A large response range reflectometric urea biosensor made from silica-gel nanoparticles

Area of Science:

• Nanomaterials Science
• Biochemistry
• Analytical Chemistry

Background:

• Development of sensitive and selective biosensors is crucial for accurate analyte detection.
• Silica-gel nanospheres (SiO2NPs) offer a versatile platform for biosensor fabrication due to their tunable properties and high surface area.
• Urea detection is important in clinical diagnostics and environmental monitoring.

Purpose of the Study:

• To formulate a novel silica-gel nanosphere (SiO2NPs) composition for urea biosensor development.
• To biochemically functionalize SiO2NPs for efficient urease immobilization and pH transducer integration.
• To evaluate the performance of the developed optical urea biosensor for reflectometric urea determination.

Main Methods:

• SiO2NPs were synthesized using a modified Stober method based on sol-gel chemistry.
• Amine functionalization of SiO2NPs was performed for urease immobilization using glutaric acid cross-linker.
• A pH-sensitive dye (ETH 5294) was adsorbed onto functionalized SiO2NPs as a pH transducer for reflectometric detection.

Main Results:

• The developed urea biosensor exhibited a linear response range of 50-500 mM with a detection limit of 10 mM.
• The biosensor showed a rapid response time of 9 minutes and good reproducibility (<10% RSD).
• Validation using urine samples demonstrated excellent correlation (R2 = 0.996) with a standard non-enzymatic method.

Conclusions:

• The developed SiO2NPs-based reflectometric urea biosensor demonstrates a promising performance with an improved dynamic linear response range.
• The biosensor is selective, showing no interference from common ions (Na+, K+, Mg2+, NH4+).
• This approach offers a viable and efficient method for urea quantification in biological samples.