Green synthesis of silver nanoparticles using Eupatorium adenophorum leaf extract: characterizations, antioxidant, antibacterial and photocatalytic activities.

The green synthesis of metallic nanoparticles has tremendous impacts in various fields as found in recent years due to their low cost, easy and environmentally friendly synthesis. In this article, we report a simple and eco-friendly method for the synthesis of silver nanoparticles (AgNPs) using an aqueous Eupatorium adenophorum (E. adenophorum) leaf extract as a bioreductant. Interestingly, Fourier transform infrared (FTIR) spectroscopy analysis established that the E. adenophorum extract not only served as a bioreductant but also acted as a capping agent to stabilize the nanoparticles by functionalizing the surfaces. Various characterization techniques were adopted, such as X-ray powder diffraction (XRD), FTIR, ultraviolet-visible absorption (UV-Vis) spectroscopy, dynamic light scattering, scanning electron microscopy and energy-dispersive X-ray spectroscopy (EDX) to analyze the biosynthesized AgNPs. Biosynthesized nanoparticles were also explored for antioxidant, antibacterial and photocatalytic activities. The AgNPs showed improved free radical scavenging activity (IC50 48.96 ± 0.84 µg/mL) and bacterial inhibitory effects against both gram-positive (Staphylococcus aureus; 64.5 µg/mL) and gram-negative (Escherichia coli; 82.5 µg/mL) bacteria. Photocatalytic investigation showed AgNPs were effective at degrading rhodamine dye (78.69% in 90 min) when exposed to sunlight. These findings collectively suggest that E. adenophorum AgNPs were successfully prepared without the involvement of any hazardous chemical and it may be an effective antibacterial, antioxidant and promising agent for the removal of hazardous dye from waste water produced by industrial dyeing processes.

Current challenges in different approaches to control COVID-19: a comprehensive review.

Background: The World Health Organization declared the outbreak of the novel coronavirus (COVID-19) as a global health emergency on January 30, 2020, and as a pandemic disease on March 11, 2020. This review highlights the international situation, risk factors, and related protections to be taken as prerequisite measures and probable treatment options for the COVID-19-infected population in the current scenario. Main text: The SARS-CoV-2 viruses and their variants caused mild-to-severe respiratory tract infection and used airborne pathways as a way of contagion. Human-to-human transmission led to an exponential growth in the rise in the number of cases making it a real burden to immobilize the rapid spread of the virus while asymptomatic patients created ambiguity for confirmation in the community. It was clear from the case studies of patients that most of them were asymptomatic but still vulnerable to the people around, and hence, in a flash, many countries around the globe went into a complete lockdown, influencing the economy and thrashing industrial outputs. On the other hand, numerous researches were made to counteract the spread through studies in antiviral therapy, immune-based therapy, vaccination development, and natural remedies. Conclusion: Although exploration for a specific drug required for the COVID-19 treatment is under extensive research worldwide and some of them are in clinical trial now. Virtual drug library screening is one of the current techniques for repurposing accessible compounds. This review could provide beneficial information about the potential current and future treatment strategies to treat the pandemic COVID-19 infection.