.

When troubleshooting background, set up a sample blank: add only the sample and diluent to the test wells, without detection antibody/HRP-conjugated antibody. If the color still develops strongly, it indicates endogenous peroxidase or a reaction between sample components and the substrate; switch to a diluent containing HRP inhibitor or purchase a kit specifically designed for tissue homogenates. For plate washing, it is recommended to use a plate washer or manually wash 5 times with 300 µL per well. Regarding lead time, domestic in-stock products are generally 2–5 days, while imported high-sensitivity products may take 1–2 weeks; confirm before placing an order.