The plasma-assisted functionalization process favors surprising effects in the biological field. In this study, the deposition of amino groups (3-aminopropyltriethoxysilane APTES precursor) and carboxyl groups (methyl methacrylate MMA precursor) on titanium substrate by mean of cold atmospheric plasma technology has been evaluated.
Surface chemical functionalization using Plasma Jet takes place thanks to the flushing of a carrier gas inside a bubbler: this contains low quantities of a volatile liquid precursor (monomer with medium-high vapor pressure). The vapors of the chemical precursor are transported by the carrier gas into the plasma; here radical polymerization reactions take place (plasma polymerization) which favor the formation of a functional coating on the surfaces.
The particular Dielectric Barrier Discharge (DBD plasma) configuration of the Nadir Plasma Jet allows not only to deposit chemical functionalities on the surface of a material using a plasma generation system and a deposition system integrated in a single device, but also a radiofrequency design which allows to preserve the functional chemical groups of the precursor conveyed in plasma. In this way, chemically active nano-coatings, are easily obtained, stable both to UV sterilization processes and to aqueous environments.
The peculiarity of the Plasma Jet to deposit functionalized nano-coatings has allowed to carry out in vitro studies of osteoblasts (MC3T3-E1 mouse cells), demonstrating that the functionalization by Plasma Jet of amino groups –NH2 (from plasma polymerization of APTES) favors the osteogenic differentiation, while the deposition of coatings functionalized with carboxyl/ester groups –COOH/R (from MMA plasma polymerization) stimulates the adhesion of osteoblasts on the surface of interest. Furthermore, the amino groups deposited on the surface help osteoblasts to release osteocalcin, thus establishing an interesting correlation between early cell morphology and subsequent stages of differentiation.
*F. Mussano et al. “In vitro characterization of two different atmospheric plasma jet chemical functionalizations of titanium surfaces” Applied Surface Science 409 (2017) 314-324