Room temperature sol-gel fabrication and functionalization for sensor applications

Abstract

The structure and physical properties of a thin titania sol-gel layer prepared on silicon and silica surfaces were examined. Spectroscopic (FTIR, UV-VIS spectroscopy), refractive index (ellipsometry) and microscopic (light microscopy and SEM/EDS) tools were used to examine both chemical uniformity and physical uniformity of the sol-gel glass layers. The conditions for the fabrication of uniform layers were established, and room temperature dopant incorporation was examined. The absorption bands of porphyrin-containing titania sol-gel layers were characterized. By addition of a metal salt to the titania layer, it was possible to metallate the free-base porphyrin within and change the UV-VIS absorbance of the porphyrin, the basis of metal detection using porphyrins. The metalloporphyrins were detected by localized laser ablation inductive coupled mass spectroscopy (LA-ICP-MS), indicating fairly uniform distribution of metals across the titania surface.

Keywords

Sol-gel / titania / titanium dioxide / evanescent field / sensor / organic compound / spectroscopy / microscopy / surface functionalization / ablation inductive coupled mass spectroscopy

References

[1] Canning J.. Properties of specialist fibers and Bragg gratings for optical fiber sensors. Journal of Sensors, 2009, 2009, 871580.

[2] Gupta R., Chaudhury N. K.. Entrapment of biomolecules in sol-gel matrix for applications in biosensors: problems and future prospects. Biosensors Bioelectronics, 2007, 22(11): 2387-2399.

[3] Jerónimoa P. C. A., Araújo A. N., Montenegro M. C. B. S. M.. Optical sensors and biosensors based on sol-gel films. Talanta, 2007, 72(1): 13-27.

[4] Huyang G., Canning J., Åslund M. L., Stocks D., Khoury T., Crossley M. J.. Evaluation of optical fiber microcell reactor for use in remote acid sensing. Optics Letters, 2010, 35(6): 817-819.

[5] Wen J. Y., Wilkes G. L.. Organic/Inorganic hybrid network materials by the sol-gel approach. Chemistry of Materials, 1996, 8(8): 1667-1681.

[6] Canning J., Padden W., Boskovic D., Naqshbandi M., de Bruyn H., Crossley M. J.. Manipulating and controlling the evanescent field within optical waveguides using high index nanolayers. Optical Materials Express, 2011, 1(2): 192-200.

[7] Park S. J., Kang Y. C., Park J. Y., Evans E. A., Ramsier R. D., Chase G. G.. Physical characteristics of titania nanofibers synthesized by sol-gel and electrospinning techniques. Journal of Engineered Fibers and Fabrics, 2010, 5(1): 50-56.

[8] Miao Z., Xu D., Ouyang J., Guo G., Zhao X., Tang Y.. Electrochemically induced sol-gel preparation of single-crystalline TiO₂ nanowires. Nano Letters, 2002, 2(7): 717-720.

[9] Wang C. C., Ying J. Y.. Sol-gel synthesis and hydrothermal processing of anatase and rutile titania nanocrystals. Chemistry of Materials, 1999, 11(11): 3113-3120.

[10] Delmarre D., Méallet R., Bied-Charreton C., Pansu R. B.. Heavy metal ions detection in solution, in sol-gel and with grafted porphyrin monolayers. Journal of Photochemistry Photobiology A: Chemistry, 1999, 124(1–2): 23-28.

[11] Rawling T., Austin C., Hare D., Doble P. A., Zareie H. M., McDonagh A. M.. Thin films of ruthenium phthalocyanine complexes. Nano Research, 2009, 2(9): 678-687.

[12] Austin C., Hare D., Rawling T., McDonagh A. M., Doble P. J.. Quantification method for elemental bio-imaging by LA-ICP-MS using metal spiked PMMA films. Journal of Analytical Atomic Spectrometry, 2010, 25(5): 722-725.

[13] Lopez T., Sanchez E., Bosch P., Meas Y., Gomez R.. FTIR and UV-Vis (diffuse reflectance) spectroscopic characterization of TiO₂ sol-gel. Materials Chemistry and Physics, 1992, 32(2): 141-152.

[14] Lopez T., Ortiz E., Gomez R., Picquart M.. Amorphous sol-gel titania modified with heteropolyacids. Journal of Sol-Gel Science and Technology, 2006, 37(3): 189-193.

[15] Lopez T., Ortiz-Ilas E., Vinogradova E., Manjarrez J., Azamar J. A., Alvarado-Gil J. J., . Structural, optical and vibrational properties of sol-gel titania/valproic acid reservoirs. Optical Materials, 2006, 29(1): 82-87.