LowCross-Buffer from Candor Bioscience is a ready-to-use buffer solution which helps to reduce interference in immunoassays. Standard sample or antibody dilution buffers such as phosphate or tris buffered saline (PBS, TBS), are either completely replaced or can be mixed with LowCross-Buffer up to a minimum content of about 50%. It is also used as washing buffer in very demanding assays, like immuno-PCR. Non specific reactions, such as cross-reactivities of antibodies (low and medium affinity), negative effects of disturbing substances in assay solutions and background effects are inhibited. LowCross-Buffer also efficiently reduces so called matrix effects, which are derived from blood preparations or sera specimen. As a result, specific detection of analytes is improved. LowCross-Buffer is a clear liquid and contains a preservative. It can be used at least 6 months if stored at 4°C. Package sizes of 50, 125 and 50 ml are available. LowCross-Buffer is applied in enzyme-linked immunosorbent assays (ELISA), Western blots, protein arrays, immunohistochemistry and lateral flow assays.
We frequently use Candor’s Low-Cross-Buffer in different assay formats such as ELISA, Western blots, Line-immunoassays and protein arrays. We repeatedly found a dramatic improvement of signal-to-noise ratios when human serum was diluted completely in LowCross instead of PBS in protein microarrays. Mixtures of PBS and LowCross (50 and 75%) resulted in higher background and weaker signals with this assay format. In applications such as Line-immunoassays and Western blots, no effect could be observed if serum was diluted in LowCross-Buffer (same signal-to-noise ratio as with PBS). However, improvement of background to some extent was achieved, when a mixture of LowCross and TBS (50 and 75%) for dilution of horse-radish-peroxidase (HRP) labelled secondary antibody was used. Utilization of LowCross-Buffer as serum dilution buffer in small scale protein arrays can indeed solve problems with non-specific background, matrix effects or antibody cross-reactions. The success as dilution buffer for secondary antibodies in Western blots and Line-immunoassays is not as impressive and might not be economical either, as larger amounts of buffer are needed. Adding basic background inhibitors such as bovine serum albumin (BSA), skim dry milk and Tween20 might be as effective, so always try first before opting for LowCross-Buffer.
PhD Student
Institute f. Med. Microbiology & Hygiene
University of Regensburg