Inactivation and Loss of Infectivity of Enterovirus 70 by Solar Irradiation

Photoinactivation of Phage Phi6 as a SARS-CoV-2 Model in Wastewater: Evidence of Efficacy and Safety

The last two years have been marked by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. This virus is found in the intestinal tract; it reaches wastewater systems and, consequently, the natural receiving water bodies. As such, inefficiently treated wastewater (WW) can be a means of contamination. The currently used methods for the disinfection of WW can lead to the formation of toxic compounds and can be expensive or inefficient. As such, new and alternative approaches must be considered, namely, photodynamic inactivation (PDI). In this work, the bacteriophage φ6 (or, simply, phage φ6), which has been used as a suitable model for enveloped RNA viruses, such as coronaviruses (CoVs), was used as a model of SARS-CoV-2. Firstly, to understand the virus's survival in the environment, phage φ6 was subjected to different laboratory-controlled environmental conditions (temperature, pH, salinity, and solar and UV-B irradiation), and its persistence over time was assessed. Second, to assess the efficiency of PDI towards the virus, assays were performed in both phosphate-buffered saline (PBS), a commonly used aqueous matrix, and a secondarily treated WW (a real WW matrix). Third, as WW is generally discharged into the marine environment after treatment, the safety of PDI-treated WW was assessed through the determination of the viability of native marine water microorganisms after their contact with the PDI-treated effluent. Overall, the results showed that, when used as a surrogate for SARS-CoV-2, phage φ6 remains viable in different environmental conditions for a considerable period. Moreover, PDI proved to be an efficient approach in the inactivation of the viruses, and the PDI-treated effluent showed no toxicity to native aquatic microorganisms under realistic dilution conditions, thus endorsing PDI as an efficient and safe tertiary WW disinfection method. Although all studies were performed with phage φ6, which is considered a suitable model of SARS-CoV-2, further studies using SARS-CoV-2 are necessary; nevertheless, the findings show the potential of PDI for controlling SARS-CoV-2 in WW.

Quantum Leap from Gold and Silver to Aluminum Nanoplasmonics for Enhanced Biomedical Applications

Nanotechnology has been used in many biosensing and medical applications, in the form of noble metal (gold and silver) nanoparticles and nanostructured substrates. However, the translational clinical and industrial applications still need improvements of the efficiency, selectivity, cost, toxicity, reproducibility, and morphological control at the nanoscale level. In this review, we highlight the recent progress that has been made in the replacement of expensive gold and silver metals with the less expensive aluminum. In addition to low cost, other advantages of the aluminum plasmonic nanostructures include a broad spectral range from deep UV to near IR, providing additional signal enhancement and treatment mechanisms. New synergistic treatments of bacterial infections, cancer, and coronaviruses are envisioned. Coupling with gain media and quantum optical effects improve the performance of the aluminum nanostructures beyond gold and silver.