New Biocompatible Cobalt‐Containing Nanocomposite as a Complex Immunomodulator with a Synergistic Effect

Use of nanomaterials (in particular cobalt oxide nanoparticles) as adjuvants is promising because of their ultralow dimension and pronounced immunomodulatory effects. Herein, arabinogalactan‐stabilized cobalt oxide nanoparticles (AG‐CoONPs) are synthesized for the first time. Using a complex of spectral (DLS, IR, and optical spectroscopy), X‐ray, and microscopic (transmission electron microscopy) methods, their two‐phase amorphous–crystalline structure is characterized. The size of obtained AG‐CoONPs ranges between 4 and 29 nm. Using animal models (mice), a pronounced stimulating effect of the obtained AG‐CoONPs is found, with an average size of 6.5 nm, on the production of B‐lymphocytes with the absence of stimulation of lymphocytic cell apoptosis. It is found that introduction of AG‐CoONPs to experimental animals is accompanied by the retention of the volume ratio of the cortical and brain substances of the thymus (the central organ of immunopoiesis) with the increase of the number of blast cells in its cortical zone, the growth of macrophages and epithelial cells in its brain substance, and the increase of its vascular channel and connective tissue volume. The obtained data demonstrate the prospects for the design of adjuvants based on AG‐CoONPs that enhance the immune response to antigen introduction, including the stimulation of specific antibodies’ production.