Nano-Enabled Antivirals for Overcoming Antibody Escaped Mutations Based SARS-CoV-2 Waves.

This review discusses receptor-binding domain (RBD) mutations related to the emergence of various SARS-CoV-2 variants, which have been highlighted as a major cause of repetitive clinical waves of COVID-19. Our perusal of the literature reveals that most variants were able to escape neutralizing antibodies developed after immunization or natural exposure, pointing to the need for a sustainable technological solution to overcome this crisis. This review, therefore, focuses on nanotechnology and the development of antiviral nanomaterials with physical antagonistic features of viral replication checkpoints as such a solution. Our detailed discussion of SARS-CoV-2 replication and pathogenesis highlights four distinct checkpoints, the S protein (ACE2 receptor coupling), the RBD motif (ACE2 receptor coupling), ACE2 coupling, and the S protein cleavage site, as targets for the development of nano-enabled solutions that, for example, prevent viral attachment and fusion with the host cell by either blocking viral RBD/spike proteins or cellular ACE2 receptors. As proof of this concept, we highlight applications of several nanomaterials, such as metal and metal oxide nanoparticles, carbon-based nanoparticles, carbon nanotubes, fullerene, carbon dots, quantum dots, polymeric nanoparticles, lipid-based, polymer-based, lipid-polymer hybrid-based, surface-modified nanoparticles that have already been employed to control viral infections. These nanoparticles were developed to inhibit receptor-mediated host-virus attachments and cell fusion, the uncoating of the virus, viral gene expression, protein synthesis, the assembly of progeny viral particles, and the release of the virion. Moreover, nanomaterials have been used as antiviral drug carriers and vaccines, and nano-enabled sensors have already been shown to enable fast, sensitive, and label-free real-time diagnosis of viral infections. Nano-biosensors could, therefore, also be useful in the remote testing and tracking of patients, while nanocarriers probed with target tissue could facilitate the targeted delivery of antiviral drugs to infected cells, tissues, organs, or systems while avoiding unwanted exposure of non-target tissues. Antiviral nanoparticles can also be applied to sanitizers, clothing, facemasks, and other personal protective equipment to minimize horizontal spread. We believe that the nanotechnology-enabled solutions described in this review will enable us to control repeated SAR-CoV-2 waves caused by antibody escape mutations.

Adhesion, proliferation and differentiation of human mesenchymal stem cell on chitosan/collagen composite scaffold.

In vitro tissue engineering requires a progenitor cell source and a porous scaffold providing three dimensional (3D) supports for growth and differentiation to attain tissue architectures. This research focused on fabrication and characterization of 3D porous scaffolds using chitosan (CS), collagen (CG) and chitosan-collagen (CS-CG) composite to investigate their influence on human mesenchymal stem cell (hMSC) adhesion, proliferation and differentiation. Material dependent variations in porous morphology and mechanical behavior of the fabricated CS, CG and CS-CG scaffold showed significant impact on hMSC adhesion, proliferation and differentiation. The maximum hMSC adhesion and proliferation was reported on CS-CG scaffold among all fabricated scaffold groups. Interconnectivity of pores structure in CS-CG scaffold was considered as preferable attribute for such enhanced growth and distribution throughout the scaffold. Besides, CS scaffold with well interconnected pores showed poor adhesion and proliferation because of inadequate adhesion motifs. In case of CG scaffold, optimum growth and distribution of hMSC occurs only at the surface because of the absence of interconnectivity in their pore structures. Likewise, osteogenic differentiation of hMSC occurs most preferably in CS-CG composite scaffold among all scaffold groups. Such enhanced hMSC proliferation and differentiation in CS-CG scaffold significantly influenced on mechanical behavior of scaffold which is essential for in vivo application of a bone tissue implant. Thus CS-CG composite scaffold holds promise to be a suitable platform for in vitro engineering of bone tissue implant.