Development of a chemiluminescent lateral flow immunoassay for in situ TNT detection

The compound 2,4,6-trinitrotoluene (TNT) is one of the most commonly used explosives for military and civilian applications. The possibility to detect TNT at trace levels in various matrices is relevant both for forensic applications and in the environmental field, due to due to TNT environmental impact and health related concerns. More recently, global security concerns have dictated a need to detect and quantify trace levels of explosives contamination on items or surfaces, which could alert searchers to the possible presence of concealed explosives. Various assays were developed that enabled TNT detection at ppb levels, including chromatography, amperometric detection, immunoassays, surface plasmon resonance and capillary electrophoresis. Since most of these methods are not applicable on field, research activities are directed towards the development of rapid and portable assays mostly based on biologically-derived molecular recognition systems. In this work, a lateral-flow chemiluminescence immunoassay for TNT detection was developed, employing a portable CCD camera for signal detection. The method, which allowed detecting TNT down to 50 ng/mL (ppb) in 15 minutes, showed the possibility to obtain semi-quantitative detection of TNT traces with a simple, rapid, low-cost and on-field applicable assay. The method was also tested on real samples obtained from swabbing surfaces of various materials exposed to controlled explosion experiments. Results were found in good agreement with those obtained with a previously developed chemiluminescence ELISA assay in conventional microtiter plate format.