Efficient SARS-CoV-2 infection antagonization by rhACE2 ectodomain multimerized onto the Avidin-Nucleic-Acid-NanoASsembly.

Nanodecoy systems based on analogues of viral cellular receptors assembled onto fluid lipid-based membranes of nano/extravescicles are potential new tools to complement classic therapeutic or preventive antiviral approaches. The need for lipid-based membranes for transmembrane receptor anchorage may pose technical challenges along industrial translation, calling for alternative geometries for receptor multimerization. Here we developed a semisynthetic self-assembling SARS-CoV-2 nanodecoy by multimerizing the biotin labelled virus cell receptor -ACE2- ectodomain onto a poly-avidin nanoparticle (NP) based on the Avidin-Nucleic-Acid-NanoASsembly-ANANAS. The ability of the assembly to prevent SARS-CoV-2 infection in human lung cells and the affinity of the ACE2:viral receptor-binding domain (RBD) interaction were measured at different ACE2:NP ratios. At ACE2:NP = 30, 90 % SARS-CoV-2 infection inhibition at ACE2 nanomolar concentration was registered on both Wuhan and Omicron variants, with ten-fold higher potency than the monomeric protein. Lower and higher ACE2 densities were less efficient suggesting that functional recognition between multi-ligand NPs and multi-receptor virus surfaces requires optimal geometrical relationships. In vivo studies in mice showed that the biodistribution and safety profiles of the nanodecoy are potentially suitable for preventing viral infection upon nasal instillation. Viral receptor multimerization using ANANAS is a convenient process which, in principle, could be rapidly adapted to counteract also other viral infections.

Semisolid Wet Sol-Gel Silica/Hydroxypropyl Methyl Cellulose Formulation for Slow Release of Serpin B3 Promotes Wound Healing In Vivo.

Foot ulcerations are a disabling complication of diabetes and no treatment is currently available based on disease mechanisms. The protein serpin B3 (SB3) was identified as a positive biomarker of successful diabetic wound healing; therefore, its exogenous administration may promote healing. The topical administration of SB3 is challenging due to its protein nature. Physical entrapment in wet sol-gel silica can stabilize the protein's conformation and permit its sustained delivery. However, irreversible syneresis and poor viscoelastic properties hamper wet sol-gel silica application as a semisolid vehicle. To overcome these limits, a sol-gel silica/hydroxypropylmethylcellulose (HPMC) hydrogel blend was developed. SB3 entrapped in 8% SiO2 wet sol-gel silica preserved its structure, was stabilized against denaturation, and was slowly released for at least three days. Blending a silica gel with an HPMC-glycerol (metolose-G) hydrogel permitted spreadability without affecting the protein's release kinetics. When administered in vivo, SB3 in silica/metolose-G-but not in solution or in metolose-G alone-accelerated wound healing in SB3 knockout and diabetic mouse models. The results confirmed that SB3 is a new pharmacological option for the treatment of chronic ulcers, especially when formulated in a slow-releasing vehicle. Silica-metolose-G represents a novel type of semisolid dosage form which could also be applied for the formulation of other bioactive proteins.