Past-expiration-date liquid disinfectants to deactivate biological and chemical toxins on building material surfaces.

In this study, we evaluated the deactivating efficacy of strong basicity-based (T4-102) and hydrogen peroxide-based (DF-200) disinfectants that were past their expiration date when used to deactivate biological and chemical toxins on building material surfaces. The decontamination efficacies of DF-200 and T4-102 disinfectants against dimethyl methylphosphonate (DMMP) and 2-chloroethyl ethylsulfide (2-CEES) were studied using GC-MS analysis. The bactericidal efficacies of disinfectants against Gram-negative E. coli and P. aeruginosa, and Gram-positive B. subtilis and S. aureus, were assessed in terms of the zone of inhibition, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC). The results indicated that the deactivation efficacy varied significantly according to the disinfectant amount, contact time, and building material. Higher efficacy of up to 99-100% was observed for biological toxins, despite passing their expiration dates. Approximately 70-78% of deactivation efficacies were observed for disinfectants against DMMP on the tile coupon at 100 µL and 24 h contact time. Moreover, the deactivation efficacy of DF-200 was better than that of T4-102. The data presented here demonstrate that the responders may use past-expiration-date disinfectants for efficacious disinfectaion in large-scale contamination incidents.

Preparation and antibacterial effects of Ag/AgCl-doped quaternary ammonium-modified silicate hybrid antibacterial material.

Organic-inorganic hybrid antibacterial materials based on Ag/AgCl and quaternary ammonium-modified silicate (Ormosil(NR4+Cl-)) were prepared by sol-gel processes and an in situ reduction method. The physical properties of Ormosil(NR4+Cl-) and the Ormosil(NR4+Cl-)/Ag hybrids were examined using FTIR, UV-Vis, SEM, XRD and NMR spectroscopy. The results indicated that Ag/AgCl was incorporated into the Ormosil(NR4+Cl-) matrix after impregnation. Morphological analysis by SEM showed uniformly-distributed Ag and AgCl particles in the Ormosil(NR4+Cl-) matrix, of spherical nature and a size around 5-20 and <200 nm. The antibacterial effects of Ormosil(NR4+Cl-) and the Ormosil(NR4+Cl-)/Ag hybrids against Gram-negative P. aeruginosa and E. coli, and Gram-positive S. aureus and B. subtilis, were assessed in terms of the zone of inhibition, minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC) and plate-counting method, and an excellent antibacterial performance was discovered. Moreover, the antibacterial performance of the Ormosil(NR4+Cl-)/Ag hybrid was better than that of Ormosil(NR4+Cl-) and the Ormosil/Ag hybrids.