Amino-functionalized CDs were also tested for the treatment of human norovirus. In this study, CDs were functionalized with 2,2′-(ethylenedioxy)bis(ethylamine) (EDA) and 3-ethoxypropylamine (EPA) via amide bond formation.77 These NMs exerted a good viral blockage. In particular, EPA-functionalized CDs were able to inhibit 100% of viral infection at concentration of 2 μg/mL, while in the case of CDs prepared with the other amines, 80% of inhibition was reported. These effects have been associated with the higher positive charge of CD-EDA compared to CD-EPA. Another surface group used for viral targeting is boronic acid (BA), which can bind glycosylated surfaces forming boronic esters. This strategy was successfully adopted to treat HIV where the boronic groups, linked to different nanoparticles (e.g., silica nanoparticles and nanodiamonds) can target gp120 receptors on the viral envelope inhibiting the infection.78 Another recent study proposed the use of CD functionalized with phenylboronic acid for prevention of HIV infection.74 The functional materials showed good inhibition properties compared to nonfunctionalized CDs by preventing the binding to the target cell in vitro. Overall, the use of CDs for stopping host cell viral entrance has shown good results in vitro. However, there is a lack of proofs in vivo limiting their applications to surface disinfection or masks. In addition, most of the in vitro studies foresee first the contact of the CDs with the viral particles and then their incubation with host cells. Deeper investigations should be performed adding the NMs at other time points (for instance in infected cells) to understand if the antiviral activity is maintained.