Simple approach for efficient encapsulation of enzyme in silica matrix with retained bioactivity.
We developed an alcohol-free sol-gel approach to encapsulate biomolecules such as horseradish peroxidase (HRP) in an electrochemically induced three-dimensional porous silica matrix by a one-step process. In this sol-gel process, the electrochemically generated hydroxyl ions at the electrode surface by applying cathodic current promote the hydrolysis of ammonium fluorosilicate to produce silica, and simultaneously the generated hydrogen bubbles play an important role in forming porous silica matrix. If HRP is mixed with ammonium fluorosilicate solution, it can be encapsulated in the forming silica matrix. Since there is no ethanol involved in the entire procedure, bioactivities of the encapsulated HRP can be effectively retained. As revealed by scanning electron microscopy (SEM) characterization, the resultant silica matrix has interconnected and network-like porous structures. Macroporous holes induced by hydrogen bubbles scattering on the relatively flat areas of porous structure can be observed. Such structure free from cracks provides effective mass transport and long-term stability. Scanning electrochemical microscope (SECM) characterization shows that the immobilized HRP molecules uniformly distribute in the silica matrix. The present HRP electrochemical biosensor exhibits a quick response (within 5 s) to H(2)O(2) in the concentration range from 0.02 to 0.20 mM (correlation coefficient of 0.9934) with a detection limit of 3 microM. The apparent Michaelis-Menten constant is 0.88 mM. The present alcohol-free sol-gel approach is effective for biomolecule encapsulation and is promising for the construction of biosensors, bioelectronics, and biofuel cells.
Yang
Si
S
Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, PR China.
Jia
Wen-Zhi
WZ
Qian
Qing-Yun
QY
Zhou
Yi-Ge
YG
Xia
Xing-Hua
XH
D002138:Calibration; D002384:Catalysis; D004563:Electrochemistry; D004566:Electrodes; D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000737:chemistry* / Q000378:metabolism*; D005459:Fluorides / Q000737:chemistry; D006046:Gold / Q000737:chemistry; D006735:Horseradish Peroxidase / Q000737:chemistry / Q000378:metabolism; D006859:Hydrogen / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D006878:Hydroxides / Q000737:chemistry; D016062:Porosity; D012824:Silicic Acid / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D014867:Water / Q000737:chemistry
D004800:Enzymes, Immobilized; D006878:Hydroxides; D014867:Water; D012824:Silicic Acid; C004832:hexafluorosilicate; D006046:Gold; D012822:Silicon Dioxide; D006859:Hydrogen; C031356:hydroxide ion; D006735:Horseradish Peroxidase; D005459:Fluorides