Development of a magnetic nanoparticle-based method for concentrating SARS-CoV-2 in wastewater.

Several virus concentration methods have been developed to increase the detection sensitivity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in wastewater, as part of applying wastewater-based epidemiology. Polyethylene glycol (PEG) precipitation method, a method widely used for concentrating viruses in wastewater, has some limitations, such as long processing time. In this study, Pegcision, a PEG-based method using magnetic nanoparticles (MNPs), was applied to detect SARS-CoV-2 in wastewater, with several modifications to increase its sensitivity and throughput. An enveloped virus surrogate, Pseudomonas phage φ6, and a non-enveloped virus surrogate, coliphage MS2, were seeded into wastewater samples and quantified using reverse transcription-quantitative polymerase chain reaction to assess the recovery performance of the Pegcision. Neither increasing MNP concentration nor reducing the reaction time to 10 min affected the recovery, while adding polyacrylic acid as a polyanion improved the detection sensitivity. The performance of the Pegcision was further compared to that of the PEG precipitation method based on the detection of SARS-CoV-2 and surrogate viruses, including indigenous pepper mild mottle virus (PMMoV), in wastewater samples (n = 27). The Pegcision showed recovery of 14.1 ± 6.3 % and 1.4 ± 1.0 % for φ6 and MS2, respectively, while the PEG precipitation method showed recovery of 20.4 ± 20.2 % and 18.4 ± 21.9 % (n = 27 each). Additionally, comparable PMMoV concentrations were observed between the Pegcision (7.9 ± 0.3 log copies/L) and PEG precipitation methods (8.0 ± 0.2 log copies/L) (P > 0.05) (n = 27). SARS-CoV-2 RNA was successfully detected in 11 (41 %) each of 27 wastewater samples using the Pegcision and PEG precipitation methods. The Pegcision showed comparable performance with the PEG precipitation method for SARS-CoV-2 RNA concentration, suggesting its applicability as a virus concentration method.

Photoinduced Shape Changes of Mixed Molecular Glass Particles Containing Azobenzene-Based Photochromic Amorphous Molecular Materials Fixed in Agar Gel.

It has been found that mixed molecular glass particles exhibit photoinduced shape changes, elongating their shapes to form stringlike structures similar to single molecular glass particles of azobenzene-based photochromic amorphous molecular materials. Furthermore, interestingly, the addition of 15 mol % photochemically inert 4,4',4″-tris[3-methylphenyl(phenyl)amino]triphenylamine enhanced the phenomenon relative to single particles of 4-[bis(4-methylphenyl)amino]azobenzene. The present mixed systems allowed to elucidate the effects of Tg and of the apparent photochromic reactivity independently by changing the mixing ratio of suitable materials. It has been clearly demonstrated that increase in the apparent photochromic reactivity enhanced monotonically the photomechanical elongation of the particles. On the other hand, it has been found that increase in Tg was favorable for the present photoinduced elongation of the particle, whereas the effect of Tg became saturated at sufficiently high Tg values.