Obtaining Dye-Modified Silica Nanoparticles and Their Characterization as Immunoanalytical Markers

Colored silica particles with encapsulated bromophenol blue dye were synthesized and characterized as potential markers for lateral flow immunoanalytical systems. Initial concentrations of monomers (aminopropyltriethoxysilane and tetraetoxysilan) and time of their polymerization were varied, and the influence of these parameters on size and optical properties of the obtained particles was studied. It was found that increase of the aminopropyltriethoxysilane concentration in the range from 6.2 to 62 µM accorded to increase of the average particles’ diameter from 2 to 5 µm. On another hand, prolonged incubation with tetraetoxysilan during 2–24 h caused lower average diameters of the obtained product—near 230 nm—on contrast with short incubation times (< 1 h). The competitive advantages of the given particles as immunoanalytical markers consist in intense coloration in blue part of spectrum (absorption peak near 600 nm) and large size, which provide higher optical signal from single labeled immune complex formed during the analysis in comparison with traditional high-dispersed nanosized labels. The obtained dye-modified particles were conjugated with antibodies for further bioanalytical application. Aggregation stability and stored antigen-binding properties for the synthesized conjugates were shown.