Gold nanoparticles (GNPs) and GNP-based multifunctional nanocomposites are the subject of intensive studies and biomedical applications. This minireview summarizes our recent efforts in analytical and theranostic applications of engineered GNPs and nanocomposites by using plasmonic properties of GNPs and various optical techniques. Specifically, we consider analytical biosensing; visualization and bioimaging of bacterial, mammalian, and plant cells; photodynamic treatment of pathogenic bacteria; and photothermal therapy of xenografted tumors. In addition to recently published reports, we discuss new data on dot immunoassay diagnostics of mycobacteria, multiplexed immunoelectron microscopy analysis of Azospirillum brasilense, materno-embryonic transfer of GNPs in pregnant rats, and combined photodynamic and photothermal treatment of rat xenografted tumors with gold nanorods covered by a mesoporous silica shell doped with hematoporphyrin.

This work was undertaken to investigate the effect of antigen-conjugated gold nanoparticles on the functional activity of cells of the reticuloendothelial system. Experiments using rat and mouse peritoneal cells assessed the dynamics of the total respiratory activity of macrophages and the activity of mitochondrial dehydrogenases on exposure to colloidal gold conjugates of high- and lowmolecular-weight antigens. Both gold nanoparticles and their antigen conjugates stimulated the respiratory activity of the macrophages and the activity of macrophage mitochondrial enzymes. This stimulation may be an essential factor determining the adjuvant properties of colloidal gold, found by us in prior work.

This review summarizes known data and the results of our own investigations into the application of gold nanoparticles as an antigen (AG) carrier and as an adjuvant in immunization in the in vivo...