Background: Influenza viruses (IVs) have become increasingly resistant to antiviral drugs that target neuraminidase and matrix protein 2 due to gene mutations that alter their drug-binding target protein regions. Consequently, almost all recent IV pandemics have exhibited resistance to commercial antiviral vaccines. To overcome this challenge, an antiviral target is needed that is effective regardless of genetic mutations.
Main body:In particular, hemagglutinin (HA), a highly conserved surface protein across many IV strains, could be an effective antiviral target as it mediates binding of IVs with host cell receptors, which is crucial for membrane fusion. HA has 6 disulfide bonds that can easily bind with the surfaces of gold nanoparticles. Herein, we fabricated porous gold nanoparticles (PoGNPs) via a surfactant-free emulsion method that exhibited strong affinity for disulfide bonds due to gold-thiol interactions, and provided extensive surface area for these interactions. A remarkable decrease in viral infectivity was demonstrated by increased cell viability results after exposing MDCK cells to various IV strains (H1N1, H3N2, and H9N2) treated with PoGNP. Most of all, the viability of MDCK cells infected with all IV strains increased to 96.8% after PoGNP treatment of the viruses compared to 33.9% cell viability with non-treated viruses. Intracellular viral RNA quantification by real-time RT-PCR also confirmed that PoGNP successfully inhibited viral membrane fusion by blocking the viral entry process through conformational deformation of HA.
Conclusion:We believe that the technique described herein can be further developed for PoGNP-utilized antiviral protection as well as metal nanoparticle-based therapy to treat viral infection. Additionally, facile detection of IAV can be achieved by developing PoGNP as a multiplatform for detection of the virus.
Surface-enhanced Raman spectroscopy (SERS) detection in microfluidics is an interesting topic because of its high sensitivity, miniaturization, and ability to perform online detection. However, the difficulties in generating SERS-based microfluidic devices with uniform signal reproducibility and high sensitivity have hindered their widespread application. In addition, the recyclability of the SERS-based microfluidic devices can contribute to their broad commercialization, but the possible contamination in the detection area and cumbersome cleaning procedures remain a challenge. In this study, we describe a repeatable SERS-based microfluidic device comprising a disposable SERS substrate and a reusable microfluidic channel. The microfluidic channel was prepared via mechanical processing, and the SERS substrate was fabricated by nanoimprint lithography and electrodeposition. The SERS substrate and microfluidic channel can be attached easily because they were assembled using screws. The SERS substrate achieved an excellent SERS enhancement factor greater than 10 8 over a large sample area, signal uniformity, and substrate-to-substrate reproducibility. This guaranteed reliable and sensitive signals in every experiment. Furthermore, the disposable SERS substrate contributed exact detection of target molecules. Finally, their practical application was demonstrated with the repeated use of the microfluidic device by detecting a specific micro-RNA, (miR-34a) at a concentration as low as 5 fM.
Well-tailored metal nanostructure arrays possessing a large number of small nanogaps have been highlighted because of their ability to enhance optical and electrical properties. In addition, it has been demonstrated that nanostructures with two or more elements present significantly enhanced and synergistic properties compared to those with a single element. However, the precise and reliable synthesis of bimetallic nanostructures possessing multiple nanogaps with high uniformity remains a major challenge. In this study, we propose the fabrication of bimetallic nanostructure patterns with numerous uncovered and external nanogaps. Silver dot arrays (SDAs) without organic capping ligands were developed via nanoimprint lithography, and several deposited Au−Ag alloy nanogranules were directly deposited on SDAs through a fast galvanic replacement reaction, without adding any additional reducing agents or capping molecules, to produce highly accessible nanogaps. These nanogaps surrounded by two types of metal elements demonstrated an excellent surface-enhanced Raman scattering (SERS) enhancement factor of up to 1.09 × 10 9 , and the highly homogeneous SDAs led to high signal uniformity (relative standard deviation < 6.5 ± 0.3%) as well as deviceto-device reproducibility. Finally, it was demonstrated that the synthesized substrates can be used as ultrasensitive and reliable SERSbased pesticide (malachite green) detection probes, down to a 10 fM concentration.
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