Info

4. Notes

1. Suggested ratios are shown in Table 1. However, other ratios, as well as other precursors, can be used. It should be taken into account that the higher the TMOS proportion, the faster the subsequent polymerization process.

2. Hydrolysis time depends on each case and should be optimized.

3. At basic pH, the condensation is favored. The appropriate basic pH will depend on the enzyme performance (not too high to inactivate it). The buffer composition is not particularly important. However, (NH4)2SO4 should not be used to avoid precipitation.

4. The 50:50 ratio is suggested. However, other ratios can be used.

5. Controls are usually performed without enzyme but using the basic buffer.

6. Sometimes the condensation occurs at faster rates. As a result the sol-gel starts to form before its deposition on the support surface. It is then convenient to carry out this step at 4°C (cold chamber).

7. The volume of mixture deposited on the support surface depends on the particular interest, but it has never to spread out from the surface of interest.

8. Our experience is based on the sol-gel immobilization on screen-printed graphite electrodes. However, the sol-gel immobilization on other supports is also possible.

9. Drying time depends on each case and should be optimized. Desiccators with or without vacuum can also be used. This step can be also performed at room temperature. However, 4°C are preferred to maintain the enzyme activity.

10. Buffer can also be used to rinse the support.

11. Although in Subheading 2.2., item 3 PVA-SbQ with degree of polymerization: 1700 is suggested, other degrees of polymerization can be used.

12. The 50:50 ratio is suggested. However, other ratios can be used. We have observed satisfactory results with the 70:30 ratio.

13. If foam or bubbles are observed after vortex mixing, briefly centrifuge using a benchtop centrifuge.

14. Our experience is based on the immobilization on screen-printed graphite electrodes, at the bottom of Maxisorp microtiter wells and on Ultrabind modified polyethersulfone affinity membranes. However, the PVA-SbQ immobilization on other supports is also possible.

15. Exposure to ultraviolet light for 2 min at 4°C is also possible. However, exposure to neon light for 3 h at 4°C is more convenient, as it provides slower polymerization and higher reproducibility.

References

1. Edmiston, P. L., Wambolt, C. L., Smith, M. K., and Saavedra, S. S. (1994) Spectroscopic characterization of albumin and myoglobin entrapped in bulk sol-gel glasses. J. Colloid Interface Sci. 163, 395-406.

2. Dave, B., Soyez, H., Miller, J. M., Dunn, B., Valentine, J. S., and Zink, J. I. (1995) Synthesis of protein-doped sol-gel SiO2 thin films: evidence for rotational mobility of encapsulated cytochrome c. Chem. Mater. 7, 1431-1434.

3. Gottfried, D. S., Kagan, A., Hoffman, B. M., and Friedman, J. M. (1999) Impeded rotation of a protein in a sol-gel matrix. J. Phys. Chem. B 103, 2803-2807.

4. Hartnett, A. M., Ingersoll, C. M., Baker, G. A., and Bright, F. V. (1999) Kinetics and thermodynamics of free flavin and the flavin-based redox active site within glucose oxidase dissolved in solution or sequestered within a sol-gel-derived glass. Anal. Chem. 71, 1215-1224.

5. Hench, L. L. and West, J. K. (1990) The sol-gel process. Chem. Rev. 90, 33-79.

6. Audebert, P., Demaille, C., and Sanchez, C. (1993) Electrochemical probing of the activity of glucose oxidase embedded in sol-gel matrices. Chem. Mater. 5, 91-913.

7. Pankratov, I. and Lev, O. (1995) Sol-gel derived renewable-surface biosensors. J. Electroanal. Chem. 393, 35-41.

8. Gun, J. and Lev, O. (1996) Sol-gel derived, ferrocenyl-modified silicate-graphite composite electrode: wiring of glucose oxidase. Anal. Chim. Acta 336, 95-106.

9. Park, T. M., Iwuoha, E. I., Smyth, M. R., and MacCraith, B. D. (1996) Sol-gel based amperometric glucose biosensor incorporating an osmium redox polymer as mediator. Anal. Commun. 33, 271-273.

10. Li, J., Tan, S. N., and Ge, H. (1996) Silica sol-gel immobilized amperometric biosensor for hydrogen peroxide. Anal. Chim. Acta 335, 137-145.

11. Park, T. M., Iwuhoa, E. I., and Smyth, M. R. (1997) Development of a sol-gel enzyme inhibition-based amperometric biosensor for cyanide. Electroanalysis 9(14), 1120-1123.

12. Wang, B., Zhang, J., and Dong, S. (2000) Silica sol-gel composite film as an encapsulation matrix for the construction of an amperometric tyrosinase-based biosensor. Biosens. Bioelectron. 15, 397-402.

13. Noguer, T., Balasoiu, A.-M., Avramescu, A., and Marty, J.-L. (2001) Development of a disposable biosensor for the detection of metam-sodium and its metabolite MITC. Anal. Lett. 34(4), 513-528.

14. Marty, J.-L. and Noguer, T. (1993) Bi-enzyme amperometric sensor for the detection of dithiocarbamate fungicides. Analysis 21, 231-233.

15. Noguer, T. and Marty, J.-L. (1997) High sensitive bienzymic sensor for the detection of dithiocarbamate fungicides. Anal. Chim. Acta 347, 63-70.

16. Noguer, T. and Marty, J.-L. (1995) An amperometric bi-enzyme electrode for acetaldehyde detection. Enzyme Microb. Technol. 17(5), 453-456.

17. Noguer, T. and Marty, J.-L. (1997) Reagentless sensors for acetaldehyde. Anal. Lett. 30(6), 1069-1080.

18. Avramescu, A., Noguer, T., Avramescu, M., and Marty, J.-L. (2002) Screen-printed biosensors for the control of wine quality based on lactate and acetalde-hyde determination. Anal. Chim. Acta 458, 203-213.

19. Andreescu, S., Noguer, T., Magearu, V., and Marty, J.-L. (2002) Screen-printed electrode based on AChE for the detection of pesticides in presence of organic solvents. Talanta 57, 169-176.

20. Carturan, G., Campostrini, R., Diré, S., Scardi, V., and De Alteriis, E. (1989) Inorganic gels for immobilization of biocatalysts: inclusion of invertase-active whole cells of yeast (Saccharomyces cerevisiae) into thin layers of SiO2 gel deposited on glass sheets. J. Mol. Catal. 57(1), L13-L16.

21. Inama, L., Diré, S., Carturan, G., and Cavazza, A. (1993) Entrapment of viable microorganisms by SiO2 sol-gel layers on glass surfaces: Trapping, catalytic performance and immobilization durability of Saccharomyces cerevisiae. J. Biotechnol. 30(2), 197-210.

22. Avnir, D., Braun, S., Lev, O., and Ottolenghi, M. (1994) Enzymes and other proteins entrapped in sol-gel materials. Chem. Mater. 6, 1605-1614.

23. Armon, R., Dosoretz, C., Starosvetsky, J., Orshansky, F., and Saadi, I. (1996) Solgel applications in environmental biotechnology. J. Biotechnol. 51(3), 279-285.

24. Roux, C., Livage, J., Farhati, K., and Monjour, L. (1997) Antibody-antigen reaction in porous sol-gel matrices. J. Sol-gelSci. Technol. 7, 135-143.

25. Gill, I. S. and Ballesteros, A. (2000) Bioencapsulation within synthetic polymers (Part 1): sol-gel encapsulated biologicals. Trends Biotechnol. 18, 282-296.

26. Noguer, T., Tencaliec, A., Calas-Blanchard, C., Avramescu, A., and Marty, J.-L. (2002) Interference-free biosensor based on screen-printing technology and solgel immobilization for determination of acetaldehyde in wine. J. AOACInt. 85(6), 1383-1389.

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