Fabrication of Dual Dye-Doped Silica Nanotube as a Fluorescent Ratiometric pH Sensor

Abstract

This study described a novel fabrication of fluorescence co-encapsulating silica nanotubes (F@SNT) and the further application of the as-synthesized nanostructure as a ratiometric pH sensor in buffer solution. Silica nanotubes (SNTs) embedded anodic alumina oxide (AAO) template was fabricated by sol-gel technique, tetramethyl rhodamine (TMR-the reference dye) was incorporated directly onto silica layer via hydrophobic interaction. Subsequently, fluorescent isothiocyanate (FITC-pH sensitive dye) was encapsulated inside poly-dimethylsiloxane (PDMS) matrix and the FITC-PDMS nanocomposite was doped into the hollow structure of SNT using nano-molding lithography. On removing AAO, free-standing SNTs were obtained and were subsequently applied as a ratiometric pH sensor in phosphate buffer solution. The dual dye-doped SNTs showed excellent fluorescence and a good pH sensing performance from pH 5.2-8.0. The results were distinguishable by the emission spectra and by fluorescent visualization. High photostability, sensitivity, biocompatibility with adjustable sizes make dual dye doped-SNT a promising nanostructure for bioapplications.

Multifunctional core–shell Co–SiO2 nanowires via electrodeposition and sol–gel techniques

“…[14][15][16] In this case, a combination of sol-gel and electrodeposition techniques is used to synthesize the nanostructures. This combination appears to be a good approach to make nanodevices due to the possibilities that sol-gel technology offers to make functionalized-sensing coatings [17][18][19] and the possible use of the core to manipulate or detect the nanosensors. However, there are no reports up to now on the use of these structures as individual nanodevices.…”