Lanthanide luminescence are known to exhibit long lifetimes, enabling highly sensitive detection in time-gated mode. Here we  further increase the sensitivity of lanthanide-based probes by using multiple luminescent labels attached to a carrier molecule. We found that up to 30 of lanthanide chelates can be attached to avidin, creating highly bright conjugates. These constructs with europium chelates displayed synergistic effect, yielding cumulative light emission higher than the sum for the equivalent amount of non-conjugated probes. However, an opposite effect was observed for terbium chelates, which showed significantly reduced brightness. However, the terbium conjugates brightness was completely restored by introduction of a rigid aromatic spacer between the chelate and the protein attachment site. Suggested luminescent avidin conjugates can find wide applications, especially in imaging of single molecules, biological micro objects, as well as for the development of highly sensitive assays, in which the signal cannot be amplified.

Highly bright avidin-based affinity probes carrying multiple lanthanide chelates for ultrasensitive detection of biopolymers

244th National Meeting (2012)

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