Near-Infrared (NIR) absorbing carbocyanine dyes have been increasingly used as they can be useful for developing bioanalytical, biomedical methods and in many other applications.  Carbocyanines are relatively easy to synthesize and can be designed to achieve particular spectroscopic properties.  For example using appropriate functional moieties absorption and fluorescence properties change when complexed to metal ions, to detect pH changes, bind to biological molecules, etc.  Fluorescence intensity of carbocyanines significantly increases by enclosing several dye molecules in silica nanoparticles.  Self quenching may become a problem for carbocyanines at high concentration in the silica nanoparticle or other confined spaces.  Large Stokes’ shift dyes can significantly decrease this problem.  This can be achieved by substituting meso position halogens in the NIR fluorescent carbocyanines with a linker containing amino moiety which also serves as a linker to covalently attach the dye molecule to the nanoparticle backbone.  This presentation discusses facile synthesis of specific carbocyanines and other fluorophores designed for synthesizing fluorescent silica nanoparticles.    To achieve this goal the best approach is to synthesize silica nanoparticles that have the fluorescent dye covalently attached to the structure of the silica nanoparticle.  This can be achieved by using modified TEOS during the synthesis.  The molar ratio of TEOS and modified TEOS will determine the fluorescent dye load in the silica nanoparticle.  Dependent on the functional groups present in the reporting dye to be used to prepare the modified TEOS and its spectral properties, the silica nanoparticle can be used for many applications such as pH sensor, metal ion sensors, latent blood stain detection, etc.  Specific application will be discussed illustrating how known dye sensors can be incorporated into silica nanoparticles.  Several advantages emerge from using silica nanoparticle protected sensors; one of them is higher dye stability.<br/> <br/>

Copolymerized fluorescent silica nanoparticles as reporters and sensors

251st National Meeting (2016)

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