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Title:

Study on influence of size and surface properties of silica nanobeads in performance ofoptical sensors

Authors & affiliations:

Aleksandar Szchenyi , Barbara Horvth, Sndor Kunsgi-Mt, Barna Kovcs

University of Pcs, Faculty of Natural Sciences, Institute of Chemistry, Department ofGeneral and Physical Chemistry, PCS, Hungary

Abstract: (Your abstract must use Normal style and must fit in this box. Your abstract should be nolonger than 300 words. The box will expand over 2 pages as you add text/diagrams into it.)

The silica nanoparticles (NPs) are widely used in many different applications such assubstrate for label dye, chemical nanosensors for intracellular sensing or drug delivery.They are biocompatible, easily functionalizable and they provide stable matrix for theapplications mentioned above.

In this work we present our results on the synthesis of modified surface silica NPs usedfor optical chemical sensors. The NPs have been synthesized by modified Stbermethod [1]. Influence of tetraethoxysilane (TEOS) and ORMOSIL precursorsconcentration and their ratio on the size, morphology, stability of the synthesized

particles have been studied, while all other parameters are kept constant. During thesynthesis ORMOSIL precursors with different polarity or functional group have beenused: methyltriethoxysilane (MTES), ethyltriethoxysilane, propyltriethoxysilane and insome cases n-octiltriethoxysilane, phenyltriethoxysilane, 3-aminopropyltriethoxysilaneand vinyltriehoxysilane. The resulting NPs have been characterized with TEM, SEM,DLS regarding size and shape. The thermal stability has been examined with TGA andDTA.

Size of the nanoparticles vs TEOS concetration

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Size of the nanoparticles vs MTES content (CTEOS=34 M)

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The modified Stber method has been used for synthesis of indicator doped NPs.During the synthesis well known pH sensitive fluorescein derivatives [2] were added to

the precursor solution. The pH sensing properties of the resulting NPs have beenexamined, and their sensor performance has been evaluated as a function of the size andsurface modifications of NPs.

[1]Stber, W.; Fink, A.; Bohn E.J. Colloid Interface Sci. 1968, 26, 62-69.[2]Bernhard M. Weidgans, Ph.D. thesis 2004

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