Synthesis and Storage Stability of Diisopropylfluorophosphate

Diisopropylfluorophosphate (DFP) is a potent acetylcholinesterase inhibitor commonly used in toxicological studies as an organophosphorus nerve agent surrogate. However, LD50 values for DFP in the same species can differ widely even within the same laboratory, possibly due to the use of degraded DFP. The objectives here were to identify an efficient synthesis route for high purity DFP and assess the storage stability of both the in-house synthesized and commercial source of DFP at the manufacturer-recommended storage temperature of 4°C, as well as −10°C and −80°C. After 393 days, the commercial DFP stored at 4°C experienced significant degradation, while only minor degradation was observed at −10°C and none was observed at −80°C. DFP prepared using the newly identified synthesis route was significantly more stable, exhibiting only minor degradation at 4°C and none at −10°C or −80°C. The major degradation product was the monoacid derivative diisopropylphosphate, formed via hydrolysis of DFP. It was also found that storing DFP in glass containers may accelerate the degradation process by generating water in situ as hydrolytically generated hydrofluoric acid attacks the silica in the glass. Based on the results here, it is recommended that DFP be stored at or below −10°C, preferably in air-tight, nonglass containers

Switchable pH-responsive polymeric membranes prepared via block copolymer micelle assembly

A process is described to manufacture monodisperse asymmetric pH-responsive nanochannels with very high densities (pore density >2 × 10(14) pores per m(2)), reproducible in m(2) scale. Cylindric pores with diameters in the sub-10 nm range and lengths in the 400 nm range were formed by self-assembly of metal-block copolymer complexes and nonsolvent-induced phase separation. The film morphology was tailored by taking into account the stability constants for a series of metal-polymer complexes and confirmed by AFM. The distribution of metal-copolymer micelles was imaged by transmission electron microscopy tomography. The pH response of the polymer nanochannels is the strongest reported with synthetic pores in the nm range (reversible flux increase of more than 2 orders of magnitude when switching the pH from 2 to 8) and could be demonstrated by cryo-field emission scanning electron microscopy, SAXS, and ultra/nanofiltration experiments

Publisher Correction: Whole-genome sequencing of a sporadic primary immunodeficiency cohort (Nature, (2020), 583, 7814, (90-95), 10.1038/s41586-020-2265-1)

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