Silica Sol-Gel Optical Biosensors: Ultrahigh Enzyme Loading Capacity on Thin Films via Kinetic Doping

Area of Science:

• Biomaterials Science
• Nanotechnology
• Analytical Chemistry

Background:

• Biosensors offer wide applications but require efficient protein integration into sol-gel networks.
• Current predoping methods limit achievable protein concentrations in thin films.
• Developing novel doping techniques is crucial for advancing biosensor performance.

Purpose of the Study:

• To introduce and validate a new kinetic doping method for loading enzymes into silica sol-gel thin films.
• To compare the efficiency of kinetic doping with traditional methods for protein incorporation.
• To demonstrate the catalytic activity of loaded enzymes for biosensing applications.

Main Methods:

• Utilized a novel kinetic doping process to incorporate cytochrome C (CytC) and horseradish peroxidase (HRP) into silica sol-gel thin films.
• Quantified enzyme loading concentrations and compared them to initial solutions.
• Assessed the retained catalytic activity of loaded enzymes in hydrogen peroxide detection.

Main Results:

• Achieved significant concentration increases for CytC (1300×) and HRP (2600×) compared to loading solutions.
• Successfully retained the catalytic function of both enzymes after incorporation into the sol-gel matrix.
• Determined final enzyme concentrations of 11 ± 1 mM for CytC and 6.0 ± 0.4 mM for HRP.

Conclusions:

• The kinetic doping method represents a substantial improvement over previous techniques for loading enzymes into sol-gel films.
• This method enables much higher enzyme concentrations, paving the way for more sensitive and efficient biosensors.
• The retained enzymatic activity confirms the viability of this approach for practical biosensing applications.