The interaction between silver nanoparticles and viruses is attracting great interest due to the potential antiviral activity of these particles, and is the subject of much research effort in the treatment of infectious diseases. In this work, we demonstrate that silver nanoparticles undergo a size-dependent interaction with herpes simplex virus types 1 and 2 and with human parainfluenza virus type 3. We show that production of silver nanoparticles from different fungi is feasible, and their antiviral activity is dependent on the production system used. Silver nanoparticles are capable of reducing viral infectivity, probably by blocking interaction of the virus with the cell, which might depend on the size and zeta potential of the silver nanoparticles. Smaller-sized nanoparticles were able to inhibit the infectivity of the viruses analyzed.

Nanotechnology is a new and developing branch that has revolutionized the world by its applications in various fields including medicine and agriculture. In nanotechnology, nanoparticles play an important role in diagnostics, drug delivery, and therapy. The synthesis of nanoparticles by fungi is a novel, cost-effective and eco-friendly approach. Among fungi, Fusarium spp. play an important role in the synthesis of nanoparticles and can be considered as a nanofactory for the fabrication of nanoparticles. The synthesis of silver nanoparticles (AgNPs) from Fusarium, its mechanism and applications are discussed in this review. The synthesis of nanoparticles from Fusarium is the biogenic and green approach. Fusaria are found to be a versatile biological system with the ability to synthesize nanoparticles extracellularly. Different species of Fusaria have the potential to synthesise nanoparticles. Among these, F. oxysporum has demonstrated a high potential for the synthesis of AgNPs. It is hypothesised that NADH-dependent nitrate reductase enzyme secreted by F. oxysporum is responsible for the reduction of aqueous silver ions into AgNPs. The toxicity of nanoparticles depends upon the shape, size, surface charge, and the concentration used. The nanoparticles synthesised by different species of Fusaria can be used in medicine and agriculture.

Quorum sensing (QS), the communication signaling network, regulates biofilm formation and several virulence factors in Pseudomonas aeruginosa PAO1, a nosocomial opportunistic pathogen. QS is considered to be a challenging target for compounds antagonistic to virulent factors. Biologically synthesized silver nanoparticles (AgNPs) are reported as anti-QS and anti-biofilm drugs against bacterial infections. The present study reports on the synthesis and characterization of Piper betle (Pb) mediated AgNPs (Pb-AgNPs). The anti-QS activity of Pb-AgNPs against Chromobacterium violaceum and the potential effect of Pb-AgNPs on QS-regulated phenotypes in PAO1 were studied. FTIR analysis exhibited that Pb-AgNPs had been capped by phytochemical constituents of Pb. Eugenol is one of the active phenolic phytochemicals in Pb leaves, therefore molecular docking of eugenol-conjugated AgNPs on QS regulator proteins (LasR, LasI and MvfR) was performed. Eugenol-conjugated AgNPs showed considerable binding interactions with QS-associated proteins. These results provide novel insights into the development of phytochemically conjugated nanoparticles as promising anti-infective candidates.