Journal of Sol-Gel Science and Technology

, Volume 59, Issue 1, pp 174–180

Effect of synthesis conditions on the microstructure of TEOS derived silica hydrogels synthesized by the alcohol-free sol–gel route

Original Paper


Silica matrices synthesized from a pre-hydrolysis step in ethanol followed by alcohol removal at low pressure distillation, and condensation in water, are suitable for encapsulation of biomolecules and microorganisms and building bioactive materials with optimized optical properties. Here we analyze the microstructure of these hydrogels from the dependence of I(q) data acquired from SAXS experiments over a wide range of silica concentration and pH employed in the condensation step. From the resulting data it is shown that there is a clear correlation between the microscopic parameters—cluster fractal dimension (D), elementary particle radius (a) and cluster gyration radius (R)—with the attenuation of visible light when the condensation step proceeds at pH < 6. At higher pHs, there is a steep dependence of the cluster density (~RD−3) with the condensation pH, and non-monotonous changes of attenuance are less than 20%, revealing the complexity of the system. These results, which were obtained for a wide pH and silica concentration range, reinforce the idea that the behavior of gels determined in a restricted interval of synthesis variables cannot be extrapolated, and comparison of gelation times is not enough for predicting their properties.


Silica hydrogels TEOS alcohol-free SAXS microstructure characterization Optical quality 

Supplementary material

10971_2011_2478_MOESM1_ESM.doc (1.6 mb)
Supplementary material 1 (DOC 1636 kb)


  1. 1.
    Brinker CJ, Scherer G (1990) Sol gel science. Academic Press, San DiegoGoogle Scholar
  2. 2.
    Gill I, Ballesteros A (1998) Encapsulation of biologicals within silicate, siloxane, and hybrid sol–gel polymers: an efficient and generic approach. J Am Chem Soc 120(34):8587–8598CrossRefGoogle Scholar
  3. 3.
    Avnir D, Brown S, Lev O, Ottolenghi M (1994) Enzymes and other proteins entrapped in sol–gel materials. Chem Mater 6(10):1605–1614CrossRefGoogle Scholar
  4. 4.
    Avnir D, Lev O, Livage J (2006) Recent bio-applications of sol-gel materials. J Mater Chem 16(11):1013–1030CrossRefGoogle Scholar
  5. 5.
    Livage J, Coradin T (2006) Living cells in oxide glasses. Rev Mineral Geochem 64(1):315–332CrossRefGoogle Scholar
  6. 6.
    Soltmann U, Böttcher H (2008) Utilization of sol-gel ceramics for the immobilization of living microorganisms. J Sol-Gel Sci Technol 342:211Google Scholar
  7. 7.
    Meunier CF, Dandoy P, Su B-L (2010) Encapsulation of cells within silica matrixes: towards a new advance in the conception of living hybrid materials. J Colloid Interface Sci 48:66–72Google Scholar
  8. 8.
    Premkumar JR, Lev O, Marks RS, Polyak B, Rosen R, Belkin S (2001) Antibody-based immobilization of bioluminescent bacterial sensor cells. Talanta 55(5):1029–1038CrossRefGoogle Scholar
  9. 9.
    Perullini M, Rivero MM, Jobbagy M, Mentaberry A, Blimes SA (2007) Plant cell proliferation inside an inorganic host. J Biotechnol 127(3):542–548CrossRefGoogle Scholar
  10. 10.
    Fiedler D, Hager U, Franke H, Soltmann U, Böttcher H (2007) Algae biocers: Astaxanthin formation in sol-gel immobilised living microalgae. J Mater Chem 17(3):261–266CrossRefGoogle Scholar
  11. 11.
    Kuncova G, Podrazky O, Ripp S, Trögl J, Sayler GS, Demnerova K, Vankova R (2004) Monitoring of the viability of cells immobilized by sol–gel process. J Sol–Gel Sci Technol 31:1–8CrossRefGoogle Scholar
  12. 12.
    Nguyen-Ngoc H, Durrieu C, Tran-Minh C (2009) Synchronous-scan fluorescence of algal cells for toxicity assessment of heavy metals and herbicides. Ecotoxicol Environ Saf 72:316–320CrossRefGoogle Scholar
  13. 13.
    Sicard C, Perullini M, Spedalieri C, Coradin T, Brayner R, Livage J, Jobbagy M, Bilmes SA (2011) CeO2 nanoparticles for the protection of photosynthetic organisms immobilized in silica gels. Chem Mater 23(6):1374–1378Google Scholar
  14. 14.
    Perullini M, Jobbágy M, Bermúdez Moretti M, Correa García S, Bilmes SA (2008) Optimizing silica encapsulation of living cells: in situ evaluation of cellular stress. Chem Mater 20:3015–3018CrossRefGoogle Scholar
  15. 15.
    Brumberger H (ed) (1993) Modern aspects of small-angle scattering.In: Proceedings of the NATO advanced study institutes, Como, ItalyGoogle Scholar
  16. 16.
    Schmidt PW, Höhr A, Neumann H-B, Kaiser H, Avnir D, Lin JS (1989) Small angle X-ray scattering study of the fractal morphology of porous silicas. J Chem Phys 90(9):5016–5023CrossRefGoogle Scholar
  17. 17.
    Vollet DR, Donatti DA, Ibãez Ruiz A, De Vicente FS (2010) Dynamical scaling in fractal structures in the aggregation of tetraethoxysilane-derived sonogels. J Appl Cryst 43(5):949–954CrossRefGoogle Scholar
  18. 18.
    Zarzycki J (1987) Fractal properties of gels. J Non-Cryst Solids 95–96(1):173–184CrossRefGoogle Scholar
  19. 19.
    Schaefer DW, Keefer KD (1984) Fractal geometry of silica condensation polymers. Phys Rev Lett 53(14):1383–1386CrossRefGoogle Scholar
  20. 20.
    Mandelbrot BB (1983) The fractal geometry of nature. Freeman, San FranciscoGoogle Scholar
  21. 21.
    Kim S, Lee K-S, Zachariah MR, Lee D (2010) Three-dimensional off-lattice Monte Carlo simulations on a direct relation between experimental process parameters and fractal dimension of colloidal aggregates. J Colloid Interface Sci 344:353–361CrossRefGoogle Scholar
  22. 22.
    Schaefer DW, Martin JE, Wiltzius P, Cannell DS (1984) Fractal geometry of colloidal aggregates. Phys Rev Lett 52(26):2371–2374CrossRefGoogle Scholar
  23. 23.
    Vollet DR, Donatti DA, Ibãez Ruiz A (2001) A SAXS study of kinetics of aggregation of TEOS-derived sonogels at different temperatures. J Non-Cryst Solids 288(1–3):81–87CrossRefGoogle Scholar
  24. 24.
    Brinker CJ, Keefer KD, Schaefer DW, Assink RA, Kay BD, Ashley CS (1984) Sol gel transition in simple silicates. J Non-Cryst Solids 63:45–59CrossRefGoogle Scholar
  25. 25.
    Strawbridge I, Craievich AF, James PF (1985) The effect of the H2O/TEOS ratio on the structure of gels derived by the acid catalysed hydrolysis of tetraethoxysilane. J Non-Cryst Solids 72:139–157CrossRefGoogle Scholar
  26. 26.
    Himmel B, Gerberb T, Bürger H (1990) WAXS- and SAXS-investigations of structure formation in alcoholic SiO2 solutions. J Non-Cryst Solids 119:1–13CrossRefGoogle Scholar
  27. 27.
    Reichenauer G (2004) Thermal aging of silica gels in water. J Non-Cryst Solids 350:189–195CrossRefGoogle Scholar
  28. 28.
    Bhatia RB, Brinker CJ, Gupta AK, Singh AK (2000) Aqueous sol-gel process for protein encapsulation. Chem Mater 12:2434–2441CrossRefGoogle Scholar
  29. 29.
    Coiffier A, Coradin T, Roux C, Bouvet O, Livage J (2001) Sol-gel encapsulation of bacteria: a comparison between alkoxide and aqueous routes. J Mater Chem 11:2039–2044CrossRefGoogle Scholar
  30. 30.
    Nassif N, Roux C, Coradin T, Rager MN, Bouvet O, Livage J (2003) A sol-gel matrix to preserve the viability of encapsulated bacteria. Mater Chem 13:203–208CrossRefGoogle Scholar
  31. 31.
    Gerberb T, Himmel B, Bürger H (1994) WAXS- and SAXS-investigations of structure formation of gels from sodium water glass. J Non-Cryst Solids 175:160–168CrossRefGoogle Scholar
  32. 32.
    Perullini M, Amoura M, Roux C, Coradin T, Livage J, Japas ML, Jobbagy M, Bilmes SA (2011) Improving silica matrices for encapsulation of Escherichia coli using osmoprotectors. J Mater Chem 21:4546–4552CrossRefGoogle Scholar
  33. 33.
    Ferrer ML, Del Monte F, Levy D (2002) A novel and simple alcohol-free sol-gel route for encapsulation of labile proteins. Chem Mater 14:3619–3621CrossRefGoogle Scholar
  34. 34.
    Ferrer ML, Yuste L, Rojo F, Del Monte F (2003) Biocompatible sol-gel route for encapsulation of living bacteria in organically modified silica matrixes. Chem Mater 15:3614–3618CrossRefGoogle Scholar
  35. 35.
    Ferrer ML, García-Carbajal ZY, Yuste L, Rojo F, Del Monte F (2006) Bacteria viability in sol–gel materials revisited: cryo-SEM as a suitable tool to study the structural integrity of encapsulated bacteria. Chem Mater 18:1458–1463CrossRefGoogle Scholar
  36. 36.
    Cavalcanti LP, Torriani IL, Plivelic TS, Oliveira CLP, Kellermann G, Neuenschwander R (2004) Rev Sci Instrum 75:4541CrossRefGoogle Scholar
  37. 37.
  38. 38.
    Vinogradova E, Moreno A, Lara VH, Bosch P (2003) Multi-fractal imaging and structural investigation of silica hydrogels and aerogels. Silicon Chem 2:247–254CrossRefGoogle Scholar
  39. 39.
    Vinogradova E, Moreno A, Lara VH, Bosch P (2003) Multi-fractal imaging and structural investigation of silica hydrogels and aerogels. Silicon Chem 2:247–254CrossRefGoogle Scholar
  40. 40.
    Avnir D, Biham O, Lidar D, Malcai O (1998) Is the geometry of nature fractal? Science 279:39–40CrossRefGoogle Scholar
  41. 41.
    Sorensen CM, Wang GM (1999) Size distribution effect on the power law regime of the structure factor of fractal aggregates. Phys Rev E 60(6):7143–7148CrossRefGoogle Scholar
  42. 42.
    Knoblich B, Gerber T (2001) Aggregation in SiO2 sols from sodium silicate solutions. J Non Cryst Solids 283:109–113CrossRefGoogle Scholar
  43. 43.
    Boukari H, Harris MT (1997) Small-angle X-ray scattering study of the formation of colloidal silica particles from alkoxides: primary particles or not? J Colloid Interface Sci 194:311–318CrossRefGoogle Scholar
  44. 44.
    Knoblich B, Gerber T (2001) The arrangement of fractal clusters dependent on the pH value in silica gels from sodium silicate solutions. J Non Cryst Solids 296:81–87CrossRefGoogle Scholar
  45. 45.
    Beelen TPM, Wijnen PWJG, Vonk CG, Van Santen RA (1989) Catal Lett 3:209CrossRefGoogle Scholar
  46. 46.
    Bohren CG, Huffmann DF (1983) Absorption and scattering of light by small particles. Wiley, New YorkGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2011

Authors and Affiliations

  1. 1.INQUIMAE-DQIAQF, Facultad de Ciencias Exactas y NaturalesUniversidad de Buenos Aires, Ciudad UniversitariaBuenos AiresArgentina
  2. 2.ECyTUniversidad Nacional de San MartínBuenos AiresArgentina
  3. 3.Institute of Physics Gleb WataghinState University of CampinasCampinasBrazil

Personalised recommendations