A Novel Immunoreagent for the Specific and Sensitive Detection of the Explosive Triacetone Triperoxide (TATP)

Abstract

Triacetone triperoxide (TATP) is a primary explosive, which was used in various terrorist attacks in the past. For the development of biosensors, immunochemical µ-TAS, electronic noses, immunological test kits, or test strips, the availability of antibodies of high quality is crucial. Recently, we presented the successful immunization of mice, based on the design, synthesis, and conjugation of a novel TATP derivative. Here, the long-term immunization of rabbits is shown, which resulted in antibodies of extreme selectivity and more than 1,000 times better affinity in relation to the antibodies from mice. Detection limits below 10 ng L-1 (water) were achieved. The working range covers more than four decades, calculated from a precision profile. The cross-reactivity tests revealed an extraordinary selectivity of the antibodies-not a single compound could be identified as a relevant cross-reactant. The presented immunoreagent might be a major step for the development of highly sensitive and selective TATP detectors particularly for security applications.

Figure 1

Chemical structures of the TATP hapten and TATP.

Figure 2

TATP calibration curves (four-parameter logistic function) and corresponding precision profiles obtained with 32 TATP standard solutions, including a blank of water. The LOD was 6 ng L⁻¹ (rabbit 1) and 5 ng L⁻¹ (rabbit 2). The IC₅₀ of the sigmoidal curves obtained were 0.50 µg L⁻¹ (rabbit 1) and 0.35 µg L⁻¹ (rabbit 2). The slopes at the test midpoint (IC₅₀) were 0.66 (rabbit 1) and 0.61 (rabbit 2). The sera (boost 11) were diluted 1:100,000; the HRP conjugate was diluted 1:300,000. Error bars in calibration curve: standard deviation (n = 3). Black square (rabbit 2: 2 µg L⁻¹): One of three replicates was masked as outlier.

Figure 3

Chemical structures of potential cross-reactants (see Table 1 and Table 2; structures 9 and 11 represent examples of an isomer mixture).