Immobilization of green fluorescence and lipase proteins in porous silica nanoparticles to improve their bioluminescence and catalytic activity

Introduction: The GFP and lipase proteins have been immobilized in the aminated silica nanoparticles through encapsulation and ionic interaction. The synthesis of porous silica nanoparticles and amination of silica surface were simultaneously performed in a water-in-oil emulsion. Methods: The materials have been characterized by zeta potential measurements, electron transmission microscopy, and fluorescence spectroscopy. The reaction mixture was analyzed by gas chromatography equipped with a mass selective detector. Results: The aminated-silica nanoparticles with a positive zeta potential interact with GFP having a negative zeta potential via ionic force. GFP immobilized by the aminated silica nanoparticles greatly enhances (ca. 2 times) the bioluminescence intensity compared to free GFP. The lipase/aminated-silica nanoparticles catalyzed the transesterification reaction of 1-hexanol and ethyl acetate. This catalyst shows better activity than free lipase and remains catalytic activity over at least eight catalytic cycles in an organic solvent. Conclusion: The result shows that the immobilization of proteins in the aminated-silica nanoparticles improves their bioluminescence and catalytic activity.