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Schematic shows the preparation of pure active water.

Supplemental material, sj-docx-1-oag-10.1177_00307270231173137 for Use of “demonstration farm” videos to affect attitude change toward animal welfare on beef, egg, and fish farms in China by Yifei Yang, Tianxu Liu, Danielle Nilsson, Kate Hartcher, Hao-Yu Shih, Zhong-Hong Wu, Zhong-Ying Liu, Michelle Sinclair, Xochitl Samayoa, Kate Henning and Kris Descovich in Outlook on Agriculture

Bulk water is generally considered to be an inert solvent because of its tetrahedral hydrogen-bonded structure. Recently, unusual properties of confined water in nanosized environments have aroused...

Liquid water, as the most environmentally friendly polar solvent, is popularly used in physical processes and chemical reactions. Its unique properties and activities come from the presence of intermolecular hydrogen bonds (HBs) with itself and other species. Scientists have been discussing properties other than known bulk water for a long time. However, the particular application of water being researched is limited today. Mass-produced active and stable plasmon-activated water (PAW) with a reduced HB network based on hot electron transfer (HET) from resonantly illuminated gold (Au) nanoparticles (NPs) was first created in 2014. In this work, we report its distinct intermolecular HBs with water-soluble alcohols and the solubility of hydrophobic solutes. Interestingly, the densities of PAW in methanol, ethanol, and propanol at various ratios all increased due to stronger HBs between PAW and the alcohols, particularly seen with propanol, compared to deionized water (DIW)-based systems. Moreover, these results reflect the decreased evaporation rates of PAW/alcohol solutions, especially observed for the solution with the maximum increased density, compared to DIW-based systems. Compared to DIW, the solubilities of hydrophobic antioxidants of curcumin and melatonin in PAW increased by ca. 240% and 120%, respectively. Moreover, sunflower oil was more soluble in the more-lipophilic PAW compared to conventional DIW. The distinct increased density of the alcohol/PAW solution lasted for at least 1 week. Innovative PAW has emerged as a promising green active solvent applicable for both hydrophilic and hydrophobic solutions.

Water is the most environmentally friendly solvent, but bulk water is conventionally considered to be a bystander in reactions performed in it. For decades, scientists have been discussing the characteristics of water that differ from bulk water in special environments. Recently, various small amounts of treated water were developed to create specific applications. In 2014, comprehensively active and stable plasmon-activated water (PAW), which was mass-produced and innovatively created by utilizing hot electron transfer (HET) from gold nanoparticles (AuNPs), was first reported. In this work, we report the maintenance of activity of purified Au-free PAW collected from water condensed from PAW vapor (PAW-V). Interestingly, the metastable PAW-V was still active with a structure of electron-doping and reduced hydrogen bonding (HB), which were confirmed by zeta potentials and the nuclear magnetic resonance (NMR) relaxation time (T1). Like PAW, PAW-V enhanced hydrogen evolution reactions (HERs) and oxygen evolution reactions (OERs), compared to deionized water (DIW). The PAW-V itself exhibited the ability to more rapidly evaporate due to reduced HBs between homogeneous molecules, while a PAW/isopropanol solution evaporated more slowly due to enhanced HBs between heterogeneous molecules. Also, PAW-V could scavenge free 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals and reduce the strong KMnO4 oxidant. The unique properties of PAW-V were maintained after storage for 3 days at room temperature in the dark. The condensed Au-free PAW has emerged as a promising green active solvent applicable in various fields of physics, chemistry and biomedicine.

High surface-enhanced Raman scattering (SERS) enhancement is generally accompanied by low signal reproducibility. Thus, various complicated technologies focusing on SERS-active substrates were developed to overcome these limitations. On the other hand, innovatively treated plasmon-activated water (PAW) with properties distinct from those of untreated bulk water was previously reported. Herein, we propose an alternative promising strategy to obtain overall improved SERS performances of analyte solutions prepared using PAW instead of conventional deionized water (DIW). Interestingly, SERS signals were higher, but the corresponding relative standard deviations were lower for the model molecules of rhodamine 6G and methyl blue, with different concentrations prepared in PAW compared to those prepared in DIW. Moreover, these overall improved SERS performances were observed when detecting the pesticides acetamiprid (AC) and imidacloprid (IM) prepared in PAW, compared to those prepared in DIW. Experimental results indicated that the limit of detection (LOD) was 5 ppb (100 ppb based on DIW) for AC prepared using PAW. Moreover, the LOD was 10 ppb for IM prepared using PAW. These extremely low values of LOD detected for AC and IM were comparable to and even better than other SERS detection methods based on solutions prepared using organic solvents or organic solvent/water systems. Moreover, using PAW to dissolve analyte provides an innovative method in SERS studies.