The suitability of a polydimethylsiloxane-based (PDMS) microfluidic two compartment system for the toxicokinetic analysis of organophosphorus compounds

Determination of tissue distribution of VX and its metabolites EMPA and EA-2192 in various rat tissues by LC-ESI-MS/MS after phosphotriesterase treatment

Phosphotriesterases (PTE) are a new and promising approach for the treatment of organophosphate poisoning, since the current therapy of such intoxications shows some limitations. A previous rat in vivo study confirmed the therapeutic effect of PTE, which were specifically designed for VX breakdown, and demonstrated rapid degradation of VX in whole blood samples. The present study now focuses on the degradation of VX and its distribution in organ tissues of the animals used in the aforementioned study. In order to gain a broader overview, we have extended the investigations to the VX metabolites EA-2192 and EMPA by using methods developed for an LC-ESI-MS/MS system. Applying these methods, we were able to verify the effectiveness of the PTE treatment and gained an overview of VX tissue distribution in poisoned but untreated rats.

Toxicokinetic analysis of the highly toxic nerve agent VX in commercially available multi-organ-chips - Ways to overcome compound absorption

Organ-on-a-chip technology is considered a next-generation platform in pharmacology and toxicology. Nevertheless, this novel technology still faces several challenges concerning the respective materials which are used for these microfluidic devices. Currently available organ-chips are most often based on polydimethylsiloxane (PDMS). However, this material has strong limitations regarding compound binding. The current study investigated options to reduce compound absorption of the highly toxic nerve agent VX (1000 µmol/L) in a commercially available organ-chip. In addition, surface effects on degradation products of VX were investigated. The alternative polymer cyclic olefin copolymers (CoC) showed significantly less compound absorption compared to PDMS. Furthermore, a coating of PDMS- and CoC-based chips was investigated. The biocompatible polymer polyethyleneimine (PEI) successfully modified PDMS and CoC surfaces and further reduced compound absorption. A previously examined VX concentration after 72 h of 141 ± 10 µmol/L VX could be increased to 442 ± 54 µmol/L. Finally, the respective concentrations of VX and degradation products accounted for > 90% of the initial concentration of 1000 µmol/L VX. The currently described surface modification might be a first step towards the optimization of organ-on-a-chip surfaces, facilitating a better comparability of different studies and results.