A Biofriendly Silica Gel for in Situ Protein Entrapment: Biopolymer-Assisted Formation and Its Kinetic Mechanism.

In an attempt to develop a biofriendly sol−gel route for the rapid formation of biofunctional silica gels, a biopolymer with good biocompatibility was used to assist the gelation of glycol-modified tetraethoxysilane (GMT) in aqueous system without the addition of any organic solvents. It was found that the biopolymer used could act as an effective accelerator for the sol−gel transition of GMT and an increase of its amount could shorten greatly the gelation time. For such a gelation reaction, its apparent activation energy was determined to be 64.9 kJ/mol according to the Arrhenius equation. In particular, the kinetic mechanism for the formation of the silica gel was investigated by using dynamic rheological data and a scaling fractal model. It was revealed that the biopolymer used could change the sol−gel transition mechanism from reaction-limited kinetics to diffusion-limited kinetics. Circular dichroism analyses confirmed the suitability of using the resultant silica gel for the in situ protein encapsulation. [ABSTRACT FROM AUTHOR]