Each aliquot of captured target was then incubated with 100 ml of TNT-PNA probe solution comprising 1 nmol of each of two TNT-PNA probes of the same length in hybridization buffer, i.e. 1 nmol of ANTHRAX-12 would be mixed with 1 nmol MOMP-12. Hybridization was carried out at room temperature for two hours. After hybridization, the probe solution was removed from the beads and the beads were washed three times with ice-cold 70 mM aqueous ammonium citrate solution.