Fluorescent silica nanoparticles have the potential to offer a safer, brighter, and more stable marker for biological materials, such as proteins and antibodies, than organic dyes currently used as bio-labels. We describe the preparation of fluorescent silica nanoparticles via a new, efficient one-step procedure and the quantification of their brightness and stability. We use a branched poly(ethylene imine), PEI, which has a multifunctional purpose: to condense the silica and form nanoparticles, to be labeled and affix the labeled group into the silica matrix, and to be reacted post-functionally to attach surface functionality to the particles. Amine-reactive fluorophores including fluorescein isothiocyanate (FITC), carboxyfluorescein succinimidyl ester (CF), and tetramethylrhodamine isothiocyanate (TRITC) were attached to the PEI, which retained its activity for silica polymerization. The amount of fluorophore was optimized and studied via steady-state and time-resolved fluorescence spectroscopy. The silica matrix serves to protect and stabilize the incorporated fluorophores, allowing them to be used in a wide range of environments for long periods of time. This method can be extended to a variety of fluorescent molecules, spanning the colors (emission wavelengths) currently used in the medical field for imaging, and this may offer a new, bright system for standard detections. In addition, we show that a portion of the amines is present on the particle surface and is available for further labeling.  As a demonstration, gold nanoparticles were attached to the surface to form well-defined heterobifunctional nanostructures. <br/>

Convenient bio-inspired approach to the synthesis of multifunctional, stable fluorescent silica nanoparticles

251st National Meeting (2016)

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