Research on highly effective antiviral drugs is essential for preventing the spread of infections and reducing losses. Recently, many functional nanoparticles have been shown to possess remarkable antiviral ability, such as quantum dots, gold and silver nanoparticles, nanoclusters, carbon dots, graphene oxide, silicon materials, polymers and dendrimers. Despite their difference in antiviral mechanism and inhibition efficacy, these functional nanoparticles-based structures have unique features as potential antiviral candidates. In this topical review, we highlight the antiviral efficacy and mechanism of these nanoparticles. Specifically, we introduce various methods for analyzing the viricidal activity of functional nanoparticles and the latest advances in antiviral functional nanoparticles. Furthermore, we systematically describe the advantages and disadvantages of these functional nanoparticles in viricidal applications. Finally, we discuss the challenges and prospects of antiviral nanostructures. This topic review covers 132 papers and will enrich our knowledge about the antiviral efficacy and mechanism of various functional nanoparticles.

With the gradual usage of carbon dots (CDs) in the area of antiviral research, attempts have been stepped up to develop new antiviral CDs with high biocompatibility and antiviral effects. In this study, a kind of highly biocompatible CDs (Gly‐CDs) is synthesized from active ingredient (glycyrrhizic acid) of Chinese herbal medicine by a hydrothermal method. Using the porcine reproductive and respiratory syndrome virus (PRRSV) as a model, it is found that the Gly‐CDs inhibit PRRSV proliferation by up to 5 orders of viral titers. Detailed investigations reveal that Gly‐CDs can inhibit PRRSV invasion and replication, stimulate antiviral innate immune responses, and inhibit the accumulation of intracellular reactive oxygen species (ROS) caused by PRRSV infection. Proteomics analysis demonstrates that Gly‐CDs can stimulate cells to regulate the expression of some host restriction factors, including DDX53 and NOS3, which are directly related to PRRSV proliferation. Moreover, it is found that Gly‐CDs also remarkably suppress the propagation of other viruses, such as pseudorabies virus (PRV) and porcine epidemic diarrhea virus (PEDV), suggesting the broad antiviral activity of Gly‐CDs. The integrated results demonstrate that Gly‐CDs possess extraordinary antiviral activity with multisite inhibition mechanisms, providing a promising candidate for alternative therapy for PRRSV infection.

Development of novel antiviral reagents is of great importance for the control of virus spread. Here, AgS nanoclusters (NCs) were proved for the first time to possess highly efficient antiviral activity by using porcine epidemic diarrhea virus (PEDV) as a model of coronavirus. Analyses of virus titers showed that AgS NCs significantly suppressed the infection of PEDV by about 3 orders of magnitude at the noncytotoxic concentration at 12 h postinfection, which was further confirmed by the expression of viral proteins. Mechanism investigations indicated that AgS NCs treatment inhibits the synthesis of viral negative-strand RNA and viral budding. AgS NCs treatment was also found to positively regulate the generation of IFN-stimulating genes (ISGs) and the expression of proinflammation cytokines, which might prevent PEDV infection. This study suggest the novel underlying of AgS NCs as a promising therapeutic drug for coronavirus.

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The interaction of magnetic iron oxide nanoparticles (MNPs) with bovine serum albumin (BSA) was investigated by fluorescence (FL), ultraviolet visible (UV-vis) absorption, Raman, and circular dichroism (CD) spectroscopy. Results indicated that MNPs quench BSA FL mainly by a static quenching mechanism. The FL quenching constants KSV were obtained as 2.44x10(8), 2.41x10(8), and 2.40x10(8) L.mol(-1) at 291, 298, and 313 K, respectively. The thermodynamic parameters of enthalpy change DeltaH(theta), entropy change DeltaS(theta), and free energy change DeltaGtheta were -0.90 kJ.mol(-1), 157.38 J.mol(-1).K(-1), and -47.80 kJ.mol(-1) (298 K), respectively. The association constant (KA) and the number of binding sites (n) were 7.64x10(7) L.mol(-1) and 46.55 at higher concentration of MNPs, and 1.35x10(6) L.mol(-1) and 284.74 at lower concentration of MNPs. The analysis results suggested that the interaction was spontaneous and the electrostatic interactions played key roles in the reaction process. In addition, the Raman and CD spectra proved secondary structure alteration of BSA in the presence of MNPs.