Surface Chemistry Engineering of Layered Double Hydroxides for Antigen Adsorption in Zika Virus Nanovaccine Development

Layered double hydroxides (LDH) are promising nanocarriers for vaccine delivery due to their biocompatibility and tunable surface properties. This study evaluated LDH and surface-functionalized derivatives containing amino (LDH–NH2) and carboxyl (LDH–COOH) groups as delivery platforms for a recombinant Zika virus (ZIKV) antigen (rpZDIII). The nanoparticles were synthesized by coprecipitation/hydrothermal treatment and afterward functionalized via silanization and succinylation. Their physicochemical characterization included hydrodynamic size, ζ potential, point of zero charge, and amine concentration, along with Fourier-transform infrared spectroscopy and thermogravimetric analyses. Protein adsorption was evaluated using bovine serum albumin, α-chymotrypsin, and the recombinant antigen rpZDIII. Cytotoxicity and immunogenicity were evaluated in HEK-293T cells and BALB/c mice, respectively. The functionalization affected the protein adsorption capacity and its retention after washing. The adsorption of rpZDIII was best described by the Freundlich model, with LDH–NH2 having the highest antigen adsorption and retention. All three formulations maintained high cell viability at lower nanoparticle concentrations (12.5–50 μg/mL). Immunization studies demonstrated that all nanoparticle formulations elicited strong antibody responses against rpZDIII; however, only unmodified LDH-induced antibodies were able to bind the full-length recombinant ZIKV envelope protein. These findings demonstrate that the surface chemistry of LDH influences the adsorption of antigens, their retention, and their further immune recognition, highlighting the importance of preserving antigen accessibility during the design of LDH-based nanovaccines.