Variability of biological effects of silicas: Different degrees of activation of the fifth component of complement by amorphous silicas

Biocompatibility of Calcined Mesoporous Silica Particles with Cellular Bioenergetics in Murine Tissues

“…On the basis of previous studies and some of our results, there are some expected differences in composition and surface chemistry between the two materials that are prepared by calcination and solvent extraction. We believe that some of these differences such as density of surface silanols and residual surfactant may have played roles in the differences in toxicity and biological activity between the two types of mesoporous silica materials, as also reported previously for other types of silica materials (26)(27)(28)42). These differences include (1) different amounts of residual surfactants: the calcined materials have no residual surfactant while the solvent extracted ones almost always have at least trace amount of surfactant; (2) different density of surface hydroxyl (or silanols) groups: the calcined materials have less number of surface silanols compared with the corresponding solventextracted samples because higher calcination temperature leads to condensation of surface silanols into siloxanes; (3) the differences in surface silanol density can further result in a difference in the materials' ability to adsorb water on their surface: the solvent-extracted materials with more silanols are expected to adsorb more water because their better ability to form hydrogen-bonding interaction than the corresponding calcined materials that have less density of surface silanols; and (4) different average pore diameters: the calcined materials have slightly lower average pore diameter than the corresponding solvent-extracted samples, as a result of silanol condensation at higher temperature in the former.…”

Macrophage silica nanoparticle response is phenotypically dependent

“…Anionic group recognizing receptors overexpressed on M1 macrophages including Kupffer cells of the liver and within the red pulp macrophages of the spleen have also been shown in vivo to increase inflammatory M1 responses [36], and M1 phenotypes have shown to be overloaded with iron oxide particles in vivo [37]. Additionally, the terminal silanols seen within the nanoparticles investigated here induce complement mediated events which could facilitate specific uptake in M1 macrophages[38]. This may suggest that silica could induce a Th1 response as a result of nanoparticle uptake within these tissues.…”

International Union of Basic and Clinical Pharmacology. LXXXVII. Complement Peptide C5a, C4a, and C3a Receptors

“…The feces of the house dust mite Dermatophagoides farinae contain a protease, DerP1, which can generate active complement peptides from C3 and C5 (Maruo et al, 1997). Asbestos and silica can also cause the cleavage of C5 (Governa et al, 2000(Governa et al, , 2002(Governa et al, , 2005. More recently, cross-talk between the complement and the coagulation cascades has been demonstrated to result in the robust generation of C3a and C5a, through the actions of factors Xa/XIa, plasmin, and thrombin (Amara et al, 2010).…”