Taras Shevchenko National University

Kyiv, Ukraine
Department of Analytical Chemistry

Analytical Application of Nanostructure Composite Silica Films

The development of sensitive elements of optical and electrochemical sensors is of great importance today.  Nanomaterials based on organic and inorganic composits i.e. silica and organic polymers are one of the most perspective for this purpose due to their unique chemical physical and mechanical properties (J. Mackerle, Nanomaterials, nanomechanics and finite elements: a bibliography (1994–2004),  Modelling Simul. Mater. Sci. Eng. 2005 13. P. 123-158 ). Optical and electrochemical sensors made from nanocrystalline materials are extremely sensitive to changes in definite chemical or physical  parameter of the environment they are designed for (P. S. Dittrich, K. Tachikawa, A. Manz ,  Micro Total Analysis System. Latest Advancement and Trends. Anal. Chem. 2006, 78, P. 3887- 3908). Such sensors are miniature, they  possess rapid response toward analyte at its trace content in the sample (ng or μg). Sol- gel synthesis is one of the most suitable method to produce composite silica nanomaterilas (Brinker C. J., Scherer G. W. Sol-gel science: the physics and chemistry of sol-gel processing. – Boston: Academic Press, 1990). Sol- gel technique  helps to: synthesize almost all kinds of materials (powders, glasses, thin films etc); synthesize composite organic- inorganic materials; coat one materials (metal, graphite, ceramic, etc) with other (silica in particular); produce homogeneous high purity 3-dimentional composites with entrapped molecules specific to definite analyte; tailoring the composition and profile of the material. 

The objective of our research is the development of new sensitive elements of electrochemical sensors and mediator free biosensors based on graphite, gold and platinum micro-electrodes modified with nanocomposite organo- mineral silica films with incapsulated  organic molecules or biomolecules.

The incorporation  of Au nanoparticles  in silica sol together with molecules of modificator following  their nanodistribution in the volume of thin film will allow to improve substantially the transport of the electron from the active site of electroactive molecule to the electrode surface. Such approach will help to enhance the amount of electroactive molecules including protein molecules on the electrode surface which results the improvement of the sensitivity of determination without additional reagents- electron mediators. The application of spin coating procedure and electrodeposition of the composite film on the electrode with small surface area will allow to obtain well-structured sensitive nano-layers with good reproductivity of the analytical signal and high signal-to-noise ratio. 

Hemoproteins such as hemoglobin, mioglobin (the mimics of peroxidase) and glucose oxidase are examined as model biological reagents for biosensor elements;  triphenylmethane- and  azo- dyes are investigated as sensitive elements for chemical sensors.

Obtained modified electrodes are subject to investigation for voltammetric determination of traces of heavy metal ions, inorganic anions, glucose, peroxide substances, dissolved oxygen, low molecular weight chlorinated organic molecules in environmental, biological objects and food.

Theoretical and practical bases of the development of mediator- free third generation electrochemical sensors  - microelectrodes modified with enzymes or organic molecules which possessed high signal-to-noise ratio is working out .

 List of related publications:

1.  S. Kounaves , O. Nadzhafova, V. Tarasov, S. Tan, Ultramicroelectrode Arrays Modified with Ionomer Entrapped Silica Film as Perspective Voltammetric Sensors for Copper, Lead and Selenium. Analytical Sciences, 2001, № 17, P. i1031- i1034.

2.  O. Yu. Nadzhafova V.V.  Gordienko, Chemical- Analytical Properties of  Films Based on Silica and Poly(vinylsulfonic) Acid, Ukr. Khim. Zhurn (Russian), 2004, №6, 70, P. 113-119

3. O. Yu. Nadzhafova, O. A. Zaporozhets, I. V. Rachinskaya, L.L. Fedorenko, N. Yusupov

4. Silica  Gel  Modified With  Lumogallion for Aluminum  Determination by Spectroscopic Methods, Talanta, 2005 Vol 67/4 pp 767-772.

5. O. Yu Nadzhafova, V. Zaitsev, M. Drozdova, A. Vaze, J. F. Rusling, Heme proteins sequestered in silica sol-gels using surfactants feature direct electron transfer and peroxidase activity, Electrochemistry Communications, 2004, 6, P. 205- 209.

6. O. Yu. Nadzhafova, M. V. Drozdova, B. Z. Bosak, Sorption of Hemoglobin onto Composite Films: Silica- Polyvinylsulfonic Acid, Visnyk of Kiev University, Khimiya,  43,  2006 P. 23- 25.

last updated 19.11.2014

anchem.knu.ua

analysis@univ.kiev.ua