Luminescent Rhodamine B doped core–shell silica nanoparticle labels for protein microarray detection

A class of hydrophilic, photostable, biocompatiable, and highly fluorescent streptavidin-functionalized silica nanoparticles were developed, in which Rhodamine B isothiocyanate molecules were covalently embedded by using Stöber method. The silica nanoparticles were ∼60 nm in size and had average fluorescence intensity 4000 times higher than dye molecules. To reduce the severe aggregation, silica nanoparticles were modified with amino groups on the surface by adding (3-aminopropyl)triethoxysilane together with methylphosphonate groups using 3-trihydroxysilylpropylmethylphosphonate, followed by functionalization with streptavidin. The resulting streptavidin-functionalized silica nanoparticles were used for the detection of by reverse-phase protein microarrays based on classical linkage system constituted by biotin-streptavidin conjugation. The calibration curve was linear over the range from 40 amol to 640 amol and the limit of detection was 10 amol, which was 8 times lower than that of streptavidin-labeled cyanine fluorescent dyes. This promising technology may be potential applied for multiplexed signaling and bioassays.

► Highly fluorescent Rhodamine B doped core–shell silica nanoparticles were developed. ► The nanoparticles were used for the detection of human IgE by protein microarrays. ► This probe has higher sensitivity than a traditional fluorescent cyanine dye.