Pellet patented technology for fast and distinct visual detection of cholinesterase inhibitors in liquids

The effect of different types of lactose monohydrate on the stability of acetylcholinesterase immobilized on carriers designed to detect nerve agents

“…To evaluate the ability of the immobilized acetylcholinesterase to detect ChI, a physostigmine (carbamate, reversible ChI) was used during the stability test under laboratory conditions, as it was considered a suitable simulant based on other studies, 19,25,27,39 and allows a quick and safe comparison of different carrier compositions in terms of their sensitivity to ChI. Figure 5 describes the dependence of Δ E 2000 on the physostigmine concentration for different samples before the stability test.…”

“…The Ellman's test solution (ETS) was prepared by mixing 0.2 mL ATChI solution and 15 mL of the Ellman's work solution. The ATChI and ETS were stable for 24 h. For the test of inhibition, physostigmine test solutions (PTS) with concentration of 0.25, 0.5, 1.0, 2.0 or 4.0 mg L −1 were prepared according to the standard methodology 19,25 …”

“…Based on earlier experiments, 19,25,26,35 Ellman's reaction was used to evaluate the activity of the immobilized acetylcholinesterase. Approximately 120 mg pellets, which corresponds to the enzymatic activity of 6.0 nkat g −1 , was placed in a glass tube with a 0.5 cm diameter and tempered to room temperature (25 ± 2 °C).…”

“…The inhibition test is designed to compare samples with different compositions. In this test, based on previous experiments and for safety reasons, physostigmine was used as a suitable cholinesterase inhibitor 19,25,26,35 . Similarly to the activity test, it was performed in a glass tube with the same amount of sample.…”

“…Otherwise, a yellow color develops on the pellets within a few seconds, which is visible to the naked eye or detectable spectrophotometrically. The disadvantage of this reaction is often an indistinct transition from white to yellow, which was investigated in other studies 19,25,26 . However, during longer storage and especially at higher temperatures, the carriers continued to turn brown, which could be problematic when stored, particularly in subtropical and tropical countries.…”